Tim Shoppa wrote: > "John Miles" <[EMAIL PROTECTED]> wrote: > >> Some of the concerns may not be major issues (e.g., it seems safe to say >> that the FLL action will correct for drift caused by the 7805's tempco, >> unless you plan to dump a can of R134a on it), but others are worth bringing >> to the magazine's attention. If you'll forward your comments to Doug Smith >> at kf6dx (at) arrl.org, he'll most likely print them in the Letters column. >> > > Having seen some bad vibes unfold through the channels of the > letters column and other communications with editors, I think that > BY FAR the most useful thing to do would be to contribute an > improvement (preferably with schematic) rather than a lengthy > textual or mathematical criticism. > > Tim. > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Since the disciplining technique is far from optimum, this may only serve to further sidetrack the less knowledgeable from the best engineering solution which can achieve a far better performance for a similar cost. A comparison of the performance of this method with the optimum method using similar receivers and crystal oscillators would have been helpful in assisting newcomers in selecting a more appropriate method.
Perhaps someone should set up a webpage detailing how one should go about disciplining a high stability crystal oscillator. Allan deviation vs tau for various GPS receivers Allan deviation vs tau for various crystal oscillators. Various phase measurement techniques and associated tradeoffs Effect of various phase measurement techniques on the system Allan deviation vs tau. Filtering phase measurements and discarding outliers. Choosing the appropriate loop time constant. Miscellaneous: Use of synchronisers to reduce probability of generating runt pulses and metastability problems. Don't use same IC to buffer different frequencies Resynchronising divider chain outputs to reference frequency clock to reduce jitter. DAC requirements and tradeoffs Monotonicity Resolution Noise Short term stability Cost etc. Monotonic high resolution DAC techniques Multibit Audio DACs PWM etc. Bruce _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
