Three DSP Tips
DRAFT

Alan Dix

at time of writing: Staffordshire University

currently:
Lancaster University

email: alan@hcibook.com

See the full draft paper (Adobe PDF) or in HTML

Full reference:

Alan Dix (1999).
Three DSP Tips. Technical Report, Staffordshire University.
http://www.hcibook.com/alan/papers/DSP99/

Abstract

Some years ago the author was involved in a project which required the detection and location of signals where the signal-to-noise ratio was between 0.001 and 0.0001 - that is, the signal was over 1000 times weaker than the background noise. This report describes three 'tricks' used to solve this problem:

  1. hand massaging of digital filters to remove DC bias;
  2. using time dependent filters to shift target frequencies to zero Hz and so allow undersampling and more complex processing at slower clock speeds;
  3. non-linear correlation filtering for stereo signals to extract common, but possibly phase shifted, signals from multiple detectors with independent noise at each source.
Although these were employed for a specific problem, they could each be used independently or used together for other DSP problems.

keywords: digital signal processing, signal-to-noise ratio, covariance, band-pass filter, Fourier analysis, stereo, real-time programming

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http://www.hcibook.com/alan/papers/DSP99/ Alan Dix