[Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Jau-Yang Chen]

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Dear Eric,

Thanks. We are more than happy that our GR-601W USB GPS receiver meets your
requirement. It's surely useful and helpful to your Bufferbloat project, NTP
project and GPSD project.

If the GPS receiver fixes the position, it could keep position-fix easily
even entering obstructed environment with its tracking engine. On the
contrary, it might be harder to fix the position from cold start with its
acquisition engine under the same obstructed environment. There is built-in
battery inside GR-601W to support the hot start and warm start. Anyway, we
fulfill the advantage of u-blox6 chipset to provide the excellent
performance.

Thanks for your introduction of Mr. Jim Thompson at Netgate as our retailer
partner in USA. It will be great and much appreciated if we could have a
channel to sell this winning product in Amazon. To thank you and Dave's good
idea and great support, GR-601W also has a nickname Macx-1.

We plan to put an article as attached on our website for advertisement.
Could you please review and comment? It will be helpful to promote Macx-1
USB GPS receiver if you could also put it in the website of your
SIG/project.

Thanks in advance and best regards,

JY


-----Original Message-----
From: Eric S. Raymond [mailto:esr@thyrsus.com]
Sent: Tuesday, May 08, 2012 10:50 AM
To: veronica
Cc: thumbgps-devel@lists.bufferbloat.net
Subject: GR-601W success

Gary sent me one of the three GR-601W samples, and I now have had time to
evaluate its performance over several days.

Please tell your product team that I am *extremely* pleased with this
device.  Not only is it is delivering good 1PPS with exactly the jitter we
predicted in the design study, it functions excellently indoors; even though
I have had it on a desk five feet from a window with a poor skyview blocked
by large trees, it does not seem to have lost satellite lock even once since
it was powered up.

I like everything about this device.  The performance, the simplicity, the
small form factor - it couldn't be better for my project's needs if I had
designed it myself. :-)  Your people did a terrific job on this and deserve
congratulations.

My next step is going to be to ensure that you have a retail partner in the
U.S. You may already have been approached by Jim Thompson at netgate; I'm
also trying to find the right person to get Amazon to carry the product.

If there is any other way in which I can assist a successful launch of the
product, please feel free to ask.  One possibility: if you have product
documentation in English other that the one data sheet I have seen, I would
be happy to review and improve it for you.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

As war and government prove, insanity is the most contagious of
diseases.	-- Edward Abbey


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Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[tz]

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They need to disable the dead reckoning feature or at least insure pps
doesn't go out if there is a problem with the fix.  For maps/nav, keeping
the stream intact for a few seconds is good, but not if you need precision.

This does not affect the hotstart memory, only what it does if it loses
enough signal so the fix is lost.
On May 9, 2012 2:43 AM, "Jau-Yang Chen" <cjy@navisys.com.tw> wrote:

> Dear Eric,
>
> Thanks. We are more than happy that our GR-601W USB GPS receiver meets your
> requirement. It's surely useful and helpful to your Bufferbloat project,
> NTP
> project and GPSD project.
>
> If the GPS receiver fixes the position, it could keep position-fix easily
> even entering obstructed environment with its tracking engine. On the
> contrary, it might be harder to fix the position from cold start with its
> acquisition engine under the same obstructed environment. There is built-in
> battery inside GR-601W to support the hot start and warm start. Anyway, we
> fulfill the advantage of u-blox6 chipset to provide the excellent
> performance.
>
> Thanks for your introduction of Mr. Jim Thompson at Netgate as our retailer
> partner in USA. It will be great and much appreciated if we could have a
> channel to sell this winning product in Amazon. To thank you and Dave's
> good
> idea and great support, GR-601W also has a nickname Macx-1.
>
> We plan to put an article as attached on our website for advertisement.
> Could you please review and comment? It will be helpful to promote Macx-1
> USB GPS receiver if you could also put it in the website of your
> SIG/project.
>
> Thanks in advance and best regards,
>
> JY
>
>
> -----Original Message-----
> From: Eric S. Raymond [mailto:esr@thyrsus.com]
> Sent: Tuesday, May 08, 2012 10:50 AM
> To: veronica
> Cc: thumbgps-devel@lists.bufferbloat.net
> Subject: GR-601W success
>
> Gary sent me one of the three GR-601W samples, and I now have had time to
> evaluate its performance over several days.
>
> Please tell your product team that I am *extremely* pleased with this
> device.  Not only is it is delivering good 1PPS with exactly the jitter we
> predicted in the design study, it functions excellently indoors; even
> though
> I have had it on a desk five feet from a window with a poor skyview blocked
> by large trees, it does not seem to have lost satellite lock even once
> since
> it was powered up.
>
> I like everything about this device.  The performance, the simplicity, the
> small form factor - it couldn't be better for my project's needs if I had
> designed it myself. :-)  Your people did a terrific job on this and deserve
> congratulations.
>
> My next step is going to be to ensure that you have a retail partner in the
> U.S. You may already have been approached by Jim Thompson at netgate; I'm
> also trying to find the right person to get Amazon to carry the product.
>
> If there is any other way in which I can assist a successful launch of the
> product, please feel free to ask.  One possibility: if you have product
> documentation in English other that the one data sheet I have seen, I would
> be happy to review and improve it for you.
> --
>                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>
> As war and government prove, insanity is the most contagious of
> diseases.       -- Edward Abbey
>
>
> _______________________________________________
> Thumbgps-devel mailing list
> Thumbgps-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>
>

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Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Taht]

What would be the change in cost and delay in manufacturing to switch to
using a supercap, rather than battery?


-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Dave Taht <dave.taht@gmail.com>:
> What would be the change in cost and delay in manufacturing to switch to
> using a supercap, rather than battery?

Why would a supercap be better?
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Taht]

On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> Dave Taht <dave.taht@gmail.com>:
>> What would be the change in cost and delay in manufacturing to switch to
>> using a supercap, rather than battery?
>
> Why would a supercap be better?

Effective lifetime of... forever. no need for replacement. insanely
fast recharge. smaller (probably). What's not to like?

I am not in a huge hurry to get into manufacturing, and I merely
wanted to cost out what what it would do to the bom, any changes to
the PCB, and get an estimate for the time it would take to do. I think
it will bump the unit cost up slightly,
but what price, forever?

> --
>                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>



-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Dave Taht <dave.taht@gmail.com>:
> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> > Dave Taht <dave.taht@gmail.com>:
> >> What would be the change in cost and delay in manufacturing to switch to
> >> using a supercap, rather than battery?
> >
> > Why would a supercap be better?
> 
> Effective lifetime of... forever. no need for replacement. insanely
> fast recharge. smaller (probably). What's not to like?

Good points.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[tz]

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For a given size (and circuit board footprint) a supercap will have much
less capacity and it has an exponential voltage decay curve, so it might
have plenty of charge but not at a voltage that will hold the data.  This
usually means hours, not days of backup.

A good rechargeable lithium will last several years, maybe longer as there
will be no charge/discharge, maintains voltage until it is nearly
exhausted, and can hold the data for days or weeks.

On Wed, May 9, 2012 at 12:55 PM, Dave Taht <dave.taht@gmail.com> wrote:

> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> > Dave Taht <dave.taht@gmail.com>:
> >> What would be the change in cost and delay in manufacturing to switch to
> >> using a supercap, rather than battery?
> >
> > Why would a supercap be better?
>
> Effective lifetime of... forever. no need for replacement. insanely
> fast recharge. smaller (probably). What's not to like?
>
> I am not in a huge hurry to get into manufacturing, and I merely
> wanted to cost out what what it would do to the bom, any changes to
> the PCB, and get an estimate for the time it would take to do. I think
> it will bump the unit cost up slightly,
> but what price, forever?
>
> > --
> >                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>
>
>
> --
> Dave Täht
> SKYPE: davetaht
> US Tel: 1-239-829-5608
> http://www.bufferbloat.net
> _______________________________________________
> Thumbgps-devel mailing list
> Thumbgps-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>

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Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Ron Frazier (NTP)]

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Hi all,

(I'm copying this only to the thumb-gps list and to TZ, the most recent 
commenter, as I don't know all the parties in the header of TZ's 
message.  You guys can forward it to whomever else may need to see it.)

Speaking strictly as a potential user of the thumb-gps device and 
amateur interested party, I would rather see a supercap, if feasible.  I 
hate the idea of devices having batteries that I have to worry about 
failing in 5-10 years.  I've had the cmos batteries fail in a few 
computers, sometimes preventing them from booting.  It can get really 
ugly trying to revive them  A good high efficiency dc-dc converter chip 
should allow you to drain all but the last bit of energy from the cap 
while maintaining whatever working voltage you need.  I cannot speak to 
size issues, as I have never designed a circuit board with one.  The 
GlobalSat BU-353 that I have has a supercap, I believe.  Exact backup 
time is not stated, but I believe it's a few days.

Sincerely,

Ron

On 5/9/2012 1:12 PM, tz wrote:
> For a given size (and circuit board footprint) a supercap will have 
> much less capacity and it has an exponential voltage decay curve, so 
> it might have plenty of charge but not at a voltage that will hold the 
> data.  This usually means hours, not days of backup.
>
> A good rechargeable lithium will last several years, maybe longer as 
> there will be no charge/discharge, maintains voltage until it is 
> nearly exhausted, and can hold the data for days or weeks.
>
> On Wed, May 9, 2012 at 12:55 PM, Dave Taht <dave.taht@gmail.com 
> <mailto:dave.taht@gmail.com>> wrote:
>
>     On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com
>     <mailto:esr@thyrsus.com>> wrote:
>     > Dave Taht <dave.taht@gmail.com <mailto:dave.taht@gmail.com>>:
>     >> What would be the change in cost and delay in manufacturing to
>     switch to
>     >> using a supercap, rather than battery?
>     >
>     > Why would a supercap be better?
>
>     Effective lifetime of... forever. no need for replacement. insanely
>     fast recharge. smaller (probably). What's not to like?
>
>     I am not in a huge hurry to get into manufacturing, and I merely
>     wanted to cost out what what it would do to the bom, any changes to
>     the PCB, and get an estimate for the time it would take to do. I think
>     it will bump the unit cost up slightly,
>     but what price, forever?
>
>     > --
>     > <a href="http://www.catb.org/~esr/
>     <http://www.catb.org/%7Eesr/>">Eric S. Raymond</a>
>
>
>
>     --
>     Dave Täht
>     SKYPE: davetaht
>     US Tel: 1-239-829-5608 <tel:1-239-829-5608>
>     http://www.bufferbloat.net
>     _______________________________________________
>     Thumbgps-devel mailing list
>     Thumbgps-devel@lists.bufferbloat.net
>     <mailto:Thumbgps-devel@lists.bufferbloat.net>
>     https://lists.bufferbloat.net/listinfo/thumbgps-devel
>
>
>
> _______________________________________________
> Thumbgps-devel mailing list
> Thumbgps-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>    

-- 

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT techstarship.com


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Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[tz]

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It doesn't work that way.  Microampere DC-DC converters?  That isn't a
swap, it is a redesign, if microamp converters are possible - the base
losses are high so you won't hit a high efficiency.  You get high
efficiencies when dealing with lots of amps.  For it to last overnight you
would need a very large (physically) cap.

