The detection of low power radio transmitters (bugs) in a typical corporate environment requires much skill and some very expensive equipment.

The detection of such devices along with video chip cameras and concealed microcomputers in a casino environment is a nightmare.

At the risk of offending TSCM (Technical Surveillance Counter Measures) professionals by oversimplifying a very complex process, I will attempt to give you an overview of the task at hand.

Radio frequency energy is all around us. If you were to stick up an antenna, say, in the middle of Sydney and look at all the signals present you would see TV stations, radio stations, a multitude of commercial two-ways, mobile phones, the list goes on.

If you were to do the same thing in Perth, you would get much the same thing only not quite so much of it.

If you were to do it on a country property you might only get the odd TV and radio station.
This ambient level of radio frequency energy is known as the 'r.f. floor'.

Radio frequency energy, for our practical purposes, starts at DC and goes up into the Giga Hertz range. Our antenna is picking up all these signals at the same time; if you were to listen, a hissing sound is all you would hear. To hear one particular frequency you 'tune in' to the one you want, thereby cutting out all the others.

A device that was permanently transmitting could be detected using a scanner. The scanner would be set to its lowest range and it would proceed to look at every single frequency until the target was found. Unfortunately if the transmitter is not radiating at the precise time (.001 sec) the scanner is looking at it, or if the scanner is just out of range, it will be missed. It also takes a considerable amount of time for a scanner to sweep the full radio spectrum in the minute increments that would guarantee detection.

A scanner is fine for eavesdropping on known bands, say police or emergency services, but it is useless as a TSCM detector. There are detectors designed specifically for the TSCM industry but they fall out of our range due to cost and the extremely high level of training required to operate them.

Near field transmission

There is a phenomenon known as the 'near field'. When very close to a transmitter, even an ultra low-power one, the radiated energy or near field transmission is much higher than the r.f. floor found in most places, even city centres.

This near field phenomenon lead to the development of hand held broadband detectors, more commonly known as bug detectors. You would have seen these used by would-be TSCM people. The idea is to walk around with the device and a set of headphones waiting for the near field transmission to break through the r.f. floor.

This technique has some merit if you are looking for a medium-power transmitter in the middle of paddock but it is unlikely to find anything remotely sophisticated in an urban environment. These devices should be left to the local Dick Tracys to impress their clients.

Not much help am I?

It gets worse. The r.f. floor in a typical casino environment is spectacularly high. Some video machines pump out more spurious r.f. energy than a professional listening device. If a bug detector does not have an adjustable threshold it will sing its head off as soon as you walk on the gaming floor forcing you to de-tune it to the point that it becomes electronically deaf.

I would not recommend that casinos purchase these devices. Assuming device use and looking for further evidence is a much better option than dismissing device use because your detector doesn't sing when you approach the target.

So, how do you detect concealed computers, transmitters and video cameras on the gaming floor?

Quite simply, you can't.

All is not lost!

Electronically equipped teams with the ability to dent your bottom line will almost certainly be using inductive ear canal receivers.

These receivers detect magnetic radiation, not radio frequency. For our purposes this magnetic radiation can only travel a few feet. This radiation is 'broadband' in the sense that to detect it you do not have to tune to a particular frequency. If an inductive loop and amplifier is brought within range of the device's output inductor, it's possible to receive the same signals that the wearer of the earpiece is receiving.

Inductive loops are both transmitters and receivers. For example if you pump a very high-power oscillating signal into such a loop while in the vicinity of someone wearing an inductive earpiece, you would drive them batty. Such a device could be hand held or incorporated under gaming tables for very little cost.

Surveillance Technology can advise on the techniques involved and the equipment required.

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