From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.perfora.net (mout.perfora.net [74.208.4.195]) by huchra.bufferbloat.net (Postfix) with ESMTP id 498852006AA for ; Wed, 9 May 2012 15:57:46 -0700 (PDT) Received: from [192.168.1.23] (adsl-074-165-057-045.sip.asm.bellsouth.net [74.165.57.45]) by mrelay.perfora.net (node=mrus3) with ESMTP (Nemesis) id 0M2bxl-1SBoy92D6j-00s6m7; Wed, 09 May 2012 18:57:44 -0400 References: <02af01cd2daf$05b24bb0$1116e310$@navisys.com.tw> <20120509164726.GA2102@thyrsus.com> <4FAAAE4F.80409@techstarship.com> <4FAAD66F.3090405@techstarship.com> <4FAADA61.9060202@techstarship.com> User-Agent: K-9 Mail for Android In-Reply-To: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 From: "Ron Frazier (NTP)" Date: Wed, 09 May 2012 18:57:30 -0400 To: Dave Taht Message-ID: X-Provags-ID: V02:K0:NbcOrX3yNcpG6sw9cFm0R0yKmzxSdQ1I7uEuFDfVTVv rCZ3siiMuCjoOPT3RLS3DAXQwB5Tmu3Uphh6XTeeVkoEzK1n/h NDUS60NPimJLX9P6SIjv4eESi7r1FyjzHUSIABjH9vE4tK+kaN Mg8VAYZ6rwZgHTveCsHbjGg3BZT90cT8981TqwMJAHYxS4mtRE Hc1vwQ/aE1tiyfYRBdfDoOW3iG9op31pg1LHy6jjlt3wpbPEm6 QS1kKTZOHTwO2pN/o+oaWEzvHn4t+KdcL77vJCpNwosnfzVBgN rWKj4pXGMNrYD0h7n6dQdw5QFcKNj6NO3h6fI6mS9Pc4+WIUkr cV1zLbD1QxO2znktJYWD3iw0ScWGUkOFyhyjR8f2/gWL9Ik1TU bVmzQnXnBR/jKZK+9ru0ZJyCua0z+qKfo0= Cc: thumbgps-devel@lists.bufferbloat.net Subject: Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 May 2012 22:57:46 -0000 Dave Taht wrote: >On Wed, May 9, 2012 at 1:58 PM, = Ron Frazier (NTP) > wrote: >> I'm just= an interested third party. =C2=A0You guys are running the show. >=C2=A0Use= the >> ideas as you see fit. =C2=A0Just give me some credit if you end up = using >my >> ideas. > >absolutely. Got another fictional character you rese= mble? You're not confusing me with esr are you? I like all captains of st= arships named enterprise, but I don't know if I resemble any of them. Sinc= erely, Ron > >And I'm totally into discussing this stuff, later, but righ= t 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) >>> =C2=A0wrote= : >>> >>>> >>>> Hi guys, >>>> >>>> I do see the point TZ was making about t= he problems of increasing >the >>>> design >>>> and production costs. =C2= =A0However, 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. =C2=A0I know th= ey >>>> exist. >>>> =C2=A0I have no idea about specs and efficiency. =C2=A0= How much amperage and >at >>>> what >>>> voltage is the unit expected to dr= aw if disconnected from the USB >power >>>> source? =C2=A0Is it expected to= continue tracking? =C2=A0I assume this will >change >>>> if >>>> an extern= al antenna is attached. =C2=A0How long should it be maintained? >>>> >>>> = =C2=A0From a user perspective, I'd recommend the following features, if >yo= u >>>> have a >>>> viable choice: >>>> >>>> * Hi sensitivity internal anten= na / chipset that can be used >indoors in a >>>> residential type structure= . >>>> * External antenna port in case you're in a steel building or >basem= ent or >>>> something with no signal. =C2=A0Use commonly available, generic= , >possibly >>>> powered, antennas. >>>> * GPS status led. =C2=A0(My BU-353= slowly flashes when it has a fix, >shows >>>> steady >>>> with power but n= o fix.) =C2=A0The led should be synchronized to the pps. >>>> * Supercap pr= eferably, or battery which is easily user replaceable >and a >>>> common pa= rt number, such as CR2032 for example. =C2=A0That battery may >be too >>>> = big, but you want something readily available. >>>> * If a battery is invol= ved, 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. =C2= =A0Something 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 wis= h to expose the pps signal