knro wrote: Ok so I did a little bit more research and turns out using GPS for NTP is useless unless your GPS unit provides precise timing via PPS. The majority of GPS dongles don't support this. Check if your is supported here: www.catb.org/gpsd/hardware.html
I configured NTP to use GPS on StellarMate, and when I ran ntpq -p, I got this:stellarmate@stellarmate:~$ ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
0.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.001
1.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.001
2.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.001
3.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.001
ntp.ubuntu.com .POOL. 16 p - 64 0 0.000 0.000 0.001
SHM(0) .GPS. 0 l - 16 0 0.000 0.000 0.000
SHM(1) .PPS. 0 l - 16 0 0.000 0.000 0.000
+sv1.localdomain 133.243.238.163 2 u 28 64 17 194.561 1.265 10.837
*time.iqnet.com 62.201.214.162 2 u 26 64 17 176.547 10.442 14.519
+x.ns.gin.ntt.ne 249.224.99.213 2 u 29 64 7 157.242 8.576 3.270
hachi.paina.net 131.113.192.40 2 u 86 64 2 241.538 21.487 2.448
-mail.lumajangka 203.160.128.132 3 u 25 64 7 330.810 5.412 3.812
-202.143.124.3 ( 194.190.168.1 2 u 19 64 7 231.419 1.184 1.969
-one.itnet.am 93.123.39.67 2 u 26 64 7 171.718 10.273 1.899
It's using online NTP servers even though I attached a GPS and it can "read" from it, but because it doesn't have PPS, it's useless. So I'd say just use GPS NMEA driver for time synchronization. The ones that provide PPA can be pretty expensive and not really worth it unless you're need nanosecond timings.
Here's something interesting, on my Stellarmate, I can't even go into ntpq or any other ntp related register. I always get "Connection Refused". I freshly installed the image once again and tried getting into NTP, but still get the error code=5 message. Like I said before, I tried purging timesyncd and reinstalling NTP. It just doesn't want to run on the Pi. This version of MATE is just crippled and I don't have the knowledge to make it do what I want to do.
And judging by the GPS:Smartphone thread, it doesn't look like THAT is working well either. You simply CANNOT have the Pi3 online when testing GPSD or NMEA, the results are false readings. Disconnect power to the Pi3, unplug the network cable, wait for the residual memory to clear, then apply power. The time will reset to whatever and WILL NOT COME BACK unless it is given an internet connection, PERIOD. This is not SYSTEM TIME, this is the time setting on the MOUNT location tab and KSTARS. That is my experience.
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