User`s guide

Locktime Theory
The Locktime tool is actually an automated histogram process. The tool gathers time measurements to
create many histograms. Statistical information from these histograms is then plotted.
The Locktime tool uses the Arm for synchronization to a signal such as a frequency lock or power-up signal.
In short, the tool creates a histogram of measurements of Functions, for example, period, rise-time, fall-
time, positive pulse width, negative pulse width and frequency measurements. A histogram of time
measurements, such as mean or peak-to-peak, is created of the period following the Arm. The period
being measured is then incremented to the 2nd period following the Arm and a histogram is created.
Then the 3rd period is measured to create a histogram and this process repeats until the Span (edges)
value has been reached. The number of time measurements in each histogram is chosen by Hits per
Edge. Statistical information from these histograms is then plotted relative to the corresponding period.
So in View, if Time is chosen, the mean (y-axis) is plotted relative to the period after the arm (x-axis).
Similarly, other Views will plot the Pk-Pk or 1-sigma values.
The Arm must be periodic in order for the measurement process to work. A single power up or a single
frequency lock will not allow this process to occur. Using a signal from a pulse generator works well as
the Arm and lock signal.
See in-depth description to see how the hardware and software are used to gather the information.
Then the tool automatically increments the Delay of edges from the arm and then builds a new
histogram of measurements. This process is repeated until the tool reaches a value set by the user
(Span). Then plots are made which relate the statistical information from a histogram (1-sigma) to
which histogram it is from, or in other words, which delayed edge is represented.
Section 4 - GigaView © WAVECREST Corporation 2005
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