American Partisan: Basic Sigint Equipment

Former US Army Signal Intelligence Analyst Madman Actual writes about his basic signals intelligence (sigint) equipment in this article from American Partisan.

Here are some basic tools to get you started on your Sigint Ninja journey, young Padawan. From left to right we have: a pen for writing, the Brushbeater RTO TACSOP(Tactical Standard Operating Procedure), above that is the antenna for an RTL-SDR dongle, above that is a manufactured Yagi antenna, below that is a Radioddity(pronounced Radi-oddity, could have swore it was radio-tiddy), below that is my Rite-in-the-Rain notebook, next is the mighty BaoFeng AR-152, my AMD Ryzen 3 powered Lenovo Laptop, a Sig 365XL because guns are cool and my finally my morning coffee.

Now that the run on sentence is complete, let’s talk SIGINT. The point of this little exercise is firstly, a functions check for my gear, and to give you a nice look at what can be used effectively. You don’t need all of these but you do need at least two. You NEED a two-way radio and a directional antenna. Yagi’s work well because of how the antenna is constructed. NC Scout has written extensively on this so I won’t waste time here.

Radioddity GS-5B

This little guy runs about $100 and is very handy to have around. It doesn’t have the transmit power of other radios in the same price range. In fact, the AR-152 is a much more capable communications device and is probably better for direction finding as well. I’m a great salesman, I know. I paid for this dumb little thing for two reasons: It’s rain proof(tested and satisfied) and it has a Received Signal Strength Indicator or “RSSI” on the display. So while you dorks are spinning in circles praying to the Sigint gods, I’ll be making precise movements to find the wascally wabbit. This bad boy has a lot of functionality to include scan mode, dual standby mode, up to 127 channel memory, and a mostly useless Bluetooth function. At least I can’t seem to find a reason to use it.

I’ve tested the 5B at range with omni-directional antennas and the RSSI is quite sensitive. A 2Watt power radio at 1 mile will usually show between a 1 and 2.5 value depending on the frequency used(one shown was used at 1 mile), wattage(low on AR-152) time of day and weather conditions(Chilly morning with no visible sun ~40F) A good rule of thumb is that the higher the frequency, the more susceptible the signal is to propagation interference. But this little bar above the frequency is a very handy tool when linked with a well tuned directional antenna. WELL TUNED is key. My trusty Sigint assistant Johnny Paratrooper and I tried this with a manufactured Yagi and while reception was phenomenal, directional sensitivity was lacking severely. A home-made, precisely cut antenna using your handy dandy RTO TACSOP with the cheat sheet will beat anything you can purchase on the web for a reasonable price.

  BaoFeng AR-152

This is functionally the same transceiver as the BaoFeng UV-5R and the like. Scanning speed is sub-par to dedicated scanners, but certainly is enough to get the job done. It also seems to be a bit more sensitive with higher squelch settings(1-5). I’m not sure if this is the antenna that comes with it but the Yagi just makes it all the better. We used this and the Yagi setup in the SIGINT Course taught by NC Scout and it works well. I highly recommend this combo for newer pupils to Radios and direction finding. It’s so easy, a caveman can do it.

Software Defined Radio(SDR)

Here we have the SDR Airspy waterfall display. We were transmitting 462.562, if you’ll notice the spike graph has a mound with a heavy spike. That’s what it looks like with a very strong signal, this particular one was within 2 feet of the SDR rabbit ear antenna. And you’ll see on the waterfall this is mirrored with the thick red line surrounded by the yellow coloring. This is simply a graphical representation of the Carrier Signal’s bandwidth being broadcast from the transmitting device, this was an AR-152 on Low power. You can see to the right on the waterfall display that around 464.200 there is some activity. This started exactly when began transmitting on 462.562, curious indeed. I transmitted in my living room with windows and mirrors and all sorts of things to bounce that signal all over.

When this happens, the mysterious phenomenon I call Signal Doppelganger occurs. Receivers will hear the same transmission but will appear as two separate frequencies on displays such as this. Clearly, one is the true signal, the other is a filthy imposter only there to confuse and disorient newbies. If you heard this with your UV-5R, you may be convinced that you got em’ but they’re too far away which is why the signal is so broken and barely readable. You’d be chasing a ghost.

Wrap Up

All considered, I highly suggest you start with a cheaper radio like the BaoFeng lineup of  UV-5R, 82L, AR-152 and many more. If you feel like forking over a Benjamin, the Radioddity GS-5B isn’t a bad choice either with the RSSI. SDR’s are NOT tactical but very useful for the Homestead or in a truck being used for Sigint Area Studies. A good Sigint Team uses a combination of tools and could be a nightmare for street commies and even a more professional force with some training and coordination. The RTO/Advanced RTO and Sigint class shows you how to use a digital tablet and an analog radio to play games with enemy communications, the Tactical Sigint Exploitation will show you some strategy and more tricks on making an effective Low Level Voice Intercept Team.