R&S FSH
Spectrum Analyzer Mode
Performing Spectrum Measurements
Operating Manual 1309.6275.12 - 14
58
C
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
measurements. The R&S FSH 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 FSH assumes that the distance of the adjacent channels to each
other is the same. In that case, you only have to enter the first spacing value. The
R&S FSH then calculates all higher adjacent channels from that value. If you change
the spacing of one of the higher channels, the R&S FSH only updates the channel
spacings above the one you have changed, but not those below.
So, for example, if you set the first adjacent channel spacing (ADJ) to 20 kHz, the
following spacings are 40 kHz (ALT1), 60 kHz (ALT2), 80 kHz (ALT3), 100 kHz (ALT4),
120 kHz (ALT5) and so on.
If you then change the spacing of the third alternate channel (ALT3) to 100 kHz, the
R&S FSH adjusts the alternate channels above the third one accordingly: 125 kHz
(ALT4), 150 kHz (ALT5) and so on.
2.1.4.3 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,
measure the signal/noise power density or obtain the signal to noise ratio.
M
Press the MEAS key.
M
Press the "Channel Settings" softkey.
M
Select the "Channel Pwr/Hz" menu item.
The R&S FSH activates normalization and switches the unit from dBm to dBm/Hz.
The channel power density in dBm/Hz corresponds to the power inside a
bandwidth of 1 Hz and is calculated as follows:
channel power density = channel power - log10(channel bandwidth)
2.1.4.4 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.
M
Press the MEAS key.
M
Press the "Power Display" softkey.
M
Select either the "Absolute" menu item to display the absolute results or the
"Relative" menu item to display the power relative to one of the transmission
channels.