There would be no booting problem.  It would merely lose the real-time
clock and/or location backup so would take a bit longer starting.

The battery (or cap) only kicks in when the power goes away and is only
needed to make the startup faster, e.g. cycling power on the computer or
router.  USB should be constantly providing 5V 99.9% of the time.

I could argue that if surviving only a short power disconnect is ok, then a
supercap might be better, but then it is probably a large engineering
change since the caps and batteries usually have vastly different
footprints.

Good batteries can last decades - even Supercaps have a finite lifetime.
It is a matter of cost, both in redesign, size, and reliability.  But do
you want to add $5-$10 to the cost of the unit to make a cheap ($30-$50)
GPS last over a decade?  Buy a second, seal it hermetically, and put it in
your freezer.

If you want to add a few thousand in NRE costs, there are a lot of other
things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.  Allow
for a detachable or external antenna (which can be run to the window).
Find a more optimal chipset.  Maybe a coin-cell port so the battery can be
replaceable.  But the point was to be as cheap as possible so in this case
it is adding one wire.

You can always break yours open and if you can find a supercap with the
specs (Sparkfun has a 3.3v available, but don't put more than 3.3v on it),
you can swap the part.

On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP) <
timekeepingntplist@techstarship.com> wrote:

> **
> Hi all,
>
> (I'm copying this only to the thumb-gps list and to TZ, the most recent
> commenter, as I don't know all the parties in the header of TZ's message.
> You guys can forward it to whomever else may need to see it.)
>
> Speaking strictly as a potential user of the thumb-gps device and amateur
> interested party, I would rather see a supercap, if feasible.  I hate the
> idea of devices having batteries that I have to worry about failing in 5-10
> years.  I've had the cmos batteries fail in a few computers, sometimes
> preventing them from booting.  It can get really ugly trying to revive
> them  A good high efficiency dc-dc converter chip should allow you to drain
> all but the last bit of energy from the cap while maintaining whatever
> working voltage you need.  I cannot speak to size issues, as I have never
> designed a circuit board with one.  The GlobalSat BU-353 that I have has a
> supercap, I believe.  Exact backup time is not stated, but I believe it's a
> few days.
>
> Sincerely,
>
> Ron
>
>
> On 5/9/2012 1:12 PM, tz wrote:
>
> For a given size (and circuit board footprint) a supercap will have much
> less capacity and it has an exponential voltage decay curve, so it might
> have plenty of charge but not at a voltage that will hold the data.  This
> usually means hours, not days of backup.
>
> A good rechargeable lithium will last several years, maybe longer as there
> will be no charge/discharge, maintains voltage until it is nearly
> exhausted, and can hold the data for days or weeks.
>
> On Wed, May 9, 2012 at 12:55 PM, Dave Taht <dave.taht@gmail.com> wrote:
>
>> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
>> > Dave Taht <dave.taht@gmail.com>:
>> >> What would be the change in cost and delay in manufacturing to switch
>> to
>> >> using a supercap, rather than battery?
>> >
>> > Why would a supercap be better?
>>
>>  Effective lifetime of... forever. no need for replacement. insanely
>> fast recharge. smaller (probably). What's not to like?
>>
>> I am not in a huge hurry to get into manufacturing, and I merely
>> wanted to cost out what what it would do to the bom, any changes to
>> the PCB, and get an estimate for the time it would take to do. I think
>> it will bump the unit cost up slightly,
>> but what price, forever?
>>
>> > --
>> >                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>>
>>
>>
>>  --
>> Dave Täht
>> SKYPE: davetaht
>> US Tel: 1-239-829-5608
>> http://www.bufferbloat.net
>>  _______________________________________________
>> Thumbgps-devel mailing list
>> Thumbgps-devel@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>>
>
>
> _______________________________________________
> Thumbgps-devel mailing listThumbgps-devel@lists.bufferbloat.nethttps://lists.bufferbloat.net/listinfo/thumbgps-devel
>
>
> --
>
> (To whom it may concern.  My email address has changed.  Replying to former
> messages prior to 03/31/12 with my personal address will go to the wrong
> address.  Please send all personal correspondence to the new address.)
>
> (PS - If you email me and don't get a quick response, don't be concerned.
> I get about 300 emails per day from alternate energy mailing lists and
> such.  I don't always see new messages very quickly.  If you need a
> reply and have not heard from me in 1 - 2 weeks, send your message again.)
>
> Ron Frazier
> timekeepingdude AT techstarship.com
>
>

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Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Taht]

jeeze guys, all I asked for was an estimate as to the change to the BOM.
Could be a Macx-2, might not be worthwhile at all.

My concern was that there are 6+ short power flickers a day - forcing
a reboot - in places like Nicaragua. These events are *interesting*
from a network analysis perspective, as flickers like this cause
massive network disturbances.

I don't care about battery life longer than about 30 seconds, although
a case could be made for 24 hours. Just wanted the analysis of what it
would really take, given how little power this thing sucks...

and I hate ANYTHING that needs a user-replaceable component, 5 years
after manufacture. So I'd prefer the actual analysis based on power
draw, etc, before
making any decisions.


On Wed, May 9, 2012 at 11:21 AM, tz <thomas@mich.com> wrote:
> It doesn't work that way.  Microampere DC-DC converters?  That isn't a swap,
> it is a redesign, if microamp converters are possible - the base losses are
> high so you won't hit a high efficiency.  You get high efficiencies when
> dealing with lots of amps.  For it to last overnight you would need a very
> large (physically) cap.
>
> There would be no booting problem.  It would merely lose the real-time clock
> and/or location backup so would take a bit longer starting.
>
> The battery (or cap) only kicks in when the power goes away and is only
> needed to make the startup faster, e.g. cycling power on the computer or
> router.  USB should be constantly providing 5V 99.9% of the time.
>
> I could argue that if surviving only a short power disconnect is ok, then a
> supercap might be better, but then it is probably a large engineering change
> since the caps and batteries usually have vastly different footprints.
>
> Good batteries can last decades - even Supercaps have a finite lifetime.  It
> is a matter of cost, both in redesign, size, and reliability.  But do you
> want to add $5-$10 to the cost of the unit to make a cheap ($30-$50) GPS
> last over a decade?  Buy a second, seal it hermetically, and put it in your
> freezer.
>
> If you want to add a few thousand in NRE costs, there are a lot of other
> things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.  Allow for
> a detachable or external antenna (which can be run to the window).  Find a
> more optimal chipset.  Maybe a coin-cell port so the battery can be
> replaceable.  But the point was to be as cheap as possible so in this case
> it is adding one wire.
>
> You can always break yours open and if you can find a supercap with the
> specs (Sparkfun has a 3.3v available, but don't put more than 3.3v on it),
> you can swap the part.
>
>
> On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP)
> <timekeepingntplist@techstarship.com> wrote:
>>
>> Hi all,
>>
>> (I'm copying this only to the thumb-gps list and to TZ, the most recent
>> commenter, as I don't know all the parties in the header of TZ's message.
>> You guys can forward it to whomever else may need to see it.)
>>
>> Speaking strictly as a potential user of the thumb-gps device and amateur
>> interested party, I would rather see a supercap, if feasible.  I hate the
>> idea of devices having batteries that I have to worry about failing in 5-10
>> years.  I've had the cmos batteries fail in a few computers, sometimes
>> preventing them from booting.  It can get really ugly trying to revive them
>> A good high efficiency dc-dc converter chip should allow you to drain all
>> but the last bit of energy from the cap while maintaining whatever working
>> voltage you need.  I cannot speak to size issues, as I have never designed a
>> circuit board with one.  The GlobalSat BU-353 that I have has a supercap, I
>> believe.  Exact backup time is not stated, but I believe it's a few days.
>>
>> Sincerely,
>>
>> Ron
>>
>>
>> On 5/9/2012 1:12 PM, tz wrote:
>>
>> For a given size (and circuit board footprint) a supercap will have much
>> less capacity and it has an exponential voltage decay curve, so it might
>> have plenty of charge but not at a voltage that will hold the data.  This
>> usually means hours, not days of backup.
>>
>> A good rechargeable lithium will last several years, maybe longer as there
>> will be no charge/discharge, maintains voltage until it is nearly exhausted,
>> and can hold the data for days or weeks.
>>
>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht <dave.taht@gmail.com> wrote:
>>>
>>> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
>>> > Dave Taht <dave.taht@gmail.com>:
>>> >> What would be the change in cost and delay in manufacturing to switch
>>> >> to
>>> >> using a supercap, rather than battery?
>>> >
>>> > Why would a supercap be better?
>>>
>>> Effective lifetime of... forever. no need for replacement. insanely
>>> fast recharge. smaller (probably). What's not to like?
>>>
>>> I am not in a huge hurry to get into manufacturing, and I merely
>>> wanted to cost out what what it would do to the bom, any changes to
>>> the PCB, and get an estimate for the time it would take to do. I think
>>> it will bump the unit cost up slightly,
>>> but what price, forever?
>>>
>>> > --
>>> >                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>>>
>>>
>>>
>>> --
>>> Dave Täht
>>> SKYPE: davetaht
>>> US Tel: 1-239-829-5608
>>> http://www.bufferbloat.net
>>> _______________________________________________
>>> Thumbgps-devel mailing list
>>> Thumbgps-devel@lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>>
>>
>>
>> _______________________________________________
>> Thumbgps-devel mailing list
>> Thumbgps-devel@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>>
>>
>>
>> --
>>
>> (To whom it may concern.  My email address has changed.  Replying to
>> former
>> messages prior to 03/31/12 with my personal address will go to the wrong
>> address.  Please send all personal correspondence to the new address.)
>>
>> (PS - If you email me and don't get a quick response, don't be concerned.
>> I get about 300 emails per day from alternate energy mailing lists and
>> such.  I don't always see new messages very quickly.  If you need a
>> reply and have not heard from me in 1 - 2 weeks, send your message again.)
>>
>> Ron Frazier
>> timekeepingdude AT techstarship.com
>
>
>
> _______________________________________________
> Thumbgps-devel mailing list
> Thumbgps-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>



-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Ron Frazier (NTP)]

Hi guys,

I do see the point TZ was making about the problems of increasing the 
design and production costs.  However, if the supercap turned out to be 
potentially feasible, I have some Circuit Cellar magazines and such that 
I could rummage through for info on micro power conversion components.  
I know they exist.  I have no idea about specs and efficiency.  How much 
amperage and at what voltage is the unit expected to draw if 
disconnected from the USB power source?  Is it expected to continue 
tracking?  I assume this will change if an external antenna is 
attached.  How long should it be maintained?

