This was something I was looking for, for a long time. The plugin makes it possible to stream the demodulated SDR# audio via UDP to another program that is listening on that specific TCP/IP address and UDP port. The same function was already available within GQRX. This for example makes it possible to receive and demodulate satellite telemetry and send it to GNURadio where the final telemetry decoding will be done.

The plugin consists of two files and the magic line for the SDR# plugin.xml file.

NAudio.dll and SDRSharp.UDPAudio.dll

Magic line: <add key=”UDPAudioPlugin” value=”SDRSharp.UDPAudio.UDPAudioPlugin,SDRSharp.UDPAudio” />

Source: UDP Audio Stream plugin

This isn’t the first time this topic is brought to our attention but after reading this call I felt obliged to share one of the important parts and a link to the original posting.

Original quote:

“According to the ITU Radio Regulations for the Amateur and Amateur-satellite Services, “Transmissions between amateur stations of different countries shall not be encoded for the purpose of obscuring their meaning, except for control signals exchanged between earth command stations and space stations in the amateur-satellite service.” A strict interpretation of this rule means that the specifications of all digital protocols used by Amateur stations should be publicly available, so that anyone is able decode the data. The use of protocols with undisclosed specifications can be seen as a try to obscure the meaning of the data.”

Source: By Dr. Daniel Estévez, an open letter about ESEO telemetry specifications.

LilacSat-2 Telemetry 23-09-2015 17:10 UTC

When you want to decode the LilacSat-2 telemetry you have to dive in to the world of *nix and GNURadio. Now I do have a lot of experience with *nix but GNURadio is every time a difficult road. But Persistence pays off.

Decoded packet:

****byte_corr = 0
* MESSAGE DEBUG PRINT PDU VERBOSE *
()
pdu_length = 112
contents =
0000: a2 54 39 00 bb a1 01 0f 09 17 11 10 29 5f 00 01
0010: 00 00 00 09 00 00 00 00 00 03 1a 05 0f cb 13 4c
0020: 26 7f 39 02 0a 1a b3 09 a2 19 c0 0a 00 00 00 00
0030: 20 05 c0 00 00 55 00 09 05 08 05 d0 d0 d0 e2 00
0040: 55 01 ec 0e 37 0f fc 0f 99 01 9c 1e 20 01 11 00
0050: 10 00 10 00 10 00 ff 3e 4d cb ff 13 f8 ff 12 00
0060: 02 00 a6 00 bd 80 31 01 00 00 00 00 aa 49 f5 8d

A brief summery:

I made with the help of SDR# and my FUNcube Dongle Pro+ SDR receiver an IQ file at 23-09-2015 17:10 UTC. Installed GNURadio with the help of the following script www.sbrac.org/files/build-gnuradio on Linux Mint.

When this was successful I cloned the gr-lilacsat source from github and compiled the gr-lilacsat source. After that I changed the lilacsat GNURadio front-end so it would accept an SDRSharp IQ recording as input.

After that only some small changes to get the front-end up and running and connect it via localhost udp sources to the BPSK 9600 demodulator block.

I got the following confirmation: BG2BHC Great! Length is OK and the 5th and 6th bytes aa/bb a1 means that the packets are beacon packets created by OBC A/B

Second decode but this time real time with a RTL-SDR dongle. We are getting somewhere.

Download the IQ recording so you can test with your GNURadio environment

The ZAcube ground station have made a Decoder application available to decode the satellite telemetry.

The application receives KISS encoded messages from a TNC and decodes the messages to understandable values. Configure the application by using the drop down boxes to select the serial port that your TNC is connected to and set the baud rate for your TNC and click connect. MixW and a virtual serial port emulator can also be used with the decoder application.

Download location: ZAcube decoder