Analog Duplex System
Subject to Export Control, see Cover Page for details.
8-33
Mod SNR Hum & Noise
The Mod SNR Hum & Noise reading measures the transmitter of the radio under test. SNR
Hum & Noise is a measurement of the level of the audio signal that is demodulated by the
Test Set when the radio sends a modulated signal versus when the signal is demodulated.
To use the Mod SNR Meter to obtain Mod Hum & Noise measurements:
1. Connect the transmitter of the radio under test to the Test Set.
2. Add modulation at the desired level to the radio under test.
3. Press the [Hum & Noise Ref Lock] Soft Key
to obtain a reference lock of the demodulated
signal received by the Test Set.
4. Remove the modulation from the radio under test.
5. The Test Set displays the Mod SNR Hum & Noise measurement relative to the level of the
demodulated received signal when the radio under test was being modulated.
Fig. 8-26 Analog Duplex Meters Tile - Hum & Noise SNR Selected
[AF Meter] Soft Key
Selects the type of AF SNR measurement to be performed, either Normal or Hum & Noise. This
soft key is only available when SNR is selected on the [AF Meter] Soft Key.
[SNR Meter] Soft Key
Selects the type of AF SNR measurement to be performed, either Normal or Hum & Noise. This
soft key is only available when SNR is selected on the [AF Meter] Soft Key
.
AF SNR Normal
When the Normal AF SNR Meter is selected the Test Set transmits a user defined, modulated
RF signal to a radio under test. The Test Set transmits the signal, cycling the modulation ON
and OFF while the signal is being transmitted. The radio under test demodulates the signal it
receives from the Test Set and sends an audio signal back to the Test Set (via the Audio In
connectors). The ratio of the level of the audio in the modulated signal versus the level of
audio in the demodulated signal is the SNR reading.
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