Lambda SR1, Руководство по эксплуатации, Страница: 190 / 317

SR1 Operation Manual 190
© 2014 Stanford Research Systems
Pulse Width Histogram of Digitial Audio Carrier
The "Eye Diagram" can be thought of as a two-dimensional histogram. The eye-diagram is constructed
by overlaying the transitions corresponding to the selected jitter detection option (preambles, stable bits,
or all bits) on a two-dimensional grid. The x-axis of this grid consists of the specified number of UIs
binned into the number of bins specified in the "X Resolution" control under the Eye Diagram heading.
The y-axis includes the range from the maximum positive to the maximum negative extent of the
transisions found. This range is then binned into the number of bins specified in the "Y Resolution"
control. The number of points falling into each bin is then mapped into a color indicating the relative
probability of that particular voltage-time point. A description of the various color-mapping options is given
in the
Digitizer Display section.
Eye Diagram of Carrier w ith 0.2UI Square Wave Jitter
As an example consider the eye diagram above produced by the digitizer looking at SR1's digital audio
output with 200 mUI of added square wave jitter. For square wave jitter the pulse edges will occur at one
of two times corresponding to the high and low portion of the square wave jitter signal. This is clearly
evident in the eye diagram as the lines of high intensity (dark green in this color mapping) are separated
by the 200 mUI jitter amplitude.