 From a user perspective, I'd recommend the following features, if you 
have a viable choice:

* Hi sensitivity internal antenna / chipset that can be used indoors in 
a residential type structure.
* External antenna port in case you're in a steel building or basement 
or something with no signal.  Use commonly available, generic, possibly 
powered, antennas.
* GPS status led.  (My BU-353 slowly flashes when it has a fix, shows 
steady with power but no fix.)  The led should be synchronized to the pps.
* Supercap preferably, or battery which is easily user replaceable and a 
common part number, such as CR2032 for example.  That battery may be too 
big, but you want something readily available.
* If a battery is involved, a small flashing led to indicate a weak 
battery alert, kind of like what is on a smoke alarm.
* My BU-353 has a magnetic base.  Something like that might be useful 
for positioning the antenna.
* May or may not be relevant, but, would 5 - 10 Hz position sensing 
improve accuracy and stability for your purposes?
* You may wish to expose the pps signal on a screw terminal or connector 
in case you want to attach other instrumentation to that signal.

Here's a possible alternative to providing an external antenna port, and 
all the hassles of piping RF around.  With my BU-353, the "puck" device 
contains both the electronics and the antenna.  The only cord coming 
from it is the USB cable.  So, it might be preferable to have a sealed 
weather proof unit, and just use extension cords for USB rather than 
extending the RF section.  I know you can easily extend USB 10 feet or 
so.  I think you can go much further with powered hubs and such.  Just a 
thought.

Here's a wild idea, maybe not practical, but, you could attach a solar 
cell to the external antenna and / or the thumb-gps case.  This could 
feed power back to the GPS board and prolong the life of the battery or 
slow the drain of the supercap while powering the antenna if the antenna 
is in the sun.  You could even draw some energy from ambient indoor 
lighting.  I have a solar powered "atomic" watch from Casio that does 
this.  It never needs a battery, never needs charging, and never needs 
setting.  Very handy.  I also have two "atomic" wall clocks that do the 
same thing.  I think they use a rechargeable battery instead of a supercap.

Here's another idea, which may or may not have already been discussed.  
Do you want to have an on board RTC, which can keep outputting valid 
time for a while, if the satellites are not available due to weather, 
jamming, interference, etc.?

Sincerely,

Ron



On 5/9/2012 2:35 PM, Dave Taht wrote:
> jeeze guys, all I asked for was an estimate as to the change to the BOM.
> Could be a Macx-2, might not be worthwhile at all.
>
> My concern was that there are 6+ short power flickers a day - forcing
> a reboot - in places like Nicaragua. These events are *interesting*
> from a network analysis perspective, as flickers like this cause
> massive network disturbances.
>
> I don't care about battery life longer than about 30 seconds, although
> a case could be made for 24 hours. Just wanted the analysis of what it
> would really take, given how little power this thing sucks...
>
> and I hate ANYTHING that needs a user-replaceable component, 5 years
> after manufacture. So I'd prefer the actual analysis based on power
> draw, etc, before
> making any decisions.
>
>
> On Wed, May 9, 2012 at 11:21 AM, tz<thomas@mich.com>  wrote:
>    
>> It doesn't work that way.  Microampere DC-DC converters?  That isn't a swap,
>> it is a redesign, if microamp converters are possible - the base losses are
>> high so you won't hit a high efficiency.  You get high efficiencies when
>> dealing with lots of amps.  For it to last overnight you would need a very
>> large (physically) cap.
>>
>> There would be no booting problem.  It would merely lose the real-time clock
>> and/or location backup so would take a bit longer starting.
>>
>> The battery (or cap) only kicks in when the power goes away and is only
>> needed to make the startup faster, e.g. cycling power on the computer or
>> router.  USB should be constantly providing 5V 99.9% of the time.
>>
>> I could argue that if surviving only a short power disconnect is ok, then a
>> supercap might be better, but then it is probably a large engineering change
>> since the caps and batteries usually have vastly different footprints.
>>
>> Good batteries can last decades - even Supercaps have a finite lifetime.  It
>> is a matter of cost, both in redesign, size, and reliability.  But do you
>> want to add $5-$10 to the cost of the unit to make a cheap ($30-$50) GPS
>> last over a decade?  Buy a second, seal it hermetically, and put it in your
>> freezer.
>>
>> If you want to add a few thousand in NRE costs, there are a lot of other
>> things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.  Allow for
>> a detachable or external antenna (which can be run to the window).  Find a
>> more optimal chipset.  Maybe a coin-cell port so the battery can be
>> replaceable.  But the point was to be as cheap as possible so in this case
>> it is adding one wire.
>>
>> You can always break yours open and if you can find a supercap with the
>> specs (Sparkfun has a 3.3v available, but don't put more than 3.3v on it),
>> you can swap the part.
>>
>>
>> On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP)
>> <timekeepingntplist@techstarship.com>  wrote:
>>      
>>> Hi all,
>>>
>>> (I'm copying this only to the thumb-gps list and to TZ, the most recent
>>> commenter, as I don't know all the parties in the header of TZ's message.
>>> You guys can forward it to whomever else may need to see it.)
>>>
>>> Speaking strictly as a potential user of the thumb-gps device and amateur
>>> interested party, I would rather see a supercap, if feasible.  I hate the
>>> idea of devices having batteries that I have to worry about failing in 5-10
>>> years.  I've had the cmos batteries fail in a few computers, sometimes
>>> preventing them from booting.  It can get really ugly trying to revive them
>>> A good high efficiency dc-dc converter chip should allow you to drain all
>>> but the last bit of energy from the cap while maintaining whatever working
>>> voltage you need.  I cannot speak to size issues, as I have never designed a
>>> circuit board with one.  The GlobalSat BU-353 that I have has a supercap, I
>>> believe.  Exact backup time is not stated, but I believe it's a few days.
>>>
>>> Sincerely,
>>>
>>> Ron
>>>
>>>
>>> On 5/9/2012 1:12 PM, tz wrote:
>>>
>>> For a given size (and circuit board footprint) a supercap will have much
>>> less capacity and it has an exponential voltage decay curve, so it might
>>> have plenty of charge but not at a voltage that will hold the data.  This
>>> usually means hours, not days of backup.
>>>
>>> A good rechargeable lithium will last several years, maybe longer as there
>>> will be no charge/discharge, maintains voltage until it is nearly exhausted,
>>> and can hold the data for days or weeks.
>>>
>>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht<dave.taht@gmail.com>  wrote:
>>>        
>>>> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond<esr@thyrsus.com>  wrote:
>>>>          
>>>>> Dave Taht<dave.taht@gmail.com>:
>>>>>            
>>>>>> What would be the change in cost and delay in manufacturing to switch
>>>>>> to
>>>>>> using a supercap, rather than battery?
>>>>>>              
>>>>> Why would a supercap be better?
>>>>>            
>>>> Effective lifetime of... forever. no need for replacement. insanely
>>>> fast recharge. smaller (probably). What's not to like?
>>>>
>>>> I am not in a huge hurry to get into manufacturing, and I merely
>>>> wanted to cost out what what it would do to the bom, any changes to
>>>> the PCB, and get an estimate for the time it would take to do. I think
>>>> it will bump the unit cost up slightly,
>>>> but what price, forever?
>>>>
>>>>          
>>>>> --
>>>>>                 <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>>>>>            
>>>>
>>>>
>>>> --
>>>> Dave Täht
>>>> SKYPE: davetaht
>>>> US Tel: 1-239-829-5608
>>>> http://www.bufferbloat.net
>>>>          


-- 

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT techstarship.com

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Taht]

A lot of that stuff I'd want to reserve for the Macx-2. Can I keep our
request of navisys limited to merely the supercap and silkscreen?

