Often, we use RadioMaster Pocket transmitters with RadioMaster ELRS receivers. They're a step above the usual FlySky systems that you can get off Amazon, at the cost of being a profound pain to deal if you don't know what you're doing. They run on ELRS, which is open source and documented at the link below:
However, this is a lot to chew on if you're not already somewhat versed in RF. I'm going to write out just what you need in order to get everything moving.
If you have a team member that you really, and I mean really don't like. Make them do this part.
NEVER attempt to set up or program your robot while your motors' shafts are connected to anything. Prop your robot up and figure things out in an environment where it cannot run away or hurt someone.
Once you get your RadioMaster Pocket, power it off and remove the microSD card and find a way to plug that microSD card into your computer.
Grab the Pocket ELRS 2.10.5 Factory SD Contents and Firmware and unzip it.
Follow the instructions in the zip file to correctly paste the new firmware into the microSD card.
It might take a hot minute to move the files over; I think they come with class 3 (kinda slow) microSD cards.
Turn on your transmitter.
Hit the SYS button.
Navigate to the ExpressLRS screen and click down on the scroller (the roller thing at the bottom right).
Use the scroller to roll down to the word BIND but don't press it yet.
Power cycle (turn the robot on and off) 3 times.
The receiver will start flashing.
Click on BIND.
Assuming your radio channels are correctly set up, your motors will probably beep at you, and some of the joysticks will make the motors move at this point.
This is an issue you should ask an officer to help you with, as it can be tricky to resolve and the consequences of this issue can be dire.
Out of the box, these are configured to operate at a lower wattage than the FS-i6 controllers, which means they're more prone to losing connection.
This means that fluctuations in the power supplied to the receiver may cause it to, for lack of better words, piss its pants and forget where it is.
It's worth noting that:
TX means the signal sent from the transmitter to the receiver
RX means the signal sent back from the receiver to the transmitter
The failsafes that you program will engage if your TX fails... not if your RX fails.
Telemetry lost occurs when RX fails, meaning your failsafes will not engage, your receiver will cease to care about any TX that is sent its way, and your receiver will choose a signal (most likely the last one you sent) to sustain, potentially causing runaway drive and weapon systems.
There are a number of ways to resolve this:
The electrical option: put a fat capacitor (somewhere around 470uF @ 50V did the trick for Liberator MKII) across your power system. This will soften power feedback from weapon impacts, which will mean the receiver experiences less of a change in power supplied to it.
The software option: Nobody in Wildcat Robotics has tried this yet, but you can modify the settings of the RadioMaster Pocket either in the ELRS menu or with LUA scritpts. Purportedly, these changes may help:
Lower the baud rate
Lower the packet rate
Lower telemetry ratio
Disable dynamic power
Disable ADC filter
If anybody tries this, you get a prize! Ping or DM Wolfgang on Discord.