I would like to experiment with amplifiers and larger antennas, and possibly with using the 433MHz radios in the US.
I have an amateur radio license here in the US.
Is there a way to insert call sign information into the data being exchanged by the radios? Perhaps by changing the device ID to your call sign or something of the sort?
It would be awesome if you could just open up Mission Planner and type in your call sign in a box and then save it to the radios and have them transmit it with every data packet.
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Regarding call-sign being transmitted at the end of communication: I'm not certain that is absolutely necessary with packet radio. Take APRS for example, the call-sign is transmitted at the beginning of every packet, The systems I've seen do not transmit a final sign-off call-sign before shutting down.
Sorry if this is a repeat, it seems I did not post my previous reply properly. For tracking my rockets, I use an Arduino between the GPS module and the data transceiver with a small program that appends my call sign as a header to the NMEA sentences (I also take the opportunity filter unnecessary NMEA sentences).
KD0GG-11>CQ:$GPGGA.... Then on the receive end I have a Rasp Pi and/or Arduino to strips the header off, parse the data to route non-NMEA telemetry and pass the NMEA string to the tracking app and or Google Earth.
This is kind of a blend between Burt's suggestion of using the processor in the MAVLink and the X.25 packet mentioned by Ron.
Would a MAVLink msg work for this?
I'm sure a new message could be inserted into the APM / Pixhawk code to send just the "Call sign" in text not binary. Could this satisfy the FCC call sign requirement? Looking at the code a see a few (type="char[16]") values that are already in the code to send
"Onboard parameter id, terminated by NULL if the length is less than 16 human-readable chars and WITHOUT null termination (NULL) byte if the length is exactly 16 chars - applications have to provide 16+1 bytes storage if the ID is stored as string"
The way I read, that if a serial window is open, it will show as a readable message in the data stream.
I have seen this question before, and have wondered just what the FCC would consider for a call sign for telemetry radio.
Myself I have been using a Turnstyle antenna adjusted for 900 Mhz on the plane, and a patch on a antenna tracker. been able to go out as far as 4 miles at 400 ft. I have a set of 1watt radios that make me wonder about this subject.
Well for packet radio and APRS modes, the call sign is transmitted as part of every data packet. If there were a simple way to do this from an end user perspective (enter your ham call sign into a box in Mission Planner) I think it would satisfy the station ID requirement for the air radio. The ground radio should be okay with just an adhesive label for the call sign.
What would be even better would be new firmware for the radios that allowed the call sign to be transmitted, without depending on the flight controller to send it. If the flight controller fails but the radio is still powered, you would still need to transmit the call sign. Current firmware allows users to configure power output, channels, etc. Adding a call sign seems like a natural addition to a future firmware release.
APRS uses AX.25 protocol. I am barely familiar with that, and not at all familiar with MAV link.
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