Testing of Transmitters for Communication Links by Software Simulation of Reference Channel and/or Reference Receiver

Abstract

A transmitter for a communications link is tested by using a (software) simulation of a reference channel and/or a reference receiver to test the transmitter. In one embodiment for optical fiber communications links, a data test pattern is applied to the transmitter under test and the resulting optical output is captured, for example by a sampling oscilloscope. The captured waveform is subsequently processed by the software simulation, in order to simulate propagation of the optical signal through the reference channel and/or reference receiver. A performance metric for the transmitter is calculated based on the processed waveform.

What is claimed is: 
     
         1 . A method for testing a transmitter for an optical fiber communications link, the method comprising:
 accessing a stored waveform for the transmitter under test, wherein the stored waveform represents an optical output generated by the transmitter in response to a data test pattern applied to the transmitter;   processing the waveform in software to simulate propagation of the waveform through a reference channel and/or a reference receiver to generate a synthesized waveform;   determining a temporal offset between logic transitions of the synthesized waveform and the data test pattern;   temporally shifting the synthesized waveform to generate an aligned synthesized waveform based on the temporal offset;   computing an optical modulation amplitude (OMA) based on the aligned synthesized waveform and the data test pattern; and   calculating a performance metric for the transmitter based on the OMA.