Wyoming Survival: Radio Direction Finding

Originally appeared on Wyoming Survival and used some of my input in response to a question a reader posed. People who say “BUT ANYTHING CAN BE DF’D SO RADIO STUFF IS USELESS” are, in my experience, lazy people using a cop-out to not put in the work necessary to learn what they need. I’ll almost go so far as to label them completely useless (almost), and describe it as the same argument as saying a rifle is useless becasue the Boomerang system (an acoustic gunshot locator) also exists. Its absolute idiocy. Had these people any real experience, they’d be asking the opinions of their betters instead of stating what they think they know. Little tidbits I’ve picked up over time. -NCS
The other day a reader brought up the fact that my article on 100% secure comms was incorrect because even though it was encrypted it could still be heard and direction found(DF). I couldn’t disagree with him so I edited my write up some.
I started to dig into radio direction finding some after that. I wanted to see how big a threat this really is and how quickly you could be DF using horrible radio procedures.
So the cheapest and most common way to DF someone or something is the use of a yagi antenna and a handheld radio or receiver with some sort of S meter. You point the antenna in the direction you get the strongest signal from. You shoot an Azimuth in the direction the signal is strongest and put that Azimuth on your map. You do this multiple times from multiple locations (multiple people working together at once) and where your Azimuth intersect should be the location of the signal…… maybe. This is slow and not very productive if there isn’t a constant signal being sent out…..(hint hint)

The video below is off the shelf DF equipment. I have ZERO experience with this but by judging by the video it works great and quick!…. with a constant known signal (hint hint)

This video is a military system. The video doesn’t really show its capabilities but you should consider its probably the best technology out there. I would like to know the speed of this system and the accuracy of the signal location….. unless I can get someone who has used it i will not have that information. After seeing what off the shelf can do I would say this would possibly be double the off the shelf equipment.

https://www.praemittias-systems.com/Wolfhound/
So am I saying you are basically doomed and don’t have team comms??
NO!!
The technology used against a team will depend on how much attention the team brings on themselves and also how much resources the teams opponent has to put against said team.
If you are a quiet group in the Mts not causing problems the chance of you getting DF are pretty slim I believe.
But you and your team still needs to practice proper radio security.
You do not need to be on the radio for everything.
Everyone in your team does NOT need to have a radio.
Shorter broadcasts are better.
SMS messages are even better.
There are other things but we will save them for later.

By NC ScoutPublished On: July 24, 2021Categories: AP Staff, Comms, Intelligence5 Comments

About the Author: NC Scout

NC Scout is the nom de guerre of a former Infantry Scout and Sergeant in one of the Army’s best Reconnaissance Units. He has combat tours in both Iraq and Afghanistan. He teaches a series of courses focusing on small unit skills rarely if ever taught anywhere else in the prepping and survival field, including his RTO Course which focuses on small unit communications. In his free time he is an avid hunter, bushcrafter, writer, long range shooter, prepper, amateur radio operator and Libertarian activist. He can be contacted at [email protected] or via his blog at brushbeater.wordpress.com .

5 Comments

Madman_Actual July 24, 2021 at 09:42

On point as always. If you keep a whole conversation under a minute and broken up or like the article states, SMS. I can assure all that its not Hollywood.
I know how to hike around a df stuff professionally, it’s not pinpoint and it takes a good amount of data to make an accurate assessment of transmitter location. Even with airborne assets. Certain parameters must be met to call a transmitter location.
That said, you have to keep a very low profile and move often between transmissions of RF.
- Mas Casa July 24, 2021 at 17:24
  
  Good info. When you say it’s not pinpoint, do you mean an ellipse?
  Seems like it would also be wise to switch bands, if possible, so as to avoid establishing a “pattern of life.”
Oarsman July 24, 2021 at 10:42

One of our local clubs is into foxhunting (hidden transmitter hunting). We have our fox sent to transmit 15 sec out of every minute. It seldom takes less than an hour to find the fox. You don’t need a license to do this stuff, so I’d encourage giving it a try. It’s a useful skill to develop.
Jefferson Thomas July 24, 2021 at 21:10

I have the Kerberos SDR which is the model prior to the KrakenSDR. (I was actually going to do an evaluation on this later but haven’t got to it yet.) The KSDR uses four antennas and it seemed to work “ok” at first but then I had a number of problems with it. As I live in the country I shouldn’t have had too much interference – at least no like if I lived in the city. Using a RPi 3b is a real exercise in patience with it so I tried a RPi4-4GRam and while better still has issues. This is NOT for pedestrian use by the way. The best use – if you can get it to work decently – is to have multiple stationary units which upload the directions to a server which maps the azimuths. Details of this system are given at their website. I am not there yet with this. Also, the KSDR systems are not going to work well for HF as the antennas will have to be too far apart to be practical with regards to the length of antenna feedline to the SDR system, and the limit on USB cable length. And lastly, as stated above, as long as comms are kept brief and infrequent, and the communicator shoots and scoots like they’re supposed to, this is unlikely to help the DF’er. State actors with big budgets, otoh, are more capable.
Freewheeler July 25, 2021 at 09:20

I made a DF tape measure yagi for 2m fox hunting. I used 2 Baofengs to test it.
To send an intermittant signal from the Baofeng one only needs to engage the emergency light button where the light blinks off and on every few seconds and shrill sound is emitted … it also sends out a beacon signal! It worked pretty good.
Both need to be on the same freq if I remember correctly.