Raytheon SNV-12, Installation And Operation Manual

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SNV-12 Operations Manual
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SW5-8 – Spare Switch
Reserved for future use.
NOTE: This switch must remain in the Off position for normal SNV-12
operation.
Table 3-73 Spare Switch
SW5-8 Spare
OFF Disabled *
ON Enabled
3.12.6.6 SVM Audio Level Settings
As shipped from the factory, the RX and TX levels for each SVM are set to -10 dBm. If level
requirements differ, both the RX (input) level and TX (output for transmit audio) may be
adjusted using the RX and TX level controls on the SVM PC board.
To check a module for correct audio levels, monitor the SVM‟s PEAK and NORM LEDs while
a typical speech reception is coming in from the associated receiver. Press the module‟s
SELECT pushbutton to force-vote the site so you can listen on the SNV-12 speaker. When the
RX level control is adjusted properly, the NORM LED on the SVM will be lit on normal audio
levels. The PEAK led should only come on during the highest audio peaks. If the NORM LED
never lights, or if the PEAK LED lights frequently, then the audio level into the SVM is not
correct and the RX level potentiometer should be adjusted.
It is important the audio levels be correctly adjusted, as they will affect the operation of the
DSP algorithms for both voting and line fault detection.
There are three ways to set the input level to the SVM:
Method 1, the preferred method:
Connect a service monitor to a receiver‟s antenna port. On the receiver‟s frequency,
generate a 1kHz tone at full deviation (FM; 3kHz normal, 2.4kHz NPSPAC. AM; 100%
modulation). Apply enough signal strength to fully quiet the receiver, typically 12 dB.
The 1kHz tone is used to simulate average voice (Test Tone).
Now connect a transmission test set to the receiver‟s output audio pair. Set the
receiver‟s “Line Out” pot to the appropriate system level (normally -10dBm) for the
linking medium to the voter (microwave link, etc.). Squelch the receiver and set the
pilot tone output level for the appropriate level (typically same as average voice) and
verify the pilot tone frequency.
With the service monitor still producing a 1kHz signal at the receive site, verify the
audio level measured at the SNV-12‟s terminal block (pins 2 & 1), for the site under
setup, is between -30 and +10dBm.