NTP via tcp NMEA feed

[Nick Taylor]

Hi guys

You may have seen that we are working with using tcp NMEA feeds for a 
device that we built - basically certain customers have existing GPS 
devices and wish to use feed from that instead of separate antenna...

Additionally often Internet connectivity is firewalled back so we drop 
back to using GPS time rather than proper NTP

Now I notice that I don't seem to see NTP coming through from NTP feed - 
the only success we had was using the shm feed and with normal setup 
ntpshmmon shows normal time feed coming through nicely which we can then 
link into chrony.

Is this expected behaviour or a bug? Is there any way to still get NTP 
from a tcp NMEA feed??

TIA

Nick

root@TSB-318:~# uname -a
Linux TSB-318 4.4.19-itb2.02 #1 PREEMPT Fri Feb 4 18:18:14 UTC 2022 
armv7l GNU/Linux
root@TSB-318:~# gpsd -V
gpsd: 3.24.1~dev (revision release-3.24-274-g1df61193e)
root@TSB-318:~#

root@TSB-318:~# gpspipe -r
{"class":"VERSION","release":"3.24.1~dev","rev":"release-3.24-274-g1df61193e","proto_major":3,"proto_minor":15} 

{"class":"DEVICES","devices":[{"class":"DEVICE","path":"tcp://192.168.2.53:2948","driver":"NMEA0183","activated":"2022-10-14T12:15:57.315Z","flags":1
}]}
{"class":"WATCH","enable":true,"json":false,"nmea":true,"raw":0,"scaled":false,"timing":false,"split24":false,"pps":false} 

$GNGGA,121558.000,5136.9292,N,00011.1093,W,1,11,1.35,88.4,M,47.0,M,,*50
$GPGSA,A,3,04,11,02,16,09,29,20,,,,,,1.63,1.35,0.91*08
$GLGSA,A,3,84,67,68,76,,,,,,,,,1.63,1.35,0.91*17
$GNRMC,121558.000,A,5136.9292,N,00011.1093,W,0.94,199.78,141022,,,A*65
$GNZDA,121558.000,14,10,2022,,*44
$GPGRS,121558.000,1,5.18,-7.62,-4.83,1.78,-0.05,-1.78,6.24,0.09,-0.97,-0.72,-2.63,*47 

$GPGST,121558.000,3.3,10,4.4,12.1,9.7,4.8,17*5A
$GNGGA,121559.000,5136.9287,N,00011.1096,W,1,12,0.94,88.3,M,47.0,M,,*5E
$GPGSA,A,3,04,11,02,06,16,09,29,20,,,,,1.26,0.94,0.84*01
$GLGSA,A,3,84,67,68,76,,,,,,,,,1.26,0.94,0.84*18
$GNRMC,121559.000,A,5136.9287,N,00011.1096,W,1.23,220.94,141022,,,A*6B
$GNZDA,121559.000,14,10,2022,,*45
$GPGRS,121559.000,1,3.42,-5.72,-3.67,11.0,2.27,-0.23,-1.94,4.96,2.01,-1.62,-1.43,-0.61,*75 

$GPGST,121559.000,3.3,11,4.3,12.4,11,4.8,19*76
^C
root@TSB-318:~# ntpshmmon
ntpshmmon: version 3.24.1~dev
#      Name  Seen@                 Clock                 Real 
                L Prc
^C
root@TSB-318:~#