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From: hanke@nessie.cs.id.ethz.ch (Norbert Hanke)
Newsgroups: comp.dsp
Subject: Re: Sine-wave generator algorithms
Message-ID: <1991Apr15.081550.26195@bernina.ethz.ch>
Date: 15 Apr 91 08:15:50 GMT
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In article <1750@tekig7.MAP.TEK.COM> gaulandm@tekig7.MAP.TEK.COM (Mike Gauland) writes:
>I'm trying to implement a sine-wave generator using a DSP.  Anyone have
>an especially quick algorithm they'd like to share?
>
>Thanks,
>Mike

I implemented a sine-wave generator using a DSP56001 using the following
algorithm:

x(t) = x(t - Ts) * exp (j * w * Ts)

where x(t) is a complex value, Ts ist the sampling interval, w ist the
desired frequency in radians/s.
The algorithm has some constraints regarding the amplitude accuracy:
using 24 bit arithmetic, the amplitude changes in a way that it is just
visible on an analogue level meter. Doing the calculation with double
precision (48 bit) should obtain a stable amplitude for a very long time.
using 32 bit on another DSP should be adequate to guarantee an implitude
accuracy of fractions of a percent over several minutes.

Norbert Hanke
Swiss Federal Institute of Technology
ETH Zurich, Switzerland