On Wed, May 9, 2012 at 1:41 PM, Ron Frazier (NTP)
<timekeepingntplist@techstarship.com> wrote:
> Hi guys,
>
> I do see the point TZ was making about the problems of increasing the design
> and production costs.  However, if the supercap turned out to be potentially
> feasible, I have some Circuit Cellar magazines and such that I could rummage
> through for info on micro power conversion components.  I know they exist.
>  I have no idea about specs and efficiency.  How much amperage and at what
> voltage is the unit expected to draw if disconnected from the USB power
> source?  Is it expected to continue tracking?  I assume this will change if
> an external antenna is attached.  How long should it be maintained?
>
> From a user perspective, I'd recommend the following features, if you have a
> viable choice:
>
> * Hi sensitivity internal antenna / chipset that can be used indoors in a
> residential type structure.
> * External antenna port in case you're in a steel building or basement or
> something with no signal.  Use commonly available, generic, possibly
> powered, antennas.
> * GPS status led.  (My BU-353 slowly flashes when it has a fix, shows steady
> with power but no fix.)  The led should be synchronized to the pps.
> * Supercap preferably, or battery which is easily user replaceable and a
> common part number, such as CR2032 for example.  That battery may be too
> big, but you want something readily available.
> * If a battery is involved, a small flashing led to indicate a weak battery
> alert, kind of like what is on a smoke alarm.
> * My BU-353 has a magnetic base.  Something like that might be useful for
> positioning the antenna.
> * May or may not be relevant, but, would 5 - 10 Hz position sensing improve
> accuracy and stability for your purposes?
> * You may wish to expose the pps signal on a screw terminal or connector in
> case you want to attach other instrumentation to that signal.
>
> Here's a possible alternative to providing an external antenna port, and all
> the hassles of piping RF around.  With my BU-353, the "puck" device contains
> both the electronics and the antenna.  The only cord coming from it is the
> USB cable.  So, it might be preferable to have a sealed weather proof unit,
> and just use extension cords for USB rather than extending the RF section.
>  I know you can easily extend USB 10 feet or so.  I think you can go much
> further with powered hubs and such.  Just a thought.
>
> Here's a wild idea, maybe not practical, but, you could attach a solar cell
> to the external antenna and / or the thumb-gps case.  This could feed power
> back to the GPS board and prolong the life of the battery or slow the drain
> of the supercap while powering the antenna if the antenna is in the sun.
>  You could even draw some energy from ambient indoor lighting.  I have a
> solar powered "atomic" watch from Casio that does this.  It never needs a
> battery, never needs charging, and never needs setting.  Very handy.  I also
> have two "atomic" wall clocks that do the same thing.  I think they use a
> rechargeable battery instead of a supercap.
>
> Here's another idea, which may or may not have already been discussed.  Do
> you want to have an on board RTC, which can keep outputting valid time for a
> while, if the satellites are not available due to weather, jamming,
> interference, etc.?
>
> Sincerely,
>
> Ron
>
>
>
>
> On 5/9/2012 2:35 PM, Dave Taht wrote:
>>
>> jeeze guys, all I asked for was an estimate as to the change to the BOM.
>> Could be a Macx-2, might not be worthwhile at all.
>>
>> My concern was that there are 6+ short power flickers a day - forcing
>> a reboot - in places like Nicaragua. These events are *interesting*
>> from a network analysis perspective, as flickers like this cause
>> massive network disturbances.
>>
>> I don't care about battery life longer than about 30 seconds, although
>> a case could be made for 24 hours. Just wanted the analysis of what it
>> would really take, given how little power this thing sucks...
>>
>> and I hate ANYTHING that needs a user-replaceable component, 5 years
>> after manufacture. So I'd prefer the actual analysis based on power
>> draw, etc, before
>> making any decisions.
>>
>>
>> On Wed, May 9, 2012 at 11:21 AM, tz<thomas@mich.com>  wrote:
>>
>>>
>>> It doesn't work that way.  Microampere DC-DC converters?  That isn't a
>>> swap,
>>> it is a redesign, if microamp converters are possible - the base losses
>>> are
>>> high so you won't hit a high efficiency.  You get high efficiencies when
>>> dealing with lots of amps.  For it to last overnight you would need a
>>> very
>>> large (physically) cap.
>>>
>>> There would be no booting problem.  It would merely lose the real-time
>>> clock
>>> and/or location backup so would take a bit longer starting.
>>>
>>> The battery (or cap) only kicks in when the power goes away and is only
>>> needed to make the startup faster, e.g. cycling power on the computer or
>>> router.  USB should be constantly providing 5V 99.9% of the time.
>>>
>>> I could argue that if surviving only a short power disconnect is ok, then
>>> a
>>> supercap might be better, but then it is probably a large engineering
>>> change
>>> since the caps and batteries usually have vastly different footprints.
>>>
>>> Good batteries can last decades - even Supercaps have a finite lifetime.
>>>  It
>>> is a matter of cost, both in redesign, size, and reliability.  But do you
>>> want to add $5-$10 to the cost of the unit to make a cheap ($30-$50) GPS
>>> last over a decade?  Buy a second, seal it hermetically, and put it in
>>> your
>>> freezer.
>>>
>>> If you want to add a few thousand in NRE costs, there are a lot of other
>>> things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.  Allow
>>> for
>>> a detachable or external antenna (which can be run to the window).  Find
>>> a
>>> more optimal chipset.  Maybe a coin-cell port so the battery can be
>>> replaceable.  But the point was to be as cheap as possible so in this
>>> case
>>> it is adding one wire.
>>>
>>> You can always break yours open and if you can find a supercap with the
>>> specs (Sparkfun has a 3.3v available, but don't put more than 3.3v on
>>> it),
>>> you can swap the part.
>>>
>>>
>>> On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP)
>>> <timekeepingntplist@techstarship.com>  wrote:
>>>
>>>>
>>>> Hi all,
>>>>
>>>> (I'm copying this only to the thumb-gps list and to TZ, the most recent
>>>> commenter, as I don't know all the parties in the header of TZ's
>>>> message.
>>>> You guys can forward it to whomever else may need to see it.)
>>>>
>>>> Speaking strictly as a potential user of the thumb-gps device and
>>>> amateur
>>>> interested party, I would rather see a supercap, if feasible.  I hate
>>>> the
>>>> idea of devices having batteries that I have to worry about failing in
>>>> 5-10
>>>> years.  I've had the cmos batteries fail in a few computers, sometimes
>>>> preventing them from booting.  It can get really ugly trying to revive
>>>> them
>>>> A good high efficiency dc-dc converter chip should allow you to drain
>>>> all
>>>> but the last bit of energy from the cap while maintaining whatever
>>>> working
>>>> voltage you need.  I cannot speak to size issues, as I have never
>>>> designed a
>>>> circuit board with one.  The GlobalSat BU-353 that I have has a
>>>> supercap, I
>>>> believe.  Exact backup time is not stated, but I believe it's a few
>>>> days.
>>>>
>>>> Sincerely,
>>>>
>>>> Ron
>>>>
>>>>
>>>> On 5/9/2012 1:12 PM, tz wrote:
>>>>
>>>> For a given size (and circuit board footprint) a supercap will have much
>>>> less capacity and it has an exponential voltage decay curve, so it might
>>>> have plenty of charge but not at a voltage that will hold the data.
>>>>  This
>>>> usually means hours, not days of backup.
>>>>
>>>> A good rechargeable lithium will last several years, maybe longer as
>>>> there
>>>> will be no charge/discharge, maintains voltage until it is nearly
>>>> exhausted,
>>>> and can hold the data for days or weeks.
>>>>
>>>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht<dave.taht@gmail.com>  wrote:
>>>>
>>>>>
>>>>> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond<esr@thyrsus.com>
>>>>>  wrote:
>>>>>
>>>>>>
>>>>>> Dave Taht<dave.taht@gmail.com>:
>>>>>>
>>>>>>>
>>>>>>> What would be the change in cost and delay in manufacturing to switch
>>>>>>> to
>>>>>>> using a supercap, rather than battery?
>>>>>>>
>>>>>>
>>>>>> Why would a supercap be better?
>>>>>>
>>>>>
>>>>> Effective lifetime of... forever. no need for replacement. insanely
>>>>> fast recharge. smaller (probably). What's not to like?
>>>>>
>>>>> I am not in a huge hurry to get into manufacturing, and I merely
>>>>> wanted to cost out what what it would do to the bom, any changes to
>>>>> the PCB, and get an estimate for the time it would take to do. I think
>>>>> it will bump the unit cost up slightly,
>>>>> but what price, forever?
>>>>>
>>>>>
>>>>>>
>>>>>> --
>>>>>>                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Dave Täht
>>>>> SKYPE: davetaht
>>>>> US Tel: 1-239-829-5608
>>>>> http://www.bufferbloat.net
>>>>>
>
>
>
> --
>
> (To whom it may concern.  My email address has changed.  Replying to former
> messages prior to 03/31/12 with my personal address will go to the wrong
> address.  Please send all personal correspondence to the new address.)
>
> (PS - If you email me and don't get a quick response, don't be concerned.
> I get about 300 emails per day from alternate energy mailing lists and
> such.  I don't always see new messages very quickly.  If you need a
> reply and have not heard from me in 1 - 2 weeks, send your message again.)
>
> Ron Frazier
> timekeepingdude AT techstarship.com
>



-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Ron Frazier (NTP)]

I'm just an interested third party.  You guys are running the show.  Use 
the ideas as you see fit.  Just give me some credit if you end up using 
my ideas.

Sincerely,

Ron


On 5/9/2012 4:46 PM, Dave Taht wrote:
> A lot of that stuff I'd want to reserve for the Macx-2. Can I keep our
> request of navisys limited to merely the supercap and silkscreen?
>
> On Wed, May 9, 2012 at 1:41 PM, Ron Frazier (NTP)
> <timekeepingntplist@techstarship.com>  wrote:
>    
>> Hi guys,
>>
>> I do see the point TZ was making about the problems of increasing the design
>> and production costs.  However, if the supercap turned out to be potentially
>> feasible, I have some Circuit Cellar magazines and such that I could rummage
>> through for info on micro power conversion components.  I know they exist.
>>   I have no idea about specs and efficiency.  How much amperage and at what
>> voltage is the unit expected to draw if disconnected from the USB power
>> source?  Is it expected to continue tracking?  I assume this will change if
>> an external antenna is attached.  How long should it be maintained?
>>
>>  From a user perspective, I'd recommend the following features, if you have a
>> viable choice:
>>
>> * Hi sensitivity internal antenna / chipset that can be used indoors in a
>> residential type structure.
>> * External antenna port in case you're in a steel building or basement or
>> something with no signal.  Use commonly available, generic, possibly
>> powered, antennas.
>> * GPS status led.  (My BU-353 slowly flashes when it has a fix, shows steady
>> with power but no fix.)  The led should be synchronized to the pps.
>> * Supercap preferably, or battery which is easily user replaceable and a
>> common part number, such as CR2032 for example.  That battery may be too
>> big, but you want something readily available.
>> * If a battery is involved, a small flashing led to indicate a weak battery
>> alert, kind of like what is on a smoke alarm.
>> * My BU-353 has a magnetic base.  Something like that might be useful for
>> positioning the antenna.
>> * May or may not be relevant, but, would 5 - 10 Hz position sensing improve
>> accuracy and stability for your purposes?
>> * You may wish to expose the pps signal on a screw terminal or connector in
>> case you want to attach other instrumentation to that signal.
>>
>> Here's a possible alternative to providing an external antenna port, and all
>> the hassles of piping RF around.  With my BU-353, the "puck" device contains
>> both the electronics and the antenna.  The only cord coming from it is the
>> USB cable.  So, it might be preferable to have a sealed weather proof unit,
>> and just use extension cords for USB rather than extending the RF section.
>>   I know you can easily extend USB 10 feet or so.  I think you can go much
>> further with powered hubs and such.  Just a thought.
>>
>> Here's a wild idea, maybe not practical, but, you could attach a solar cell
>> to the external antenna and / or the thumb-gps case.  This could feed power
>> back to the GPS board and prolong the life of the battery or slow the drain
>> of the supercap while powering the antenna if the antenna is in the sun.
>>   You could even draw some energy from ambient indoor lighting.  I have a
>> solar powered "atomic" watch from Casio that does this.  It never needs a
>> battery, never needs charging, and never needs setting.  Very handy.  I also
>> have two "atomic" wall clocks that do the same thing.  I think they use a
>> rechargeable battery instead of a supercap.
>>
>> Here's another idea, which may or may not have already been discussed.  Do
>> you want to have an on board RTC, which can keep outputting valid time for a
>> while, if the satellites are not available due to weather, jamming,
>> interference, etc.?
>>
>> Sincerely,
>>
>> Ron
>>
>>
>>
>>
>> On 5/9/2012 2:35 PM, Dave Taht wrote:
>>      
>>> jeeze guys, all I asked for was an estimate as to the change to the BOM.
>>> Could be a Macx-2, might not be worthwhile at all.
>>>
>>> My concern was that there are 6+ short power flickers a day - forcing
>>> a reboot - in places like Nicaragua. These events are *interesting*
>>> from a network analysis perspective, as flickers like this cause
>>> massive network disturbances.
>>>
>>> I don't care about battery life longer than about 30 seconds, although
>>> a case could be made for 24 hours. Just wanted the analysis of what it
>>> would really take, given how little power this thing sucks...
>>>
>>> and I hate ANYTHING that needs a user-replaceable component, 5 years
>>> after manufacture. So I'd prefer the actual analysis based on power
>>> draw, etc, before
>>> making any decisions.
>>>
>>>
>>> On Wed, May 9, 2012 at 11:21 AM, tz<thomas@mich.com>    wrote:
>>>
>>>        
>>>> It doesn't work that way.  Microampere DC-DC converters?  That isn't a
>>>> swap,
>>>> it is a redesign, if microamp converters are possible - the base losses
>>>> are
>>>> high so you won't hit a high efficiency.  You get high efficiencies when
>>>> dealing with lots of amps.  For it to last overnight you would need a
>>>> very
>>>> large (physically) cap.
>>>>
>>>> There would be no booting problem.  It would merely lose the real-time
>>>> clock
>>>> and/or location backup so would take a bit longer starting.
>>>>
>>>> The battery (or cap) only kicks in when the power goes away and is only
>>>> needed to make the startup faster, e.g. cycling power on the computer or
>>>> router.  USB should be constantly providing 5V 99.9% of the time.
>>>>
>>>> I could argue that if surviving only a short power disconnect is ok, then
>>>> a
>>>> supercap might be better, but then it is probably a large engineering
>>>> change
>>>> since the caps and batteries usually have vastly different footprints.
>>>>
>>>> Good batteries can last decades - even Supercaps have a finite lifetime.
>>>>   It
>>>> is a matter of cost, both in redesign, size, and reliability.  But do you
>>>> want to add $5-$10 to the cost of the unit to make a cheap ($30-$50) GPS
>>>> last over a decade?  Buy a second, seal it hermetically, and put it in
>>>> your
>>>> freezer.
>>>>
>>>> If you want to add a few thousand in NRE costs, there are a lot of other
>>>> things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.  Allow
>>>> for
>>>> a detachable or external antenna (which can be run to the window).  Find
>>>> a
>>>> more optimal chipset.  Maybe a coin-cell port so the battery can be
>>>> replaceable.  But the point was to be as cheap as possible so in this
>>>> case
>>>> it is adding one wire.
>>>>
>>>> You can always break yours open and if you can find a supercap with the
>>>> specs (Sparkfun has a 3.3v available, but don't put more than 3.3v on
>>>> it),
>>>> you can swap the part.
>>>>
>>>>
>>>> On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP)
>>>> <timekeepingntplist@techstarship.com>    wrote:
>>>>
>>>>          
>>>>> Hi all,
>>>>>
>>>>> (I'm copying this only to the thumb-gps list and to TZ, the most recent
>>>>> commenter, as I don't know all the parties in the header of TZ's
>>>>> message.
>>>>> You guys can forward it to whomever else may need to see it.)
>>>>>
>>>>> Speaking strictly as a potential user of the thumb-gps device and
>>>>> amateur
>>>>> interested party, I would rather see a supercap, if feasible.  I hate
>>>>> the
>>>>> idea of devices having batteries that I have to worry about failing in
>>>>> 5-10
>>>>> years.  I've had the cmos batteries fail in a few computers, sometimes
>>>>> preventing them from booting.  It can get really ugly trying to revive
>>>>> them
>>>>> A good high efficiency dc-dc converter chip should allow you to drain
>>>>> all
>>>>> but the last bit of energy from the cap while maintaining whatever
>>>>> working
>>>>> voltage you need.  I cannot speak to size issues, as I have never
>>>>> designed a
>>>>> circuit board with one.  The GlobalSat BU-353 that I have has a
>>>>> supercap, I
>>>>> believe.  Exact backup time is not stated, but I believe it's a few
>>>>> days.
>>>>>
>>>>> Sincerely,
>>>>>
>>>>> Ron
>>>>>
>>>>>
>>>>> On 5/9/2012 1:12 PM, tz wrote:
>>>>>
>>>>> For a given size (and circuit board footprint) a supercap will have much
>>>>> less capacity and it has an exponential voltage decay curve, so it might
>>>>> have plenty of charge but not at a voltage that will hold the data.
>>>>>   This
>>>>> usually means hours, not days of backup.
>>>>>
>>>>> A good rechargeable lithium will last several years, maybe longer as
>>>>> there
>>>>> will be no charge/discharge, maintains voltage until it is nearly
>>>>> exhausted,
>>>>> and can hold the data for days or weeks.
>>>>>
>>>>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht<dave.taht@gmail.com>    wrote:
>>>>>
>>>>>            
>>>>>> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond<esr@thyrsus.com>
>>>>>>   wrote:
>>>>>>
>>>>>>              
>>>>>>> Dave Taht<dave.taht@gmail.com>:
>>>>>>>
>>>>>>>                
>>>>>>>> What would be the change in cost and delay in manufacturing to switch
>>>>>>>> to
>>>>>>>> using a supercap, rather than battery?
>>>>>>>>
>>>>>>>>                  
>>>>>>> Why would a supercap be better?
>>>>>>>
>>>>>>>                
>>>>>> Effective lifetime of... forever. no need for replacement. insanely
>>>>>> fast recharge. smaller (probably). What's not to like?
>>>>>>
>>>>>> I am not in a huge hurry to get into manufacturing, and I merely
>>>>>> wanted to cost out what what it would do to the bom, any changes to
>>>>>> the PCB, and get an estimate for the time it would take to do. I think
>>>>>> it will bump the unit cost up slightly,
>>>>>> but what price, forever?
>>>>>>
>>>>>>
>>>>>>              
>>>>>>> --
>>>>>>>                 <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>>>>>>>
>>>>>>>                
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Dave Täht
>>>>>> SKYPE: davetaht
>>>>>> US Tel: 1-239-829-5608
>>>>>> http://www.bufferbloat.net
>>>>>>
>>>>>>              


