NLJD: device to ponder about
Typically has an antenna and a control unit. The antenna is mounted on an extendable pole, and really nothing more than a microwaveguide which both emit & collect the signal (with something known as a duplexer). The control unit is usually a multiple channel, highly sensitive radio receiver tuned to specific second and third harmonic frequencies. While it is possible that we measure higher harmonics (4th, 5th,6th etc..)but its of no use as it has a very less TSCM value. TSCM means technical surveillance counter measures and it’s a set of measures to identify and locate hostile & illegal technical devices planted at your company for information collection purposes.
NLJD may be used to identify:
Active or live bugs
Turned on bugs
Turned off bugs
Burnt out bugs
Covert/ concealed video cameras
Resonant cavity devices
Concealed cellular, PCs, GSM phones
Electronic timers for hidden bombs
Hidden tape recorders (even broken ones!)
As the power input increases the greater the range of the unit and the penetration into the solid material. However with increasing power levels the sensitivity of the device decreases. Find it hard to believe, I know, I felt the same.. Also NLJD transmitting power is relatively meaningless, the sensitivity & bandwidth of the receiver is a far more important issue.