User's Manual

MM102554V1 REV B
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and battery alarm are also designed to provide the proper levels without adjustments. The LINE output
level should be adjusted with a 100 mVrms, 1 kHz signal in on MIC HI or a 1 Vrms, 1 kHz signal in on
VOL/SQ HI.
10.5.2 DSP Line In Level Adjustment
Typically, the TX AUDIO and LINE OUT levels should be adjusted prior to adjusting the DSP LINE IN
level. DSP TX AUDIO and DSP LINE/TX AUDIO are typically line audio or VOL/SQ HI audio that has
been processed by the DSP Board.
A DSP Board is always present; this DSP processed line in audio will normally be selected by analog
switches U14 (DSP LINE/TX AUDIO to line out) and U15 (DSP TX AUDIO to transmit audio) on the
System Module when line in audio is selected. The level for DSP TX AUDIO and DSP LINE/TX AUDIO
must be adjusted on the DSP Board.
10.5.3 DSP Level Adjustments
The DSP LINE IN level into the DSP must be adjusted using U15-0 (DSP line cancellation level) and
U15-1 (DSP line input level) located on the DSP Board. If two-wire audio is used then both electronic
pots must be adjusted. If four-wire audio is used then only U15-1 needs to be adjusted.
For two wire installations the DSP line cancellation level pot (U15-0) is used to remove what the T/R
Shelf is sending to the line. While the T/R Shelf is sending received audio down the line, the line
cancellation pot should be adjusted to minimize the signal level at TP1 on the DSP Board. This leaves
only what is received from the remote. This signal is then level adjusted using the DSP line input level
adjust pot (U15-1) and input into the DSP.
NOTE
System Modules 19D902590G6 & G7 have TP1 extended to the board edge connector and
may be metered on the MASTR III backplane at J5, Pin 28A.
If four-wire audio is used, the DSP line cancellation pot must be set to zero.
The DSP also performs a compressor function on its DSP line input. The threshold for this compressor
must be adjusted as well. The line level should be adjusted on the DSP Board prior to setting the
compressor threshold.