[time-nuts] lunatic fringe time standards

Bob Camp lists at rtty.us
Fri Apr 16 07:39:28 EDT 2010


Hi

I was thinking purely about speed and the apparent need to get the counter running at THz rates. A divide by 10^7 Johnson counter would be a bit large. Except for the feedback issue, it could be quite fast.

Bob


On Apr 16, 2010, at 12:26 AM, jimlux wrote:

> Bob Camp wrote:
>> Hi
>> The only real limit on a Johnson counter is how clever you get making sure
>> that only one stage is a 1 and all the rest are zeros. There are *lots* of
>> ways to take care of that, each with it's own set of trade offs. Bob
> 
> 
> Of course, if your goal is "minimizing gates" or "minimizing transistors", particularly if you need 1 out of N decoding.. a ring/Johnson counter might be a better strategy than a smaller counter with lots of states and more complex decoding.
> 
> But, if "counting" or "addressing", then standard counters or LFSRs are better.  The LFSR with multiple feedback is nice because every stage is identical.
> 
> 
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