PLL to generate low frequencies

Ben Bradley wrote:
> On Tue, 03 Jun 2008 15:18:35 -0700, Tim Wescott <tim@seemywebsite.com>
> wrote:
> 
>> Jerry Avins wrote:
>>> Ben Bradley wrote:
> 
>>>>    The original poster lists freqnencies from 10Hz to 16Hz each with
>>>> 15 decimal places, yet in the original post he says "I would need
>>>> roughly a 0.01Hz frequency resolution" which would indicate only two
>>>> decimal places would be needed for each frequency.
>>>>
>>>>    Looks like a typical Usenet question, not even the OP knows what
>>>> he's asking.
>>> He knows what he's asking. He just doesn't seem to know what he's 
>>> talking about.
>>>
>>> Jerry
>> Which is why he's asking.
>>
>> I missed the precision specifier, and got caught up in all the digits -- 
>> comes from a too-strict education in freshman physics, I suppose.
> 
>    They didn't have gotcha-problems with irrelevant info to teach you
> to "read the whole problem before trying to solve it?" :)
> 
Probably.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

>>    They didn't have gotcha-problems with irrelevant info to teach you
>> to "read the whole problem before trying to solve it?" :)
>> 
>Probably.

In our defense, once you get past the first post and don't have a full
quote, you can't read the OP unless you have two windows. :)

Mark

>>>    They didn't have gotcha-problems with irrelevant info to teach you
>>> to "read the whole problem before trying to solve it?" :)
>>> 
>>Probably.
>
>In our defense, once you get past the first post and don't have a full
>quote, you can't read the OP unless you have two windows. :)
>
>Mark
>

Yes this is an old thread but, the original posters question is very
similar to a GPS disciplined oscillator problem. Where the input is 1 Hz
aka 1PPS from a GPS and the output is 10Mhz from a disciplined oscillator.
For an example look at
http://ve2zaz.net/GPS_Std/Downloads/VE2ZAZ_GPS_Derived_Std_QEX_09_10_2006.pdf
(figure 1).

Depending on the frequency you would adjust both the pre scale of the
input from divide by 16 to perhaps divide by 32 and also the 16 bit value
of Latch value from 6800 hex to another value calculated to get 10Mhz. If
you arrive at a less than prefect multiplication you could vary the
calculated value between the two fixed values using either more one than
the other, any jiter would be lost by the low pass filter.

Stanley