https://www.rtl-sdr.com/using-an-rtl-sdr-and-rpitx-to-unlock-a-car-with-a-replay-attack/
Over on YouTube user ModernHam has uploaded a video showing how to perform a replay attack on a car key fob using a Raspberry Pi running RPiTX and an RTL-SDR....
rtl sdrusingrpitxunlockcar