Experiments with the Fluke 207-1 VLF Receiver/Comparator

I wanted to learn how the Fluke receiver works and see whether I could make this old beast work better than the designers originally thought it could by using software tools to post-process the collected data. This page has some info on these experiments.

First, I wanted to see how quickly the phase tracking circuits in the receiver could work. The receiver has four tracking rates, ranging from 1 microsecond per second (about a 5 second time constant) to 0.03 microseconds per second (about a 150 second time constant).

WWVB identifies itself by increasing the phase of its signal 45 degrees at ten minutes after the hour, and returning to the original phase five minutes later. This signal offers a good test of the receiver's tracking speed. I captured the receiver output through the phase change by recording ten samples per second, which should be fast enough to accurately track the receiver response to the phase change.

This is the result using the fastest tracking rate:

This is the fastest tracking rate, with 10 sample averaging (effectively 1 sample per second):

This is the result using the slowest tracking rate:

This is the slowest tracking rate, with 10 sample averaging (effectively 1 sample per second):