Agilent Technologies J-BERT N4903B, Руководство пользователя, Страница: 179 / 572

8 Either enter the
transition density
manually, or run a measurement to update
this value.
Clock Setup - Reference
The
Clock Setup
window contains the following elements:
Error Detector Bit Rate
The bit rate of the data reaching the error detector is displayed in the lower right
corner of the user interface.
The bit rate of the error detector is set by the clock signal received by the error
detector. If the output bit rate of your device is not equal to its input bit rate, the
pattern generator and error detector will be operating at different frequencies.
Clock Mode
The error detector supports two different clock modes:
•
External Clock Source
If this mode is selected, the Serial BERT uses the clock signal that is connected
to the Clock In port.
•
Clock Data Recovery
If this mode is selected, the Serial BERT derives the exact bit rate from the
incoming data stream. To make this function work, the approximate clock rate
must be specified in the
Clock Rate
field (with an accuracy of 0.01%).
Clock Rate
This field is used to specify the approximate clock rate for CDR mode. Serial
BERT needs this value to be about 0.01% accurate to find the actual bit rate in the
data stream.
Use the numeric keypad to enter the value followed by the unit that you can select
with the
G/n
,
M/
μ,
k/m
, and
X1
keys on the front panel.
Alternatively, you can select a value from the
Preset
list.
Setting up the Error Detector
5
Agilent J-BERT N4903B High-Performance Serial BERT 179