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R&S FSH
Digital Modulation Analyzer
Measurements on GSM Signals
Operating Manual 1173.6275.12 - 30
259
9.3.3 Configuring the Measurement
9.3.3.1 Selecting the Training Sequence
The training sequence (or midamble) is a known bit sequence required to synchronize
the user equipment and the base station. The number of bits that carry the training
sequence depend on the modulation. They are transmitted in the center of the GSM
burst.
The standard defines eight training sequences (numbered 0 to 7). The R&S FSH is
able to determine the training sequence in a burst automatically. Alternatively, you can
select the training sequence manually.
Manual selection of the training sequence may become necessary if two base stations
operate on the same frequency, for example. In that case, you can select to measure
one base station rather than the other.
► Press the "Signal Settings" softkey.
► Select either the "TSC Manual…" or "TSC Auto" menu item.
In case you have selected the "Manual" menu item, the R&S FSH opens an input field
to select a particular training sequence.
9.3.3.2 Selecting the Unit of the Carrier Frequency Error
If possible, you should synchronize the receiver and the transmitter.
The carrier frequency error can have the unit Hz or ppm.
► Press the MEAS key.
► Press the "Display Settings" softkey.
► Select the "Hz" or "ppm" menu item.
The R&S FSH shows the carrier frequency error in the unit you have selected.