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TSCM
Technical Surveillance and Countermeasures

This section deals with equipment that has been used (or is currently being used) for finding clandestine transmitters, covert listening devices (bugs) and monitoring the frequency spectrum in general. Note that there will be overlaps with other categories on this website.

TSCM equipment on this website
Wire-line bug detector Russian countermeasures receiver for the 100 MHz to 12 GHz frequency range Mason surveillance receivers Micro-Tel precision surveillance receivers Scanlock series of TSCM receivers and other Audiotel equipment Innovative add-on for the Scanlock Mark VB Various bug detection devices made by Research Electronics International (REI)
REI
Enhanced Omni-Spectral Correlator (bug finder)
Powerful hand-held bug tracer Cable checker for mains cables and telephone lines Sadelco FS-3 field strength meter NRP field strength indicator with built-in frequency counter Dare CR-3000/C frequency counter with integrated field-strength indicator Rohde & Schwarz FSH-3 portable spectrum analyzer HE-100 directional antennas ZAP Checker - field strength indicator
ZAP
Optoelectronics Scout 40 automatic frequency counter 10 MHz - 1.4 GHz Sensitive near-field test receiver 30 MHz - 2 GHz Rohde & Schwarz EB-200 Monitoring Receiver 10 kHz - 3 GHz Capri (7042) LW receiver, used by the Stasi for finding carrier frequency bugs
Non-linear Junction Detector · NLJD
A non-linear junction detector, commonly abbreviated to NLJD, is a countermeasures device for the detection of semi-conducting materials, such as the P-N barrier in electronic components like diodes, transtors and ICs. As most covert listening devices (bugs) are built from such parts, it is possible to discover their electronic circuits, regardless of whether the device is powered or not.

When a semi-conducting object is illuminated by an RF signal of a particular frequency f1, the non-linear properties of the object will cause harmonics of that frequency to be generated, in particular the 2nd and 3rd harmonics (f2 and f3). By examining the minute f2/f3 harmonic signals reflected by the object, it is possible to discover the object, even when it is hidden from sight.

Note that other semi-conducting materials, such as a rusty nail or an oxidised piece of metal, also generate harmonic frequencies and may there­fore cause an NLJD to generate a false positive.
  
Broom ECM with broom-stick antenna

For this reason, modern NLJDs often examine the ratio between the 2nd and the 3rd harmonic. With an electronic P-N junction, the second harmonic will generally be stronger than the third, allowing an electronic circuit to be discriminated from a rusty nail with reasonable certainty.

The NLJD was invented during WWII by Charles Bovill, who used it to discover corrosion below painted surfaces on airplanes. In 1972, shortly after Bovill had become technical director at Allen International Ltd. (Westminster, London, UK), the device was renamed Broom and was marketed as a bug-finder. The Broom was later marketed by Audiotel in Corby (UK) as the Scanlock Broom, succeeded in 1990 by the Scanlock Broom ECM and in 1995 by the Scanlock Super Broom.

Non-linear junction detectors on this website
Audiotel Scanlock Broom ECM
Known non-linear junction detectors (NLJDs)
  • 1972
    UK
    Broom
  • 1990
    UK
    Scanlock Broom
  • 1995
    UK
    Scanlock SuperBroom
  • ?
    USA
    REI SuperScout
  • ?
    USA
    REI Eagle
  • ?
    USA
    REI Orion
  • ?
    USA
    Hawk
  • ?
    USA
    Boomerang 4
  • ?
    USA
    Locator
  • 1985
    USSR
    Orchidea-3
  • ?
    Russia
    Lornet 36
  • ?
    Russia
    Lux
References
  1. Wikipedia, Nonlinear junction detector
    Retrieved November 2018.
Further information
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Crypto Museum. Created: Saturday 24 December 2016. Last changed: Friday, 09 November 2018 - 09:18 CET.
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