Agilent Technologies J-BERT N4903, User Manual

Page: 97 / 434

This option is used for hardware-generated PRBS patterns. You can
specify a pattern with n bit length. A trigger pulse is sent when this
pattern is found in the PRBS. The trigger repetition rate is one pulse
per 512 pattern repetitions.
Example:
Pattern length: 2^7-1 (127) bits
N-bit pattern: 1110001
Data Out
Trigger Out
10 1 . . . . 1 1000100 10 1 1 1000100 . . . .
•
Shift Trigger Position
Clicking the left and right buttons will move the bit trigger position
back and forward by one bit.
Delay Control Input
Delay Control Input - Concepts
The Serial BERT features a wide bandwidth voltage controlled delay
line in its pattern generator data path, which can be used to delay the
data relative to the clock. The delay is controlled by an external signal
connected to the Delay Ctrl In connector on the pattern generator front
panel.
The delay control input is intended primarily for jitter tolerance testing,
where a data signal with a defined amount of jitter is needed. Random
jitter (RJ) can be created by applying high bandwidth white Gaussian
noise, periodic deterministic jitter (DJ) with sinusoidal (SJ) or
rectangular/triangle signals (PJ).
The delay control input is most useful for the generation of high
frequency, low amplitude jitter. Higher amounts of jitter at lower
frequencies (wander) can be generated by supplying an FM modulated
clock to the pattern generator's clock input (Clk In) in external clock
mode.
Setting up the Pattern Generator
3
Agilent J-BERT N4903 High-Performance Serial BERT 97