The police and military have computerized radio direction finding capability which is astounding these days. It is unrealistic to believe that criminal gangs would not have the tech.
Using off the shelf, computer driven scanners and a netbook computer engineering students at VA Tech built one, which in US Army tests took only 4 seconds receiving a transmission to generating a location pinpoint, a blinking dot on Google maps.
Intel agencies, police and military have this technology and use it. You've gotta love the ignorant and the arrogant people who spend so much time on their cell phones and are utterly clueless as to elementary ELINT.
Use rf comms only for mission essential communications, keep transmissions brief, use the minimum transmit power to establish and maintain communications. If you transmit, you can be found. We use radio "fox hunts" as a game and with practice you get very good at it. To make "the game" last longer use narrow bandwidth modes of transmission with computer controlled frequency hopping, with low transmit power and high gain yagi antennas with good side rejection and a high front-to-back ratio, taking advantage of terrain shadowing and reflection, while keeping on the move. Point to point burst laser transmission can provide high data rates over line of sight paths.
But generally, low tech tradecraft is best, unless lost and you WANT to be found.
Two things come to mind.
First is that this capability has been used since the 1960s and we were trained against it then. Even then compressed transmissions were the norm. We often operated in radio silence and used prearranged fire coordinates to keep messages only a couple of seconds long.
Even then, with the limited number of frequencies available and the number of operators wishing to use them the chaos of a Battalion or Divisional radio net is astounding. Getting a fix on a single frequency might net you 40 locations in a square mile.
Second, I worked with urban street gangs for years and know of none that had electronic technology mastered. If they ran across the equipment somewhere they would not know what it was and their first impulse would be to pawn it for drug money. The primary use of this technology, I am sure, would be government against resistance.
I am sure that with today's technology a trained operator can get an almost instant fix on a transmission.
With current military grade gear a radio bearing fix is instant.
Mutilple networked battlefield sensors dispersed over an area by UAVs can identify rf, sounds or light flashes and triangulate target position and range in a few seconds.
Locating artillery, rocket or mortar firing location and initiating counter-battery fires similarly takes only a few seconds.
What is the objective of this thread Charles?
A number of SUK posters have run the gauntlet of UK government agency radio Direction Finding for many years and have never been caught. The link between transmitting and getting caught is not a done deal.
You've described a threat. So, as a radio man, what counter measures do you propose for us?
I don't see lugging my portable VHF or 6m contesting beams around as being too good for opsec, as they attract too much attention from observers.
Anyway, from a personal perspective, our planned use of radio coms is to maintain connection with our group in the immediate area, and secondly to maintain contact for support information and intelligence gathering from dispersed survivor groups.
We are working on the principal that if the military are concertedly looking for us, they’ll find us, with or without radio transmissions, and if they do find us there is little we are capable of doing that will effectively resist them.
For the local stuff we are using broad band VHF/UHF hand-helds operating split frequencies at very low power, into very stubby and inefficient antennas. Testing indicates that transmit range on these devices is just a couple of miles.
For the second group. we’ve been testing with just 5w and have pretty much UK-wide coverage using sky wave techniques that are rather difficult to DF from beyond the visual horizon.
I was merely pointing out that no rf communication available to civilians these days can be considered "secure." As for DFing unlicensed users, at least in the US, law enforcement asks us to assist only when the unlicensed users are causing interference with a licensed service. In the Washington, DC area there was a group of fellows using CB radios transmitting on the 10m amateur band, dispatching a pirate taxicab outfit which were putting out spurs getting into some fire department radios, so our volunteer group was asked to locate them. We rolled up their whole operation in a few days, police and FCC raided the taxicab office, confiscated 16 taxicabs and radios, and deported a bunch of illegals without "green cards."
Much more fun than chasing and recovering nweather balloons, which we also do regularly for the National Weather Service.
If you want to be discreet and low profile you shouldn't say anything over the radio you would not want to read on the front page of The Times. That's all.
