Gpredict format which sends doppler correction to a listening port in GNU Radio

#1

Hello!

I would like to ask in which format does Gpredict use to communicate with gnu radio.
I’m using predict_doppler block in gnuradio as a receiver (https://github.com/wnagele/gr-gpredict-doppler). I have the following configuration in Gpredict:

Host:localhost
Port:4532
Radio type RX only
Rest is empty

I would like to manually control frequency via rigctld/rigctld. I tried following commands but it doesn’t work properly.

rigctld -m 2 -t 4532 -T 127.0.0.1 -s 9600 -vvvvv

I would like to point out, that Gpredict works perfectly and correction is really awesome and accurate. Is it possible to simulate a similar output as Gpredict does?

Thank you for any response and suggestions about this topic.

73,
Dominik

#2

I’m not sure if this helps, but you don’t need rigctld to use Gpredict with GQRX… Have you tried simply not initiating rigctld?

–Roy
K3RLD

#3

Thank you Roy for Consulting.

I would like to send packets to GNU radio manually in terminal as it would send Gpredict. I found in Gpredict manual quite a bit ifnormation about rigctl and rotctl, so I assume it uses those 2 commands.

Dominik

#4

Dominik,

It’s a bit confusing… rigctld is the server and rigctl (without the d) is the client. So, if I understand you correctly, you have to use rigctl (not rigctld) to send commands to a GNU Radio program. rigctld is the server that e.g. gpredict sends comands to. However, a GNU Radio program using gr-gpredict-doppler implements this server functionality.

Alex

#5

Hello Alex,

I’m aware of the server and the client differences in those commands. I tried both, but I wasn’t successful with the connection to the doppler block in GNU radio which is waiting for the right input signal.Usually, I got this response:

[doppler] Waiting for connection on: 127.0.0.1:4532
[doppler] Connected from: 127.0.0.1:46660
[doppler] received unknown command: \dump_state
[doppler] Disconnected from: 127.0.0.1:46660

I’m not quite sure what Gpredict does when I hit the Engage button in the Radio Control tab. I assumed it opens a server, and then sends updated information about doppler frequency to the block in GNU radio.

Dominik

#6

I don’t remember the exact sequence, but I would guess that when you hit Engange in gpredict, it will connect to the server and send set/get frequency commands, nothing else.