From: Olli Niemitalo (email@example.com) Subject: Trick: Simultaneous parabolic approximation of sin and cos Newsgroups: comp.dsp Date: 2001-06-30 05:15:09 PST
Name: Simultaneous parabolic approximation of sin and cos
Date: Mon, 19 Apr 1999 17:50:23 +0200 From: rainer storn <firstname.lastname@example.org> Newsgroups: comp.dsp Subject: Square root computation THIS WORK IS PLACED IN THE PUBLIC DOMAIN
Name: Square root computation
Category: Algorithmic Trick
Application: e.g. Magnitude computation
Advantages: Simple and fast
Once in a while the square root of data has to be computed on a DSP. A method that comes to mind is polynomial approximation of the square root function.
Subject: Trick : Tone Generation From: Darrell <email@example.com> Date: 1999/04/19 Newsgroups: comp.dsp THIS WORK IS PLACED IN THE PUBLIC DOMAIN
Name: Sinusoidal tone generator
Application: If they need to generate a continuous tone of specific frequency and amplitude.
Advantages: Fast and accurate.
I've seen this trick in a few different places, although never the (very simple) deriviation.
In DSP, the exact value of a mathematical function usually isn't needed: a degree of inaccuracy usually can be tolerated, and computational speed usually is a primary concern. The right combination of accuracy and speed is very much application-specific.
Approximation of mathematical functions, therefore, is an important subject in DSP. Highly accurate approximations are well known. However, here we present some less-well known approximation DSP tricks which provide an outstanding combination of speed and accuracy.
Subject: DSP Trick: Fixed-pt. Atan2 with Self Normalization From: Jim Shima Date: 1999/04/23 Newsgroups: comp.dsp THIS WORK IS PLACED IN THE PUBLIC DOMAIN
Name: Fast fixed-pt.
From: Ray Andraka <firstname.lastname@example.org> Subject: Quick and dirty logarithm trick Date: 22 Jun 2000 00:00:00 GMT Newsgroups: comp.dsp THIS WORK IS PLACED IN THE PUBLIC DOMAIN
Name: Quick and dirty logarithms
Application: Needs fairly precise logarithm of a value quickly.
Advantages: Very fast, very little computation. Look up table is small for precision to well under a dB. Compact hardware implementation. Works for arbitary logarithm bases.
How to Create Oscillators in Software
by Matt Donadio
Oscillators can be created in software directly, using the "sine" function, or they can be calculated indirectly using several different iterative methods. We survey those methods here.
First, let's assume that:
From: Jim Thomas Subject: Fast floting point to mu-law conversion Date: 6 May 1999 THIS WORK IS PLACED IN THE PUBLIC DOMAIN
Name: Fast floating point to mu-law conversion
Application: When you need to convert audio data to mu-law and don't have a lot of time to mess around.
Advantages: Very Fast (I implemented this in a seven cycle loop on a Sharc processor).
Introduction: This trick is based upon the happy coincidence that mu-law compressed
From: Grant Griffin Subject: DSP Trick: Magnitude Estimator Date: 02 Oct 1999 00:00:00 GMT THIS WORK IS PLACED IN THE PUBLIC DOMAIN
Name: Magnitude Estimator
Application: Signal strength measurement, AM demodulation, etc.
Advantages: This estimation algorithm is very quick compared to calculating magnitude to full precision using a square-root operation.