EXFO PSO-100 Series Optical Sampling Oscilloscopes - Manual (Page 128)

Asynchronous Sampling Principle
120 PSO-100
Frequency Holes
The offset frequency Δf is more conveniently expressed in terms of a
corresponding time step, Δt (ps/sample), given by
and referred to as the bit-slot scanning step. For correct synchronization
you provide an estimate of the bit rate (in correct f
s
/2 interval) and then the
software computes Δt.
Frequency Holes
Due to the asynchronous sampling principle the system has no control over
where the samples are taken relative to the input signal time position. This
is generally not a problem since dramatic effects do not occur with large
probability. A normal sampled 43.2 Gb/s eye diagram with 32 k samples
and one layer is shown.
Δt
1
f
s
---- M
B
----- – =