What is 433 MHz remote switching?

As per Annexure 1 of National Frequency Allocation Plan 2022, very low power equipment working on 433 MHz band are exempt from licensing. That is how they are widely used for remote control of devices like lights, motors used for opening gates, security systems, home automation and many more. I came to know about 433 MHz remote switching during a discussion with VU2TUM regarding ways to switch antennas remotely. Imagine that you are living in an apartment with limited access to the terrace. You are permitted to bring only one coaxial cable down from the terrace to your apartment. It is then that you have to consider remote switching of antennas. This is not an uncommon scenario among ham radio operators living in cities.

As usual, I gave an online search and found several options of buying 433 MHz remote switching modules with remote controls online. Just enquired with my local vendor in the city and to my great surprise, he had a single piece for sale. Went there today morning and got this today morning. He connected a power supply to it from the shop and demonstrated remote control switching on of the red LED on the board. Now I have to plan how to install it and switch antennas on the terrace remotely. Though I am living in my own house and not in an apartment, I have limitations in bringing down too many coaxial cables into the shack. That is why I am also interested in this 433 MHz remote switching unit. In my next post I plan to check the output of the remote using my RTL-SDR to see if I can capture it on the waterfall and check the actual frequency. You may be aware that unlike the infrared remotes which we usually use for television and other devices at home, signals from this can penetrate walls and reach the terrace from your shack.