Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: What GPS sentence (NMEA) to use for APRS  (Read 961 times)
LA9XNA
Member

Posts: 257




Ignore
« on: November 28, 2018, 06:25:09 PM »

What is the NMEA sentence(S) to ya with APRS.
I'm making a APRS display with Raspberry Pi and  the PI 7"LCD monitor together with an UBLOX NEO-7M.
Currently only over internett but in the future I will also add transmitting capabilities.
Logged
VE7KNL
Member

Posts: 29




Ignore
« Reply #1 on: November 29, 2018, 05:26:34 AM »

Is this what your looking for?
http://www.aprs.net/vm/DOS/PROTOCOL.HTM
Logged
LA9XNA
Member

Posts: 257




Ignore
« Reply #2 on: December 01, 2018, 11:30:37 PM »

No it is what NMEA sentences the GPS must be programmet to work with aprs software.
Logged
WB5UAA
Member

Posts: 81




Ignore
« Reply #3 on: December 02, 2018, 03:37:18 AM »

https://www.u-blox.com/sites/default/files/products/documents/NEO-7_DataSheet_%28UBX-13003830%29.pdf

The UBLOX NEO-7M produces the following sentences:
GGA (3D location)
GLL (Lat/Long)
GSA (Satellite data)
GSV (Detailed Satellite data)
RMC (Position, velocity, time)
VTG (Velocity)
TXT (error messages)

Depending on the APRS software you're using (or programming), I would guess you could use any sentence with position data in it  (GGA, GLL, RMC) for an APRS application.

The challenge in using GPS sentences is (1st) using a GPS receiver that produces the sentences you want and (2) parsing the sentence(s) you want to use.

Accurate position is used in APRS.  You can use accurate time also.  And if you're mobile, accurate velocity can be used.

Along with the standard GPS sentences, some other GPS receiver manufacturers produces proprietary sentences.  And some GPS receivers allow you to send commands to it to customize the sentences it outputs and the baud rate it sends them out the serial port, like my Novus GPSDO.

(edit) and if you send it a command, the challenge is doing the XOR on the sentence you send it for the *hh field so it accepts it as a valid command.
« Last Edit: December 02, 2018, 03:43:32 AM by WB5UAA » Logged
LA9XNA
Member

Posts: 257




Ignore
« Reply #4 on: December 04, 2018, 04:13:14 AM »

Im usinf Xastir on a Rasberry Pi with the Compass distribution.
The GPS is a Ublox Neo-7m with the sentences GGA, GLL & RMC.
I get the GPS to stream data to the RPI by using the command stty -F /dev/ttyS0 9600 and monitoring by the command cat </dev/ttyS0
Xastir is set up with 9600 bd and /dev/ttyS0 but i get "GPS data is older than 30 seconds" when checking the gps status.
Logged
WB5UAA
Member

Posts: 81




Ignore
« Reply #5 on: December 04, 2018, 05:01:30 PM »

I'm not sure what you're asking now, but I've played around with a couple of UBLOX GPS receivers along with Xastir (on a couple of distributions like Fedora and "Andy's ham radio Linux", but not on Compass.  A quick google of Compass indicates it's just another distribution off of the Debian/Ubuntu branch--I have a version 2 Pi, but it's loaded with Raspbian at the moment.)  My UBLOX's use USB for interfacing and setup for Xastir includes attaching to /dev/ttyACM0.  Since it's USB, baud rate doesn't matter, but it has to be set to something in Xastir.  (4800 8n1, 9600 8n1 and higher all work the same.)

In the past, I've had to change the group ownership on the port prior to starting up Xastir in order to get it to work.  (dialup group?  I think).  But the latest version of Xastir seems to have fixed this and I don't need to change group ownership any more.

If you see it on your first serial port using cat  (from root?), but Xastir isn't seeing it, all I can suggest is checking the permissions on that port. You may need to change the group to something Xastir is a member of.  (#chown or #chgrp)

Or maybe just update your version of Xastir to the latest version?
Logged
LA9XNA
Member

Posts: 257




Ignore
« Reply #6 on: December 04, 2018, 05:37:02 PM »

I  managed to fix it.
The data form the GPS where all garbeled.
The fix is simpel just to ground the board and put in some decupeling capacitors on the 5V line.
After that the GPS came up in a few seconds.  Smiley

https://www.ebay.com/itm/Ublox-NEO-7M-000-MWC-APM2-6-GPS-Module-2-4G-Antenna-Replace-NEO-6M-GYGPSV3-NEO7-/182490600841?var=&hash=item2a7d499589
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!