R&S SMJ100A, Operating Manual

Page: 208 / 874

Instrument Function
R&S
®
SMJ100A
192 Operating Manual 1403.7458.32 ─ 14
The signal is fed in at the "Data Enable" input of the BERT interface. It is generated by
the DUT but can also be provided by the R&S
SMJ in the form of a marker signal.
Note: If the data is not enabled, the BER measurement is stopped completely. The
identification circuit for "Pattern Ignore" as well as the PRBS generator of the BER
measurement wait as long as data is not enabled. If the data is enabled, the measure-
ment is continued.
The figure shows a 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.
"Not Used" Any signal at the "Data Enable" input is ignored; all data at the BERT
data input is used for the measurement.
"High" The "Data Enable" signal is used. The only data measured is the data
at the BERT data input during a high level of the "Data Enable" sig-
nal. The measurement is interrupted during a low level of the "Data
Enable" signal.
"Low" The "Data Enable" signal is used. The only data measured is the data
at the BERT data input during a low level of the "Data Enable" signal.
The measurement is interrupted during a high level of the "Data
Enable" signal.
Remote command:
:BERT:SETup:DENable
on page 515
Pattern Ignore
Activates/deactivates ignoring of pure "0" or "1" bit sequences at least 32 bits long.
Activating "Pattern Ignore" excludes faulty frames from the measurement.
In the case of some mobile radio standards, pure "0" or "1" bit sequences are gener-
ated when errors (e.g. an incorrect checksum) are detected within a frame. These
sequences, instead of the frame data, are provided for the BER measurement and sig-
nal that the frame in question should not be used for the measurement.
The R&S SMJ ignores sequences of 32 bits or longer.
Note: While ignoring the bits, the PRBS generator for the BER measurement keeps
running. Following the "0" or "1" sequence, the BER measurement is continued as if
the ignored sequence had contained PRBS data.
If "Pattern Ignore" is switched on, synchronization time is 32 bits longer.
If "Pattern Ignore" and "External Restart" are active at the same time, the measure-
ment terminates immediately when the restart signal is applied. None of the 32 bits
within the "Pattern Ignore" detector is evaluated.
If "Data Enable" and "Pattern Ignore" are active at the same time, "Data Enable" is
given priority, i.e. bits that are not enabled are not examined for "0" or "1" sequences.
Bit and Block Error Rate Measurements - BERT Block