[gpsd-users] 1PPS works on CH340G based usb-serial converter

[Chen Wei]

hi list,

The GPS is a ublox-5 module. The 1PPS wire is soldered to CH340G's DCD
pin:

https://dl.dropboxusercontent.com/u/509097/CH340G-usb-gps-1PPS.png

NTP only works with PPS from gpsd shared memory. The Type 22 reference
clock of NTP is not working, probably because the 1PPS from this USB-GPS
combination is not good enough, which indicated by the kernel error
message "hardpps: PPSJITTER: bad pulse". The kernel accept 1PPS from the
same GPS module when it connected to GPIO though.

The jitter of this USB-GPS is around 300-700 micro-seconds.

remote           refid       st t when poll reach   delay   offset  jitter
==========================================================================
-10.0.0.1       71.80.83.0    2 u    5   64  377    0.460   1.934   0.181
-10.0.0.6       133.100.8.2   2 u   56   64  377    0.362   3.074   0.416
-118.163.81.62  192.168.0.2   2 u   92  512  377   45.559   1.034   0.502
+133.100.8.2    .GPS.         1 u  234  512  165   99.013   3.982   0.681
-118.143.17.82  .MRS.         1 u  662  512  176   39.613  10.487   0.507
+127.127.28.0   .GPS.         0 l   12   16  377    0.000   1.909   1.067
*127.127.28.1   .PPS.         0 l   11   16  377    0.000   0.219   0.438



-- 
Chen Wei