TECHNICAL DESCRIPTION AND OPERATING MANUAL ST131 <PIRANHA II> and ST131N
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2.2.1 OVERLOAD INDICATION
The appearance of the inscription "OVERLOAD" (position 5, Figure 14) means that at the entrance to
the main unit there is the signal exceeding the allowable maximum input signal at that setting.
In the "RADIO 30-4400 MHz" channel with the factory setting, this message can be caused by the 10
mW signal power at a distance of about one meter, or one watt at a distance of about ten meters.
Moment of appearance of this inscription set in the MENU (section 2.3). By default, this indication
appears only for the long-term overload. You can change that setting by pressing the
button,
selecting "ADVANCED SETTINGS" and checking "More indicat. of overloading." After that it will be
displayed by any, even the short-term overload.
To avoid the overload, do the following:
change your location or turn off the source of this signal, if possible.
successively
decrease the amplifier gain input value (
) and then pressing
until
the overload is removed from display.
In the "RADIO 30-4400 MHz" channel to avoid the overload use the attenuator located in the UHF
converter. Once pressing the button
leads to automatically calculated level from 5 to 30 dB in
steps of 5 dB to eliminate overload (with indication in position 10, Figure 15). Manually, the necessary
attenuation of the input signal can be selected from the list after clicking on
.
If the attenuator value is 30 dB, overload in "RADIO 30-4400 MHz" channel will be triggered by the 1 W
signal at 1 meter.
It should be noted that the source of overload may be signals that are beyond the investigated
band (“BAND”
mode) but still in the frequency range of this channel (“FULL RANGE” mode). This can
lead to the "OVERLOAD" indication although the signal is not seen on the spectrogram.
2.3 MAIN MENU
To enter main MENU press the
button.
"Memory data transfer…" – turns on the main unit into the two-way data transfer. See “ST131
Analyzer Pro. User’s Manual" to get description of that process.
"Save user’s settings..." – saves the current settings (preview by clicking
). To restore the
saved settings, select "User's settings..." in the start menu.
“LPF demodulation” – selection of cutoff frequency of the 1
st
order low-pass filter at the output
of the demodulator.
Figure 16
