User guide

Using an External Signal for Inserting Errors
To configure the Serial BERT to insert a single error into the output stream
according to an external signal:
1
Connect an external instrument to the Error Add port.
The signals received at this port must be TTL-compatible.
2
Click Error Add Setup menu item from the PG Setup submenu.
3
Select External (Error Add) and click OK to close the dialog box.
Now, upon a rising edge of the signal at the Error Add port, an error will be
generated in the output stream by flipping a single bit within a bit block of 128 bits
(resulting in a maximum BER of 1/128 or 10
-2
).
T I P
You can use an external signal to set up a bit error rate to fit your needs. The
frequency of the external signal can be calculated by multiplying the desired bit
error rate by the clock frequency.
If, for example, you want a bit error rate of 3x10
-7
and you are running a test at 12.5
䠠G b/s, the frequency of the external signal is:
3x10
-7
x 12.5x10
9
= 3750 Hz
Using the Serial BERT to Insert Errors
To configure the Serial BERT to automatically insert errors in the output stream to
achieve a desired bit error rate:
1
Click Error Add Setup menu item from the PG Setup submenu.
2
Select Internal.
3
Use one of the following options to define the Error Insertion Rate:
– Error Rate allows you to select a BER from a list.
– Average Number of Bits Between Errors allows you to specify the average
number of regular (correct) bits that are sent without errors before inserting
the next error.
4
Click OK to close the dialog box.
4 Setting up the Pattern Generator
158 Agilent J-BERT N4903B High-Performance Serial BERT