R&S FSH
Spectrum Analyzer Mode
Performing Spectrum Measurements
Operating Manual 1173.6275.12 - 30
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► Select the channel you want to
change the spacing for.
► Activate the input by pressing the
ENTER key.
► Enter the channel spacing you
need.
The R&S FSH now takes the new
values into account for future
measurements.
When performing measurements on multi-carrier signals, you can define the spacing of
the transmission (Tx) channels to one another. By default, the R&S FSH assumes
equal spacing between all Tx channels in the system. Therefore, the spacing you enter
for the first two Tx channels is automatically applied to all other Tx channels.
If you do measurements on systems with a different channel spacing for each Tx
channel, 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
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.
