Technical description and operating manual ST 167 and ST167W5
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7.2 RECOMENDATIONS FOR DRT SEARCH
All “digital” standards are used for illegal data transmission. A lot of factors contribute to this, primary of
them are:
Availability
Relatively low price
Difficulty finding
In most cases information receiving point can be anywhere in the world.
GSM 2,3,4 и 5G
To detect radio emissions from listening devices using cellular standards, it is
advisable to exclude from the control all other standards. This will speed up the detection
process, as standards are monitored sequentially.
Cell phones are working as a transmitter:
In moment of connection with base station.
In the presence of audio signal in audio path of the phone (talking) after connection.
During data transfer (SMS).
All other time phone working in a receiver mode.
Emitted power of listening devices with GSM transmitter, and as a result its detection range depends
from base station distance. As farther- then bigger will be emitted power. In cities detection range of
GSM900/1800 is up to 10 meters and farther. Emitted power of devices with 3G transmitter is significantly lower
and, respectively, detection range will be much smaller.
DECT
For listening and data transfer mobile phones with room listening or “Baby monitor” function can be used.
In ST167 in case of maximum signal level indication in all DECT frequency range separated signal
indication for phones and base stations functions is intended.
There is no such separation on the spectrum. Spectrum using for unauthorized DECT signals detection
is based on principle, that both devices, as only appeared ones and already available will use free channels for
the broadcast. For searching of its source channel number should be remembered, selectively they are shown
on the upper part of display, by pressing
go to channel level indication( fig. 9) and by pressing
and
buttons needed channel can be chosen. Next, moving with ST167 by looking on signal level indication
(increasing- decreasing) source location can be determined.
«Usual» base station and phone detection range is about 5 meters.
WLAN
This standard can be used for video surveillance, audio information transition, data transmission, both in
real time and with accumulation, compression and subsequent transfer in uncertain time moment (for example,
at night).
Fig.31
