Sekotech ST-300 SPIDER, Руководство по эксплуатации, Страница: 47 / 68

OPERATING MANUAL
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All activity in the band, while the line is in a de-energized state, will be displayed on the screen.
Since no eavesdropping devices powered from the line can be active at this time, all these signals
can be considered ‘safe’, and brought about by external factors (random noise, broadcasting
signals, etc). To eliminate these signals from further testing, a differential mode of the receiver
is used.
Activate “DIFFERENTIAL MODE” (“F3” button) (2.6.2).
A differential panoramic display of activity in the band will appear. From this point on, all the
signal levels measured previously are set as the new zero baseline, and only the newly appeared
signals will be shown. When voltage is supplied to the line, any high-frequency transmitters
attached to it will be activated. It is their activity that will be displayed.
Power the line again using the switch in the switch fuse box. If new signals appear in the differential
spectrum, turn on automatic receiver mode (“F2” button – “Search”). Data on the detected signals will
be shown in a table (2.6.5), with the first line selected by default.
Bring your Test Sound Player in the room. Turn it on and choose “click” as the test sound type. Adjust
the volume (1.3.6).
Connect headphones to the “PHONE” socket of the Main Unit (6, Fig. 2) and put them on.
Adjust the volume in the headphones (4, Fig.2). Listen to the AM-demodulated output.
Change demodulation to FM (“F2” button). Listen to the FM-demodulated output.
For frequency tuning, activate the mode of monitoring at a set frequency (“ENTER”) (2.6.5). Using
the and keys, select the frequency with peak magnitude (9, Fig.33). To deactivate set frequency
monitoring, press “ENTER” again.
To analyze a demodulated signal with the oscilloscope, press “F3”. Press “F3” again to return to the
automatic mode with its table view.
Go to the next table line ( key).
Repeat the monitoring procedure, toggling AM/FM-modulation with the “F2” button.
Proceed in this manner to analyze all the detected signals.
If no new signals are detected in the differential panorama upon supplying voltage to the line,
there are no active eavesdropping devices connected to it. However, there can be remotely
controlled ones that are currently on standby. These can searched for using active detection
methods, such as non-linear junction detection.
If new signals do appear in the differential representation of the band when voltage is applied
again to the line, and the test sound can be heard through the headphones, an active high-
frequency transmitter attached to the line is in the room. As ST300 is active in the same room
as the transmitter, the activity of the latter may be detected not only at its carrier frequency,
but at sub-harmonics as well. The highest of the ‘new’ peaks is likely to correspond to the carrier
frequency.
If new signals do appear in the differential representation when voltage is supplied again to the
line, but the test sound cannot be heard through the headphones at any point while they are
being analyzed, a digital (or encoding) high-frequency transmitter may be active on the line.
Such signals would require further analysis and their sources should be found.
If, upon supplying voltage to the line, a radical increase of the background level is registered
within the band from 10 to 100MHz, this may signal the activity of a PLC-modem. Once all
the detected signals have been analyzed, one should check how the differential representation
changes when the office appliances are plugged in, one after another. This way it can be
established which appliance is the source of the suspect signal.
Exit the automatic mode (“ESC” button). A differential diagram will be representing activity in the
powered line with no appliances plugged in.
Exit the differential mode (“F3” button). The current diagram will be representing activity in the
powered line with no appliances plugged in.
Reenter the differential mode (“F3” button). The differential diagram will be representing activity in
the powered line, with all the previously detected signals set as the new ‘zero’ baseline.