Bruce, would you mind being more specific and offer a solution. Thanks Bert Kehren In a message dated 3/25/2013 7:09:41 A.M. Eastern Daylight Time, bruce.griffi...@xtra.co.nz writes:
The lack of synchronisers when crossing clock domains is a design flaw that should be corrected. Bruce ewkeh...@aol.com wrote: > Brooks GPSDO may be 15 years old but is still perfect for today's > applications. If you look at tvb's Tbolt plot or Ulrich's plots with and without > sawtooth correction for a day or two the limit is GPS. The basic unit has a > resolution of 1.73 E-13 in mode 7. Brooks uses a 40 bit filter. I have > increased resolution using 100 MHz in stead of 24 and increasing filter time from > 30 to 60 and 120 seconds. 240 is also an option, I would only recommend > any thing above 30 seconds if you use a Rb. The only thing wrong is that > chips that where available 15 years ago are now hard to find. My answer is a $ > 1 gate array and if some one will step up to the plate and modify the > available ASM code to generate the RS232 code to control a FE 5680A I will make > a G/A design and a board design available. While at it also look at putting > it in a 18 pin PIC. If interested contact me off list. > With hundreds of 5680's out there many will appreciate a low cost simple > solution. Working with the presently available ASM code now out there it will > be a very small effort needed to transfer it to the latest version 1.402.1 > when it becomes available. It will take some one willing and able to pick > up at the point where the filter output drives the DAC and develops code > that reads the info from the 5680 and generates the correction code. The 5680 > does not control a DAC but the DDS in the 6.8 GHz loop. > As to the input circuit, having looked at many alternatives I still thing > it is the best for a 1 pps input from GPS and its limitations. Hope to have > some data available of 1.402.1 driving a Morion in the next couple of days. > I also have a couple of A&A boards with all original chips and some of my > 100 MHz boards with components. Please contact me off list if interested. > Bert Kehren Miami > > > > > > In a message dated 3/25/2013 2:30:36 A.M. Eastern Daylight Time, > att...@kinali.ch writes: > > On Mon, 25 Mar 2013 00:43:02 -0400 > "Daniel Schultz"<n8...@usa.net> wrote: > > >> Another great ham passes on, I'm sorry I never had a chance to meet him. >> > Definitly a sad day.... > > >> Is the GPS controller that Brooks published still useful today, or has >> > it been > >> superseded by something newer? >> > That highly depends on what you want and what you need. > > Shera's design is definitly one of the simplest GPSDOs out there. > And with that it defines what the lowest complexity to get something > accurate is. If the performance of this circuit is enough for you, > i wouldn't go for anything else. Of course, if you need better performance > or want to tinker and see what can be done with home made equipment, then > you should go for different circuits. > > Attila Kinali > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.