User guide

next. The chosen method impacts the measurement duration. The specified
parameters influence both measurement duration and precision.
You can choose one of six search methods:
• Downwards linear
• Downwards logarithmic
• Upwards linear
• Upwards logarithmic
• Binary search
• Extended binary
For a description of these methods refer to “Vertical Search Methods” on page
436.
For linear search, you can set the step size.
• Downwards linear starts from the maximum (which depends on the jitter
frequency). A step size of 100 mUI, for example, may result in a sequence of
1000 UI, 999.9 UI, 999.8 UI, and so on.
The test for one frequency stops when the BER limit is met or zero amplitude
is reached.
• Upwards linear starts from the minimum. A step size of 100 mUI, for example,
will result in a sequence of 0.1 UI, 0.2 UI, 0.3 UI, and so on.
The test for one frequency stops when the BER limit is exceeded or the
maximum amplitude is reached.
For logarithmic search, you can set the minimum amplitude and the ratio. The ratio
is the factor by which the present amplitude value is multiplied to calculate the
next amplitude.
• Downwards logarithmic starts from the maximum (which depends on the jitter
frequency). A ratio of 0.666, for example, may result in a sequence of 1000 UI,
666 UI, 444 UI, and so on.
The test for one frequency stops when the BER limit is met or the specified
minimum amplitude is reached.
• Upwards logarithmic starts from the specified minimum amplitude. A ratio of
1.5, for example, may result in a sequence of 0.1 UI, 0.15 UI, 0.225 UI, 0.3375
UI, and so on.
The test for one frequency stops when the BER limit is crossed or the maximum
amplitude (which depends on the jitter frequency) is reached.
For binary search, you can set the accuracy.
Jitter Tolerance Tests 8
Agilent J-BERT N4903B High-Performance Serial BERT 445
Linear search
Logarithmic search
Binary search