Use GPS Time on PC

[Dockhead]

Originally Posted by Moo

Use O's mux capabilities to output to a time setting utility. Input from the COM port and out to whatever via network.

If your time utility is COM port input only you'll have to use a COM port mux such as GPSGate or similar and use virtual ports.

Consider machine latency in your choice but what is a second or so between friends

OK, thanks!


Do you know a time-setting utility which is NOT "COM port input only"?

[muttnik]

Some observations which may be obvious to some but not obvious to others...


NMEA gps strings aren't a particularly accurate way of setting your time. If you don't have a functional real time clock they may be ok for setting your time to the nearest second (which is probably good enough for most people) but the NMEA strings alone will be offset and subject to lots of jitter so you *definiteyl* don't want to go anywhere near continually adjusting your time from the nmea strings alone.



To use a GPS receiver as a reference clock to feed ntpd you need a receiver which also outputs a PPS signal to synchronize the nmea strings to exact seconds. As an exercise a couple of years back I built an ntp reference clock from a raspberry pi hooked up to an adafruit ultimate gps receiver (which does output a pps signal). I used kplex to feed the nmea strings to ntpd (for the hell of it) but the "normal" (and easier) way is just to use gpsd. Of course a rasperry pi doesn't have the hardware to be a decent reference clock (not least because of dodgy network performance) but it's a fun project for some.


Of course the easiest thing is valhalla360's suggestion to fix the clock....

[AedanC]

Originally Posted by muttnik

Of course the easiest thing is valhalla360's suggestion to fix the clock....

That's fine if you don't have too much drift. I have a tablet PC for navigation and it's completely disconnected to the internet. It's clock seems to drift like mad, I spotted that it was 4-5 hours out at the end of last summer. I'll definitely have to install something to give it time for this year.

[hoolie]

Originally Posted by muttnik

... ...

Of course the easiest thing is valhalla360's suggestion to fix the clock....

But the OP's problem, which is one I share as I have the same type of miniPC, is that the clock stops when the device is unpowered. There's no back-up battery to keep it going so time has to be set each time the PC is turned on.

[Jubilee39]

There used to be an utility called GPStime. I think that the author incorporated it into his great utility called GPS Utility. Great little program for transferring GPS info between different GPS, changing file types etc, I have used it for about a dozen years. Easy to set computer time to GPS time/

[ChrisseH]

Originally Posted by Jubilee39

There used to be an utility called GPStime. I think that the author incorporated it into his great utility called GPS Utility. Great little program for transferring GPS info between different GPS, changing file types etc, I have used it for about a dozen years. Easy to set computer time to GPS time/

Looks interesting, but will it work with Windows 10?

[Moo]

Originally Posted by ChrisseH

Looks interesting, but will it work with Windows 10?

Yep I use it on W10.

[valhalla360]

Originally Posted by hoolie

But the OP's problem, which is one I share as I have the same type of miniPC, is that the clock stops when the device is unpowered. There's no back-up battery to keep it going so time has to be set each time the PC is turned on.

Actually, the OP says something failed with the battery backup for time.

But even for your situation, do they make a battery backup for the clock similar to a regular PC? So many computer functions rely on time, I would be surprised if it's not an option.

[valhalla360]

Originally Posted by AedanC

That's fine if you don't have too much drift. I have a tablet PC for navigation and it's completely disconnected to the internet. It's clock seems to drift like mad, I spotted that it was 4-5 hours out at the end of last summer. I'll definitely have to install something to give it time for this year.

Sounds like a bad clock...no way it should be off by hours unless something is broken.

[transmitterdan]

Dockhead,

Have a look at this web site:

https://www.meinbergglobal.com/english/sw/ntp.htm

I have not studied it in detail. But this might get you started on your way.

Also see: https://www.satsignal.eu/software/net.htm

[Dockhead]

Originally Posted by muttnik

Some observations which may be obvious to some but not obvious to others...


NMEA gps strings aren't a particularly accurate way of setting your time. If you don't have a functional real time clock they may be ok for setting your time to the nearest second (which is probably good enough for most people) but the NMEA strings alone will be offset and subject to lots of jitter so you *definiteyl* don't want to go anywhere near continually adjusting your time from the nmea strings alone.



