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 superseded by something newer?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 -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown _______________________________________________ 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.