You went quite?? On Sat, Feb 27, 2010 at 9:54 AM, paul swed <[email protected]> wrote:
> Gerard you have some great comments already and welcome back to the > electronics hobby. > A couple of things. > Curious about whats on the board etc. > > Here would be my thoughts. > If the same 10 MC signal thats the reference is also the input. > Then any funny numbers are the process leftovers or jitter. > I think this would also help you find the max resolution quickly. > Once you introduce external signals it becomes more difficult to understand > whats happening. > > I built a LORAN C simulator driven by a Rb reference. > When I drive the austron 2100 with the same reference the austron > ultimately settles at its max resolution of 1 E-13. > Very interesting first project you clearly have a good background in > applied electronics > > > On Sat, Feb 27, 2010 at 7:36 AM, Bruce Griffiths < > [email protected]> wrote: > >> Gerard PG5G wrote: >> >>> Hello all, >>> First post here, so I'll start with a quick introduction. I trained as >>> an electronic engineer but don't work in that field any more, which >>> has >>> given me the appetite back to do some electronic engineering as a >>> hobby. I have been a licensed ham for over 25 years (more than 60% of >>> my life I realised the other day) and used to be rather active on HF >>> as >>> PA3DQW. At the moment I live in the UK where I am licensed as M0AIU. >>> I recently designed and build a frequency counter and I need some help >>> with verifying its performance. I believe it gives me 11 digits in 1 >>> second. I say believe because I have not got the hardware to verify >>> this. At the moment my assumption is based on calculations and limited >>> testing with the equipment available to me. >>> My counter is a "continuous time stamping reciprocal counter". I >>> implemented this as a USB powered device, with the hardware taking the >>> time stamps and sending it over USB to a windows PC. Some software >>> written in C++ takes care of analysing the data. >>> The hardware takes 5000 time stamps per second using a high speed TDC. >>> The hardware is a single PCB measuring about 50 by 80 mm. it requires >>> an external 10MHz reference and apart from using this as the time base >>> it also uses this for self-calibration of the TDC. The unit requires >>> no >>> further calibration. >>> The PC software takes these time stamps and the associated counts and >>> uses regression to calculate the slope. This slope represents the >>> frequency of the input signal. I am sure people on here are familiar >>> with the counters made by Pendulum, and I have to confess that their >>> marketing material was helpful in putting this thing together. >>> Since the hardware is true zero dead time, the final capabilities of >>> this counter are determined by software. At the moment I can >>> simultaneously display the input at multiple gate times (see the >>> attached screen shot). For gate times over 1 second I have the option >>> to use overlapping gates, so that the display gets updated every >>> second. >>> Because there is no dead time I can also calculate Allan Deviation. >>> The >>> two displays at the bottom of the page show both normal and >>> overlapping >>> Allan deviation at tau=10s. I am still working on the software to do >>> this at multiple tau in real time and display it as a graph and a >>> table. >>> So, after this lengthy introduction here is my request for some >>> assistance. Is there somebody on the list who can assist me in >>> verifying the performance of this frequency counter? Ideally somebody >>> with access to two highly stable and known frequency sources. I can >>> send the hardware by mail, but if there happens to be somebody with >>> this kind of gear not too far from where I am (50 north of London) I >>> will travel. In exchange you get to keep the hardware and will be >>> supplied with whatever software I come up with. >>> Thanks in advance and regards, >>> Gerard, PG5G >>> >>> >> Are you calculating ADEV and MDEV using the slopes determined by the >> regression fit? >> If so, what you calculate isn't ADEV or MDEV. >> >> You need to use the raw timestamps taken at a rate of 5000/sec directly to >> produce estimates of ADEV, MDEV. >> What is the resolution of the TDC? >> >> Bruce >> >> >> >> _______________________________________________ >> 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. >> > > _______________________________________________ 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.
