Digital Signal Processing Logic

PLLs Phase Locked Loops

FFT Fast Fourier Transform

CVSD Continuous Variable Slope Delta

Filters

• The data rates for audio are so low compared to what an FPGA is capable of, that processing the data bit serially (ie one bit at a time) allows for pretty complex circuits for amazingly little logic at the cost of a small delay. Larger FPGAs can be used to implement true real-time digital filters. The common implementations are
  • FIR/IIR parallel digital filters
    • See "Astronomical Issues Part 3: Filters and Undersampleing" by Ingo Cyiax in Circuit Cellar #107 pg 45
    • Difference between FIR and IIR
  • Majority serial filter which is easy, low-cost, and simple but inserts a delay.
    • VHDL sample
• digital twist
• Tony Fishers digital filter code generator
• Micro controller interfacing to analog sensors (such as the LM335A) Simple running average filter.
• A Simple Digital Filter

Phase Accumulators

• http://www.g4dvj.demon.co.uk/dds.htm
• Book Advanced Digital Signal Processing by Zelniker and Taylor
• Book The Scientist and Engineer's Guide to Digital Signal Processing  
• http://kmt.hku.nl/~pieter/SOFT/RESP/html/PoZeTools.html Command line and CGI-BIN applications written in ANSI-C that: Given a set of poles and zeros, plots the frequency response, calculates filter coefficients, plots the impulse response and prints the linear difference equation.+
• http://www.csdmag.com/newframe.htm
• http://www.goldwave.com/features.php

See:

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