on a screw terminal or >connector >>>> in >>>> c= ase 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. =C2=A0With my BU-353, the "puck" = device >>>> contains >>>> both the electronics and the antenna. =C2=A0The o= nly cord coming from it >is >>>> the >>>> USB cable. =C2=A0So, it might be = preferable to have a sealed weather >proof >>>> unit, >>>> and just use ext= ension cords for USB rather than extending the RF >>>> section. >>>> =C2=A0= I know you can easily extend USB 10 feet or so. =C2=A0I think you can >go m= uch >>>> further with powered hubs and such. =C2=A0Just 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. =C2=A0Th= is could >feed >>>> power >>>> back to the GPS board and prolong the life o= f the battery or slow >the >>>> drain >>>> of the supercap while powering t= he antenna if the antenna is in the >sun. >>>> =C2=A0You could even draw so= me energy from ambient indoor lighting. =C2=A0I >have a >>>> solar powered = "atomic" watch from Casio that does this. =C2=A0It never >needs a >>>> batt= ery, never needs charging, and never needs setting. =C2=A0Very >handy. =C2= =A0I >>>> also >>>> have two "atomic" wall clocks that do the same thing. = =C2=A0I think they >use a >>>> rechargeable battery instead of a supercap. = >>>> >>>> Here's another idea, which may or may not have already been >disc= ussed. >>>> =C2=A0Do >>>> you want to have an on board RTC, which can keep = outputting valid >time >>>> for a >>>> while, if the satellites are not ava= ilable due to weather, jamming, >>>> interference, etc.? >>>> >>>> Sincerel= y, >>>> >>>> Ron >>>> >>>> >>>> >>>> >>>> On 5/9/2012 2:35 PM, Dave Taht wr= ote: >>>> >>>>> >>>>> 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 al= l. >>>>> >>>>> My concern was that there are 6+ short power flickers a day = - >forcing >>>>> a reboot - in places like Nicaragua. These events are >*in= teresting* >>>>> from a network analysis perspective, as flickers like this= cause >>>>> massive network disturbances. >>>>> >>>>> I don't care about b= attery life longer than about 30 seconds, >although >>>>> a case could be m= ade for 24 hours. Just wanted the analysis of >what it >>>>> would really t= ake, given how little power this thing sucks... >>>>> >>>>> and I hate ANYT= HING that needs a user-replaceable component, 5 >years >>>>> after manufact= ure. So I'd prefer the actual analysis based on >power >>>>> draw, etc, bef= ore >>>>> making any decisions. >>>>> >>>>> >>>>> On Wed, May 9, 2012 at 11= :21 AM, tz =C2=A0 =C2=A0wrote: >>>>> >>>>> >>>>>> >>>>>> I= t doesn't work that way. =C2=A0Microampere DC-DC converters? =C2=A0That >is= n't a >>>>>> swap, >>>>>> it is a redesign, if microamp converters are poss= ible - the base >losses >>>>>> are >>>>>> high so you won't hit a high effi= ciency. =C2=A0You get high >efficiencies >>>>>> when >>>>>> dealing with lo= ts of amps. =C2=A0For it to last overnight you would >need a >>>>>> very >>= >>>> large (physically) cap. >>>>>> >>>>>> There would be no booting proble= m. =C2=A0It would merely lose the >real-time >>>>>> clock >>>>>> and/or loc= ation 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. =C2=A0USB should be constantly providing 5V 99.9% of the tim= e. >>>>>> >>>>>> I could argue that if surviving only a short power disconn= ect 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 ba= tteries can last decades - even Supercaps have a finite >>>>>> lifetime. >>= >>>> =C2=A0It >>>>>> is a matter of cost, both in redesign, size, and relia= bility. >=C2=A0But do >>>>>> you >>>>>> want to add $5-$10 to the cost of t= he unit to make a cheap >($30-$50) >>>>>> GPS >>>>>> last over a decade? = =C2=A0Buy a second, seal it hermetically, and put >it in >>>>>> your >>>>>>= freezer. >>>>>> >>>>>> If you want to add a few thousand in NRE costs, the= re are a lot >of >>>>>> other >>>>>> things I would redesign. =C2=A0Use a U= SB 2.0 chip to get 125uS jitter. >>>>>> =C2=A0Allow >>>>>> for >>>>>> a det= achable or external antenna (which can be run to the >window). >>>>>> =C2= =A0Find >>>>>> a >>>>>> more optimal chipset. =C2=A0Maybe a coin-cell port = so the battery can >be >>>>>> replaceable. =C2=A0But 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 t= han >3.3v on >>>>>> it), >>>>>> you can swap the part. >>>>>> >>>>>> >>>>>>= On Wed, May 9, 2012 at 1:50 PM, Ron Frazier (NTP) >>>>>> =C2=A0 =C2=A0wrote: >>>>>> >>>>>> >>>>>>> >>>>>>> Hi a= ll, >>>>>>> >>>>>>> (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 p= otential user of the thumb-gps device >and >>>>>>> amateur >>>>>>> interest= ed party, I would rather see a supercap, if feasible. =C2=A0I >hate >>>>>>>= the >>>>>>> idea of devices having batteries that I have to worry about >f= ailing in >>>>>>> 5-10 >>>>>>> years. =C2=A0I've had the cmos batteries fai= l in a few computers, >sometimes >>>>>>> preventing them from booting. =C2= =A0It can get really ugly trying to >revive >>>>>>> them >>>>>>> A good hig= h 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. =C2=A0I cannot speak to size issue= s, as I have >never >>>>>>> designed a >>>>>>> circuit board with one. =C2= =A0The GlobalSat BU-353 that I have has a >>>>>>> supercap, I >>>>>>> belie= ve. =C2=A0Exact 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 ci= rcuit board footprint) a supercap will >have >>>>>>> much >>>>>>> less capa= city 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. = >>>>>>> =C2=A0This >>>>>>> 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 un= til it is >nearly >>>>>>> exhausted, >>>>>>> and can hold the data for days= or weeks. >>>>>>> >>>>>>> On Wed, May 9, 2012 at 12:55 PM, Dave Taht >>>>>>> =C2=A0wrote: >>>>>>> >>>>>>> >>>>>>>> >>>>>>>> On W= ed, May 9, 2012 at 9:47 AM, Eric S. >Raymond >>>>>>>> =C2= =A0wrote: >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> Dave Taht: >>>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>> 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, >>>>>>>> bu= t what price, forever? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> -- >>= >>>>>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Eric S. >>>>>>>>> Raymond >>>>>>>>> >>>>>>>>>= >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Dave T=C3=A4ht >>>>>>>> SK= YPE: davetaht >>>>>>>> US Tel: 1-239-829-5608 >>>>>>>> http://www.bufferblo= at.net >>>>>>>> >>>>>>>> >> >> >> >> -- >> >> (To whom it may concern. =C2= =A0My email address has changed. =C2=A0Replying to >former >> messages prio= r to 03/31/12 with my personal address will go to the >wrong >> address. = =C2=A0Please 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. =C2=A0I don't always see new messages very quickly. =C2=A0If you ne= ed a >> reply and have not heard from me in 1 - 2 weeks, send your message = >again.) >> >> Ron Frazier >> timekeepingdude AT techstarship.com >> > > > = >-- >Dave T=C3=A4ht >SKYPE: davetaht >US Tel: 1-239-829-5608 >http://www.b= ufferbloat.net -- Sent from my Android Acer A500 tablet with bluetooth k= eyboard 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 m= e and don't get a quick response, don't be concerned. I get about 300 email= s 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 fro= m me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude= AT techstarship.com