[time-nuts] DDS'ery

[Javier Herrero]

Hello,

No, it is not the same. If you just use the MSB of the accumulator, it 
has a lot of period jitter. It can be unnoticeable if the ration between 
reference frequency and output frequency is very high.

Think on the process inversely: draw a sine wave, and sample it at for 
example 4.3 samples per period, and look when the sample becames 
positive and when it is negative (that would be the same to take only 
the MSB).

Best regards

Javier

El 20/06/2011 16:46, Luis Cupido escribió:
> Folks, a quick one...
>
> A DDS, that is an accumulator with a DAC followed by a low pass filter 
> and comparator (zero crossing) to produce a square wave to drive a PLL 
> or a MIXER or else (at logic levels).
>
> Isn't it the very same thing as just using the most significant bit of 
> the accumulator.
>
> Or am I missing something here ?
>
> Comments appreciated.
> thanks.
>
> Luis Cupido.
> ct1dmk.
>
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-- 
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Javier Herrero                            EMAIL: jherrero at hvsistemas.com
Chief Technology Officer
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