-- 

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT techstarship.com

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Taht]

On Wed, May 9, 2012 at 1:58 PM, Ron Frazier (NTP)
<timekeepingntplist@techstarship.com> wrote:
> I'm just an interested third party.  You guys are running the show.  Use the
> ideas as you see fit.  Just give me some credit if you end up using my
> ideas.

absolutely. Got another fictional character you resemble?

And I'm totally into discussing this stuff, later, but right now I'm
too busy with codel....

>
> Sincerely,
>
> Ron
>
>
>
> On 5/9/2012 4:46 PM, Dave Taht wrote:
>>
>> A lot of that stuff I'd want to reserve for the Macx-2. Can I keep our
>> request of navisys limited to merely the supercap and silkscreen?
>>
>> On Wed, May 9, 2012 at 1:41 PM, Ron Frazier (NTP)
>> <timekeepingntplist@techstarship.com>  wrote:
>>
>>>
>>> Hi guys,
>>>
>>> I do see the point TZ was making about the problems of increasing the
>>> design
>>> and production costs.  However, if the supercap turned out to be
>>> potentially
>>> feasible, I have some Circuit Cellar magazines and such that I could
>>> rummage
>>> through for info on micro power conversion components.  I know they
>>> exist.
>>>  I have no idea about specs and efficiency.  How much amperage and at
>>> what
>>> voltage is the unit expected to draw if disconnected from the USB power
>>> source?  Is it expected to continue tracking?  I assume this will change
>>> if
>>> an external antenna is attached.  How long should it be maintained?
>>>
>>>  From a user perspective, I'd recommend the following features, if you
>>> have a
>>> viable choice:
>>>
>>> * Hi sensitivity internal antenna / chipset that can be used indoors in a
>>> residential type structure.
>>> * External antenna port in case you're in a steel building or basement or
>>> something with no signal.  Use commonly available, generic, possibly
>>> powered, antennas.
>>> * GPS status led.  (My BU-353 slowly flashes when it has a fix, shows
>>> steady
>>> with power but no fix.)  The led should be synchronized to the pps.
>>> * Supercap preferably, or battery which is easily user replaceable and a
>>> common part number, such as CR2032 for example.  That battery may be too
>>> big, but you want something readily available.
>>> * If a battery is involved, a small flashing led to indicate a weak
>>> battery
>>> alert, kind of like what is on a smoke alarm.
>>> * My BU-353 has a magnetic base.  Something like that might be useful for
>>> positioning the antenna.
>>> * May or may not be relevant, but, would 5 - 10 Hz position sensing
>>> improve
>>> accuracy and stability for your purposes?
>>> * You may wish to expose the pps signal on a screw terminal or connector
>>> in
>>> case you want to attach other instrumentation to that signal.
>>>
>>> Here's a possible alternative to providing an external antenna port, and
>>> all
>>> the hassles of piping RF around.  With my BU-353, the "puck" device
>>> contains
>>> both the electronics and the antenna.  The only cord coming from it is
>>> the
>>> USB cable.  So, it might be preferable to have a sealed weather proof
>>> unit,
>>> and just use extension cords for USB rather than extending the RF
>>> section.
>>>  I know you can easily extend USB 10 feet or so.  I think you can go much
>>> further with powered hubs and such.  Just a thought.
>>>
>>> Here's a wild idea, maybe not practical, but, you could attach a solar
>>> cell
>>> to the external antenna and / or the thumb-gps case.  This could feed
>>> power
>>> back to the GPS board and prolong the life of the battery or slow the
>>> drain
>>> of the supercap while powering the antenna if the antenna is in the sun.
>>>  You could even draw some energy from ambient indoor lighting.  I have a
>>> solar powered "atomic" watch from Casio that does this.  It never needs a
>>> battery, never needs charging, and never needs setting.  Very handy.  I
>>> also
>>> have two "atomic" wall clocks that do the same thing.  I think they use a
>>> rechargeable battery instead of a supercap.
>>>
>>> Here's another idea, which may or may not have already been discussed.
>>>  Do
>>> you want to have an on board RTC, which can keep outputting valid time
>>> for a
>>> while, if the satellites are not available due to weather, jamming,
>>> interference, etc.?
>>>
>>> Sincerely,
>>>
>>> Ron
>>>
>>>
>>>
>>>
>>> On 5/9/2012 2:35 PM, Dave Taht wrote:
>>>
>>>>
>>>> jeeze guys, all I asked for was an estimate as to the change to the BOM.
>>>> Could be a Macx-2, might not be worthwhile at all.
>>>>
>>>> My concern was that there are 6+ short power flickers a day - forcing
>>>> a reboot - in places like Nicaragua. These events are *interesting*
>>>> from a network analysis perspective, as flickers like this cause
>>>> massive network disturbances.
>>>>
>>>> I don't care about battery life longer than about 30 seconds, although
>>>> a case could be made for 24 hours. Just wanted the analysis of what it
>>>> would really take, given how little power this thing sucks...
>>>>
>>>> and I hate ANYTHING that needs a user-replaceable component, 5 years
>>>> after manufacture. So I'd prefer the actual analysis based on power
>>>> draw, etc, before
>>>> making any decisions.
>>>>
>>>>
>>>> On Wed, May 9, 2012 at 11:21 AM, tz<thomas@mich.com>    wrote:
>>>>
>>>>
>>>>>
>>>>> It doesn't work that way.  Microampere DC-DC converters?  That isn't a
>>>>> swap,
>>>>> it is a redesign, if microamp converters are possible - the base losses
>>>>> are
>>>>> high so you won't hit a high efficiency.  You get high efficiencies
>>>>> when
>>>>> dealing with lots of amps.  For it to last overnight you would need a
>>>>> very
>>>>> large (physically) cap.
>>>>>
>>>>> There would be no booting problem.  It would merely lose the real-time
>>>>> clock
>>>>> and/or location backup so would take a bit longer starting.
>>>>>
>>>>> The battery (or cap) only kicks in when the power goes away and is only
>>>>> needed to make the startup faster, e.g. cycling power on the computer
>>>>> or
>>>>> router.  USB should be constantly providing 5V 99.9% of the time.
>>>>>
>>>>> I could argue that if surviving only a short power disconnect is ok,
>>>>> then
>>>>> a
>>>>> supercap might be better, but then it is probably a large engineering
>>>>> change
>>>>> since the caps and batteries usually have vastly different footprints.
>>>>>
>>>>> Good batteries can last decades - even Supercaps have a finite
>>>>> lifetime.
>>>>>  It
>>>>> is a matter of cost, both in redesign, size, and reliability.  But do
>>>>> you
>>>>> want to add $5-$10 to the cost of the unit to make a cheap ($30-$50)
>>>>> GPS
>>>>> last over a decade?  Buy a second, seal it hermetically, and put it in
>>>>> your
>>>>> freezer.
>>>>>
>>>>> If you want to add a few thousand in NRE costs, there are a lot of
>>>>> other
>>>>> things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.
>>>>>  Allow
>>>>> for
>>>>> a detachable or external antenna (which can be run to the window).
>>>>>  Find
>>>>> a
>>>>> more optimal chipset.  Maybe a coin-cell port so the battery can be
>>>>> replaceable.  But the point was to be as cheap as possible so in this
>>>>> case
>>>>> it is adding one wire.
>>>>>
>>>>> You can always break yours open and if you can find a supercap with the
>>>>> specs (Sparkfun has a 3.3v available, but don't put more than 3.3v on
>>>>> it),
>>>>> you can swap the part.
>>>>>
>>>>>
>>>>> On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP)
>>>>> <timekeepingntplist@techstarship.com>    wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>> (I'm copying this only to the thumb-gps list and to TZ, the most
>>>>>> recent
>>>>>> commenter, as I don't know all the parties in the header of TZ's
>>>>>> message.
>>>>>> You guys can forward it to whomever else may need to see it.)
>>>>>>
>>>>>> Speaking strictly as a potential user of the thumb-gps device and
>>>>>> amateur
>>>>>> interested party, I would rather see a supercap, if feasible.  I hate
>>>>>> the
>>>>>> idea of devices having batteries that I have to worry about failing in
>>>>>> 5-10
>>>>>> years.  I've had the cmos batteries fail in a few computers, sometimes
>>>>>> preventing them from booting.  It can get really ugly trying to revive
>>>>>> them
>>>>>> A good high efficiency dc-dc converter chip should allow you to drain
>>>>>> all
>>>>>> but the last bit of energy from the cap while maintaining whatever
>>>>>> working
>>>>>> voltage you need.  I cannot speak to size issues, as I have never
>>>>>> designed a
>>>>>> circuit board with one.  The GlobalSat BU-353 that I have has a
>>>>>> supercap, I
>>>>>> believe.  Exact backup time is not stated, but I believe it's a few
>>>>>> days.
>>>>>>
>>>>>> Sincerely,
>>>>>>
>>>>>> Ron
>>>>>>
>>>>>>
>>>>>> On 5/9/2012 1:12 PM, tz wrote:
>>>>>>
>>>>>> For a given size (and circuit board footprint) a supercap will have
>>>>>> much
>>>>>> less capacity and it has an exponential voltage decay curve, so it
>>>>>> might
>>>>>> have plenty of charge but not at a voltage that will hold the data.
>>>>>>  This
>>>>>> usually means hours, not days of backup.
>>>>>>
>>>>>> A good rechargeable lithium will last several years, maybe longer as
>>>>>> there
>>>>>> will be no charge/discharge, maintains voltage until it is nearly
>>>>>> exhausted,
>>>>>> and can hold the data for days or weeks.
>>>>>>
>>>>>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht<dave.taht@gmail.com>
>>>>>>  wrote:
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond<esr@thyrsus.com>
>>>>>>>  wrote:
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> Dave Taht<dave.taht@gmail.com>:
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> What would be the change in cost and delay in manufacturing to
>>>>>>>>> switch
>>>>>>>>> to
>>>>>>>>> using a supercap, rather than battery?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> Why would a supercap be better?
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> Effective lifetime of... forever. no need for replacement. insanely
>>>>>>> fast recharge. smaller (probably). What's not to like?
>>>>>>>
>>>>>>> I am not in a huge hurry to get into manufacturing, and I merely
>>>>>>> wanted to cost out what what it would do to the bom, any changes to
>>>>>>> the PCB, and get an estimate for the time it would take to do. I
>>>>>>> think
>>>>>>> it will bump the unit cost up slightly,
>>>>>>> but what price, forever?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>>                <a href="http://www.catb.org/~esr/">Eric S.
>>>>>>>> Raymond</a>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Dave Täht
>>>>>>> SKYPE: davetaht
>>>>>>> US Tel: 1-239-829-5608
>>>>>>> http://www.bufferbloat.net
>>>>>>>
>>>>>>>
>
>
>
> --
>
> (To whom it may concern.  My email address has changed.  Replying to former
> messages prior to 03/31/12 with my personal address will go to the wrong
> address.  Please send all personal correspondence to the new address.)
>
> (PS - If you email me and don't get a quick response, don't be concerned.
> I get about 300 emails per day from alternate energy mailing lists and
> such.  I don't always see new messages very quickly.  If you need a
> reply and have not heard from me in 1 - 2 weeks, send your message again.)
>
> Ron Frazier
> timekeepingdude AT techstarship.com
>



