From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f43.google.com (mail-yw0-f43.google.com [209.85.213.43]) (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 1E643200BFD for ; Wed, 2 May 2012 14:43:05 -0700 (PDT) Received: by yhkk6 with SMTP id k6so425005yhk.16 for ; Wed, 02 May 2012 14:43:04 -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=K81xjWkRgAbWN4VVtbL/Zf/sw6tL9SUBwcPlIiudgq4=; b=loLTVN9GgqpCjMuJkI0P7TcOI3xlq9JKqB9jZfkCxS9bTZboilSpsTk34C7o/CmF9S kMHiFIMVDqCt3NG8fWioINCFDyYfdIcLywflxttmosbz1pw59T/8y2fv+XG7ty3tZpZJ /ccmNzfpn3WDK5lC5zoc5S1nDfi/xqr1y4QNZTtuidgx3WFdnFWR3EgaE/X1Jjo2gomZ QkI14pj81zqv2BU2ZzUC8dMcJvoYq/gp4Ld8YhO+JI87Z4ELaYa8vphNlthPUH6oqt6C 8u4gGN1iDCnarlzF0Tor1FmpTOQBIcS/J2RbeMJlIL1oedswATpCEGoXJ+/gA1Z8t5Xg GTGQ== MIME-Version: 1.0 Received: by 10.60.31.67 with SMTP id y3mr40941794oeh.41.1335994982529; Wed, 02 May 2012 14:43:02 -0700 (PDT) Received: by 10.182.113.40 with HTTP; Wed, 2 May 2012 14:43:02 -0700 (PDT) Received: by 10.182.113.40 with HTTP; Wed, 2 May 2012 14:43:02 -0700 (PDT) In-Reply-To: <20120502211935.9EAE180003B@ip-64-139-1-69.sjc.megapath.net> References: <20120502131310.7dd7f799.gem@rellim.com> <20120502211935.9EAE180003B@ip-64-139-1-69.sjc.megapath.net> Date: Wed, 2 May 2012 17:43:02 -0400 Message-ID: From: tz To: Hal Murray Content-Type: multipart/alternative; boundary=e89a8f647b715afb7a04bf149212 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 21:43:06 -0000 --e89a8f647b715afb7a04bf149212 Content-Type: text/plain; charset=ISO-8859-1 Depending on the gps, there can be a dead-reckoning mode that will extrapolate things for some time (often settable). The pps may or may not follow. On May 2, 2012 5:19 PM, "Hal Murray" wrote: > > gem@rellim.com said: > > Looking for that check in the gpsd code, I do not see it in the PPS path > or > > in the NMEA path. I wonder when that disappeared? That may explain some > > things... I'll go add that back in now. > > I think there is another piece of fine print in that area. I'm not sure > where I saw it, probably one of the Garmin docs. > > The idea is that you can't trust the first few seconds of data when it > switches from not-enough satellites to enough. I've seen it give bogus > position (way off) marked as valid. I think they all happened right after > recovering from not-enough-satellites. > > I'll scan log files if anybody wants examples. > > > -- > These are my opinions, not necessarily my employer's. I hate spam. > > > > --e89a8f647b715afb7a04bf149212 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

Depending on the gps, there can be a dead-reckoning mode that will extra= polate things for some time (often settable).=A0 The pps may or may not fol= low.

On May 2, 2012 5:19 PM, "Hal Murray" &= lt;hmurray@megapathdsl.net&g= t; wrote:

gem@rellim.com said:
> Looking for that check in the gpsd code, I do not see it in the PPS pa= th or
> in the NMEA path. =A0I wonder when that disappeared? =A0That may expla= in some
> things... =A0I'll go add that back in now.

I think there is another piece of fine print in that area. =A0I'm not s= ure
where I saw it, probably one of the Garmin docs.

The idea is that you can't trust the first few seconds of data when it<= br> switches from not-enough satellites to enough. =A0I've seen it give bog= us
position (way off) marked as valid. =A0I think they all happened right afte= r
recovering from not-enough-satellites.

I'll scan log files if anybody wants examples.


--
These are my opinions, not necessarily my employer's. =A0I hate spam.


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