LORNET STAR 24S Nonlinear Junction Detector

The LORNET-STAR Non-Linear Junction Detector (NLJD) is designed to detect hidden electronic devices containing p-n junction semiconductors, such as covert audio and video transmitters, audio and video recorders, and improvised explosive device (IED) trigger and timing circuits.

Price: on request

Code: PRIBAGL007

The operating principle of an NLJD is based on illuminating a target object with high-power RF energy (either continuous or pulsed) and receiving the response re-emitted by the object at frequencies multiples of the frequency of the emitted signal (its second- and third-order harmonics).

The NLJD’s ability to detect hidden electronic components stems from the nonlinear properties of semiconductors. Any electronic device contains printed circuit boards (PCBs) with conductors (virtual antennas) to which various semiconductor elements (diodes, transistors, microchips) are connected. For a high-frequency emitted signal, all these elements can be considered nonlinear reflectors. This high-frequency emitted signal induces an alternating electromotive force in the conductors, which is converted by elements with a nonlinear volt-ampere characteristic into RF signals at frequencies multiples (harmonics) of the emitted frequency.

These harmonics are then re-emitted into space and detected by NLJD receivers tuned to these frequencies. Detection of the second and third harmonics of the probe signal by NLJD receivers indicates the presence of a hidden electronic device in the illuminated area, regardless of whether that device is turned on or off. Conventionally, the detected nonlinear object is assumed to be of artificial origin if the level of the second harmonic exceeds that of the third. Otherwise, the detected object is considered a natural nonlinear junction of the MOM (metal-oxide-metal) type.

Application experience with NLJD shows that identifying the nature of the detected object may not always be effective (for example, a rusty metal object may exhibit a higher second harmonic level). In this case, additional identification methods may be useful. This is where harmonic spectrum analysis is particularly useful. In an ambiguous situation, one may wish to apply a physical impact to the object under investigation (for example, by hitting it) while simultaneously observing the second and third harmonic spectrum (or listening to the demodulated harmonic response through headphones). Natural objects subjected to a physical impact will exhibit a broadening of the spectrum (regrowth), while the harmonic spectrum of an artificial (electronic) object will remain essentially unchanged. During demodulation, the spectrum regrowth will manifest as a hissing sound through the headphones.