[time-nuts] Frequency division by 81

[Gilles Clement]

Hi Robert,
You are right, its the lambda divider that was discussed. Need to better understand this approach....
74HC40103 could also do the 81 Pi-divide easily,  but I tend to prefer the PICDIV concept where the controller is clocked by the signal to divide (So limited or no noise is  added). AVR family could do it, as most of the instructions take only one clock.
Gilles.


> Le 20 juin 2020 à 19:48, Robert LaJeunesse <lajeunesse at mail.com> a écrit :
> 
> Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is pretty much your standard square-wave producing digital divider, such as a 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown at https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. What the Calosso-Rubiola paper promotes is the Lambda divider, which is depicted in figure 2 of the paper.
> 
> Bob L. 
> 
>> Sent: Friday, June 19, 2020 at 10:27 AM
>> From: "Gilles Clement" <clemgill at gmail.com>
>> To: "Poul-Henning Kamp" <phk at phk.freebsd.dk>
>> Cc: "Discussion of precise time and frequency measurement" <time-nuts at lists.febo.com>
>> Subject: Re: [time-nuts] Frequency division by 81
>> 
>> Hi, 
>> Could you point me to a practical design example of a Pi divider ?
>> 
>> 
>> Envoyé de mon iPad
>> 
>>>> Le 19 juin 2020 à 08:56, Poul-Henning Kamp <phk at phk.freebsd.dk> a écrit :
>>> 
>>> --------
>>> 
>>>> I need to divide the output of an OCXO by a factor D=81 for testing purposes. So with minimum added phase noise.
>>> 
>>> Two stages of divide by 9 PI-dividers ?
>>> 
>>>  http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf
>>> 
>>> -- 
>>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>>> FreeBSD committer       | BSD since 4.3-tahoe    
>>> Never attribute to malice what can adequately be explained by incompetence.
>> 
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