Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread Glen English VK1XX
well. thank you everyone for your contributions ! I had a good night in reading the references. I agree the cascaded band-limited limiter strategy is eminently suitable. That LT part looks like an excellent option, of course, horses-for-courses caveat applies for freqs and risetimes... On

Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread Magnus Danielson
Hi, Yes, indeed, so for many purposes the 6957 is probably good enough, and actually better than many classical approaches (i.e. direct comparators). It is when you design for a fixed or very narrow range of frequencies that you should consider rolling your own, assuming the performance of the

Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread Bob kb8tq
Hi Assuming we are still talking about a test instrument that needs to handle a variety of levels and a range of frequencies, the 6957 is probably as good as anything. With a “full up” Collins style circuit, you very much need to optimize for a specific input. Change that and you change the

Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread Magnus Danielson
Hi, On 2019-07-27 12:07, Attila Kinali wrote: > On Sat, 27 Jul 2019 18:21:50 +1200 (NZST) > Bruce Griffiths wrote: > >> The LTC6957 is a better choice for squaring up sinewaves: >> http://www.ko4bb.com/getsimple/index.php?id=phase-noise-and-other-measurements-with-a-timepod > If you want to have

Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread ew via time-nuts
In all our critical work we use the LTC6957,we call it the Bruce circuit, only problem at 78 and 80 difficult to solder Bert Kehren In a message dated 7/27/2019 4:04:50 AM Eastern Standard Time, bruce.griffi...@xtra.co.nz writes: The LTC6957 is a better choice for squaring up sinewaves:

Re: [time-nuts] FSA3011 Frequency Stability Analyzer

2019-07-27 Thread Hal Murray
tim...@timeok.it said: >Another question is whether in the case of the FSA3011 there is the > problem of the timewrap that would not allow > the long acquisitions. Wha's the problem? If it's just running out of high order bits in a counting register, I can fix that with a

Re: [time-nuts] FSA3011 Frequency Stability Analyzer

2019-07-27 Thread tim...@timeok.it
Tom, A good test, even if not too numerical, could be ADEV between a good Rubidium like the HP5065A and another equal or better reference made both with the TICC and with the FSA3011. The comparison of the two graphs would give us a first visual answer about the differences.

Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread Bruce Griffiths
The LTC6957 is a better choice for squaring up sinewaves: http://www.ko4bb.com/getsimple/index.php?id=phase-noise-and-other-measurements-with-a-timepod CERN amongst others use it. The pin programmable filtering allows its bandwidth to be optimised to suit the input signal frequency and amplitude.

Re: [time-nuts] Frequency Stability Analyzer - ZCDs

2019-07-27 Thread Glen English VK1XX
Hi there is quite a bit done in this area of FPGAs, IDELAYS etc for this application. and also quite a bit written already on TIMENUTS I find from archives. From my POV, the pressure on the design is the input circuitry...My gut is to start with a ADCMP572 and drive several FPGA pins  with