From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f171.google.com (mail-ob0-f171.google.com [209.85.214.171]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 5CBE82020B8 for ; Wed, 2 May 2012 04:09:11 -0700 (PDT) Received: by obfk16 with SMTP id k16so1581535obf.16 for ; Wed, 02 May 2012 04:09:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=XScgQcjb54c9RpFe/+RS2BJNJOkv9pP3M+cl3U/jOoI=; b=ZE0DUMiepzUHVIfVUGIAlesPONAzxh1960Y+PArHSwnGn9bntloV86+v1ezbMRTVIe wEinFEONXoLsm5FpoYwx8v3idx8tFyopyW+TZfhJV1SrJZ+N/U8pzwtMQlUUdjJIFvwT IntITuYu3FXf/ZLqAvbgjHpD+PennHIQ2aDCHNpahyGJcc4Q6R+Xd6zZN7a4aXRpuzW7 NMHxVpkfDlLNFcj6yPFSsxJ0861ciV/85hMphn98bqA+POn1cT1IfeYVF72wb+X6a0em ElSCKg437QGdcwINxppB2fxk3dYZoZJu8b65Su4et6fUCdGGggHgu/s6RyvfPC3OIKN4 tgeg== MIME-Version: 1.0 Received: by 10.182.183.73 with SMTP id ek9mr13781322obc.15.1335956949803; Wed, 02 May 2012 04:09:09 -0700 (PDT) Received: by 10.182.113.40 with HTTP; Wed, 2 May 2012 04:09:09 -0700 (PDT) Received: by 10.182.113.40 with HTTP; Wed, 2 May 2012 04:09:09 -0700 (PDT) In-Reply-To: <20120502033345.GA11913@thyrsus.com> References: <20120501151435.4a6a5373.gem@rellim.com> <20120502033345.GA11913@thyrsus.com> Date: Wed, 2 May 2012 07:09:09 -0400 Message-ID: From: tz To: esr@thyrsus.com Content-Type: multipart/alternative; boundary=f46d04478a316da3a604bf0bb755 Cc: thumbgps-devel@lists.bufferbloat.net, gpsd-dev@nongnu.org Subject: Re: [Thumbgps-devel] [gpsd-dev] PPS over USB 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, 02 May 2012 11:09:11 -0000 --f46d04478a316da3a604bf0bb755 Content-Type: text/plain; charset=ISO-8859-1 SkyTraq has a different version of the 638 (not just different firmware) that emits corrections to the pps edge to go to 10nS, and after a lock it will work down to 1 satellite and maintain accurate pps. I don't know of any others that retain pps if they don't have a 3d lock. The antenna is important but it won't overcome an obscured view of the sky - at best you will get multipath or other errors with the weak signals. On May 1, 2012 11:33 PM, "Eric S. Raymond" wrote: > Dave Taht : > > I'm a little confused. > > > > There are two threads going by today. One is about a sirfIII and the > > other a ublox 6 > > > > I have been assuming they are one and the same, but perhaps I'm confused. > > You are. The first set of prototypes, from UniTraq, were SiRF-III + > CP2101. > These won't do - turns out the CP2101 driver can't wait on a handshake > state > change because the vendor never released enough programnming information. > > Gary is talking about the second set of prototypes, from NaviSys. > That's the uBlox + PL2303 device. It works. The next step is to > get them into volume production. > > > Secondly an item that has not been looked into much is the quality of > > the antennas, or the quality of the clock source when only a single > > sat is available.... > > Quality of antenna will matter for the device's ability to function in > weak-signal conditions, e.g. indoors. Clock time should be OK even with > a single sat - multiple birds are needed for the spherical trig to compute > position, but atomic time you get directly from each sat sample. > > > Thirdly, wow.... when can I get one of these puppies to play with? > > Gary has three. He's keeping one and sending me the second. Since OpenBSD > has no TICMIWAIT, Chris Kuethe is out of contention for the third and it > should logically go to you. > -- > Eric S. Raymond > _______________________________________________ > Thumbgps-devel mailing list > Thumbgps-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/thumbgps-devel > --f46d04478a316da3a604bf0bb755 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

SkyTraq has a different version of the 638 (not just different firmware)= that emits corrections to the pps edge to go to 10nS, and after a lock it = will work down to 1 satellite and maintain accurate pps.

I don't know of any others that retain pps if they don't have a = 3d lock.

The antenna is important but it won't overcome an obscured view of t= he sky - at best you will get multipath or other errors with the weak signa= ls.

On May 1, 2012 11:33 PM, "Eric S. Raymond&q= uot; <esr@thyrsus.com> wrote:<= br type=3D"attribution">
Dave Taht <dave.taht@gmail.com>:
> I'm a little confused.
>
> There are two threads going by today. One is about a sirfIII and the > other a ublox 6
>
> I have been assuming they are one and the same, but perhaps I'm co= nfused.

You are. =A0The first set of prototypes, from UniTraq, were SiRF-III + CP21= 01.
These won't do - turns out the CP2101 driver can't wait on a handsh= ake state
change because the vendor never released enough programnming information.
Gary is talking about the second set of prototypes, from NaviSys.
That's the uBlox + PL2303 device. =A0It works. =A0The next step is to get them into volume production.

> Secondly an item that has not been looked into much is the quality of<= br> > the antennas, or the quality of the clock source when only a single > sat is available....

Quality of antenna will matter for the device's ability to function in<= br> weak-signal conditions, e.g. indoors. =A0Clock time should be OK even with<= br> a single sat - multiple birds are needed for the spherical trig to compute<= br> position, but atomic time you get directly from each sat sample.

> Thirdly, wow.... when can I get one of these puppies to play with?

Gary has three. =A0He's keeping one and sending me the second. =A0Since= OpenBSD
has no TICMIWAIT, Chris Kuethe is out of contention for the third and it should logically go to you.
--
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0<a href=3D"http://www.catb.org/~esr/">Eric= S. Raymond</a>
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