I am new to dealing with radio modules so i know my question may be so simple
what is the reason of being many channles in the rf module?
for example "HC-12" or "nrf24" rf modules have over 100 channels!
-should i for example if i am building an rc car make every button on the transmitter on a channel?
-or should i make the whole project on the same channel?
but i think if i make the whole data that i send it from the transmitter to the reciver on a single channel i will not be able to make two actions in the same time for example in the rc car i will not be able to go forward and go left in the same time
i am sorry if the question is so simple but i searched for it and i didn't find any answer
Another simple answer is that the ISM bands are quite wide, megahertz, that many user channels may be useful. There is no point in designing equipment to use the entire band of frequencies that are available for ISM use.
Signal latency is one reason to use several channels. For example, one channel could be the panic button that shuts down everything with an emergency. That signal needs to have a priority over all other normal data traffic. Putting the panic button on its own channel can result in less latency of response with the receiver.
I do not mean that you should assign one channel for every button dial switch knob or key. I mean for you to be logical about your channel assignments. For instance with my drone I assign f,b,l,r,u,d to one channel. The arm switch has its own channel as does the beeper.
Another reason for having multiple channels is interference. Sometimes an RFI source is much stronger on some channels than on others. So you can avoid those.
Thats is the normal situation, although to reduce the possibility of selecting a single frequency where there is a lot of interference, some RC systems hop between different frequencies.
UHF radio modules are often a poor, as in not legal, choice for radio control. In the typical ISM bands used by the modules, 434Mhz, 868Mhz, 915Mhz, there are often legal duty cycle limits of 10% or even 1%. This means the transmitter could only be allowed to transmit 1% of the time, which means in effect you may not be able to send the radio control packets very often, so you have a very slow to respond control system.
2.4Ghz modules, such as NRF24 and LoRa SX1280 operate in a band where there are few restrictions, and this is the common choice for most modern commercial radio control systems.
To see how radio control can work on a single frequency\channel there is a simple example of using the LoRa SX1280 device to read a joystick and button, convert it into a series of bytes that are sent as a single packet which the receiver picks up and moves a pair of servos accordingly. See the \examples\SX128X_examples\RemoteControl folder of this library;