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Re: [External] Re: Time precision in gps_fix_t
From: |
Greg Troxel |
Subject: |
Re: [External] Re: Time precision in gps_fix_t |
Date: |
Wed, 22 Jan 2020 15:34:51 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (berkeley-unix) |
"Gary E. Miller" <address@hidden> writes:
> Yo Greg!
>
> On Wed, 22 Jan 2020 12:54:12 -0500
> Greg Troxel <address@hidden> wrote:
>
>> "Gary E. Miller" <address@hidden> writes:
>>
>> > Yo Greg!
>> >
>> > On Wed, 22 Jan 2020 12:16:02 -0500
>> > Greg Troxel <address@hidden> wrote:
>> >
>> >> All true, but Marco asked a perfectly fair question about gpsd
>> >> losing the subsecond time-of-fix.
>> >
>> > I see no evidence of that. If that is true it is a serious bug.
>>
>> I don't have the logs handy, but I was doing captures of the json data
>> (gpspipe -w) from an M8030 set to 2 Hz. Adjacent lines had the same
>> timesstamps, both with 0 subsecond fix times.
>
> Multiple TPV with the same time stamp is not unusual. Care to share your
> raw dumps?
Sorry, I don't have raw dumps available to share. I will if I can
generate some.
This was a clear pattern of two TPV lines with the same timestamp, for
every second.
> Regardless, getting time to 100 micro seconds from the serial data
> is unlikely by at least 2 orders of magnitude.
I am not talking about time sync. If one has > 1 Hz positions, you
want to be able to have those time tagged correctly so you can
interpolate based on your (synchronized) system clock to get
within-second position estimates. This is a very noticable issue with
lots of nav programs on android (probably more about not extrapolating
the pointer, vs multiple positions per s).
- Time precision in gps_fix_t, Marco Spanghero, 2020/01/21
- Re: Time precision in gps_fix_t, Gary E. Miller, 2020/01/21
- Re: Time precision in gps_fix_t, Greg Troxel, 2020/01/22
- [External] Re: Time precision in gps_fix_t, Burton, John, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t, Greg Troxel, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t, Gary E. Miller, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t, Greg Troxel, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t, Gary E. Miller, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t,
Greg Troxel <=
- Re: [External] Re: Time precision in gps_fix_t, Gary E. Miller, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t, Kai Harrekilde-Petersen, 2020/01/22
- Re: [External] Re: Time precision in gps_fix_t, Gary E. Miller, 2020/01/22
- Re: Time precision in gps_fix_t, Gary E. Miller, 2020/01/22
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