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Re: [gpsd-dev] RFC: GPSd on Android as a system service
From: |
Greg Troxel |
Subject: |
Re: [gpsd-dev] RFC: GPSd on Android as a system service |
Date: |
Fri, 03 May 2019 07:12:02 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (berkeley-unix) |
"Gary E. Miller" <address@hidden> writes:
> You have an interesting heuristic. I looked at the u-blox regressions with
> ubxtool. Once you have elevation and azimuth, you have the Ephemeris.
>
> Makes sense because you computer elevation and azimuth from your
> position and the Ephmeris data.
I don't follow this, because the almanac exists to let you compute
elevation and azimuth roughly, so you can know what's above the horizon
and guess at the doppler shift.
I have a new device ("VFAN", with ublox M8030), and I was seeing
satellites listed with az/el, el near 0, 0 C/N, and apparently not
tracked. I suspect those have almanac and not ephemeris.
> In almost all cases the GPS either has both Almanac and Ephemeris at the
> same. A few cases of startup have the Almanac a few cycles after the
> Ephemeris, not worth trying to figure out that narrow window. Just set
> both if you have elevation and azimuth.
Agreed that almanac is not worth worrying about, as usually it is kept
and around later.
> Or just set them on all the time as gpsd does not put sats with no
> elevation and azimuth in the JSON.
I think it's useful to know the locations the satellites that aren't
being tracked.
But maybe I'm missing something.
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> address@hidden Tel:+1 541 382 8588
>
> Veritas liberabit vos. -- Quid est veritas?
> "If you can’t measure it, you can’t improve it." - Lord Kelvin
Pp
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, A.S., 2019/05/02
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Gary E. Miller, 2019/05/02
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Adam Serbinski, 2019/05/02
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- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Adam Serbinski, 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Gary E. Miller, 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, A.S., 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Gary E. Miller, 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, A.S., 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Gary E. Miller, 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Adam Serbinski, 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Gary E. Miller, 2019/05/06
- Re: [gpsd-dev] RFC: GPSd on Android as a system service, Adam Serbinski, 2019/05/06