Signals Intelligence for Regular Folk – Part 2, by Tunnel Rabbit

(Continued from Part 1.  This concludes the article.)

A $20 SDR-UTL dongle can cover 1.8MHz to 1.2 GHz, and see and hear the entire 220MHz Ham band, or the entire spectrum with the right software. Yet who would use precious power to monitor a band with no traffic on it anyway? The more expensive Dongle covers most everything else including frequencies that drones would use… With the $20 dongle, a poor man’s frequency analyzer, one can see weak transmissions even though they cannot hear them. And one can spot spurious transmissions, secondary harmonics, that can lead to the identification of those using the notorious Baofeng UV-5R. Having a Baofeng or two, I’ve tested this.  If the user is using something besides a Baofeng, I would consider them the more serious threat.  So even you-guys with a Yaesu, Kenwood, or whatever fine radios, can be identified by their lack of spurious RF!

Detection, DF-ing, and Intrusion

To better detect threats using low power radio, rip the television antenna off the chimney that is actually this often dual band UHF/VHF antenna horizontally polarized receiving antenna, but mount to pole so that is vertical (that is up and down orientation), and point it in the direction of the most likely avenue of approach.  Using the old  cable that is on the old television antenna, strip and push one of the bare wires into the scanners antenna plug, and attached the other wire to the body of radio or ground of that antenna base of the scanner.  This is the tricky part, but the correct connector and a 50 ohm, or even 75 ohm cable TV cable without the proper connector can be run from the antenna to the scanner. It is of course best to plan ahead, and do it the correct and reliable way. Program the scanner with only GMRS/FRS, MURS, and even CB frequencies, and others if you can.  Use a second scanner on the same cable to sweep the entire 2 meter Ham band.

The common as dirt radio out there. is the ubiquitous GMRS/FRS radios and represents the most likely radio that Bubba and his gang might use if knocking off preppers. CB radio will be their second choice, and possibly even 2 meter. GMRS/FRS radios have a very short range, so we use a direction antenna that will pick up the weakest signal. and exclude signals that are not as much of a threat.  We would want to hear all traffic in the area as well, but our focus should first be at the front door, and primary avenue of approach.  If any traffic is heard they are very close by, and so is the threat. It would be best to put a patrol out to confirm and gauge the threat, or at least put eyes out on the approach, and ready the defense.

Jamming

If you can ‘up’ your game, purchase an open banded mobile transceiver such as the Anytone UT-5558, or similar inexpensive mobile for around $100, and put it on a discone antenna or Tram 1181 antenna. Get a CB for this job too.  If a threat is determined to be using a frequency, simply plug that frequency into to mobile transceiver, set the power to 5 watts, and using a rubber band place over the mic’s push to talk (PTT) button) so that the radio transmits continuously.  This a crude form of jamming, the dreaded sound of silence, is the ‘open mic’. They’ll figure Bubba has messed up again, and is resting on his mic button. Playing music adds to the effect and fun. It really upsets people. It is unlikely that Bubba has a back up channel designated, and it is possible that this simple stupid trick can take the momentum out his attack. But also listen to see if the threat does have an alternate channel, and then jam that too. Ooooh, that would give them the hebe-gebbies!

People accustomed to instant communications with their buddies feel lost and isolated without their cell phone, and now radio. Do this using a mobile transceiver that can transmit continuous on it lowest power setting of 5 watts, as the Baofeng has a very short duty cycle (transmit time), and could over heat and fail if used as continuous method of ‘open mic’ form of jamming.  A better use of a Baofeng in this role would be to monitor their traffic, and selectively interfering with their traffic.  This method takes more attention and finesse, yet may actually be more effective at causing confusion or FUD (fear, uncertainty, and doubt).  Interjecting short comments, or affirmative and negative responses in their lingo or manner, may be enough to disorganize them.

