[ntp:questions] Meinberg ntp server and zeros after the point in time field $GPRMC

Dave Baxter spam at goes.nowhere.com
Wed Aug 7 08:27:01 UTC 2013


In article <ktsq80$vdl$1 at dont-email.me>, david-
taylor at blueyonder.co.uk.invalid says...
> 
> On 06/08/2013 19:30, poi_83 at mail.ru wrote:
> > I have 2 GPS receiver, which I want to use for the ntp server.
> > 1. Trimble Lassen IQ
> > 2. Navia ML8088s
> > First I was able to set up to work with
> > It has the format
> > $GPRMC,154024.00,A,4853.7462,N,02652.2962,E,000.3,318.9,060813,03.9,E,A*04(two
> > zeros after the point in time field)
> > And the second one does not work
> > It has the format
> > $GPRMC,154024.000,A,4853.7462,N,02652.2962,E,000.3,318.9,060813,03.9,E,A*04(three
> > zeros after the point in time field)
> >
> > How to configure the Meinberg ntp server software so that it viewed the
> > following format
> 
> Nick,
> 
> As I said in my e-mail, I can't answer your question as I don't know 
> enough about the internal configuration, but I would be very surprised 
> if the number of decimal places mattered.  No chance one PC has the 
> period and the other the comma as the decimal separator?  You may even 
> have found a bug!
> 
> Are the two sentences above actual sentences, or simulated?  I ask 
> because if they are actual sentences I am surprised that the checksum 
> (the *04) is the same.  Also, I don't understand what the final "A" just 
> before the checksum is.  It's not mentioned here:
> 
>    http://www.gpsinformation.org/dale/nmea.htm#RMC
> 
> but it is mentioned here:
> 
>    http://home.mira.net/~gnb/gps/nmea.html#gprmc
> 
> and appears to be for NMEA 3.00.  I don't know what version of NMEA NTP 
> supports - you would need to visit the source code to be sure.

Nick.

It's also worth investigating, if the GPS RX device can be configured to 
send only two decimal places after the point in the time field.  I don't 
know the Navia product range, in fact, never heard of it, but if you 
have access to documentation, it might be worth a trawl through that.

I had a quick look at:-
http://naviaglonass.ru/wp-content/uploads/ML8088s_operations_manual.pdf

No mention of such features.  :(

(An interesting little device though, GPS/GLONAS RX, with PPS!  
Evaluation boards/kits available.  Serial & USB interfaces.)

(It's companion, the GL8088s handles all three GLONASS/GPS/GALILEO 
systems...  If/when Galileo is deployed)


Meinberg does work with NMEA strings, and PPS (If you use a hacked 
system file.)  I (and others) have run it with such GPS's in the past, I 
was using a Garmin GPS-16 and running it all on Windows 2000, back in 
the day.

I do remember using David Taylor's site as the basic "How To" when I 
first did that.

Now..  I'm sure others will correct me if I'm wrong.  NTPD that Meinberg 
have "re-packaged" I think will work with other NMEA sentences that 
includes a time field.  Maybe the GPS and Meinberg can be configured to 
issue/use that?

Lastly, if using Windows is not a "nesesary feature" (because you also 
need to run other stuff on the same PC) take a look at:-

	http://blog.doylenet.net/?p=145

How to set up a single older PC, as a dedicated Stratum-1 NTP server, 
using a GPS with PPS (Garmin GPS-18 in this case) and FreeBSD as the OS.

A little out of date now, it uses FreeBSD V8, but the principles are 
good, and the results speak for themselves.  It works "Very Well" 
indeed.  I've one such (an old P3/600) that's been running 24-7 now for 
over 770 days without a hitch.  (Not many Windows machines will do that 
all by themselves.)

Options are many, all it takes is time.  Punn intended.

Regards.

DaveB.



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