R&S FSL Cable TV Measurements (Option K20)
1300.2519.12 2.57 E-11
13. Turn off the test transmitter or remove the cable when prompted and confirm by pressing the
ENTER key.
The R&S FSL will measure the noise sweeping with a small resolution filter in the span specified in
the C/N Setup dialog box.
14. Press the MKR key and, using the rotary knob, move the marker to the frequency you want to
measure the noise at. The noise density at this marker is measured and translated to the reference
noise bandwidth you specified in step 10.
Fig. 2-38 C/N Off–Service 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. The Off–Service mode is the most accurate
way to measure C/N, but you must turn off the active channel.
C/N In–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.
5. Press the MEAS key.
6. Press the Analog TV softkey.
7. Press the C/N softkey.
8. To change the limits, press the Edit Table softkey.
9. To adjust the input attenuator, press the Adjust Attenuation softkey.
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