To use a GPS receiver as a reference clock to feed ntpd you need a receiver which also outputs a PPS signal to synchronize the nmea strings to exact seconds. As an exercise a couple of years back I built an ntp reference clock from a raspberry pi hooked up to an adafruit ultimate gps receiver (which does output a pps signal). I used kplex to feed the nmea strings to ntpd (for the hell of it) but the "normal" (and easier) way is just to use gpsd. Of course a rasperry pi doesn't have the hardware to be a decent reference clock (not least because of dodgy network performance) but it's a fun project for some.


Of course the easiest thing is valhalla360's suggestion to fix the clock....

Thanks; really useful information.


Yes, I guess I just need to "fix the clock", which means throwing the computer in the trash and buying and setting up a new one


This is a cheap Atom media server box which I am sure is not worth repairing.


OTOH, maybe I don't care that much. I had trouble with my tracks and my log last summer, and I thought this was from the system clock.


However, I am now hearing that OpenCPN does not use system clock time for this. Can you confirm that? Does OpenCPN use system clock time for anything? If for nothing, then I might just ignore this issue.

[Dockhead]

My Log plugin is definitely using system time, not GPS time. Is there some way to choose which time it uses? It is set to use UTC time (not GPS Auto etc.). The version is 1.4006, which I think is the latest.



As an alternative I have a utility which updates the system clock, but I need data for it. I can configure one COM port -- COM1 only (for some reason) as a talker, and I can choose baudrate, priority, etc., but my utility doesn't find it -- gives "The port COM1 initiation failure" when I click "Read Port".


Any tips?

[conachair]

Originally Posted by Dockhead

My Log plugin is definitely using system time, not GPS time.

Just did a quick test, looks like if gps time is available from NMEA my logbook uses that, if I turn off all connections the logbook uses system time. Quick glance looks like time is coming in with the RMC & GGA sentences, logbook 1.3007 on win10 >

[nohal]

Originally Posted by Dockhead

As an alternative I have a utility which updates the system clock, but I need data for it. I can configure one COM port -- COM1 only (for some reason) as a talker, and I can choose baudrate, priority, etc., but my utility doesn't find it -- gives "The port COM1 initiation failure" when I click "Read Port".


Any tips?

You can not use the same port in two applications at the same time. There are some utilities allowing you to create chains of interconnected virtual serial ports on Windows, like com0com that might let you achieve what you are trying to do.

OpenCPN itself also contain code to do it, I have never used it on Windows, but if you set SetSystemTime to 1 in the configfile, it will get executed.

[Kenomac]

Originally Posted by Dockhead

OK, I cracked it another way.


Unfortunately it is rather kludgy. Maybe SignalK is better, but I've already wasted half the day on this and I have a long list of boat jobs.


Here it is:


1. I used this app, "GPS Time and Test": https://download.cnet.com/GPS-Time-a...-10446293.html


2. It needs GPS time date via a COM port. Unfortunately that COM port can't be in use for anything else So I can't use the boat network datastream being used by OpenCPN


3. However, I have a USB connection to my AIS black box, which throws off that data. And so if I connect the AIS box and do NOT run ProAIS2, the program which connects to the black box, THEN GPS Time & Test WORKS




Note however that it does not work as it automatically loads upon startup. I have to shut it down, and then "Run As Administrator", in order for it to have authority to change PC clock time.


Et voila! I hope this helps someone with the same problem I had.


Actually I think that system time is a non-trivial issue which must affect MOST offshore users. For proper function of lgbook and VDR, you must have accurate time. When you are connected to Internet, your system can correct the time itself. But offshore without Internet, you will have some time drift at best, and at worst some time breakdown like I have.



I bet the OpenCPN developers could write a small program which would extract GPS time from the datastream running in O, and bomb the system clock with it. I'll add it as a feature request.

I spend zero amount of time fussing with pc navigation, instead we use an Apple MacBook Pro for computer stuff along with a couple of iPads and Raymarine e127 chart plotters. Absolutely zero down time and time wasted fussing with stuff.

We still have the HP pc running Nobeltec Time Zero, but it hardly ever gets used, and I spent more time over a two week period several years ago trying to get that POS working than I've spent on all the Apple stuff combined over the past eight years. Last season, I only turned on the pc once, and I think it was by mistake.

Something to consider... unless you enjoy wasting days messing around with computers.