Broadcasting RTCM3 correction data as NTRIP server/caster

[HamzaCetin0]

Hi, thank you for amazing work. I have a question about steaming RTCM data as NTRIP server. I want to stream the RTCM data as a NTRIP server and than some other users(clients) to get the data. I use "gnssserver --inport "/dev/tty.ACM0" --hostip 0.0.0.0 --outport 2101 --ntripmode 1 --protfilter 4 --format 2 --ntripuser myuser --ntrippassword mypassword" command to stream the data. Then on another terminal I run "gnssdump --socket 0.0.0.0:2101" command to connect the localhost and get the RTCM data as a client. After connecting the network on the server side it it shows that I am connected but on the client side nothing happend. I cant see any data flow on the terminal. I dont know what it is wrong. Can you help me with this?

[semuadmin]

Hi @HamzaCetin0,

If your intention is to run gnssserver as an NTRIP Caster, you will need to use an NTRIP Client such as gnssntripclient to receive the data, rather than gnssdump which is basically just a serial parser.

So, based on your example above, you would need to use something like:

gnssntripclient --server localhost --mountpoint pygnssutils --ntripuser myuser --ntrippassword mypassword

You should then see a stream of incoming RTCM3 data something like this...

2024-06-12 11:09:58.030652: Using mountpoint pygnssutils

2024-06-12 11:09:58.034132: <RTCM(1077, DF002=1077, DF003=0, DF004=295816001, DF393=1, DF409=0, DF001_7=0, DF411=0, DF412=0, DF417=0, DF418=0, DF394=234547957876129792, NSat=7, ..., DF404_07=-0.39680000000000004)>
2024-06-12 11:09:58.034893: <RTCM(1087, DF002=1087, DF003=0, DF416=3, DF034=47398001, DF393=1, DF409=0, DF001_7=0, DF411=0, DF412=0, DF417=0, DF418=0, DF394=73751941456330752, NSat=5, ..., DF404_05=0.038700000000000005)>
...etc.

NB: Bear in mind that, for all this to work, the receiver at /dev/tty.ACM0 must be an RTK-compatible receiver (e.g. ZED-F9P) which is configured as an RTK base station - gnssserver will not do this automatically. See https://github.com/semuconsulting/pyubx2/blob/master/examples/f9p_basestation.py for an illustration of how to do this using pyubx2, or you could use PyGPSClient's NTRIP Caster functionality.

I'm converting this Issue to a DIscussion Q&A topic - if you have any further queries, please add them to the discussion.

Hope this helps.

[HamzaCetin0]

Thank you so much for your reply. Now everything is ok. I can see the data on the terminal. I have one more question about the output of the data. Is there any way to get the data by typing the local address and the port number on the browser? And how to save this data to a file?

[semuadmin]

Hi again,

Although NTRIP is essentially an HTTP protocol, you would typically need to use an NTRIP Client of some kind to retrieve the data in a usable format. You could, at a push, access the data via a simple web browser, but it would be a fairly clunky process and may not work with some caster/browser combinations.

For example, if you have gnssserver running as per your example above and enter the URL http:https://localhost:2101/pygnssutils into a web browser, then (depending on your browser's security configuration) you'll first be prompted for your NTRIP login credentials:

Once you've entered valid credentials, then (depending on your browser's MIME and Downloads configuration) the ensuing RTCM data is treated as a generic binary data stream which can be saved as a binary file (you may need to pause the download in order to access the saved *.part data file):

Note that if you simply want to access an RTCM correction data stream within your own private LAN or WAN, you don't necessarily have to use NTRIP - you could simply stream the raw binary RTCM data via a TCP socket e.g.

gnssserver -I "/dev/tty.ACM0" -H 0.0.0.0 -O 51000 -N 0

... and consume it using any TCP socket reader e.g.

gnssdump -S localhost:51000

Again, you could access this data stream via a web browser, but it will simply appear as binary gibberish:

To save the parsed RTCM data to a file using gnssntripclient, you can use the --logtofile 1 option:

gnssntripclient --server localhost --mountpoint pygnssutils --ntripuser myuser --ntrippassword mypassword --verbosity 2 --logtofile 1

The gnssntripclient CLI utility doesn't currently support saving binary RTCM3 data to a file (I may add this functionality in a future release), but it's relatively straightforward to write a Python script to do this using its underlying GNSSNTRIPClient class - see, for example: https://github.com/semuconsulting/pygnssutils/blob/main/examples/rtcm_ntrip_client.py.

[HamzaCetin0]

Got it. Thank you so much for your contribution.