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by aquarat
Fri Sep 07, 2012 9:52 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

The Raspberry Pi NMEA/PPS combination is proving to be more reliable than my x86/GPS-OCXO combination : http://devrat.aquarat.za.net/assets/120907offset.png This graph is from The NTP Pool Project . I grabbed it at around 23:50 7th September 2012 GMT+2. I switched my NTP routing over to the Raspberr...
by aquarat
Fri Sep 07, 2012 6:09 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

And how about this :

Code: Select all

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
oGPS_NMEA(0)     .GPS.            0 l    6    8  377    0.000    0.002   0.002
yay :D
by aquarat
Fri Sep 07, 2012 5:26 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hey Paul

Revelation! The NMEA driver in ntpd reads the PPS too... so only one "server" line is required to get both NMEA and PPS data into ntpd.

Indeed ntpq -p now selects the NMEA source with an 'o' which indicates a PPS source.
by aquarat
Thu Sep 06, 2012 4:11 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hey Paul

Considering the price of the GPS a jitter of 5ms is fairly impressive :) .
by aquarat
Wed Aug 29, 2012 7:51 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

I've just bought a Motorola Oncore UT+ GPS... I'm going to give that a quick try.

Your new graphs page is super cool by the way, well done.
by aquarat
Wed Aug 29, 2012 11:36 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Yes it's very strange. I've tried fudging the NMEA source to stratum 3... both sources are still makred with an 'x' :( I'm going to try the ntp IRC channel on FreeNode.
by aquarat
Wed Aug 29, 2012 9:25 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

It's quite strange, this is what's output per second : $PGTOP,11,2*6E $GPZDA,085126.000,29,08,2012,,*5C The GPS software indicates that only about 5% of the bandwidth is in use. 49 characters are present, so 392 bits / 9600 bits = ~4% Your website's very cool, it's nice the way you explain everythin...
by aquarat
Tue Aug 28, 2012 10:39 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Based on what I saw on the oscilloscope I fudged time2 on the GPS by -0.650. It seems this is the wrong direction, but the results are still interesting : remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0)...
by aquarat
Tue Aug 28, 2012 4:41 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hi Paul Here are some screenshots of the PPS (yellow) vs the NMEA (blue 9600bps). http://devrat.aquarat.za.net/assets/osc01.jpg and http://devrat.aquarat.za.net/assets/osc02.jpg I haven't worked out how to offset two inputs on this oscilloscope... I haven't read the manual (todo list ;) ). And to an...
by aquarat
Tue Aug 28, 2012 12:31 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

That's a fantastic idea @ Oscilloscope, I'll give it a try a little later (just got a digital Oscilloscope recently and have enjoyed using it on other projects... I used to use an analog oscilloscope before that). I have noticed that sometimes NTPd shows the offsets between the PPS and NMEA as only ...
by aquarat
Tue Aug 28, 2012 10:19 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Done @ remove fudge... now I'm getting confused : remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0) .GPS. 0 l 7 8 377 0.000 902.809 484.651 xPPS(0) .PPS. 0 l 6 8 377 0.000 -0.024 0.022 10.0.0.8 .PPS. 1 u ...
by aquarat
Tue Aug 28, 2012 9:48 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Just tried, both PPS and GPS are marked with an x (false ticker?). The debugging output indicates something has changed : GPS_NMEA(0) gpsread: 33 '$GPZDA,094800.000,28,08,2012,,*50' GPS_NMEA(0) processing 33 bytes, timecode '$GPZDA,094800.000,28,08,2012,,*50' GPS_NMEA(0) effective timecode: 2012-08-...
by aquarat
Tue Aug 28, 2012 9:01 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Pic : (hosted on a pi)
Image
by aquarat
Tue Aug 28, 2012 7:46 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