-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Ron Frazier (NTP)]

Dave Taht <dave.taht@gmail.com> wrote:

>On Wed, May 9, 2012 at 1:58 PM, Ron Frazier (NTP)
><timekeepingntplist@techstarship.com> wrote:
>> I'm just an interested third party.  You guys are running the show.
> Use the
>> ideas as you see fit.  Just give me some credit if you end up using
>my
>> ideas.
>
>absolutely. Got another fictional character you resemble?

You're not confusing me with esr are you?  I like all captains of starships named enterprise, but I don't know if I resemble any of them.

Sincerely,

Ron

>
>And I'm totally into discussing this stuff, later, but right now I'm
>too busy with codel....
>
>>
>> Sincerely,
>>
>> Ron
>>
>>
>>
>> On 5/9/2012 4:46 PM, Dave Taht wrote:
>>>
>>> A lot of that stuff I'd want to reserve for the Macx-2. Can I keep
>our
>>> request of navisys limited to merely the supercap and silkscreen?
>>>
>>> On Wed, May 9, 2012 at 1:41 PM, Ron Frazier (NTP)
>>> <timekeepingntplist@techstarship.com>  wrote:
>>>
>>>>
>>>> Hi guys,
>>>>
>>>> I do see the point TZ was making about the problems of increasing
>the
>>>> design
>>>> and production costs.  However, if the supercap turned out to be
>>>> potentially
>>>> feasible, I have some Circuit Cellar magazines and such that I
>could
>>>> rummage
>>>> through for info on micro power conversion components.  I know they
>>>> exist.
>>>>  I have no idea about specs and efficiency.  How much amperage and
>at
>>>> what
>>>> voltage is the unit expected to draw if disconnected from the USB
>power
>>>> source?  Is it expected to continue tracking?  I assume this will
>change
>>>> if
>>>> an external antenna is attached.  How long should it be maintained?
>>>>
>>>>  From a user perspective, I'd recommend the following features, if
>you
>>>> have a
>>>> viable choice:
>>>>
>>>> * Hi sensitivity internal antenna / chipset that can be used
>indoors in a
>>>> residential type structure.
>>>> * External antenna port in case you're in a steel building or
>basement or
>>>> something with no signal.  Use commonly available, generic,
>possibly
>>>> powered, antennas.
>>>> * GPS status led.  (My BU-353 slowly flashes when it has a fix,
>shows
>>>> steady
>>>> with power but no fix.)  The led should be synchronized to the pps.
>>>> * Supercap preferably, or battery which is easily user replaceable
>and a
>>>> common part number, such as CR2032 for example.  That battery may
>be too
>>>> big, but you want something readily available.
>>>> * If a battery is involved, a small flashing led to indicate a weak
>>>> battery
>>>> alert, kind of like what is on a smoke alarm.
>>>> * My BU-353 has a magnetic base.  Something like that might be
>useful for
>>>> positioning the antenna.
>>>> * May or may not be relevant, but, would 5 - 10 Hz position sensing
>>>> improve
>>>> accuracy and stability for your purposes?
>>>> * You may wish to expose the pps signal on a screw terminal or
>connector
>>>> in
>>>> case you want to attach other instrumentation to that signal.
>>>>
>>>> Here's a possible alternative to providing an external antenna
>port, and
>>>> all
>>>> the hassles of piping RF around.  With my BU-353, the "puck" device
>>>> contains
>>>> both the electronics and the antenna.  The only cord coming from it
>is
>>>> the
>>>> USB cable.  So, it might be preferable to have a sealed weather
>proof
>>>> unit,
>>>> and just use extension cords for USB rather than extending the RF
>>>> section.
>>>>  I know you can easily extend USB 10 feet or so.  I think you can
>go much
>>>> further with powered hubs and such.  Just a thought.
>>>>
>>>> Here's a wild idea, maybe not practical, but, you could attach a
>solar
>>>> cell
>>>> to the external antenna and / or the thumb-gps case.  This could
>feed
>>>> power
>>>> back to the GPS board and prolong the life of the battery or slow
>the
>>>> drain
>>>> of the supercap while powering the antenna if the antenna is in the
>sun.
>>>>  You could even draw some energy from ambient indoor lighting.  I
>have a
>>>> solar powered "atomic" watch from Casio that does this.  It never
>needs a
>>>> battery, never needs charging, and never needs setting.  Very
>handy.  I
>>>> also
>>>> have two "atomic" wall clocks that do the same thing.  I think they
>use a
>>>> rechargeable battery instead of a supercap.
>>>>
>>>> Here's another idea, which may or may not have already been
>discussed.
>>>>  Do
>>>> you want to have an on board RTC, which can keep outputting valid
>time
>>>> for a
>>>> while, if the satellites are not available due to weather, jamming,
>>>> interference, etc.?
>>>>
>>>> Sincerely,
>>>>
>>>> Ron
>>>>
>>>>
>>>>
>>>>
>>>> On 5/9/2012 2:35 PM, Dave Taht wrote:
>>>>
>>>>>
>>>>> jeeze guys, all I asked for was an estimate as to the change to
>the BOM.
>>>>> Could be a Macx-2, might not be worthwhile at all.
>>>>>
>>>>> My concern was that there are 6+ short power flickers a day -
>forcing
>>>>> a reboot - in places like Nicaragua. These events are
>*interesting*
>>>>> from a network analysis perspective, as flickers like this cause
>>>>> massive network disturbances.
>>>>>
>>>>> I don't care about battery life longer than about 30 seconds,
>although
>>>>> a case could be made for 24 hours. Just wanted the analysis of
>what it
>>>>> would really take, given how little power this thing sucks...
>>>>>
>>>>> and I hate ANYTHING that needs a user-replaceable component, 5
>years
>>>>> after manufacture. So I'd prefer the actual analysis based on
>power
>>>>> draw, etc, before
>>>>> making any decisions.
>>>>>
>>>>>
>>>>> On Wed, May 9, 2012 at 11:21 AM, tz<thomas@mich.com>    wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> It doesn't work that way.  Microampere DC-DC converters?  That
>isn't a
>>>>>> swap,
>>>>>> it is a redesign, if microamp converters are possible - the base
>losses
>>>>>> are
>>>>>> high so you won't hit a high efficiency.  You get high
>efficiencies
>>>>>> when
>>>>>> dealing with lots of amps.  For it to last overnight you would
>need a
>>>>>> very
>>>>>> large (physically) cap.
>>>>>>
>>>>>> There would be no booting problem.  It would merely lose the
>real-time
>>>>>> clock
>>>>>> and/or location backup so would take a bit longer starting.
>>>>>>
>>>>>> The battery (or cap) only kicks in when the power goes away and
>is only
>>>>>> needed to make the startup faster, e.g. cycling power on the
>computer
>>>>>> or
>>>>>> router.  USB should be constantly providing 5V 99.9% of the time.
>>>>>>
>>>>>> I could argue that if surviving only a short power disconnect is
>ok,
>>>>>> then
>>>>>> a
>>>>>> supercap might be better, but then it is probably a large
>engineering
>>>>>> change
>>>>>> since the caps and batteries usually have vastly different
>footprints.
>>>>>>
>>>>>> Good batteries can last decades - even Supercaps have a finite
>>>>>> lifetime.
>>>>>>  It
>>>>>> is a matter of cost, both in redesign, size, and reliability.
> But do
>>>>>> you
>>>>>> want to add $5-$10 to the cost of the unit to make a cheap
>($30-$50)
>>>>>> GPS
>>>>>> last over a decade?  Buy a second, seal it hermetically, and put
>it in
>>>>>> your
>>>>>> freezer.
>>>>>>
>>>>>> If you want to add a few thousand in NRE costs, there are a lot
>of
>>>>>> other
>>>>>> things I would redesign.  Use a USB 2.0 chip to get 125uS jitter.
>>>>>>  Allow
>>>>>> for
>>>>>> a detachable or external antenna (which can be run to the
>window).
>>>>>>  Find
>>>>>> a
>>>>>> more optimal chipset.  Maybe a coin-cell port so the battery can
>be
>>>>>> replaceable.  But the point was to be as cheap as possible so in
>this
>>>>>> case
>>>>>> it is adding one wire.
>>>>>>
>>>>>> You can always break yours open and if you can find a supercap
>with the
>>>>>> specs (Sparkfun has a 3.3v available, but don't put more than
>3.3v on
>>>>>> it),
>>>>>> you can swap the part.
>>>>>>
>>>>>>
>>>>>> On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP)
>>>>>> <timekeepingntplist@techstarship.com>    wrote:
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> (I'm copying this only to the thumb-gps list and to TZ, the most
>>>>>>> recent
>>>>>>> commenter, as I don't know all the parties in the header of TZ's
>>>>>>> message.
>>>>>>> You guys can forward it to whomever else may need to see it.)
>>>>>>>
>>>>>>> Speaking strictly as a potential user of the thumb-gps device
>and
>>>>>>> amateur
>>>>>>> interested party, I would rather see a supercap, if feasible.  I
>hate
>>>>>>> the
>>>>>>> idea of devices having batteries that I have to worry about
>failing in
>>>>>>> 5-10
>>>>>>> years.  I've had the cmos batteries fail in a few computers,
>sometimes
>>>>>>> preventing them from booting.  It can get really ugly trying to
>revive
>>>>>>> them
>>>>>>> A good high efficiency dc-dc converter chip should allow you to
>drain
>>>>>>> all
>>>>>>> but the last bit of energy from the cap while maintaining
>whatever
>>>>>>> working
>>>>>>> voltage you need.  I cannot speak to size issues, as I have
>never
>>>>>>> designed a
>>>>>>> circuit board with one.  The GlobalSat BU-353 that I have has a
>>>>>>> supercap, I
>>>>>>> believe.  Exact backup time is not stated, but I believe it's a
>few
>>>>>>> days.
>>>>>>>
>>>>>>> Sincerely,
>>>>>>>
>>>>>>> Ron
>>>>>>>
>>>>>>>
>>>>>>> On 5/9/2012 1:12 PM, tz wrote:
>>>>>>>
>>>>>>> For a given size (and circuit board footprint) a supercap will
>have
>>>>>>> much
>>>>>>> less capacity and it has an exponential voltage decay curve, so
>it
>>>>>>> might
>>>>>>> have plenty of charge but not at a voltage that will hold the
>data.
>>>>>>>  This
>>>>>>> usually means hours, not days of backup.
>>>>>>>
>>>>>>> A good rechargeable lithium will last several years, maybe
>longer as
>>>>>>> there
>>>>>>> will be no charge/discharge, maintains voltage until it is
>nearly
>>>>>>> exhausted,
>>>>>>> and can hold the data for days or weeks.
>>>>>>>
>>>>>>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht<dave.taht@gmail.com>
>>>>>>>  wrote:
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> On Wed, May 9, 2012 at 9:47 AM, Eric S.
>Raymond<esr@thyrsus.com>
>>>>>>>>  wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Dave Taht<dave.taht@gmail.com>:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> What would be the change in cost and delay in manufacturing
>to
>>>>>>>>>> switch
>>>>>>>>>> to
>>>>>>>>>> using a supercap, rather than battery?
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Why would a supercap be better?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> Effective lifetime of... forever. no need for replacement.
>insanely
>>>>>>>> fast recharge. smaller (probably). What's not to like?
>>>>>>>>
>>>>>>>> I am not in a huge hurry to get into manufacturing, and I
>merely
>>>>>>>> wanted to cost out what what it would do to the bom, any
>changes to
>>>>>>>> the PCB, and get an estimate for the time it would take to do.
>I
>>>>>>>> think
>>>>>>>> it will bump the unit cost up slightly,
>>>>>>>> but what price, forever?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>>                <a href="http://www.catb.org/~esr/">Eric S.
>>>>>>>>> Raymond</a>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Dave Täht
>>>>>>>> SKYPE: davetaht
>>>>>>>> US Tel: 1-239-829-5608
>>>>>>>> http://www.bufferbloat.net
>>>>>>>>
>>>>>>>>
>>
>>
>>
>> --
>>
>> (To whom it may concern.  My email address has changed.  Replying to
>former
>> messages prior to 03/31/12 with my personal address will go to the
>wrong
>> address.  Please send all personal correspondence to the new
>address.)
>>
>> (PS - If you email me and don't get a quick response, don't be
>concerned.
>> I get about 300 emails per day from alternate energy mailing lists
>and
>> such.  I don't always see new messages very quickly.  If you need a
>> reply and have not heard from me in 1 - 2 weeks, send your message
>again.)
>>
>> Ron Frazier
>> timekeepingdude AT techstarship.com
>>
>
>
>
>--
>Dave Täht
>SKYPE: davetaht
>US Tel: 1-239-829-5608
>http://www.bufferbloat.net


