R&S AFQ100A Operating Manual page 180

R&S AFQ100A
Data Enable
The data signals usually contain not only PRBS data but also other data (e.g. sync and preambles) 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.
frame
access header
data
clock
data
enable
Fig. 4-6 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 the associated clock and Data Enable signals are indicated.
Pattern Ignore
Bit sequences of 32 bits or more with only "1" or "0", which some mobile radio standards provide
instead of frame data when faulty frames are detected, can also be excluded from the measurement
using the Pattern Ignore function (see figure).
PRBS at Generator
PRBS at DUT Output
BER "active"
Fig. 4-7 Example of functionality of Pattern Ignore: 50 bits were set to "0" by the DUT. These 50 bits plus the preceding
"0" are ignored in the bit error rate measurement.
1401.3084.32
Bit Error Rate Measurements - BERT Block
user data guard
Drop Out of DUT
50 Bits
These bits are ingored
4.69 E-3