Cable TV Measurements (Option K20) R&S FSL
1300.2519.12 2.60 E-11
Fig. 2-40 C/N Quiet Line measurement
The lower pane shows the final C/N ratio and whether it is passed or failed. It also shows the most
important correction factors used to calculate the C/N ratio.
In Quiet Line mode the noise reading will be not as accurate as in Off–Service mode, due to the still
active channel. But you don't have to turn off channels for a quick check.
CSO measurement
This measurement determines the ratio of signal power and the level of second order beats.
The signal power is normally the peak power of the modulated vision carrier, which is the power of the
unmodulated vision carrier. You can modify this default setting with the softkey Reference Power (for
details refer to chapter 4, section "Cable TV Measurements (Option K20)").
The measurement can be performed in 2 different ways, as shown in the following examples:
• CSO Off–Service measurement
• CSO Quiet Line measurement
The measurement display is split into two panes. The upper pane displays the spectrum of the
measured beats. The lower pane displays the result table for the measurement and whether the limits
are passed or failed.
CSO Off–Service measurement
Test setup:
Refer to the section Analog TV test setup.
Procedure:
1. Press the SWEEP key.
2. Press the Single Sweep softkey.
3. Press the FREQ key.
4. Enter 210.25 MHz for the vision carrier frequency of the input signal.
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