All times are UTC+01:00




Post new topic  Reply to topic  [ 6 posts ] 
Author Message
 Post subject: uMPX GPS Setup
PostPosted: Tue Nov 09, 2021 11:28 pm 

Joined: Sat Apr 01, 2017 10:21 pm
Posts: 18
Want to use uMPX with GPS to synchronize 2 transmitters on a SFN. As I understand, the encoder only needs NMEA via USB or serial. Appears the decoder side will also need 1PPS injected into the sound card. Does anyone know how that injection would be accomplished with ASI 5810 sound cards? My GPS receivers have serial and 1PPS outputs. Would the 1PPS be injected into the analog input of the sound card, or is it more complicated than that? I've been looking for a connection schematic, but haven't found anything. Thanks!


Top
   
 Post subject: Re: uMPX GPS Setup
PostPosted: Sun Nov 14, 2021 4:14 pm 
Site Admin
User avatar

Joined: Mon Mar 17, 2008 1:40 am
Posts: 10351
Hi, does your 1PPS output have 1 line or 2? If it has 2, chances are that you can connect it, if the voltage levels aren't too high. Otherwise you might need to make some changes. We do know how to do it with certain receivers (I can't promise that it will work on all, and I need to look up the details), and we have convertor boxes from a 6-pin DIN to audio 1PPS + USB.


Top
   
 Post subject: Re: uMPX GPS Setup
PostPosted: Tue Nov 16, 2021 7:35 am 

Joined: Fri Nov 23, 2012 4:34 pm
Posts: 194
I am also interested to know about this. Previously tried to get NMEA data into Steretool standalone for the uMPX encoder but had difficulties.
Had a GPS device connected via USB but couldn't figure out how to successfully use the name field. (ST expects data at 9600 baud but the USB device worked at a different rate, I think 4800 baud?)
Is this a possibility for time stamping on the encoder end?


Top
   
 Post subject: Re: uMPX GPS Setup
PostPosted: Wed Nov 17, 2021 10:57 pm 
Site Admin
User avatar

Joined: Mon Mar 17, 2008 1:40 am
Posts: 10351
Odd - we're explicitly opening the device at that bitrate. If it only supports 4800 that might be a problem. Can you try to open it in a DOS box? You can just try something like
Code:
type COM4
and that will show you the data if the bitrate etc are set correctly. Which can be done with a command called "mode". If it's just a matter of also supporting 4800 that should be easy enough to add on our end, but I need to know first if it works with mode and type.

Example MODE call (this one works for the device that we're using):
Code:
mode COM3 baud=9600 parity=N data=8
So first set mode for the COM port that you're using, then use type to see the input. If it looks like readable text (basically a lot of numbers separated by commas), it works.


Top
   
 Post subject: Re: uMPX GPS Setup
PostPosted: Sat Nov 20, 2021 7:14 am 

Joined: Fri Nov 23, 2012 4:34 pm
Posts: 194
Thanks Hans. I'd been trying with a G-STAR IV USB GPS (BU353S4). It appears fine as a COM port in Win 10 and when I tested at the time, I was able to receive NMEA data via a test application.
The test application was receiving at 4800 baud I think, but I could not get ST to recognize this data to timestamp uMPX.
When I get a chance (hopefully soon) I will post a few tests, including results of what you have suggested.


Top
   
 Post subject: Re: uMPX GPS Setup
PostPosted: Sun Nov 28, 2021 3:53 pm 

Joined: Fri Nov 23, 2012 4:34 pm
Posts: 194
Just tested this. I could not get the commands you posted to work properly. Only once could I see text data which looked like NMEA, but I had set the port to 4800 baud?
Using PuTTY was more successful. Opening the port at 9600 baud gave odd characters, but at 4800 baud NMEA data seemed to pass data fine.

It seems that (as standard) the device passes NMEA at 4800 baud. Searching the internet revealed a guide and some software (for the SiRF chipset?) which can be used to change baud rate.
Running at 9600 baud now, Stereotool reads the NMEA data and gets 'GPS lock' for time stamping! :D

I guess the question now is whether or not it would be useful for users to be able to change COM port settings within ST?


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 6 posts ] 

All times are UTC+01:00


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Limited