I disconnected the GPS while ntpd was running, reconfigured the GPS (using an x86 win32 exe) and connected it again. All sentences were disabled except ZDA and PGTOP (which the software won't let me disable). Hopefully it'll stay like this : remote refid st t when poll reach delay offset jitter ====...
by aquarat
Mon Aug 27, 2012 10:00 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0) .GPS. 0 l 1 8 17 0.000 -4.269 2.552 xPPS(0) .PPS. 0 l 8 8 7 0.000 -5.375 1.827 ntp-dev-4.2.7p295 does the same thing. This is the debugging output : ntpd...
by aquarat
Mon Aug 27, 2012 8:53 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

The result of installing and running ntpd 4.2.6p3 : remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0) .GPS. 0 l - 8 377 0.000 0.644 0.048 xPPS(0) .PPS. 0 l 7 8 377 0.000 0.656 0.039 NTPd selects the NMEA ...
by aquarat
Mon Aug 27, 2012 4:07 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

I compiled : ntpd 4.2.6p5 ntpd 4.2.6p5@1.2349 Fri Aug 24 17:26:25 UTC 2012 (1) This seems like a good time to switch to IRC :P . I've been meaning to give the rasp irc channel a try... using a client running on a Pi of course. I've just started compiling 4.2.6p3 with --enable-all-clocks --enable-ATO...
by aquarat
Mon Aug 27, 2012 4:02 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

The results from your new config : remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0) .GPS. 0 l 7 8 3 0.000 -0.438 0.057 xPPS(0) .PPS. 0 l 6 8 3 0.000 -0.415 0.047 I tried setting minpoll to 1 a while back...
by aquarat
Mon Aug 27, 2012 3:24 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hey Paul The kernel I'm using was provided by chrisrpt. He uploaded them onto 4shared. I downloaded them and re-uploaded them to my Google Drive (4shared requires that you register and makes you jump through hoops). The files are available here : Modules : https://docs.google.com/open?id=0B9fzQK17Pq...
by aquarat
Mon Aug 27, 2012 2:02 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hi Paul This is the output from an x86 machine running NTPd : remote refid st t when poll reach delay offset jitter ============================================================================== +SHM(0) .NMEA. 0 l 8 16 377 0.000 20.047 1.267 *SHM(1) .PPS. 0 l 7 16 377 0.000 -0.002 0.002 +tick.meraka...
by aquarat
Sun Aug 26, 2012 4:49 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

I read in the ntp.conf man page that adding "true" to the server line of a source can force it past various protection algorithms so that the source will always be considered for selection (so adding "true" and "prefer" to a source should cause that source to always be selected?). I added "true" to ...
by aquarat
Sun Aug 26, 2012 4:25 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hey Paul Thanks for the explanation... but I'm still having problems. I tried using your ntp.conf suggestions and weird stuff started to happen; NTPd started using the NTP Pool servers, the PPS offsets/jitter data wasn't populated in ntpq -p's output, even after an hour had elapsed. Eventually I rem...
by aquarat
Sat Aug 25, 2012 3:07 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

and now : remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0) .GPS. 0 l 8 64 377 0.000 -85.283 85.560 xPPS(0) .PPS. 0 l 7 8 377 0.000 4.254 1.179 xstratum1.neolog .PPS. 1 u 39 64 377 36.674 10.515 5.234 xor...
by aquarat
Sat Aug 25, 2012 3:03 pm
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

NTPd has been running for a few hours with the fudge constant you suggested and this is the output of ntpq -p : remote refid st t when poll reach delay offset jitter ============================================================================== xGPS_NMEA(0) .GPS. 0 l 25 64 377 0.000 -93.407 50.441 x...
by aquarat
Sat Aug 25, 2012 8:38 am
Forum: Other projects
Topic: NTP PPS
Replies: 285
Views: 136807

Re: NTP PPS

Hey Chrisrpt Thanks for the info. It's surprisingly difficult finding information on some of the shm drivers for ntp. NTPd has been running for about 11 hours and this is the output : remote refid st t when poll reach delay offset jitter ==============================================================...

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