Chapter 5
Test and Measurement Functions
CX300 Meters
Rev. 001
CX300 ComXpert Operation Manual
22130634
5 - 38
February, 2022
5.6.9 Audio Noise Meters
The CX300 supports SINAD, Signal to Noise (SNR) and Distortion noise measurements.
The type of noise measurement to be performed is selected from the
Type menu
.
To Configure Audio Noise Meters
Audio Noise meter controls and settings are accessed from the
Noise (Audio)
settings menu
.
Audio Noise meter signal routing is configured on the Audio Controls Window (see
See section 5.7, “Audio Controls and Signal Routing”, on page 5-42
).
Type (cont)
Normal
When the Normal Demod 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 radio under test then sends this modulated signal back
to the test set. The test set receives and demodulates the
signal received from the radio under test. The SNR reading
is the ratio of the level of the demodulated audio signal when
the Modulation Generator is ON versus the level when the
Modulation Generator is OFF.
Notch BW
This field sets the notch filter bandwidth used when performing
Hum & Noise SNR Measurements.
Notch Frequency
This field defines the frequency that is being measured when
performing noise measurements.
Notch Enable
Selects whether or not a notch filter is used for performing Hum
and Noise & SNR Measurements. When Hum & Noise SNR
Notch Filter Mode is enabled, the notch filter removes the sub
audible CTCSS or CDCSS tone.
Table 5-17 Demod SNR Meter Controls and Settings
Parameter
Description