[LinuxPPS] Synchronizing a ZDA message with NTP using linuxPPS

[Ben DuPont]

Divi.Oillo at ifremer.fr wrote:
> Hi
>
> Here is my new ntp.conf (NMEA disabled + stratum 15 on local clock)
>
> ------------------------------------------------------------
> #Undisciplined Local Clock
> server 127.127.1.0
> fudge 127.127.1.0 stratum 15
>
> #Generic NMEA GPS Receiver
> #server 127.127.20.0 mode 8 minpoll 4 maxpoll 16 prefer
> #fudge 127.127.20.0 flag1 1 flag2 0 flag3 1
>
> #PPS Clock Discipline
> server 127.127.22.0 minpoll 4 maxpoll 16
> fudge 127.127.22.0 flag2 0 flag3 1
>
> #134.246.11.121
> server ntpserver minpoll 4 maxpoll 16 prefer
> -------------------------------------------------------------
>
> ldattach 18 /dev/ttyS0
>
> sudo ./ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> source 0 - assert 1269202324.429792497, sequence: 19 - clear   
> 1269202324.929765692, sequence: 19
> source 0 - assert 1269202325.429609642, sequence: 20 - clear   
> 1269202324.929765692, sequence: 19
> source 0 - assert 1269202325.429609642, sequence: 20 - clear   
> 1269202325.929522149, sequence: 20
> source 0 - assert 1269202326.429642163, sequence: 21 - clear   
> 1269202325.929522149, sequence: 20
>
> techsas:> cat /sys/devices/virtual/pps/pps*/assert
> 1269202380.425496211#75
> techsas:> cat /sys/devices/virtual/pps/pps*/assert
> 1269202382.425170657#77
>
> techsas:> sudo ntpd
>
> techsas:> ntpq -pn
>       remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *127.127.1.0     .LOCL.          15 l   37   64   17    0.000    0.000   0.001
> x127.127.22.0    .PPS.            0 l    4   16  377    0.000  -403.35   5.537
> x134.246.11.121  .1PPS.           1 u   63   64   37    0.187   80.869   5.745
>
> It seems that PPS works?
>
> but sometimes I have:
> techsas:> sudo ./ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> time_pps_fetch() error -1 (Connection timed out)
> time_pps_fetch() error -1 (Connection timed out)
>
> And I need to kill ldattach and restart it (ldattach 18 /dev/ttyS0)
>
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>
>
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>   

What gps hardware are you using?  What kernel and ntp version are you 
using and what patches (if any)?

Ben