[time-nuts] Self-contained divider board/design available?

Robert Atkinson robert8rpi at yahoo.co.uk
Fri Mar 12 20:09:12 UTC 2010


Hi,Have you looked at Tom's PIC microcontroller based divider? See http://www.leapsecond.com/tools/PPSDIV.ASMIt's a singe chip solution with multiple outputs and synchronisation. The 10MHz is used the clock input to the PIC and the firmware flips the output after a given number of processor cycles.If you don't program PIC's There are people on the list including myself who can do it for you.If you want a kit, the TAPR TADD-2 was based on Tom's idea. Details are here http://www.tapr.org/kits_tadd-2.html
Regards,Robert G8RPI

--- On Fri, 12/3/10, Bert, VE2ZAZ <ve2zaz at yahoo.ca> wrote:

From: Bert, VE2ZAZ <ve2zaz at yahoo.ca>
Subject: [time-nuts] Self-contained divider board/design available?
To: time-nuts at febo.com
Date: Friday, 12 March, 2010, 19:37

Hello Everyone,

I warn you, this is a topic that has been discussed before...

I enjoyed ko4bb's high level description of oscillator stability measurement (http://www.ko4bb.com/Timing/FAQ-1.php). Now I am looking into getting or putting together a self contained divider board that will allow me to make T.I. measurements at the PPS rate from a 10MHz reference using a HP 5370A counter. I am sure some of you have such boards. Are there any designs documented anywhere? Are there PCBs available?

Otherwise, I have a tube full of 74AC163 sync. binary counters I believe could do the job. Intent was to put a cascade of 8 of these on a board. What recommendations would you give? I presume output re-timing is required with these devices since the TC output may have glitches, right? Is a simple NPN transistor in common-emitter configuration good enough to buffer and scale the input signal, or should I go for a tuned input? 

When it comes to performance, I understand there is quite a broad range of possible solutions, from the lousiest to the sharpest. My goal is to have a resonably good board that can deal with GPS-grade accuracy/stability. I don't intend to make atomic-level stability measurements (at least not for now, but who knows in the future...). ADEV measurement on GPS receivers, generators and oscillators is the objective.

As you can see, this brings you back to basics. This is where I will start implementing T.I. measurements from...

Thanks in advance,

Bert.
ps. please also reply direct, as I subscribe to Time-Nuts in the digest mode.



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