Agilent Technologies E4428C, User Manual

Page: 319 / 700

Chapter 9 295
BERT
Bit Error Rate Tester–Option UN7
The reference data is generated by stored data bits. If the BERT measurement accepts data bits immediately
after receiving a trigger, set the trigger delay to On and the trigger delay count to a value corresponding to
the data format. For PN9 set the delay to 9. If the cycle count is set to more than 1, it is not necessary to store
data bits and no unnecessary delay occurs. Refer to
Figure 9-27 and “Repeat Measurements” on page 296 .
Figure 9-27
Data Processing
Data Rates
Data rates up to 60 MHz are supported for BERT analysis on un-framed or framed PN sequences. Note that
the BERT analyzer supports only continuous PN sequences.
Synchronization
Immediately after the trigger event, the DSP for the BERT measurement tries to establish synchronization
using the first incoming bit stream.
If the
Bit Delay Off On
softkey is set to
On
, the number of bits specified by the
Delayed Bits
are ignored. The
synchronization checking is repeated using an error-free bit string, lengthened by the
Delayed Bits
, until
synchronization is established.
When the
BERT Resync Off On
softkey is set to
On
, the BERT measurements will automatically be restarted if
the intermediate BERT measurement result exceeds the value specified by the
BERT Resync Limits
.