Keysight Technologies N5991ST3A SATA, User Manual

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76 Keysight N5991 SATA Test Automation Software Platform User Guide
5 Receiver Tests
Rcvr SSC Tolerance Test
This test is available for all data rates.
Purpose and Method
This test characterizes the maximum down spread SSC with which the
DUT can still work.
First, this method uses relatively large steps to step linearly down from '0'
ppm using the value of SSC Step Size until the value of Max SSC Deviation
is reached. When an error is found, it goes back to the previous passed
test point. It steps down from there with the selected SSC Step Size value
until an error occurs again. The maximum passed value is the final test
point that did not return any error. The step size value for the larger steps
at the beginning depends on the relation between the “SSC Step Size” and
Max Deviation. It is calculated as:
For the default values of SSC Step Size = 50 ppm and Max Deviation =
5000 ppm, the value of initial step size is 500 ppm. Once the maximum
passed value has been found, the test performs the same method as above
for the lower limit with Min SSC Deviation and negative steps instead of
Max SSC Deviation and positive steps. This algorithm avoids initializing a
DUT repeatedly, which makes the DUT come out of the loopback mode. If
an error is encountered, it requires fewer test points than a simple linear
search.
Connection Diagram
Refer to Figure 20 (M8020A) and Figure 21 (M8040A)
Parameters in Expert Mode
• Number of Allowed Frame Errors: The number of frame errors that are
allowed. The default value is '0'.
• Number of Frames: The number of frames used for frame error
measurement.
• SSC Step Size: The minimum distance between two tested SCC.
• Max SSC Deviation: If no error occurs, this is the highest SSC deviation
to be tested.