Axnes Aviation AS
Document number
Revision
Date
AX-PSB-UMAN-0027
Issue E
2015-03-05
Page 2-4
The MP20 will detect a headset/helmet connection through a change of the impedance over
the microphone terminals. The DC resistance trough the microphone line is required to be
less than 10 kΩ.
Note:
Some types of electret microphones change their DC resistance when subjected to
very high sound input. This can cause the impedance to go over the threshold of the
headset/helmet operation mode (10K).
2.9 Post installation calibration
When the MP20 is taken into use, normally no adjustments are needed, and factory values
can be used. In some cases adjustment might be needed as listed below:
White noise in headset.
Adjust the squelch
– Pre software version 3.0
2
:To adapt the
squelch on the Polycon MP20, press the large front PTT button and simultaneous operate
‘volume up’ or ‘volume down’. Squelch setting is displayed in the display.
Software version 3.0
2
and higher: Press the Volume up and Channel down once
simultaneously to enter menu mode. To browse through the menu press channel up/down.
Select option ‘’ SL’’ – the display will change to display the value of the set squelch level. The
squelch level can be adjusted by using the Vol up / down buttons to set as required.
When optimal level is found press the side PTT button to save and exit.
It is recommended to note down the optimal level for future reference in the calibration
parameter sheet found in Appendix A.
Factory squelch level: Individual values, normally between 18-21.
NIVOX transmission from Polycon MP20 series hand held radio not triggered or
triggered by noise.
Adjust
Analogue trigger level
– Analogue trigger level is the level of the
voice on top of the background noise needed to trigger VOX transmission. Lowering the
analogue trigger level will make the VOX operation of the radio more sensitive to rapid
changes in the background noise, and will require a lower voice overlay level to trigger
transmission. Increasing the setting will make the radio VOX operation more robust to rapid
changes in the background noise, but will require higher levels of voice overlay to trigger
transmission.
Note: The when the noise environment or analogue level change the radio needs a few
seconds to adapt the new noise level. It is recommended to adjust the analogue level in a
noise environment similar to the operational environment.
To adjust the analogue trigger level, press the Volume up and Channel down once
simultaneously to enter menu mode.To browse through the menu press channel up/down.
Select option ‘’AL’’ – the display will change to display the value of the set analogue level.
The analogues level can be adjusted by using the Vol up / down buttons to set as required.
2
Units with software version 3.0 or higher will show the software version as two digits in the display at
startup.
