Teledyne LeCroy PeRT3 Eagle Systems - Manual (Page 17)

PeRT 3 Eagle User Manual Version 1.6
LeCroy Corporation
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Chapter 3: Basic Principles of Operation
The PeRT 3 Eagle generates a serial bit stream for testing of receivers through a
two-stage process. In the first stage, the bit stream is developed in accordance with the
protocol being used (if selected) and the test patterns selected. This bit stream is
originally generated to be as clean and precise as possible.
In the second step, the clean bit stream generated in the first step is passed through a
series of stages which introduce controlled distortions into the signal. There are many
choices for type of distortion, each type has many possible levels, and multiple types of
distortion can be overlapped to produce complex, but controllable, irregularities in the
signal generated. The system is designed to allow the user to test signal distortions along
many different axes (types and combinations of signal degradation), and allows the user
to establish either a simple PASS/FAIL test at a given level of distortion, or to explore the
performance envelope of a receiver by multiple tests, each of which introduces
increasing levels of distortion along different axes until predefined bit error levels are
exceeded.
In the process of testing a receiver, the device containing the receiver is first connected
to the system, then the device may go through an initialization phase, after which the
device is placed into a test mode (e.g., a simple loopback mode) which returns the signal
to the PeRT
3
Eagle for analysis using a clean (distortion free) return path. This allows
the PeRT 3 Eagle to monitor the bit error ratios encountered by the receiver with minimal
interference from the return path.