Spectrum Analyzer Mode
R&S
®
Cable Rider ZPH
174
User Manual 1321.0950.02 ─ 07
8.1.3.2
Setting the Reference Level
The reference level is the power level that the R&S Cable Rider ZPH expects at the RF
input. When selecting the reference level, make sure that you do not overload the R&S
Cable Rider ZPH by applying a signal whose power exceeds the maximum reference
level.
As the power is measured with a small resolution bandwidth compared to the signal
bandwidth, it is still possible to overload the R&S Cable Rider ZPH, even if the trace is
within the measurement diagram.
To prevent an overload, perform the measurement with the largest resolution band-
width possible using the peak detector. If you set these parameters, it is not possible
for the trace to exceed the reference level.
To simplify operation and to prevent incorrect measurements, the R&S Cable Rider
ZPH has an automatic routine for setting the reference level.
1. Press the [MEAS] key.
2. Select the "Level Adjust" softkey.
The R&S Cable Rider ZPH performs a measurement to determine the ideal refer-
ence level.
It uses a resolution bandwidth of 1 MHz, a video bandwidth of 1 MHz and the peak
detector. After finishing the automatic measurement, the R&S Cable Rider ZPH
sets the ideal reference level.
8.1.3.3
Setting the Channel Bandwidth
The channel bandwidth specifies the frequency range around the center frequency,
over which the R&S Cable Rider ZPH performs the power measurement.
1. Press the [MEAS] key.
2. Select the "Channel BW" softkey.
The R&S Cable Rider ZPH opens an input field to define the channel bandwidth.
3. Enter the channel bandwidth you need.
The R&S Cable Rider ZPH sets the appropriate span for the channel bandwidth
that you have entered (span = 5 x channel bandwidth). This ensures that no incor-
rect channel power measurements are made.
The minimum channel bandwidth that you can set is 2 kHz at a span of 1 kHz.
8.1.3.4
Defining the Percentage of Occupied Bandwidth
By default, the power percentage inside the occupied bandwidth is 99 %, a number
most standards require. If you measure standards that specify another power percent-
age you can change that value.
1. Press the [MEAS] key.
Performing Spectrum Measurements
