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Appendix H: Viavi CX300 Tests
MAINTENANCE GUIDE | MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS
Figure H-5: Receiver Reference Sensitivity Measurement
Reference Sensitivity:
To check receiver sensitivity, select DISTORTION on the screen to open the NOISE panel. Under TYPE, select
SINAD. Monitor the SINAD meter while slowly reducing the RF carrier level as shown in Figure H-5. The 12 dB
SINAD point should be at an RF carrier level less than the specified Analog Sensitivity point of the receiver. The
high and low limits are set at 11.5 dB and 12.5 dB SINAD.
Enter the Reference Sensitivity (12 dB SINAD) reading on the MT-4E Test Sheet.
If the distortion or reference sensitivity measurements are not within Zetron published specifi cations, the RF
Preselector may need re-alignment. Refer to the Receiver RF Preselector Alignment and Tuning section.
Squelch:
Adjust the RF carrier level up and down until the receiver squelches and unsquelches. There should be
approximately 6.0 dBm of hysteresis between the squelch and unsquelch points. The squelch point can be
adjusted in the Squelch Levels area of the Service section on the RSS.
The Receiver operates on a Noise based squelch (default) or a Received Signal Strength based squelch
(optional). The squelch can be set globally for all channels, or on a per channel basis. To set the squelch Open
and Close points, inject an RF signal at the desired Open or Close level and click the Set button.
Enter the Squelch and Unsquelch readings on the MT-4E Test Sheet.
