Spectrum Analyzer Mode
R&S
®
Cable Rider ZPH
184
User Manual 1321.0950.02 ─ 07
If you do measurements on systems with a different channel spacing for each Tx chan-
nel, you can also set the channel spacing for each Tx channel separately by entering
the respective number in the fields.
If the spacings are not equal, the channel distribution according to the center frequency
is as follows:
●
Odd number of TX channels
The middle TX channel is centered to center frequency.
●
Even number of TX channels
The two TX channels in the middle are used to calculate the frequency between
those two channels. This frequency is aligned to the center frequency.
Adjacent or alternate channel spacing is also available for single-carrier measure-
ments. The R&S Cable Rider ZPH can perform measurements on up to 12 adjacent
channels. Usually the first adjacent channel to the Tx channel is referred to as the
adjacent channel (ADJ). All others are called alternate channels (ALT1 to ALT11).
By default, the R&S Cable Rider ZPH assumes that the distance of the adjacent chan-
nels to each other is the same. In that case, you only have to enter the first spacing
value. The R&S Cable Rider ZPH then calculates all higher adjacent channels from
that value. If you change the spacing of one of the higher channels, the R&S Cable
Rider ZPH only updates the channel spacings above the one you have changed, but
not those below.
8.1.5.3
Normalization of Measurement Results
By default, the power of the channels and adjacent channels is displayed in the unit
dBm. It is also possible to display the power density of the signal to, for example, mea-
sure the signal/noise power density or obtain the signal to noise ratio.
1. Press the [MEAS] key.
2. Select the "Power Display" softkey
The R&S Cable Rider ZPH opens a submenu to select the power display settings.
3. Enable the "Channel Pwr/Hz" checkbox.
The R&S Cable Rider ZPH activates normalization and switches the unit from dBm
to dBm/Hz.
The channel power density in dBm/Hz corresponds to the power inside a band-
width of 1 Hz and is calculated as follows:
a) channel power density = channel power - log10(channel bandwidth)
8.1.5.4
Displaying Absolute and Relative Results
You can set up the result display to either show the absolute power of the adjacent
channels or the power relative to one of the transmission channels.
1. Select the "Power Display" softkey
The R&S Cable Rider ZPH opens a submenu to select the power display settings.
Performing Spectrum Measurements
