HP 8591C, User Manual, Page: 64 / 373

Channel Measurements
Making Channel Measurements
Optimizing the Dynamic Range
Limiting the number of carriers input to the analyzer allows the measurement routine to select a lower
attenuator value. Hence a lower noise floor. This can be done with individual channel filters, a high
pass filter, a low pass filter or an adjustable
filter.
When the attenuator switches to the next higher value, the noise floor raises 10 which degrades
the signal to noise ratio by 10 For C/N, the attenuator switches from 0 to 10 at
Keeping the total power just below that will obtain the best signal to noise.
A 1 for smaller than 10 step attenuator used in conjunction with a filter will provide the best
coverage of signal range for optimizing the total power at the input.
Optimizing the Total Power at the Input
If the analyzer correction value dictates that it is necessary to optimize the analyzer noise floor for a
particular configuration, press the following keys:
CABLE TV ANALYZER Setup Analyzer Input
TOTL PWR INPUT
For carrier to noise, the attenuator switch point from 0 to 10 attenuation is at It
follows that the attenuator switch point from 10 to 20 is at + 47 and increments
proportionately with each 10 step in attenuation. For distortion measurements of CSO and CTB the
attenuator switch point is
Then it follows that the attenuator switch point from 10 to
20 is at and increments proportionately for each attenuator switch point.
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