Measuring the Carrier-to-Noise Ratio
R&S FSH
1145.5973.12 4.54
E-14
•
The video bandwidth of the recommended peak detector must be at least as wide as the resolution
bandwidth. If the RMS detector is used, the video bandwidth must be at least three times the
resolution bandwidth. This prevents incorrect results due to the compression of signal peaks by the
video filter.
•
The peak detector is recommended. It ensures that the peak power of the vision carrier is correctly
measured.
•
The sweep time is coupled to span, resolution bandwidth and video bandwidth. Set the sweep time
in such a way that the filters can settle. Too short a sweep time distorts the measurement result.
Press the SELECT MEASURE
softkey.
The menu for selecting the reference measurement
opens.
Using the rotary knob or the cursor keys, select
CW Tx and confirm your choice with the ENTER key
or the F1 softkey.
The R&S
FSH starts the CW
Tx reference
measurement. C/N-CW Tx appears in the upper right-
hand corner of the display. Reference channel and
channel bandwidth are set in accordance with the last
CW Tx reference measurement.
In the CW Tx operating mode, the count marker is automatically activated. After each sweep, the
marker is set to the highest power in the reference channel. Marker power and marker frequency are
indicated at the top edge of the display. The marker power corresponds to the reference.
Manual reference mode
As an alternative to the C/N reference measurement, the R&S FSH allows you to manually determine
the C/N reference.
Press the REF MEASURE softkey.
Using the rotary knob or the cursor keys, select MAN REFERENCE POWER / LEVEL and confirm
your choice with the ENTER key or the F4 softkey.
Using the numeric keypad, enter the desired reference and terminate your entry with the appropriate
unit key or the ENTER key.
The R&S FSH indicates the selected reference at the bottom of the display.
Setting the reference channel
The reference channel is set by entering the channel number in accordance with the selected
channel/frequency table or by entering the channel center frequency. In the DIGITAL Tx operating
mode, the 8VSB/ATSC pilot frequency can also be entered. In the ANALOG TV operating mode, you
can additionally enter the vision carrier frequency.
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Tel:0755-83589391
Fax:0755-83539691
Website: www.Sengt.com
