Message-ID: <3AB87F85.984E0355@usa.net>
Date: Wed, 21 Mar 2001 11:16:37 +0100
From: "Alberto di Bene" <dibene@usa.net>
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To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: RE PICs and DDS etc.
References: <E14fRuW-0007ul-00@mail1.isys.net>
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Klaus von der Heide wrote:

> [snip]
> The problem is the discrete time the DDS uses. The high order bit
> only changes at the clock edges. The result is a square wave with
> heavy phase jitter.  For example, draw a sine wave (3 waves),
> sample it at about 8/3 of its frequency in your sketch, and generate
> the square wave from these sample values (all on the paper).
> The one-periods and the zero-periods then are one or two clock cycles
> long. That's what Andy in other words already said.
> If a DAC is used then time is continuous and a clean square wave can
> be obtained.

Hi Klaus,
                 yes, that makes a lot of sense. It seems that, after all,
a DAC is needed... TNX for clarifying.

Time is continous... this was a great debate in the Theoretical Physics field
many, many years ago. But now I have lost contact with that ambient
and don't know what the present theories say. But this is totally off-topic...

73  Alberto   I2PHD