[gpsd-users] gpsd serves wrong time. (when GPS is not recieving)

[浦部直也]

Hi, all.

I'm using gpsd 3.7 on my time server built with Debian 4.0.

It's serving time source to ntpd (4.2.6p3), by 127.127.28.1 
which is refering PPS from GPS antena.

Garming GPS 18x LVC is connected via /dev/ttyS0 and serving 
serial message and PPS signal.

It's working properly, if GPS antenna gets enough signal from 
satellites. (when GGA sentence shows GPS quality to 1 or 2)

But if GPS antenna can't get enough signal from satellites (when GGA 
sentence shows GPS quality to 0) and this situation continues while
several hours, then system time of the server returns to several
hours ago.

It's repeats probably eternaly. so server's sytem time repeating 
 between two or three hours.

Could you help to make gpsd to service correct time even if 
GPS signal reached or unreached. At least the server should 
serve by self driven clock.

Here is peerstats of my ntpd.

56325 27278.202 127.127.28.1 9654 0.004145022 0.000000000 0.000717936 
0.001470032
56325 27342.201 127.127.28.1 9654 0.000000000 0.000000000 8.000830983 
0.003432048
56325 27358.201 127.127.28.1 9654 0.000000000 0.000000000 12.000468913 
0.003360884
56325 27374.201 127.127.28.1 9654 0.000000000 0.000000000 14.000257878 
0.002857348
56325 27390.201 127.127.28.1 9654 0.000000000 0.000000000 15.000137360 
0.000488281
56325 27406.201 127.127.28.1 8654 0.000000000 0.000000000 15.500069601 
0.000488281
56325 27422.201 127.127.28.1 8063 0.000000000 0.000000000 15.750031972 
0.000488281
56325 27438.200 127.127.28.1 8063 0.000000000 0.000000000 15.875011282 
0.000488281
 -> GPS antenna lost the signal here. ***
56325 31566.203 127.127.28.1 9074 -4294.894606980 0.000000000 7.937744141 
0.000488281
 -> Still lost the signal, but clock from gpsd is arrive.
56325 31559.309 127.127.28.1 9094 -4294.897130980 0.000000000 7.937744141 
0.000488281
56325 31623.306 127.127.28.1 9694 0.000000000 0.000000000 11.937862070 
0.000488281
56325 35863.310 127.127.28.1 96b4 -8589.794324982 0.000000000 7.937744141 
0.000488281
56325 40151.310 127.127.28.1 96d4 -12884.691575984 0.000000000 7.937744141 
0.000488281
56325 31570.617 127.127.28.1 9014 -4294.897224980 0.000000000 7.937744141 
0.000488281
 -> The clock of gpsd returns 8581 seconds.
56325 31634.614 127.127.28.1 9614 0.000000000 0.000000000 11.937862070 
0.000488281
56325 35858.619 127.127.28.1 9634 -8589.794484982 0.000000000 7.937744141 
0.000488281
56325 40162.619 127.127.28.1 9654 -12884.691726985 0.000000000 7.937744141 
0.000488281
 -> It's repeats more than several days.

Thanks.

Naoya Urabe