Local GPS NTP Time Server

Accessible at: 192.168.1.12 Project files stored here: “\\192.168.1.11\zfs_mirror3\Projects\Dormant\NTP Raspberry Pi Server” 

 Build Data 

 Runs Raspian on a Raspberry PI 

 Static IP Address was set in: /etc/dhcpcd.conf 

 

 Installed ntpstat with this: 

 sudo apt install ntpstat 

 Usage 

 Here's some descriptions of the different tools for administrating NTP. 

 NTPSTAT 

 Use ntpstat to check if the NTP service is in sync: 

 ntpstat 

 It will return something like this: 

 synchronised to NTP server (149.20.54.20) at stratum 3 

 time correct to within 42 ms

 polling server every 1024 s 

 For our local NTP server (with GPS receiver), we see this: 

 pi@raspberrypi:~ $ ntpstat

synchronised to UHF radio at stratum 1

 time correct to within 2 ms

 polling server every 64 s 

 The ntpstat utility also returns an exit status, as a quick tell of synchronization. 

 Use this, following a call to ntpstat: 

 echo $? 

 The return value will mean one of these: 

 

 If exit status 0 – Clock is synchronised. 

 exit status 1 – Clock is not synchronised. 

 exit status 2 – If clock state is indeterminant, for example if ntpd is not contactable. 

 

 NTPQ 

 Use ntpq -p to see the following: 

 

 PPTSTEST 

 Use this to test the pps signal: sudo ppstest /dev/pps0 

 The output should spit out a new line every second that looks something like this (your output will be a bit farther from x.000000 since it isn’t yet using the GPS PPS): 

 

 GPSMON 

 Use the gps monitor function to check the realtime availability of GPS and satelite count and position, with this: 

 gpsmon 

 This will present the following: 

 

 CGPS 

 Or, using the following for a simpler gps status check: 

 cgps 

 This will create the following output: 

 

 References 

 How to troubleshoot an NTP server: https://support.ntp.org/Support/TroubleshootingNTP 

 The following link is probably not what was used to build the house time server. But, this is an interesting reference on how to build a Raspberry pi GPS time server: Building a Raspberry Pi Stratum 1 NTP Server 

 Here’s a good reference on how to tune and configure the NTP setup on a RaspBerry PI:  Building a Raspberry-Pi Stratum-1 NTP Server 

 Another reference:  Millisecond accurate Chrony NTP with a USB GPS for $12 USD - Austin's Nerdy Things 

 Good reference on the Shared Memory Driver, and how the 127.127.28.x address is used:  http://doc.ntp.org/archives/drivers/driver28/