SIGINT SBRs

Strategically Bad Radios

Above is a photo of a TinySA and two Retevis Model RT19s. The TinySA is by far my favorite piece of gear for finding signals and I will shamelessly plug this thing until I die. It’s inexpensive and is about the same size as a Razor flip phone. The RT19 is about the same size and features a 500 milliAmp battery about .5W output for transmitting, 2 channels(UHF), and cannot be encrypted. Remember the title of the article.

Many moons ago, NC Scout and I discussed what radios a G-team should be using in guerilla operations against a more advanced occupying force. Obviously, High Frequency(HF) is the most difficult to track simply due to the infrastructure required to direction find those signals. Naturally, light weight comes to mind which puts HF comms right out. A Yagi tuned for HF bands is somewhere of 15-30lbs depending on the material used….not exactly a man-portable piece of equipment. Very High Frequency and Ultra High Frequency antennas are much smaller and more portable.

VHF antennas can be cumbersome but when they are made with portability in mind, can be folded and stored quite nicely in most packs. UHF antennas are very portable which makes that band a great pick for your standard Signal Operating Instruction/Index(SOI). UHF works best in urban areas with a lot of structures that the transmitted signal must reflect, refract, and diffract around/through. However, it typically does not broadcast over long distance when using your typical handheld radio. VHF is great but your friend’s fishing boat has a VHF transceiver on it for a reason. VHF is great for transmitting where reflection is a problem i.e. bodies of water and mountainous areas(rocks). It travels farther with little loss in audio quality.

Our field tests in the best and worst conditions put the RT19 transmitting no more than about .8 miles. That signal was broken and unreadable but broke squelch on a crystal clear, dry night with a full moon. The TinySA read the farthest readable signal(.6 miles) at about -80 dBm which is 10 PicoWatts. “Decibel-Milliwatt” is different from “Decibel” in that it is connected with the actual power level of that signal at the receiver measured in Watts, where as decibels is a relative measurement with no absolute. Meaning, dBm can be used to judge about how far you are from the transmitter. This won’t be GPS accurate but can tell you whether or not that right now is a good time to not move a muscle and stfu.

Guerillas typically should be spaced out but not so far as to be useless to each other. Radios such as the RT19 are a decent choice because they offer great signature reduction. Encryption only helps if you talk too much, anyway. That does not mean that a bigger, encrypted, farther reaching radio should be disregarded. Those have place at a certain time. But in a more tactical environment, sending a hasty one word voice message over the air with very little power is going to be much safer than allowing someone further away to tune in and monitor your frequencies. Keeping a lower signal profile is key to staying hidden for longer, which means you get more intelligence collection and less holes in you.

Disclaimer: I purchased these at a cheaper price about a year ago. I’m sure there are even better SBRs on the market, just keep that principle in mind.