The study of harmonic emissions created by an illuminating signal. As a means to detect eavesdropping equipment. The Superscout NLJD system utilized this approach a few years later.
There are P-Type and N-Type silicon layers in a semiconductors. Non-linear junction is the place where they meet. When two different metals come into contact the junction forms. Rust on a screw can also have Nonlinear connections . The springs in an automobile, or the support structure in any piece of furniture.
By flooding a suspicious region or target with a pure microwave RF signal. A Non-Linear Junction Detector may detect suspected eavesdropping equipment. The reflected harmonic signal is then measured at various frequencies.
An antenna and a control unit are usually included in the instrument. The antenna is nothing more than a microwave waveguide. That both emits and absorbs signals. Installation is on an extensible pole (with a duplexer). Very sensitive radio receiver tuned to specific second and third harmonic frequencies. While the 4th, 5th, 6th, and extra harmonics may measure, those above the third have a limited TSCM value.
A Non-Linear Junction Detector can help you find:
- Bugs that are alive or active
- Bugs that are dormant
- Turned On Bugs
- Turned Off Bugs
- Burned Out Bugs
- Bugs that have died
- Covert or Concealed Video Cameras
- Transmitters for Microwaves
- Remote Control or Remote Powered Bugs
- Devices with Resonant Cavity
- GSM, PCS, and Concealed Cellular Phones
- Microphones that aren’t wired
- Tape Recorders in the Dark (even broken ones)
How to Use a Non Linear Junction Detector Correctly?
Before employing an NLJD, a thorough Non-Alerting TSCM examination must be performed on the region. A Non-Alerting check for any sort of free space electromagnetic signals. including any signals or voltages present on all conductor combinations, must be performed. Before using the NLJD, the region must be evaluated for thermal and IR irregularities.
If you have a limited amount of time to complete the TSCM inspection. you should focus your efforts on other aspects of the sweep, such as the RF survey . When you have the luxury of time and your schedule allows it. The NLJD, like the portable X-Ray or thermal imager, becomes a useful instrument.
Slowly brushing or sweeping the antenna over every surface in the suspicious region is required for proper functioning. It takes 2-5 minutes per square yard of surface area to complete the technique, which is sluggish and time-intensive. With such a device, sweeping a tiny 15 * 15-foot office will generally take four hours.
Every surface in the space, including walls, floors, ceilings, furniture, and fixtures, is painted by the TSCM professional. When a circular polarised antenna is utilized, the time it takes to sweep can be cut in half.
The region to investigate is clean first in a quiet mode of operation. With the instrument employed to listen and track the quieting impact that RF fields have.
During this time, the NLJD’s audio output may be examined with headphones. To identify sync buzz from television transmitters. Emissions from the bias oscillator in some tape recorders.
The illuminating signal will then be turned on, and the NLJD will be used to scan the walls and surfaces from at least 6-8 feet away from the area to be inspected. The goal of this scan is to identify and assess objects that cause false positives. Once these items have been approved, removing of these from the inspection area.
After all large harmonic reflectors have been removed from the region. The spacing between the NLJDs is set to 2-3 feet. Repeating of this process, to further isolate and analyze probable hits.
Finally, the distance between the object or area being viewed is lowered to between two feet and actual touch. For the initial contact sweeps, the lowest workable signal levels are employed first, and the entire region is evaluated again.
After then, boosting of the power somewhat (no more than 25%), and the entire area is cleaned again. If workable, boost the power by as little as possible by doing repeated. Overlapping sweeps over the region in different directions.
Sweep the area’s flat surfaces (such as walls) at a rate of 3 seconds per square foot or less. An ideal cleanroom will take at least 30 minutes to inspect with an NLJD. While a tiny office will take 2-3 hours, and a medium-sized office would take at least 3-4 hours. For the NLJD inspection, a bigger executive office may take 6-8 hours or several days. (On a lighter note, the TSCM specialist will appear to be doing Tai Chi with a painter’s pole.)