Relax time
If the measured BER is higher than the target bit error ratio, the device
under test may have lost synchronization. For devices that need some
time to recover from the situation, a relax time can be specified. This
time takes effect each time the BER limit has been exceeded. The next
BER measurement starts after this time has elapsed.
Vertical Search Methods
You can specify that the jitter amplitude changes in linear steps from
maximum to minimum or vice versa. The step size is adjustable.
You can also specify that the jitter amplitude changes in logarithmic
steps from maximum to minimum or vice versa. Minimum and ratio are
adjustable.
Alternatively, you can also specify one of two dynamic (binary) search
methods.
Searching Down/Up
Both search directions, upwards and downwards, are supported. This
helps to find out whether the device exhibits some degree of hysteresis.
The BER measured at a specific jitter amplitude may be different if this
amplitude is approached downwards or upwards.
When you search in downward direction (from maximum to minimum),
the test for one frequency stops as soon as the measured BER falls below
the target bit error ratio.
The following figure shows an example of a logarithmic search
downwards.
Jitter Tolerance Tests
7
Agilent J-BERT N4903 High-Performance Serial BERT
341
Searching downwards
Summary of Contents for J-BERT N4903
Page 1: ...S Agilent J BERT N4903 High Performance Serial BERT User Guide s Agilent Technologies...
Page 68: ...2 Setting up Patterns 68 Agilent J BERT N4903 High Performance Serial BERT...
Page 158: ...4 Setting up the Error Detector 158 Agilent J BERT N4903 High Performance Serial BERT...
Page 314: ...6 Evaluating Results 314 Agilent J BERT N4903 High Performance Serial BERT...
Page 374: ...7 Jitter Tolerance Tests 374 Agilent J BERT N4903 High Performance Serial BERT...
Page 394: ...8 Solving Problems 394 Agilent J BERT N4903 High Performance Serial BERT...
Page 434: ...Index 434 Agilent J BERT N4903 High Performance Serial BERT...
