Measurement Of The C/N Ratio - Promax -4 Manual De Uso

Follow the steps below to take this measurement:
1. Tune the desired video carrier and wait a few seconds until the read level
is stabilized.
2. Press the V/A key
3. Wait until the measurement is stabilized (3 seconds maximum)
Example 12. Measuring the V/A ratio for the following signal
Video frequency = C55 (743.25 MHz)/Video carrier level = 74 dBµV (14 dBmV)
Audio subcarrier frequency = 5.5 MHz/Audio carrier level = 64 dBµV (4 dBmV)
Leave the V/A mode simply by pressing any key or turning the rotary switch.

4.2.7 Measurement of the C/N ratio

This function allows the user to measure the ratio of the video carrier level to
the noise level present in the channel.
Follow the steps listed below to take this measurement.
1. Tune the video carrier in the channel and wait a few moments until the
read level is stabilized.
2. Press the C/N key
3. Wait a few seconds until the measurement is stabilized (maximum 10
seconds)
When the C/N key is pressed, the instrument automatically takes a series of
measurements in order to arrive at the closest approximation to the noise level. The
time of approximation is a function of the content of the picture that is being transmitted
and of the C/N value itself.
When the noise level is lower than the sensitivity of the instrument, a limit value
">" will appear on the display, indicating that the C/N value the user is trying to measure
is greater than this limit value.
Page 22
USER'S MANUAL. PROMAX-4
Novembre 1999