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TSCM NLJD Audiotel ← Broom
Non-Linear Junction Detector · NLJD
- under construction
SuperBroom
is a Non-Linear Junction Detector (NLJD),
or Harmonic Radar,
introduced in 1996 by Audiotel in Corby (UK),
as the successor to the Broom ECM.
Unlike its predecessor, which can only receive the 2nd harmonic,
SuperBroom can detect the 2nd and the 3rd harmonic simultaneously.
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This has the advantage over the original Broom,
that it is easier to detect
the difference between a semiconductor junction (which predominantly
produces a 2nd harmonic) and a regular non-linear junction between metal
objects (which generally produces a stronger 3rd harmonic).
In other words: by looking at the ratio between the reflected 2nd and 3rd
harmonic, one can tell the difference between a
bug and, say, a rusty nail.
In addition, the Type Approved (TA) variant, uses frequency hopping
over the 10 optimum channels, 1 to avoid false-positive triggering.
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Furthermore, the output of the transmitter can be selected between
6 µW and 2 W. 2
The image above shows a typical SuperBroom kit, that was used by a
European agency for many years. The device consists of a
main unit, with
a rectangular antenna — attached to a telescopic stick — connected via a
fixed black cable. When operated, a display on the antenna shows the
currently selected power output, whilst a LED bar mimics the signal
strength display of the main unit.
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In Europe, 19 channels have been allocated in the 869.400 to 869.650 MHz band.
On startup, SuperBroom selects the optimum 10 channels, that have the least
interfering signals. This improves detection and greatly reduces
false-positive triggering. The channels are listed in the manual [A].
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Approved levels in Europe are 20 mW (EU Low) and 500 mW (EU High).
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- SuperBroom ECM
- SuperBroom Plus
- SuperBroom Plus TA
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© Crypto Museum. Created: Wednesday 25 September 2019. Last changed: Monday, 29 November 2021 - 11:52 CET.
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