Performing Coarse Level Adjustment (Transmit Audio Path 1 kHz)

Prerequisites:

Prerequisites include:

The MLC 8000 Analog Comparator/MLC 8000 Subsite Link Converter is already codec calibrated to produce -10 dBm +/-1.5 dB, and PL/DPL is disabled.
For the GTR 8000 base radios in Circuit-based simulcast systems, perform the “Rx Wireline Alignment Procedure” in the CSS Online Help.

When and where to use:

The following procedure describes how the base radio's internal Tx Deviation Adjustment procedure adjusts the transmitter deviation to 60% system ±100 Hz. Adjust the input level to eliminate the ±100 Hz discrepancy in the deviation.

Procedure:

On either the prime or slave DSM-II port interfacing to the comparator, turn on the 1 kHz test tone. (With the Rx TLP CLR set to 0 dB, the level of the tone is -10 dBm ±0.1 dB.) Activate the 1 kHz test tone as follows:
1. From the DSM-II Test window, move the cursor with the arrow keys to highlight the TONE field of the desired port. Press Enter.
2. Use the arrow keys to select the 1 kHz tone. When the desired setting is displayed, press Enter.
3. Press the S key to save changes. The port outputs a 1 kHz tone at the Rx output.
With the 1 kHz tone going into the comparator, the comparator is unsquelched and voting that channel.
With the Transmission Test Set in the bridged mode, monitor the audio line between the comparator and the CSCI.
On the CSCI, disable PL/DPL by closing SW100-2 (Mute PL/DPL). Verify TDATA mute by observing the green LED on the CSCI change from illuminated to blinking.
Monitor the audio lines between the CSCI and SDA.

NoteIf the system is configured for broadcast, the monitoring point is between the CSCI and the DSM-II.
Adjust the CSCI output (R112) for a nominal -10 dBm output (-10 dBm in = -10 dBm out). Tolerance is . ±0.10 dB; final adjustment is done in 7.
At each site on the channel, key up the one site base radio and measure the deviation with a service monitor. Use the Bessel Null calibration and DSA to check deviation. This increases the accuracy and minimizes issues with noise. See Calibrating the DSA to Measure FM Deviation.

NoteThe base radio can be keyed-up by activating the E1-Lead in the remote, loopback, or sl-lb DSM-II ports.
If the measured deviation is not 60% system deviation (1.5 kHz for 12.5 kHz channels, 2.4 kHz for NPSPAC channels, or 3.0 kHz for 25 kHz channels), adjust the Rx TLP CLR in the remote site DSM-II port. The deviation should be as close to target (1.5 kHz, 2.4 kHz, or 3.0 kHz) as the adjustment allows.
Repeat 6 and 7 for every site on the channel.
When the deviation for the last site has been verified, turn off the 1 kHz tone.
Repeat 2 through 9 for every channel in the system.