As for "countermeasures" when we practice the "fox hunt" the fellow hiding with the transmitter uses a narrow beam directional with good side rejection and the highest possible front to back ratio. He also uses the lowest transmit power in the narrowest bandwidth, taking advantage of terrain shadow and reflection. Microwave burst transmissions with narrow focussed directional wave guide are state of the art. Keep transmissions short. Use frequency hopping. The cadets at VA Tech are experimenting with laser burst transmissions to send data over line of sight paths. All is good fun for geeks.
(4 November 2013, 16:25)CharlesHarris Wrote: [ -> ]I was merely pointing out that no rf communication available to civilians these days can be considered "secure." As for DFing unlicensed users, at least in the US, law enforcement asks us to assist only when the unlicensed users are causing interference with a licensed service. In the Washington, DC area there was a group of fellows using CB radios transmitting on the 10m amateur band, dispatching a pirate taxicab outfit which were putting out spurs getting into some fire department radios, so our volunteer group was asked to locate them. We rolled up their whole operation in a few days, police and FCC raided the taxicab office, confiscated 16 taxicabs and radios, and deported a bunch of illegals without "green cards."
Much more fun than chasing and recovering nweather balloons, which we also do regularly for the National Weather Service.
If you want to be discreet and low profile you shouldn't say anything over the radio you would not want to read on the front page of The Times. That's all.
As for "countermeasures" when we practice the "fox hunt" the fellow hiding with the transmitter uses a narrow beam directional with good side rejection and the highest possible front to back ratio. He also uses the lowest transmit power in the narrowest bandwidth, taking advantage of terrain shadow and reflection. Microwave burst transmissions with narrow focussed directional wave guide are state of the art. Keep transmissions short. Use frequency hopping. The cadets at VA Tech are experimenting with laser burst transmissions to send data over line of sight paths. All is good fun for geeks.
Thanks Charles,
Agreed that using equipment available and affordable to us normal folk, that every radio transmission should be considered a public broadcast, and that we must exercise caution with what we say on air.
Direction finding a taxicab firm and weather balloon is not complicated at all, as neither employ any form of Opsec operating protocol. Taxi firms make almost continuous high power transmission on a very predictable frequency. Weather balloons have fixed frequency and fixed timing of transmissions albeit at lower power. Both of these make for easy triangulation.
The guys in UK who succeed when playing cat and mouse with direction finders have developed a self-preservation operating methodology that is very similar to military radio operating protocol:
- Keep transmissions very short, use code words and pulses of dead keying.
- Change transmission locations often
- Transmit and receive on different frequencies
- Keep power used to a minimum
- Change transmit and receive frequencies very frequently (frequency hopping).
- Use of narrow bandwidth (Select the narrow mode on the radio’s programming)
Pulse coded laser beam transmission has already been discussed in the coms section of this forum. Technology is available off the shelf that allows voice modulation over laser. We are currently experimenting with laser coms and the biggest issue faced is reliable alignment of between field portable transmitters and receivers as the beam-width is so narrow.
Using Lightspeeds guide above, and a pre prepared code book, will make it very difficult for even a sophisticated bandit to find you.
For example, your local group could be issued with a map of the area with numbered grid. A short spoken message like "forty six ninety two" lasts two seconds and can be decoded to mean "I need medical help at map reference ninety two".
(5 November 2013, 12:26)Steve Wrote: [ -> ]Using Lightspeeds guide above, and a pre prepared code book, will make it very difficult for even a sophisticated bandit to find you.
For example, your local group could be issued with a map of the area with numbered grid. A short spoken message like "forty six ninety two" lasts two seconds and can be decoded to mean "I need medical help at map reference ninety two".
Spot on Steve.
That's a tried and tested method
Charles, I sincerely doubt that the authorities (without an enormous amount of blind dumb luck) could monitor, much less track a 10 word PSK31 data transmission sent at 10 watts of power with a beam antenna, given the number of frequencies available. Hell, the HHS can't even set up a website that works! Just don't use the same frequency, excessive power, or make the message too long and you should be OK...