BASIC OPERATIONS
59
A spectrogram of the de-energized cable is displayed on the screen. When the power is off,
eavesdroppers that are powered by the mains will not work. All detected signals can be
considered "safe" (interference, signals from broadcasting radio stations, etc.). To exclude such
signals during further testing, it is necessary to use the DIFFERENTIAL mode.
9. Turn on the DIFFERENTIAL mode ("F3").
A difference spectrogram is displayed on the screen. The levels of all previously received
signals will be taken as "0". Only newly appearing signals will be displayed on the screen.
10. Turn on the power switch in the switchboard.
If a high-frequency transmitter is installed on the power mains, then it will turn on when power
is applied. The signals of the eavesdropping device will be detected.
When new signals appear in the difference spectrogram, it is necessary to turn on the
AUTOMATED mode ("F2" - "Search").
A table of detected signals will be generated on the screen. The cursor will be set to the first
line (signal with the lowest frequency).
11. Turn on PTS and set the volume.
12. Connect headphones ("PHONE") and set the volume.
13. Analyze the demodulated signal by turning on the demodulators "AM" and "FM" ("F2").
14. If necessary, adjust the frequency of the signal, activate the "SIGNAL ANALYSIS AT FIXED
FREQUENCY" function ("ENTER"). Use the or buttons to set the frequency at which the signal
legibility will be maximum. To deactivate the "SIGNAL ANALYSIS AT FIXED FREQUENCY" function,
press "ENTER" again.
15. Analyze the demodulated signal on an OSCILLOSCOPE ("F3"). Return to the table of the
AUTOMATED mode ("F3").
16. Set the tabular cursor to the next line.
17. Repeat signal analysis, changing types of modulation of AM/FM ("F2").
18. Similarly test all detected signals.
The absence of new signals in the difference spectrogram when the power supply is turned on
(when turning on the power switch in the switchboard)
means that there are no active
eavesdropping devices on the power mains.
Please note that defective and / or disconnected eavesdropping devices with a remote control
that are in standby mode can be connected to the cable. Search for such devices using NLJD.
Options for possible changes in the difference spectrogram when the power switch is
turned on and the reasons for their occurrence:
2. New signals detected. During their analysis, it was possible to hear the control sound.
The reason: an analog HF transmitter installed in the room transmits information via cable
2. New signals detected. During their analysis, it was not possible to hear the control sound.
The reason: a digital (or coded) HF transmitter is operating in the line. Additional analysis of
such signals and search for their source is required.
3. Increase of the background level in the frequency range of 10-100 MHz.
The reason: the PLC modem is operating in the line.
