[time-nuts] WWVB Simulator
msimon6808 at yahoo.com
Wed Jan 11 03:17:41 EST 2017
After doing some more design work on my WWVB simulator I came up with a DC way to change output levels from 2 V to 2 uV (p-p). in 20dB steps. That would be at "full power" output. Reduced output will be 17 dB down from that. Well into the weeds at low signal levels. That would be quite some trick with computer simulation.
Of course the 2 uV is going to be noisy. When isn't that the case?
That should be good for testing receivers across the whole range of possible amplitude inputs. Note that the results may be problematic at and below below 200 uV. Still, an indication is better than no results.
I'm also looking into an absolute value circuit vs a Costas Loop and gating to get the phase of the received signals correct. It should be easier in some respects (no temporary glitches when the phase changes). And harder in others - frequency response will be a trick - and a pair of very well matched resistors is needed. They are not very expensive these days.
Fortunately neither absolute accuracy nor accuracy across a band of frequencies is necessary. The circuit just needs to be stable (enough). And respond equally to positive and negative cycles.
When I get my test set built and tested I'm going to do some experiments. Engineering is the art of making what you want from what you can get at a profit.
I like Polywell Fusion.
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