[hafqa] [hafqa] [Bug 2877] New: Incorrect GPS timestamps reported over D-BUS

[From: bugzilla-daemon at lists.maemo.org]

https://bugs.maemo.org/show_bug.cgi?id=2877

           Summary: Incorrect GPS timestamps reported over D-BUS
           Product: System software
           Version: 4.0
          Platform: N810
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Medium
         Component: general
        AssignedTo: carlos at maemo.org
        ReportedBy: response at gmail.com
         QAContact: hafqa at maemo.org


SOFTWARE VERSION:
(Control Panel > General > About product)

OS2008 Final

STEPS TO REPRODUCE THE PROBLEM:

When GPS is on, fix data is sent over D-BUS several times a second

[user at nokia ~]$ dbus-monitor --system
signal sender=:1.76 -> dest=(null destination) path=/org/gpsd;
interface=org.gpsd; member=fix
   double 1.20207e+09
   int32 0
   double 0.005
   double 47.xxx
   double -122.xxx
   double nan
   double 131.1
   double nan
   double 313.06
   double nan
   double 0
   double nan
   double 0
   double nan

The first double in this message is the GPS time (in UTC). The time is always
exactly 1 day (24 hours) larger than it should be

[user at nokia ~]$ python
>>> from time import *
>>> ctime(1.20207e+09)
'Sun Feb 3 12:20:00 2008'
>>> ctime()
'Sat Feb 2 11:29:25 2008'

In the example above, dbus-monitor displays the double value with 5 significant
digits, losing 4 digits (10000 seconds = 2.5 hours). However, if I hack
dbus-monitor to display doubles with %f instead %g, the times match exactly
(down to the second), while the date is always 1 off.

EXPECTED OUTCOME:

GPS time should match UTC time.

ACTUAL OUTCOME:

GPS time is 86400 seconds greater than UTC time.

REPRODUCIBILITY:
(always/sometimes/once)

always

EXTRA SOFTWARE INSTALLED:

OTHER COMMENTS:

I get the same problem with external GPSs, so if there is a bug it is likely in
gpsd and not in gpsdriver.

I wonder if this bug contributes to slow satellite acquisition times on N810.
If there is an off-by-one error in gpsd, perhaps the internal GPS is
initialized with an incorrect time, invalidating almanac / ephemeris data.


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