Revisiting SDR

Six years ago, I did some experimenting with an RTL-2132U USB dongle as a software defined radio on a Mac. Being stuck at home due to the coronavirus quarantine, I decided to dig it out and try setting it up.

After banging my head on the wall for a few hours trying to get various software packages to work, I downloaded CubicSDR onto my MacBook Pro running Catalina, and it pretty much just worked.

Here's a screenshot with the thing tuned to 102.9 WMGK:

I'm able to receive 92.5, 94.1, and 102.9 easily. 93.3 WMMR comes in poorly, but I'm in a little bit of a hole and my antenna is far from optimal. I'm using the little thing that came with the dongle.

I think I have an adapter cable that will allow me to connect the dongle to an SO-239 connector, which will be good because then I can use a 2M/70cm mag mount antenna and monitor local repeaters.

Software Defined Radio

As explained in Wikipedia:

Software-defined radio (SDR) is a radio communication system where components that have been typically implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system.

Traditionally, SDR has been an expensive endeavor. However, some clever hackers discovered that some very cheap TV tuner USB dongles based on the RTL2832U chip can be used as wide range radio receivers.

Back on August 9th I ordered one of these RTL2832U-based USB TV tuner dongles from Amazon for $8 and change. It shipped from China and arrived today. I then downloaded and installed SDR# using this quick start guide. So far, I just have it receiving FM broadcast signals. Here’s what it looks like tuned to the local classic rock station:

As described by Sparks, this $8 dongle can be used as an RF spectrum analyzer to discover what signals are in your area. This cheap piece of hardware plus some free software, and a laptop, Raspberry Pi, or BeagleBone Black system can be used as a portable, low-cost signals intelligence gathering system.