--

Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9 Mail.
Please excuse my potential brevity.

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and such.
I don't always see new email messages very quickly.  If you need a reply and
haven't heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT techstarship.com

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Ron Frazier (NTP) <timekeepingntplist@techstarship.com>:
> * Hi sensitivity internal antenna / chipset that can be used indoors
> in a residential type structure.

The Macx-1 already has this.  It's sitting on my desk 5 feet from a window 
blocked by large trees and hasn't lost lock once since it got here. Gary
says it's working just as well in his basement.

Truly, this is the most indoor-friendly GPS I've ever seen.  Puts the
general run of SiRF mice to shame, and raises my opinion of uBlox a
*lot*.

> * External antenna port in case you're in a steel building or
> basement or something with no signal.  Use commonly available,
> generic, possibly powered, antennas.

Doesn't have it.  Doesn't seem to need it!

> * GPS status led.  (My BU-353 slowly flashes when it has a fix,
> shows steady with power but no fix.)  The led should be synchronized
> to the pps.

Has it.

> * Supercap preferably, or battery which is easily user replaceable
> and a common part number, such as CR2032 for example.  That battery
> may be too big, but you want something readily available.

Doesn't have it.  But the unit price is low enough that I don't care;
the widget is disposable.

> * If a battery is involved, a small flashing led to indicate a weak
> battery alert, kind of like what is on a smoke alarm.

Doesn't have it.

> * My BU-353 has a magnetic base.  Something like that might be
> useful for positioning the antenna.

Has it.

> * May or may not be relevant, but, would 5 - 10 Hz position sensing
> improve accuracy and stability for your purposes?

No, not for a timing GPS.  And modules with multiHz sampling are tres
expensive.

> * You may wish to expose the pps signal on a screw terminal or
> connector in case you want to attach other instrumentation to that
> signal.

You may wish it.  I don't.  I *like* the sealed case, the low parts 
count, and the rock-bottom cost.  For the kind of deployment we're
doing, this design is optimal.

> Here's a possible alternative to providing an external antenna port,
> and all the hassles of piping RF around.  With my BU-353, the "puck"
> device contains both the electronics and the antenna.  The only cord
> coming from it is the USB cable.  So, it might be preferable to have
> a sealed weather proof unit, and just use extension cords for USB
> rather than extending the RF section.  I know you can easily extend
> USB 10 feet or so.  I think you can go much further with powered
> hubs and such.  Just a thought.

Way ahead of you.  This is why I *didn't* spec an antenna.  One cable
is simpler (therefore better) than two.

> Here's a wild idea, maybe not practical, but, you could attach a
> solar cell to the external antenna and / or the thumb-gps case.
> This could feed power back to the GPS board and prolong the life of
> the battery or slow the drain of the supercap while powering the
> antenna if the antenna is in the sun.  You could even draw some
> energy from ambient indoor lighting.  I have a solar powered
> "atomic" watch from Casio that does this.  It never needs a battery,
> never needs charging, and never needs setting.  Very handy.  I also
> have two "atomic" wall clocks that do the same thing.  I think they
> use a rechargeable battery instead of a supercap.
>
> Here's another idea, which may or may not have already been
> discussed.  Do you want to have an on board RTC, which can keep
> outputting valid time for a while, if the satellites are not
> available due to weather, jamming, interference, etc.?

Custom hardware.  Expensive.  Not suitable for bufferbloat deployment.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[tz]

[-- Attachment #1: Type: text/plain, Size: 836 bytes --]

On Wed, May 9, 2012 at 5:14 PM, Eric S. Raymond <esr@thyrsus.com> wrote:

> Ron Frazier (NTP) <timekeepingntplist@techstarship.com>:
>
> > * May or may not be relevant, but, would 5 - 10 Hz position sensing
> > improve accuracy and stability for your purposes?
>
> No, not for a timing GPS.  And modules with multiHz sampling are tres
> expensive.
>

Multi Hz is usually a feature of the chipset.  If ti is Antares/Ublox it
might be able to do 5Hz with WAAS or 10Hz without.

(I have 3 Wintec Bluetooth/USB modules that use antares/ublox that I used
because they were 10Hz, and they weren't that much more expensive and that
was a few years ago).
(Even my Skytraq 20Hz isn't that much more expensive).

But that might be a good question - would WAAS improve the timing?

If there is a "first batch": available, I'd sign up to be on it.

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Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Hart]

On Wed, May 9, 2012 at 6:43 AM, Jau-Yang Chen <cjy@navisys.com.tw> wrote:
> To thank you and Dave's good idea and great support, GR-601W
> also has a nickname Macx-1.

I've held my tongue for a while hoping followup messages would
enlighten me, but they haven't.  I think it is generous and kind to
nickname a product to thank a potential customer for their suggestion.
 At the same time, I feebly admit I don't see the connection between
Eric Raymond and Dave Taht and the nickname Macx-1.  Perhaps the
meaning or thought behind the choice was explained in email I didn't
see?

Thanks,
Dave Hart

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Dave Hart <davehart@gmail.com>:
>  At the same time, I feebly admit I don't see the connection between
> Eric Raymond and Dave Taht and the nickname Macx-1.  Perhaps the
> meaning or thought behind the choice was explained in email I didn't
> see?

Lemme see if I can find it...ah, here it is

https://lists.bufferbloat.net/pipermail/thumbgps-devel/2012-May/000194.html

After that, Dave started calling the device the Macx-1.  Not my idea, honest!

