RPiTX is a piece of software that you can run on your Raspberry Pi unit, which with no additional hardware turns it into a full radio transmitter, capable of transmitting FM, AM, SSB and other signals anywhere from 5 kHz to 500 MHz. Of course remember that the methods used to do this emit a lot of harmonics, so to be legal and safe filtering should be used on the signal output.
Over on Twitter Cyril @kotzebuedog has been experimenting with RPiTX and his radio controlled toy car. From the videos and images, it appears that he’s used GNU Radio to create the required control signals which then transmits the data to the RC car via RPiTX. With this he’s been able to create a program to control his RC car with his computer gaming joystick.
— Cyril (@kotzebuedog) March 26, 2017
— Cyril (@kotzebuedog) March 27, 2017