Specifications
Measuring the Carrier-to-Noise Ratio R&S FSH
1145.5973.12 2.24 E-10
Measuring the Carrier-to-Noise Ratio
(Available as of firmware version 8.0 or higher.)
The R&S FSH offers a carrier/noise measurement for measuring the ratio of carrier power to noise
power. It performs the measurement in two steps. First, the carrier power of a transmission channel is
measured or a reference power determined which is then used for C/N calculation. In the second step,
the R&S FSH measures the noise power of an unoccupied transmission channel and calculates the
ratio of carrier power to noise power.
Determining the carrier power (reference power or reference level)
The R&S FSH offers the carrier power measurement for three different types of modulation.
• Digital Tx
In the Digital Tx operating mode, the channel power of a reference channel is measured. This is
common with digitally modulated carriers where power is equally distributed, i.e. the carrier power is
independent of the modulation signal.
• Analog TV
In the Analog TV operating mode, the peak power of the vision carrier is measured. This is common
with amplitude-modulated TV signals.
• CW Tx
In the CW Tx operating mode, the power of an unmodulated carrier is measured.
• Manual entry of a reference power or a reference level
You can also enter a reference power or reference level manually. The R&S FSH then uses this
value for C/N calculation.
Noise power and C/N power ratio
For noise power measurements, the R&S FSH is set to an unoccupied transmission channel where it
measures the noise power in accordance with the selected channel bandwidth. If required, the
R&S FSH also displays the power ratio with reference to the noise power density of the transmission
channel (C/N
0
). C/N
0
= C/N + 10 lg(channel bandwidth/Hz)
Activating the C/N measurement:
¾ Press the MEAS key.
¾ Press the MEASURE softkey.
The menu for measurement functions opens.
¾ Using the rotary knob or the cursor keys, select
CARRIER / NOISE from the menu and confirm your
choice with the ENTER key or the MEASURE
softkey.
The R&S FSH activates the carrier/noise mode and
starts the carrier power measurement that was
selected last.
The major measurement parameter settings are
available directly in the main menu of the carrier/noise
measurement or can be entered using the appropriate
keys.