Over on his blog Radoslav has created a post showing how he has used a HackRF to wirelessly control a toy RC car by reverse engineering the wireless control protocol, and generating the control signals in a C++ program.
Having already created the rf-car HackRF RC car control software on GitHub a few years ago, Radoslav was easily able to modify it for a new RC car that his daughter received. The process was to simply look up the FCC data on it, finding that it operated with 2.4 GHz and used GFSK modulation. He then used the Inspectrum signal analysis tool to determine the bit strings used to control the car. Finally using, his C++ interface to the HackRF he implemented the new bit string and GFSK modulation.
The video below demonstrates Radoslav controlling the RC car with the keyboard on his laptop.
In the past we've posted about another project that also used a HackRF and computer to control a RC drift car, and another project that used the RPiTX software to control an RC toy car with GNU Radio and a Raspberry Pi.