GNU Radio Flowgraphs that work with the Astrodev Lithium radio as part of the Virginia Cubesat Constellation mission.

The flowgraphs in this repository, when combined with an appropriate SDR device (in this case an Ettus Research B210 for development) WILL radiate in the FCC controlled 400 MHz Satellite Band (And so will the Lithium radio). It is the responsibility of the user of the flowgraphs in this repository to ensure that they follow ALL FCC regulations and guidelines for the proper use of these flowgraphs. A couple of recommendations for best practices to remain compliant with all US Laws and FCC Regulations:

• Obtain an FCC License for operation in this band (i.e. Experimental License).
• Contain all Radiated Emissions in a Faraday Cage such as those available from Ramsey Electronics.
• Utilize Coaxial Cabling between all transmitters and receivers, lowest possible output power levels, and heavy attenuation to both protect the receiver front ends and minimize leaked RF levels.

IT IS THE RESPONSIBILITY OF THE END USER TO ENSURE THEY ARE IN COMPLIANCE WITH ALL LOCAL, STATE, AND FEDERAL LAWS WHEN USING THESE FLOWGRAPHS. THE CREATOR OF THESE FLOWGRAPHS ASSUMES NO LIABILITY FOR OTHERS ACTIONS WITH THESE FLOWGRAPHS.

These flowgraphs rely on blocks from Daniel Estevez's gr-kiss GNU Radio Out-Of-Tree Module (OOTM). PyBOMBS is the recommended installation method and the required recipes are available in the gr-etcetera repository that is linked to default PyBOMBS installations.

The gr-kiss OOTM has been deprecated and functionality has been rolled into gr-satellites. However, the flowgraphs in this repo use the gr-kiss module due to a couple of bugs in gr-satellites that are preventing functionality for the author (something to do with bad imports of the AO73 blocks in gr-satellites, which are not being used in these flowgraphs, but are crashing them anyway). It is highly likely that these bugs are user error in the pybombs installation by the creator of the flowgraphs in this repo (Zach Leffke), and not the fault of the author of gr-satellites. It is possible to use the flowgraphs in this repo with the gr-satellites KISS/HDLC blocks if someone else has an installation of that OOTM that is working properly, but in their current form these flowgraphs expect the gr-kiss derived blocks. It is planned to swap out the gr-kiss blocks for the gr-satellites equivalent blocks once the installation issue is resolved.

These flowgraphs utilize the KISS Protocol for transporting AX.25 Frames into and out of the flowgraphs via TCP socket connections. For the moment, a couple of VERY rough python scripts are being used to handle the KISS Frame input/output for these flowgraphs. The current versions of these scripts can be found in the python_packet repository. Capture files of Amateur Radio Terrestrial APRS traffic (144.39 MHz, AX.25 UI Frames) are included in the repo stored in 'KISS File' Format for use as test data on the uplink. UNDERSTAND THAT THESE RECORDED CAPTURE FILES CONTAIN A NUMBER OF OTHER PEOPLE'S CALLSIGNS IN THE 'SOURCE' FIELD OF THE AX.25 FRAME. THESE FILES ARE FOR RESEARCH AND DEVELOPMENT ONLY AND SHOULD NOT BE RADIATED OVER THE AIR (YOU WOULD BE ILLEGALLY USING SOMEONE ELSE'S CALLSIGN). SEE THE SECTION ON FCC & LIABILITY IN THIS README FOR WAYS TO USE THESE FILES RESPONSIBLY (FARADAY CAGE, COAX CABLING, MODIFY THE 'SOURCE' ADDRESS FIELD OF THE AX.25 FRAME TO AN FCC CALLSIGN ASSIGNED TO YOU).

The 'kiss_net_playback.py' script will inject KISS frames from the stored capture file into the TX flowgraph. The 'kiss_net_rx.py' script will receive kiss frames from the RX flowgraph and parse them into DICT/JSON format. The scripts in the python_packet repository are constantly under development and changing, so do not be surprised if they don't work after a clone. Always check the commit messages to see the status of the scripts. After these python scripts have been updated, cleaned up, and are more stable, they will be copied into this repository or a different appropriate repository for higher layer data processing for the VCC mission and this README will be updated.