Re: [gpsd-users] GPS reporting wrong time to SHM

[Alexander Carver]

On 8/16/2012 01:31, Eric S. Raymond wrote:
> Alexander Carver <address@hidden>:
> > It now appears that my calculation was off in sign and I wasn't a
> > second in the future, I was a second in the past.  I modified
> > timebase.h to set the leap seconds to 16.  So the question is why is
> > gpsd (or at least my copy) ignoring MID 52 completely?
>
> Good question. Here's what you can do to help answer it.
>
> 1. Capture a log that contains a MID52.
>
> 2. Verify that the log contains a MID52 by replaying the log with
>     gpsfake and checking with either gpsmon or by turning the
>     debug level of gpsd up to where it dumps packets.
>
> 3. Post the log here, so I and others can replay it in our environments.

I'll get a log for you later this week but as a quick test I 
instrumented the large switch structure in driver_sirf.c (it's the 
switch(buf[0]) on or about line 1094) that identifies the message ID and 
then calls the appropriate functions.  The case statement for MID 52 
never fires.  I also changed the report just before that switch 
statement (the raw packet ID message) so that it would fire at a lower 
debug level (gpsd is very slow to start up at D7 so I changed it to 
LOG_PROG instead of LOG_RAW).  No detection of MID 52 there either.

SiRFDemo's log shows it does exist on the wire (note this is parsed out 
by SiRFDemo so it's not a raw binary log).  You can see the first number 
in some of the lines is 52 which is the message itself.  The time is 
right (approximately 19:10:15 UTC when I started the log), the date is 
right (16-08-2012) and the leap seconds are right (16.0) and the status 
is 0x07 (time is valid, UTC time reported, time is not stale).  I'll 
work on a binary capture to feed into gpsfake.



SiRFDemo log:
4,677,41463073,12,1,64,22,191,34,31,31,32,32,31,32,29,33,32,8,111,53,191,48,48,48,48,48,48,47,47,48,48,7,127,15,191,30,31,30,31,32,31,31,30,30,31,27,315,17,191,41,40,40,40,40,40,40,40,41,41,26,252,48,191,40,40,40,40,39,40,39,40,40,39,4,172,8,191,32,32,31,32,31,31,31,30,31,32,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,193,77,191,45,44,44,44,44,44,43,44,44,44,28,19,58,191,41,41,41,41,41,41,40,41,41,41,11,48,14,191,38,38,38,38,38,38,37,37,38,38,15,298,26,191,40,41,41,40,41,41,41,41,41,41,138,160,48,63,39,40,40,40,40,39,40,40,40,40
2,-2499843,-4649019,3569234,0.000,-0.125,-0.125,132,1.0,2,677,41463073,9,1,8,7,27,26,17,28,11,15,0,0,0
27,1,3,3,3,3,3,3,3,3,3,3,0,0,1,-884,4,-1848,7,-1318,8,-472,11,-1151,15,-763,17,-427,26,-559,27,-734,28,-455,0,0,0,0
52,19,10,15,16,8,2012,16,0,7
Visible List
SVID:17  Az:194  El:078
SVID:28  Az:021  El:058
SVID:08  Az:111  El:053
SVID:26  Az:252  El:048
SVID:15  Az:299  El:026
SVID:01  Az:064  El:022
SVID:27  Az:316  El:017
SVID:07  Az:128  El:015
SVID:11  Az:049  El:014
SVID:04  Az:173  El:008

4,677,41463173,12,1,63,22,191,32,32,33,30,33,32,31,31,33,32,8,111,53,191,48,48,48,48,48,47,48,48,48,48,7,127,15,191,31,31,31,32,31,31,32,31,31,30,27,315,17,191,40,40,40,40,40,39,40,40,40,40,26,252,48,191,39,40,39,39,39,39,39,39,40,40,4,172,8,191,31,32,32,33,33,33,33,32,33,33,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,193,78,191,44,44,44,44,44,44,44,44,44,44,28,21,58,191,41,41,41,41,41,41,41,41,42,41,11,48,14,191,38,37,37,37,37,37,36,37,38,38,15,298,26,191,41,41,40,41,41,41,41,40,41,41,138,160,48,63,40,40,40,40,40,40,40,40,40,40
2,-2499842,-4649019,3569234,0.000,0.000,0.000,132,1.0,2,677,41463173,9,1,8,7,27,26,17,28,11,15,0,0,0
27,1,1,1,1,1,1,1,1,1,1,1,0,0,1,-882,4,-1839,7,-1327,8,-475,11,-1154,15,-760,17,-428,26,-559,27,-730,28,-453,0,0,0,0
52,19,10,16,16,8,2012,16,0,7
4,677,41463273,12,1,63,22,191,31,32,33,30,32,30,31,33,33,31,8,111,53,191,48,48,48,48,48,47,47,48,47,47,7,127,15,191,30,31,30,30,30,31,31,31,31,31,27,315,17,191,40,40,40,40,40,40,40,40,40,40,26,252,48,191,39,40,39,40,40,40,40,40,40,39,4,172,8,191,33,33,33,33,33,32,32,33,32,32,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,193,78,191,44,45,44,44,45,44,44,44,44,44,28,21,58,191,41,41,41,42,41,41,41,41,42,41,11,48,14,191,37,38,38,38,38,38,38,38,38,38,15,298,26,191,40,41,41,41,40,41,41,40,41,41,138,160,48,63,39,40,39,39,39,39,39,39,40,39
2,-2499842,-4649018,3569233,0.000,-0.125,0.000,132,1.0,2,677,41463273,9,1,8,7,27,26,17,28,11,15,0,0,0
27,1,1,1,1,1,1,1,1,1,1,1,0,0,1,-880,4,-1842,7,-1329,8,-477,11,-1156,15,-791,17,-398,26,-590,27,-728,28,-451,0,0,0,0
52,19,10,17,16,8,2012,16,0,7
4,677,41463373,12,1,63,22,191,33,30,33,31,33,33,33,32,34,32,8,111,53,191,48,48,48,48,48,48,48,48,48,47,7,127,15,191,33,32,32,31,32,30,32,30,28,32,27,315,17,191,40,40,40,40,41,40,40,40,41,41,26,252,48,191,40,40,40,39,40,39,39,39,39,39,4,172,8,191,32,32,33,33,33,33,34,33,33,34,0,0,0,0,0,0,0,0,0,0,0,0,0,0,17,193,78,191,44,44,44,44,45,44,44,44,44,44,28,21,58,191,41,41,41,42,42,41,42,41,41,41,11,48,14,191,38,38,38,38,39,38,38,38,38,38,15,298,26,191,41,41,40,40,41,41,41,41,41,41,138,160,48,63,39,39,39,39,39,39,39,39,39,39