[Today’s run: rest day leading up to race on Saturday]
The next logical step in my education about time and frequency standards would be to do some data gathering to characterize the stability of my GPSDO relative to the cesium standard. This would not be so much a measure of absolute frequency but of the changes between the two.
The situation is this: We have two signals, both very close to 10,000,000 cycles per second (Hz, Hertz). The difference between the two signals will slightly change, but they will always be within .001 Hz of each other. The size of the items to be measured (10 million Hz) is large in comparison to the difference to be measured (.001 Hz).
This is done with a very high speed Time Interval Counter. It needs to be fast enough to measure the difference in time between the arrival of one cycle of source A and the arrival of one cycle of source B. Kind of mind boggling.
Anyway, I happen to have a frequency counter with a TIC option and it is fast enough to do the job. So the next thing is to hook this baby up to the two signal sources to do the measurement. Done. It works. I can see the number on the front of the box. It shows the difference between two 10 MHz signals as a measurement between 0 and 99 (resolution of 100 slices).
Then, you really want to get figures at regular intervals over time so you can see the change in the difference between the two signals. Usually this is done through a computer interface on the TIC. And mine has a computer port on the back (GPIB)! Now we get to the hard part. There are a few different methods for attaching a computer to that port and getting the data from the TIC into my computer. The cheapest appears to be about $150. Yuck. I’m told that a patient ebay-watcher can score something cheaper, eventually.
And that’s kind of where things are going to stay for awhile. I’m still planning to take the Cs box to the ham radio swapmeet at the end of this month and put a serious price on it. If I can get it sold then happy for me. But if I bring it back home I may eventually get the logging connection made and see where we go from here.