Eye Scan - Quantifi Photonics BERT 1005 Series User Manual

8.3.9

Eye scan

An eye scan is used for diagnostic testing and validation. The horizontal axis of the eye represents the
clock phase alignment of the error detector to the received bit, and the vertical axis represents the
decision threshold voltage level, also referred to as the slicer level. At each point on this two-dimensional
matrix of clock phase alignment and slicer level, the counted bit error rate is represented on a
logarithmic color map.
The bit error rate tester (BERT) eye scan differs from the traditional oscilloscope eye pattern, mainly in
the sampling rate. The BERT samples all bits as they are received during testing, whereas a traditional
equivalent-time sampling scope only takes one sample per trigger (such that it is only sampling for a
small fraction of the time). Therefore, for error rates that are very low, the BERT method of the eye
pattern testing is much more precise in showing where the thresholds in the contour are.
8.3.9.1 Configure eye scan settings
To configure the eye scan settings for a channel, click the EYE tab and configure the following settings:
• VERTICAL RESOLUTION: The voltage step-size that is used as the vertical resolution of the eye
diagram.
•
HORIZONTAL RESOLUTION: The phase step-size that is used as the horizontal resolution of the
eye diagram.
•
PATTERN: The data pattern that the ED is expecting to receive.
8.3.9.2 Start / Stop eye scan
The eye scan for a channel can be started or stopped by clicking the START / STOP buttons under the
corresponding channel. To apply the function on all channels, use the top START / STOP ALL buttons.
• Eye scan can only be run for one channel at a time. If you start or stop the eye scan for all
channels, it will be started or stopped for each channel sequentially.
• Eye scan cannot be started for a channel if error detection is in progress for the same channel.
Quantifi Photonics Ltd. Version 2.04
Bit Error Rate Tester | BERT 1005
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