Performance Considerations For Optical Modulation Analysis

Figure 1: Error-vector magnitude defined

In recent posts, we've covered the fundamentals of coherent signals and the basics of optical modulation analyzers. Let's now turn to the operational parameters of OMAs, in particular system bandwidth, and how that figure of merit in an OMA can determine how far your measurement system can take you in terms of meaningful analysis.

Using Your Oscilloscope's X-Y Display

Figure 1: Shown are some common
Lissajous patterns in an X-Y display

If you're fortunate enough to own an oscilloscope with X-Y display capabilities, you have a valuable tool at your disposal. From classic Lissajous patterns to state transition diagrams for today's quadrature communication systems, X-Y plots give us a window of the functional relationships between two waveforms.

Check Constellation Diagrams for Digital Data Integrity

Data-communication systems that rely on quadrature signal generation to phase-encode data can run into a number of signal-corrupting snags. These can include things like Gaussian noise, non-coherent single-frequency interference, phase noise, and attenuation in the channel and/or receiver, to name a few. But did you know that you can use your digital oscilloscope to diagnose problems like these?