When you get bored with that, as they transmit, hit them with an intermittent open mic when they attempt to ‘talk’ to each other. That way, their team assumes that they are ‘walking over’ each other on the air. They will not suspect that they are being selectively being jammed, at least not right away.  And when you get tired of that, hit them with dreaded sound of death, silence, the continuous ‘open mic’. Transmitting loud music might be heard by your LP/OP who can hear their radios!  So many options….You may also transmit disinformation! One can create a false conversation, or tell them they are out numbered and surrounded, and should give up. You choose.  Bluff or not, you are at least letting them know that you are well organized and more capable, and they may decide leave to find lower hanging fruit. Perhaps your neighbor? Time for an ambush!  One may even use a digital recorder on their smart phone to record voices, and play them back, so that the enemy believes that they are hearing a familiar voice.  P25 traffic can also be interfered with in this way, even if you do not have DMR. But that is deeper than we really need to go here.

Your Mind Is Your Primary Weapon

Just remember that your mind is your primary and best weapon, and you can use radio as an extension of that weapon. Old age and treachery can be a match for youth and brawn. One might be surprised that grandpa is more dangerous with a radio, than several guys with guns.  That is because grandpa knows that there is more than one way to skin a rabbit.

Here is the gear that makes it go ‘much more, more better’, using a Tram 1411 Broad Band Discone/Scanner Base Antenna, and the necessary accoutrements:

Item #1: The Tram Discone antenna.

Item #2: 50 foot cable with PL 259 connecting ends.

Item #3: Lightning protection adapter.

Item #4: BNC Male to SO239 pigtail type adapter to connect to the scanner.

Grand Total for the outfit: $102.

Option A: A ‘splitter’ to connect more than one scanner or receiver. Additional pigtail cables and adapters will also be needed to complete the connection, such as is item #4, if another scanner would be attached.

Option B: A pigtail cable and adapter for connecting a mobile or hand held radio. This is a short 3′ cable with two PL259 connector ends.

Why a Discone?

The discone antenna is the Swiss Army knife of antennas. Listening will be more important than talking, but it can do both, well enough. Most of the antennas that I make are broad banded, because after awhile the antenna farm gets so thick, coupling, and all sorts of entangling hassles make running the farm problematic. I will take the compromise of a less efficient radiator of radio waves to increase bandwidth to reduce cost, cables, confusion and interference with other antennas. After making one good discone from scratch, at $48, it is smarter to buy this one.

The home brew is flatter than a pancake across the spectrum. It can be done, but why bother if it is this inexpensive? My discone also picks up shortwave very well, even Australia, better than the long wire, or the dipole that is usually recommended.  Any frequency that the Baofeng, or just about any radio you will like have, can transmit on this antenna.  This is a one stop shop and go answer.  Of course before transmitting on it, disconnect all other radios.  It entirely possible to run several scanners or receivers on this one antenna using a ‘splitter’.

Check the SWR

Anyone remotely involved with radio, whether listening or transmitting can use this antenna. I would check the SWR on CB frequencies on this one, but I am confident that it will test < 1.5:1 from 144 to 490Mhz. If you need high gain, then this is not the one. Yet a good radiator is not always best, when lower power is your friend, an antenna that is high gain is not your friend. Purchasing this discone antenna would an efficient use of limited resources and space.

Note: For those in the know, 53 feet of RG58 coax is by most standards is unacceptably “lossy.”  It is inefficent should one intend to deliver the maximum power an antenna. As in all engineering, comprise is apart of the process, however, we can use this compromise to our advantage, while providing versatility to a utility, and at low cost, and in an environment were an optimal effective radiated power (ERP) is not the goal, but a where a reduced RF (radio waves) footprint is desirable. 1 watt is acceptable, yet 250mw might better. A mobile radio, unless the operator tweaks the output down, puts out on it’s minimum power setting, 5 watts.  We will lose 6Db (decibels of energy) for every 100 feet of RG58 with frequencies used in area of 150mhz. With 50 feet of RG58, the loss is about 3Db.  Run that though your favorite ERP calculator, and 5 watts is reduce to 2.5 watts out the door, or at the antenna. I would be happier if it were 1 watt.

Granted, this is a lousy way to reduce an RF footprint, but is better than nothing. Remember Rule 1 for radio: In a war zone, ‘low power is your friend’.  Military style radio operation runs counter to that of Amateur Radio’s unstated mission, to talk to as many as possible, as far away as possible. In the not too distant future, we should first strive do so as a military operation would do, and attempt to communicate to as few as possible, and within the smallest radius possible.  The other part comes latter.