Remote Control

[NZ0I]

I've been having a chat (email exchange) with Joseph Huberman in which we've discussed providing remote control to the dual-band fox transmitter design. I've long felt that adding remote control wasn't very practical since it would require the addition of a receiver to each transmitter, increasing the cost and complexity of the system. The additional complexity could also introduce reliability issues since it can be difficult to ensure a reliable control link to all foxes on a course. The larger transmitter size, and the need for a separate antenna for the control link, made the whole system seem clearly undesirable.

But it occurred to me during our conversation that there is a strategy that should allow the foxes to share the control channel with their normal transmit frequency. 

Generally one would not want to use the same frequency (or even the same band) as the fox transmitter to send control signals. Doing so would remove the ability to control the foxes while they are on the air and can't receive the control signals. But, at slightly greater expense and complexity, one could make the receivers function "QSK" (full break-in) so that they could copy control signals sent in between the dits and dahs of the fox transmissions. That is an interesting idea since it would remove the requirement for a second antenna for the control receiver - but the fox design would have to allow the fox's receiver and transmitter to share the same antenna. 

This approach would also open up the possibility of incorporating the dual-band ARDF receiver we are working on into the foxes to serve as the control receiver. The PLL discussed in an earlier thread should support having the receivers detect and decode CW or TTY control messages. Using this scheme a normal fox transmitter could also serve as the remote control station for controlling transmitters remotely.

Maybe a provision for QSK control could be designed into the fox transmitters as an option, for those who don't mind having larger transmitters and can afford a more expensive system. I think we would still want the timing system in place to allow the transmitters to maintain a very-low-power-consumption state when they aren't needing to listen for control signals, and perhaps to serve as a timing-only backup system in the event that the remote control system fails.

Any thoughts or comments on the subject of adding a dual-band ARDF receiver (functioning QSK) to the fox transmitters as an option, the same way that the 80m automatic antenna tuner is an option?