Talk:Direct digital synthesis

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merge with Digitally Controlled Oscillator?[edit]

Like in the german WP there are articles about DCO and DDS. To me it looks like the same thing. --82.149.82.142 11:06, 24 July 2007 (UTC)[reply]

A link for the lazy user: DCO. Is there any page comparing the different frequency generators? --Petter.kallstrom (talk) 21:17, 14 November 2009 (UTC)[reply]

I also vote for merging. One difference might be a fixed versus a programmable look-up-table, but for the rest the concept is exactly the same. --151.65.233.84 (talk) 18:33, 19 August 2008 (UTC)[reply]

Lacking in theoretical basis[edit]

The article lacks a proper theoretical and mathematical basis. There is no reference to the importance of the Nyquist–Shannon sampling theorem to the operation of a DDS. The comment: "In order to generate a reasonable representation of the waveform, at least a minimum number of samples must be taken from it" is imprecise and potentially misleading (the 'minimum number' might be two). There is no mention of the importance of a Reconstruction filter after the DAC nor of the consequences in respect of Aliasing if it is inadequate or omitted altogether. RichardRussell (talk) 23:35, 10 December 2009 (UTC)[reply]

Rewrite[edit]

This page was in sad shape and I'm starting basically from scratch. The problem lies in a confusion of terms. Some authors use NCO and DDS interchangeably but this is technically incorrect. By convention, an Nco is the digital part (discrete time, discrete value) of a DDS which includes an NCO, a DAC, a reconstruction filter and a reference oscillator. The plan here is to describe the DDS system and wikilink to each of the components where the meat of the technical discussion will reside. I am also rewriting Numerically-controlled oscillator. The Dac and recon filter pages I'm leaving alone for now.

Feel free to contribute! JPatterson (talk) 17:30, 15 January 2010 (UTC)[reply]

The older version referred to DDS as a method rather than a device. I think that might be a better way to go... Hobit (talk) 14:55, 20 January 2010 (UTC) Ah, I see it was moved to synthesizer. _that_ I strongly disagree with. Direct Digital Synthesis is, in and of it self, an important DSP concept. Hobit (talk) 14:57, 20 January 2010 (UTC)[reply]

The articles, both old and new, describe an apparatus not a method. I changed the name to reflect that fact. DD Synthesis redirects here but if you wanted to write an article that describes the method, you could still do that. I think the DSP concept your are looking for is the numerically controlled oscillator which is the discrete time, discrete value portion of the DDS. JPatterson (talk) 15:23, 20 January 2010 (UTC)[reply]

Yep. The older versions of this article (pre move) actually discussed the method. In fact the lede used the word "method" I believe. I may fork this back to the DSP notion in a bit--I think both articles should exist. Hobit (talk) 22:44, 20 January 2010 (UTC)[reply]

Right, it said "Direct Digital Synthesis (DDS) is an electronic method for digitally creating arbitrary waveforms and frequencies from a single, fixed source frequency.". But then the rest of the article went on to describe the apparatus not the method. Perhaps we could create a DD Synthesis page with the above lead and a "see also" pointing here?

What is "spurious"?[edit]

Hi there. This could completely be a technical term (jargon) that I don't get, but this seems to me like there's a word missing:

Disadvantages include spurious due mainly to truncation effects in the NCO, crossing spurious resulting from high order (>1) Nyquist images, and a higher noise floor at large frequency offsets due mainly to the Digital-to-analog converter.[6]

Spurious what? I believe this should be spurious products but am not learned enough on the subject.

AnyyVen (talk) 14:50, 31 October 2014 (UTC)[reply]

Why isn't the article "Digital synthesizer" linked here?[edit]

Isn't [[digital synthesizer|Digital synthesizer] related to this article? Isn't direct digital synthesis the typical architecture for digital synthesizers? I am thinking about editing but I'm not sure. - WorldQuestioneer (talk) 17:57, 16 January 2020 (UTC)[reply]