Technical description and operating manual ST 167 and ST167W5
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7 RECOMENDATIONS
7.1 GENERAL RECOMENDATIONS
During surveillance devices search it should be considered that ST167 is intended for only
RADIOTRANSMITTING devices search. Excluding this class of surveillance devices there are devices,
which are using wirelines of different purpose, optical etc. They are using both in common with radio
transmitting surveillance devices and independently.
Before doing any search events, if possible, it is necessary to provide activation conditions both for
remote control ART and DRT on basis wireless data transfer standards. Best variant is imitation of
important meeting with appropriate sound. Real situation could be complicated due to, for example,
hidden video camera presence.
When searching DRT microphone sensitivity range should be considered. It is no more than 10
meters. Usually, DRT are placed as close as possible to the meeting point – inside of meeting table
or interior which are nearby to it.
Possible emission levels of modern ART and DRT are very wide. In general case it can be from Watts
to tens microwatts. For example, emission power of classic ART with FM Modulation and range of
few hundred meters is about tens milliwatts. Maximum power of GSM transmitter- 2W (with
maximum distance from the base station). Minimum real power of 3G and 4G transmitters –
microwatts (with minimum distance from the base station)
Extreme cases, both large and small are quite specific and rarely found. Particularly, it can be low
power repeater, designed for signal transmission on distance of few meters outwards from the room
and its subsequent transmission through other channels (wireline for example). In usual practice
emission level is about milliwatts.
ST167 is a broadband receiver providing signal receiving with wavelength from tens of meters to
centimeters. Radio waves spread with such wavelength difference, especially in cities, is significantly
different.
Supplied HF antenna, certainly, isn’t optimal for all frequencies. During absolute measurement it is
recommended to use antennas, which are exactly corresponds to selected frequency range of the
main block ST167.
Detection of source location is made on base of receiving signal level scale increasing when
approaching to the signals source location (amplitude method)
When signal level is above -40dBm, as usual, it means that device is very close (from centimeters
to 1 meter) to the source.
Real signal level can de different up to 10 times due to the only dimensional orientation of the
receiving antenna measurement.
Reflection of signals from walls, heating radiators, ceiling and interior can give false impression of
signal level.
