Using the Same Frequency for Control and FPV/Telemetry
In theory, it should be possible for multiple devices to communicate with each other on different channels on the same band, without having to establish whose turn it is to speak. In reality, this only works if they're not in close proximity. What happens is that a device operating at 905mhz with a "4mhz wide" channel. In reality, 903mhz and 907mhz are just the places where signal response starts to drop precipitously... but there remains minimal spectrum pollution over the entire 900-930mhz band. The only time that this is strong enough to actually matter is when one device is trying to transmit at 905mhz, and another device is trying to receive a very faint signal a few feet away at 920mhz. The higher power the transmitters (and the longer the ranges involved), the worse this effect gets. As a result, most people tend to use only one 900mhz band device, only one 2.4ghz band device, et cetera on the same plane, despite the fact that they are capable of multi-channel operation.