There was a time when just about every ham had a pricey VHF or UHF transceiver in their vehicle or on their belt. It was great to talk to friends while driving. You could even make phone calls from anywhere thanks to automatic phone patches. In 1980 cell phones were uncommon, so making a call from your car was sure to get attention.
Today, ham radio gear isn’t as pricey thanks to a flood of imports from companies like Baofeng, Jingtong, and Anytone. While a handheld transceiver is more of an impulse buy, you don’t hear as much chat and phone calls, thanks to the widespread adoption of cell phones. Maybe that’s why [Bastian] had bought a cheap Baofeng radio but never used it.
He was working on a traffic light project and wanted to send an RF signal when the light changes. He realized the Baofeng radio was cheap and cheerful solution. He only needed a way to have the PC generate an audio signal to feed the radio. His answer was to design a UDP packet to audio flow graph in GNU Radio. GNU Radio then feeds the Baofeng. The radio’s built-in VOX function handles transmit switching. You can see a video demonstration, below.
What we didn’t see is how he plans to demodulate the signal on the receiving end. Of course, you could do that with GNU Radio as well. You could also repurpose some ham packet radio software should you want more network-like connectivity. Don’t forget you need to be sure you have the right licenses in your locality for your desired frequency band. These radios will often transmit on a wide range of frequencies, so be careful.
This is a good example of how you can use GNU radio for more than just SDR. We’ve seen it used to generate test patterns, for example. If you want to try your hand at GNU Radio, we talked about how to get started with no special hardware.