[time-nuts] Ebay FE-5680A Rb

Hal Murray hmurray at megapathdsl.net
Thu Dec 15 01:52:53 EST 2011


albertson.chris at gmail.com said:
> The prime factors are 13, 3, 2, 2, 2, and lots more 2s 

There are also a couple of 5s in there.

[~]$ factor 63897600
63897600: 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 5 5 13


> There really is no reason to clock a DDS with a nice even number frequency.
> OK the even freq. makes the math easier but it's all done in software so
> "easier" does not matter.

I'll bet there are some second order considerations in there.  How about 
spurs?  If your starting frequency is "nice" relative to your target 
frequency, the spurs will be smaller and/or farther away.

----------

bell.peter at gmail.com said:
> It's exactly 52 times the 1.2288MHz reference that IS95/CDMA2K uses - this
> may be a coincidence, but I somehow doubt it. 

DDS calculations get (much) easier if you have the right clock frequency.

I'm not enough of a wizard in that area to guess why they want that number.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.







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