R&S SMJ100A, Руководство по эксплуатации

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Instrument Function
R&S
®
SMJ100A
184 Operating Manual 1403.7458.32 ─ 14
input halts the measurement and restarts it when the data sequence begins, and the
BER results of the relevant (sub)sequences are integrated.
Figure 5-2: The length of the signal is too short for a complete PRBS sequence; PRBS generation is
restarted by the Restart signal when the signal begins anew.
Frames generated by the R&S SMJ or the R&S WinIQSIM2 software contain continu-
ous PRBS data, i.e. the PRBS sequence is continuously written to the user data fields.
Consequently, if the R&S
SMJ is used as a data source, a restart is only necessary if
(e.g. when using a waveform) the total length of the signal does not equal a whole-
number multiple of a PRBS sequence.
Figure 5-3: TDMA signal generated by the R&S SMJ with user data that contains the PRBS data
sequence. The PRBS sequence is continuously written to the user data fields.
5.4.8 Data Enable
In the case of the bit error rate measurement, the data signals usually contain not only
PRBS data but also other data (e.g. sync and preambles, see figure) that would result
in bit errors. The BER measurement for this data can then be interrupted using the
"Data Enable"signal. The "Data Enable" signal is fed in at the BERT input.
Figure 5-4: TDMA signal with user data that contains the PRBS data sequence and various check
fields which should be ignored for the bit error rate measurement. Below that are the
associated clock and Data Enable signals.
In the case of the block error rate measurement, the "Data Enable" signal masks the
user data (see following figure).
Bit and Block Error Rate Measurements - BERT Block