Analog Duplex System
Subject to Export Control, see Cover Page for details.
8-28
[Mod Meter] Soft Key
Selects type of measurement to be displayed in Modulation Meter. Selecting SNR (Signal to
Noise Ratio) enables the [SNR Meter] Soft Key which allows user to select the type of SNR
measurement to be performed (Normal SNR or Hum & Noise).
[SNR Meter] Soft Key (Mod)
Selects the type of Mod/AF SNR measurement to be performed, either Normal or Hum & Noise.
The [SNR Meter] Soft Keys are only available when SNR is selected on the [Mod Meter] and/or
[AF Meter] Soft Keys.
Mod SNR Normal
When the Normal Mod SNR Meter is selected, the Test Set transmits an audio signal to a
radio under test in an ON/OFF cycle. The internal signal of the radio under test is modulated
with the audio signal it receives from the Test Set. The desired audio generator must be
enabled before the [SNR Meter] Soft Key
is selected. The radio under test sends this
modulated signal back to the Test Set. The Test Set receives and demodulates the signal
received from the radio under test. The ratio of the level of the demod audio signal when the
Mod Generator is ON versus the level when the Mod Generator is OFF is the SNR reading.
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 not modulated.
To use the Mod SNR Meter to obtain Mod Hum & Noise measurements:
4. Connect the transmitter of the radio under test to the Test Set.
5. Add modulation at the desired level to the radio under test.
6. Press the [Hum & Noise Ref Lock] Soft Key
to obtain a reference lock of the demodulated
signal received by the Test Set.
7. Remove the modulation from the radio under test.
8. 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.
[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.
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 desired modulated signal must be
enabled before the [SNR Meter] Soft Key
is selected. 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.
To Next Page
Loading...