Navisys people: the context you may be missing is that I'm ridiculously
famous among Internet geeks, and Charles Stross is a very capable and
popular writer of science fiction who happends to have known me *before*
I was famous.  The resemblences between myself and the fictional character
Manfred Macx are sufficiently obvious that a lot of Internet geeks 
can easily pick up on them - it's what's called in English an "in-joke",
a form of humor shared within a particular social group but opaque to
outsiders.
-- 
		<A href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Hart]

On Wed, May 9, 2012 at 8:37 PM, Eric S. Raymond <esr@thyrsus.com> wrote:
> Dave Hart <davehart@gmail.com>:
>>  At the same time, I feebly admit I don't see the connection between
>> Eric Raymond and Dave Taht and the nickname Macx-1.  Perhaps the
>> meaning or thought behind the choice was explained in email I didn't
>> see?
>
> Lemme see if I can find it...ah, here it is
>
> https://lists.bufferbloat.net/pipermail/thumbgps-devel/2012-May/000194.html
>
> After that, Dave started calling the device the Macx-1.  Not my idea, honest!
>
> Navisys people: the context you may be missing is that I'm ridiculously
> famous among Internet geeks, and Charles Stross is a very capable and
> popular writer of science fiction who happends to have known me *before*
> I was famous.  The resemblences between myself and the fictional character
> Manfred Macx are sufficiently obvious that a lot of Internet geeks
> can easily pick up on them - it's what's called in English an "in-joke",
> a form of humor shared within a particular social group but opaque to
> outsiders.

Thanks, Manfred.  I had a creeping feeling I had missed the
connection, but didn't use the force (gmail search) with "macx" as I
should have.

Here's hoping wiring PPS to DCD in GPS pucks using 232-to-USB adapters
becomes the standard.  I would expect over time vendors would not see
any reason to continue making designs without the extra trace.

Cheers,
Dave Hart

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Ron Frazier (NTP)]

On 5/9/2012 5:03 PM, Dave Hart wrote:
> On Wed, May 9, 2012 at 8:37 PM, Eric S. Raymond<esr@thyrsus.com>  wrote:
>    
>> Dave Hart<davehart@gmail.com>:
>>      
>>>   At the same time, I feebly admit I don't see the connection between
>>> Eric Raymond and Dave Taht and the nickname Macx-1.  Perhaps the
>>> meaning or thought behind the choice was explained in email I didn't
>>> see?
>>>        
>> Lemme see if I can find it...ah, here it is
>>
>> https://lists.bufferbloat.net/pipermail/thumbgps-devel/2012-May/000194.html
>>
>> After that, Dave started calling the device the Macx-1.  Not my idea, honest!
>>
>> Navisys people: the context you may be missing is that I'm ridiculously
>> famous among Internet geeks, and Charles Stross is a very capable and
>> popular writer of science fiction who happends to have known me *before*
>> I was famous.  The resemblences between myself and the fictional character
>> Manfred Macx are sufficiently obvious that a lot of Internet geeks
>> can easily pick up on them - it's what's called in English an "in-joke",
>> a form of humor shared within a particular social group but opaque to
>> outsiders.
>>      
> Thanks, Manfred.  I had a creeping feeling I had missed the
> connection, but didn't use the force (gmail search) with "macx" as I
> should have.
>
> Here's hoping wiring PPS to DCD in GPS pucks using 232-to-USB adapters
> becomes the standard.  I would expect over time vendors would not see
> any reason to continue making designs without the extra trace.
>
> Cheers,
> Dave Hart
>
>    

Hi Dave,

Good to see you.  Just wondering, are there any GPS applications which 
will croak because of having DCD being pulsed in that manner?  Maybe you 
need a dip switch to turn that signal on or off.  Also, are there other 
applications which expect the pps to be coming though another 
handshaking pin besides DCD?

Sincerely,

Ron


-- 

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT techstarship.com

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Ron Frazier (NTP) <timekeepingntplist@techstarship.com>:
> Good to see you.  Just wondering, are there any GPS applications
> which will croak because of having DCD being pulsed in that manner?

Why should the applications care? Only GPSD ever *sees* that port - the
applications are decoupled from it.


>                                                             Also,
> are there other applications which expect the pps to be coming
> though another handshaking pin besides DCD?

Note that GPSD will actually notice PPS over RI and CTS as well.
It doesn't care - a transition on any handshake line is treated
as a PPS event, because the onlty thing it ever means from a GPS.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Hart]

On Wed, May 9, 2012 at 9:38 PM, Eric S. Raymond <esr@thyrsus.com> wrote:
>>                                                             Also,
>> are there other applications which expect the pps to be coming
>> though another handshaking pin besides DCD?
>
> Note that GPSD will actually notice PPS over RI and CTS as well.
> It doesn't care - a transition on any handshake line is treated
> as a PPS event, because the onlty thing it ever means from a GPS.

While I appreciate GPSD's flexibility, I advise against exercising it
needlessly.  All of the PPSAPI implementations which support serial
port control line input that I'm aware of want to see it on the
carrier detect line.  If you know you'll only ever care about using
the hardware with GPSD, any control line will do for PPS, but to use
it directly with ntpd, the PPSAPI implementations dictate using the
DCD line.

I had a vague recollection GPSD could use PPSAPI where it's available.
 If that's true, when GPSD is using PPSAPI, isn't it restricted to
using carrier detect in practice?

Cheers,
Dave hart

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Dave Hart <davehart_gmail_exchange_tee@davehart.net>:
> While I appreciate GPSD's flexibility, I advise against exercising it
> needlessly.  All of the PPSAPI implementations which support serial
> port control line input that I'm aware of want to see it on the
> carrier detect line.  If you know you'll only ever care about using
> the hardware with GPSD, any control line will do for PPS, but to use
> it directly with ntpd, the PPSAPI implementations dictate using the
> DCD line.
> 
> I had a vague recollection GPSD could use PPSAPI where it's available.
>  If that's true, when GPSD is using PPSAPI, isn't it restricted to
> using carrier detect in practice?

Which line the PPS arrives on is a hardware feature of the GPS completely
decoupled from anything PPSAPI has any control over.

There's no code-complexity cost for being flexible.  Here's what the
code looks like:

#define PPS_LINE_TIOC (TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS)

    /* 
     * Wait for status change on any handshake line. The only assumption here 
     * is that no GPS lights up more than one of these pins.  By waiting on
     * all of them we remove a configuration switch.
     */
    while (1) {
	int ok = 0;
	char *log = NULL;
	char *log1 = NULL;

        if (ioctl(session->gpsdata.gps_fd, TIOCMIWAIT, PPS_LINE_TIOC) != 0) {
	    gpsd_report(LOG_ERROR, "PPS ioctl(TIOCMIWAIT) failed: %d %.40s\n"
	    	, errno, strerror(errno));
	    break;
	}

That definition of PPS_LINE_TIOC is quite literally the only place in
GPSD where the identity of the PPS pin matters. It used to not include
TIOCM_CTS, but we got a bug report from someone using sonething called
an "Xtreme104 12 port serial board" which actually mungs all the
handshake lines into CTS.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Dave Hart]

On Thu, May 10, 2012 at 6:31 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> Dave Hart <davehart_gmail_exchange_tee@davehart.net>:
>> I had a vague recollection GPSD could use PPSAPI where it's available.
>>  If that's true, when GPSD is using PPSAPI, isn't it restricted to
>> using carrier detect in practice?
>
> Which line the PPS arrives on is a hardware feature of the GPS completely
> decoupled from anything PPSAPI has any control over.
>
> There's no code-complexity cost for being flexible.  Here's what the
> code looks like:
>
> #define PPS_LINE_TIOC (TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS)

I understand gpsd's flexibility when providing PPS timestamping using
TIOCMIWAIT.  My impression, without auditing a bunch of code, is that
PPSAPI implementations in OSes commonly are watching only the CD line.
 That's the case with the few I've looked at closely, although they're
not among the most commonly used.

Cheers,
Dave Hart

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[tz]

[-- Attachment #1: Type: text/plain, Size: 2335 bytes --]

But this requires a recompile to change lines, not a command line option,
or some detection method.  If gpsd is compiled for RI, it wont respond to
DCD.
On May 10, 2012 2:31 AM, "Eric S. Raymond" <esr@thyrsus.com> wrote:

> Dave Hart <davehart_gmail_exchange_tee@davehart.net>:
> > While I appreciate GPSD's flexibility, I advise against exercising it
> > needlessly.  All of the PPSAPI implementations which support serial
> > port control line input that I'm aware of want to see it on the
> > carrier detect line.  If you know you'll only ever care about using
> > the hardware with GPSD, any control line will do for PPS, but to use
> > it directly with ntpd, the PPSAPI implementations dictate using the
> > DCD line.
> >
> > I had a vague recollection GPSD could use PPSAPI where it's available.
> >  If that's true, when GPSD is using PPSAPI, isn't it restricted to
> > using carrier detect in practice?
>
> Which line the PPS arrives on is a hardware feature of the GPS completely
> decoupled from anything PPSAPI has any control over.
>
> There's no code-complexity cost for being flexible.  Here's what the
> code looks like:
>
> #define PPS_LINE_TIOC (TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS)
>
>    /*
>     * Wait for status change on any handshake line. The only assumption
> here
>     * is that no GPS lights up more than one of these pins.  By waiting on
>     * all of them we remove a configuration switch.
>     */
>    while (1) {
>        int ok = 0;
>        char *log = NULL;
>        char *log1 = NULL;
>
>        if (ioctl(session->gpsdata.gps_fd, TIOCMIWAIT, PPS_LINE_TIOC) != 0)
> {
>            gpsd_report(LOG_ERROR, "PPS ioctl(TIOCMIWAIT) failed: %d
> %.40s\n"
>                , errno, strerror(errno));
>            break;
>        }
>
> That definition of PPS_LINE_TIOC is quite literally the only place in
> GPSD where the identity of the PPS pin matters. It used to not include
> TIOCM_CTS, but we got a bug report from someone using sonething called
> an "Xtreme104 12 port serial board" which actually mungs all the
> handshake lines into CTS.
> --
>                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
> _______________________________________________
> Thumbgps-devel mailing list
> Thumbgps-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/thumbgps-devel
>

[-- Attachment #2: Type: text/html, Size: 3100 bytes --]

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

tz <tz2026@gmail.com>:
> But this requires a recompile to change lines, not a command line option,
> or some detection method.  If gpsd is compiled for RI, it wont respond to
> DCD.

No. It should respond to any of the lines ggiven in the TIOCMIWAIT mask.

#define PPS_LINE_TIOC (TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS)

It's seeing CD here.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>

Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[Eric S. Raymond]

Dave Hart <davehart_gmail_exchange_tee@davehart.net>:
> Here's hoping wiring PPS to DCD in GPS pucks using 232-to-USB adapters
> becomes the standard.  I would expect over time vendors would not see
> any reason to continue making designs without the extra trace.

That's actually the outcome I'm trying to engineer.  Unfortunately the other
company I was talking with, UniTraq, has gone silent.  They may have 
lost interest.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>