TECHNICAL DESCRIPTION AND OPERATING MANUAL ST131 <PIRANHA II> and ST131N
17
“ON/OFF switch” (position 5, Figure 2) is designed to switch on/off the ST131 main unit.
“Volume control” (position 3, Figure 2) regulates the output audio level of the built-in loudspeaker
or headphones. Adjustment is possible if it is provided for a particular mode (an icon of volume control
accessibility is indicated in position 12, Figure 15). Numerical value of the volume level (0-99) is displayed
in position 11.
Use automatic adjustment of the current spectrogram and oscillogram in vertical screen
size by pressing the
button.
Manually moving the horizontal axis of the spectrogram is made
by
and
.
One press
changes the displayed boundaries of levels by 5 dB in position 6, figure 14. So you can make vertical
shift of the spectrogram to view it more comfortable. If you work with the oscillogram, these buttons
increase or decrease the displayed amplitude of the signal.
Reset of the averaged results of the detectors is carried out by pushing the
button.
2.2 INDICATION
The common way of signal indication in the ST131 are spectrograms. Common elements are
shown in Figure 15.
1 Start and end of the displayed frequency range.
2 Short name of the current channel.
3 Mode.
4 Sub-mode.
5 Overload Indicator / The maximum possible level of
signal that displayed without overload. *
6 The lower and upper level of the displayed signal
(dynamic range).
7 Frequency and maximum level of signal considering the spectral resolution. **
8 Noise level.
9 Gain value of the input amplifier of the main unit.
10 Attenuator value of the ST131.UHF converter (“RADIO 30-4400 MHz" and “WIRE 30-3000 MHz"
channels) or the number of the selected RJ-45 connector pair ("WIRE 0.01–30 MHz” and “WIRE 0.3-15
KHz" channels).
11 Battery level indicator.
12 Volume level indicator.
13 Mute or sound control availability indicator.
* The maximum possible signal level without overload is implemented only for the "RADIO 30-4400
MHz" and "WIRE 30-3000 MHz" channels.
**For example, spectral resolution in the FULL RANGE mode of the "RADIO 30-4400 MHz" channel
is 32 MHz. Indication of 930 MHz frequency means that the maximum signal is within the range of
930+/-16 MHz. Thus the accuracy of measuring frequency is +/- 16 MHz.
Figure 15