HP 8591C, User Manual, Page: 63 / 373

Channel Measurements
Making Channel Measurements
Note that when an external preamplifier is used and EXT AMP YES NO is
activated (YES is underlined), the noise contribution of the
is also calculated and corrected for. The values for external preamplifier
gain and noise figure are used for this calculation. This is the only use
made of the values entered with the external preamplifier
(EXT AMP YES NO , EXT AMP GAIN , or EXT AMP
FIG
Hints
1. When using a tunable bandpass filter, first peak the filter using
CARRIER
Then
press
CARRIER/NOISE
Place the marker to measure the carrier-to.-noise close enough to
the carrier to minimize any roll-off effect of the bandpass filter.
2. Pressing GO
TO CSO/CTB
allows you to measure the CSOKTH without having to turn the
modulation back on, then off again [for analyzers without Option 1071, or to reselect a quiet line
analyzers with Option
3. Carrier-to-Noise Measurement Accuracy is degraded as the
cable
TV system noise approaches the
analyzer noise. This is reflected in the magnitude of the Analyzer Noise Correction Value.
When in the carrier-to-noise measurement, press
More,
then
MORE INFO
Note the
analyzer noise correction value.
if less than 0.5 then C/N accuracy
if equal to 0.5 then C/N accuracy
if equal to 3 then C/N accuracy
if equal to 7 then C/N accuracy
if greater than 7 it is out of measurement range
5. The analyzer input attenuator sets the noise floor of the analyzer. The attenuator is set to not
overload the first mixer. For carrier to noise, the attenuator switch point from 0 to 10 is at
total power at the input.
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