Bill Janssen wrote: > I thought that someone was designing a circuit that could be used to compare > two oscillators. > > What happened to that project? I now have a HP 5370A so I have > something, but > I would like to make simultaneous measurements on three or four "precision" > clocks.I am not qualified to design a "state of the art" device, so I am > looking for others > to do that. > > Thanks > Bill K7NOM > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Bill
Ulrich and I have designed and Ulrich is currently testing a CPLD implementation of the improved version of the HP K34-5991A linear phase detector. It includes programmable prescalers (1-256) so that frequency like 10MHz and 5MHz for example can be compared. The maximum input frequency is about 50MHz. It has 2 quadrature phase outputs. The prescalers also allow the phase detector gain to be adjusted. The phase detector has a triangular wave characteristic with a period of 4 cycles of the input frequency to the phase detector (ie at the built in prescaler output). Preliminary results using a very crude kitchen table "breadboard" indicate that instabilities of a few parts in 1E12 are easily seen within an hour or so. Sensitivity is likely to be much better than this but a 10X prescaler was used on each 10MHz input. Comparing 3 or 4 standards requires using a set of distribution amplifiers plus a set of linear phase comparators to achieve the desired configuration. This is more flexible than trying to anticipate exactly how many channels a user may want, it also has less crosstalk than an implementation with more than 2 input frequencies to a single board or CPLD. With external prescalers the maximum input frequency can be extended to 100MHz or more. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts