[email protected] wrote on 02/02/2010 07:20:24 PM: > From: > > Bruce Griffiths <[email protected]> > > To: > > Discussion of precise time and frequency measurement <[email protected]> > > Date: > > 02/02/2010 07:27 PM > > Subject: > > Re: [time-nuts] Triangle Waves > > Sent by: > > [email protected] > > Magnus Danielson wrote: [snip] > > Just a reality check question here... a simple triangle oscillator is > > very easily created by two op-amps, one for an integrator and one for > > Schmitt trigger operation. If you want better long-term stability open
> > the loop and insert a 10 Hz from your favourite divider chain of a > > trusted 10 MHz or so. Would such a design be limiting your measurement > > goals considerable, and would any flaws be reasonably to overcome by > > better design? > > > > Cheers, > > Magnus > > > For beat frequencies in the 1-100Hz range one only need verify the ZCD > jitter and delay variations etc., to within a few nanosec. > In the short term such jitter tantalisingly close to what a well > designed audio oscillator is capable of. > Unfortunately the trigger jitter in most counters is very large for > frequencies in this range so verifying the low jitter of an audio > oscillator requires using a ZCD or equivalent. Would integration of a 50% duty cycle square wave generate an adequate triangle wave? Modern opamps make pretty good low-noise integrators, although one would need to use a good integration capacitor to ensure linear ramps. The square wave would come from a simple binary divider chain, which will clean many things up and ensure a stable duty cycle, whatever the nature of the original signal source. Joe Gwinn _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
