Like many engineers I know I didn't really enjoy learning about Radio Frequency (RF) during my college days. A mixture of a professor that was much more focused on graduate level research going on versus lowly undergrad intro to RF courses and the 'black magic' nature of RF led me to be as disenfranchised as most of my peers.
Fast forward a few years out of school I find RF is a very fascinating world that is happening all the time around us. One of my recent purchases has been a HackRF (on BangGood) , a very versatile device that can receive and send a huge variety of signals across a massive frequency range (1MHz - 1GHz!). I opted for a version of the hackrf that contains a screen and external controls so it doesn't need to be tethered to a PC at all times. It is called the Portapack and mine came with Mayhem firmware (on Github) which I have been very impressed by.
I moved houses early 2020 and the new place had a shared gate in the back that has a remote that operates using dip switches and basically just blasts a constant signal to get the gate to open and close. As one of my first exercises with the HackRF I was able to very easily discern what frequency the remote operates on and record several seconds of it that could be played back at will to operate the gate.
It was as easy as finding the exact frequency using 'Calls' functionality and then recording using the remotes for a few seconds with a wide enough bandwidth that the whole signal was captured. Unsurprisingly the HackRF works much better than the stock remote which has a tiny antenna and needs to be rather close to the gate to operate.
We'll see what the next stop for the HackRF is, I also have interest in ADS-B (airplane transponders) tracking and have a few purpose antennas for that. Might be using the HackRF to find the optimal ADS-B receiving local after I move in a month and get a solar powered ADS-B tracking setup going.