Hi again Guys,
I have FE-5680A, I have purchased some months ago, and it does give indication of frequency locked.
If I recall, the state of the pin is low when it’s locked, so it’s high when it boots, the signal does walk a bit at boot time,
and settles in a couple of minutes.
could it be that your GPS is providing the 1 second pulse within a 100nS window ?
That would be fine, the other clock wouldn’t walk away from it if the frequency was more correct.
Remember in the video, I am the one making the big jump of the red trace to the left in my pic program,
just so you can continue to see the smaller movement at the same scale.
Without that intervention, the red trace always slows down.. will run off the screen to the right.
First, get rid of the pic for now. Trigger the scope off of the 1 PPS from the GPS and look at the 10 MHz from the Rb directly. If there's a drift, you should see it directly.
Another thing that would take a bit more work is to build a divider out of logic gates, i.e. digital counters. That way, there will be no question of whether something's getting lost in the pic.
I thought about it too long without disengaging my mind from the problem.
I figured out the first one by now, but not had time to try yet. The second suggestion I should have also thought of.
There’s already a 100 kHz signal from the pic’s hardware PWM module, already divided down to a 1Hz pulse with logic.
That wouldn’t test the timer routine, but I would see any problem with clock input to the pic.
But the first one definitely... When I first got the Rb module my scope only had one working channel.
The idea of comparing things is new to me, this is the first time.
Now I really like the look of the new cheaper four channel Rygol being talked about here.
Thanks for all the replies. I won’t ask questions again till I’ve tried all of that.