Wavetek 3SR Specifiche Scaricare il pdf (Pagina 53)

4-30

An "aggregate" result summary can be accessed by pressing the LIM

soft key. This performs a limit check of all channels contained within

the scan and reports an overall pass/fail conclusion. The aggregate

limit check is not performed with each scan update, however, a

Check soft key is provided to repeat the limit check whenever

desired.

The Limits On/Off soft key toggles the limit check feature on & off.

When turned off, the limit annunciators do not appear.

4.7 HOW TO MEASURE C/N

It is a good engineering practice to use a bandpass filter on the input

of the receiver when making C/N measurements. This is to ensure

accuracy and extend measurement range. If a preamplifier is used to

boost test point levels prior to measurement, it should be placed

between the bandpass filter and the receiver. This measurement is

simply a comparison in amplitude between the video carrier refer-

ence signal and the noise (FCC limit: > 43 dB). The noise measure-

ment must be made at least 2 to 2.5 MHz from any other carrier on

the system.

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Wavetek 3SR Specifiche Pagina 53