ADDA: CD Data Conversion

Who Are We? Christa Brown Kurt Sanner Vassos Soteriou Ricky Radaelli-Sanchez Links Copression Digital Audio A/D Conversion Have a little fun! Thanks Richard Schreier for some matlab stuff K.C. Pohlmann for some gifs and jpgs (delta modulation/sigma-delta modulation)

Introduction to Digital Audio Techniques CD-ROM technology has risen to completely dominate the media for music storage over the past decade. The development of this new device required more than new hardware, it also required a very modern process to construct the music in a completely digital format, and reconstruct it inexpensively. In its transformed state, the formerly analog, continuous-time signal known as music can now be manipulated using algorithms and analytic techniques with a computer chip before being reconstructed again as an analog signal for our ears. This allows an almost perfect reproduction of the original signal. The basic techniques of signal quantization and sampling theory used for digitizing the signal are common to all digital-to-analog and analog-to-digital conversion of data for analysis. Recently, two techniques, 1-bit digital-to-analog data conversion and 16 times oversampling of the already-sampled signal have been implemented for optimal CD-Audio signal reconstruction with minimal error at minimal cost. Topics Quantization Sampling Input Filtering Aliasing Decible Levels Recorded Output Filtering 16x Oversampling Zero Padding Pulse Code Modulation Multi-Bit Converters Problems With Multi-Bit Converters Solutions Real World Solutions Delta Modulation Sigma Delta Modulation Matlab sin1k.m: Produces a 1kHz sinusoid. code sin10k.m: Produces a 10kHz sinusoid. code sin30k.m: Produces a 30kHz sinusoid. code add3sins.m: Adds together the 1kHz, 10kHz, and 30kHz sinusoids, simulating and analog signal which will be the input to the CD-AUDIO recording device. code invcheby.m: Produces an eighth order inverse chebyshev filter to filter the input. code infilter.m: Produces a simulation of an analog inverse chebyshev filter, to which the input signals created above are applied. code saplein.m: Samples the output of the inverse chebyshev filter and quantizes each sample to be stored in CD-AUDIO format. The quantization values are in the range of -1 to +1 code oversample.m: Oversamples the sampled, filtered signal 16 times. code dstrial.m: Sends the oversampled signal to a sigma-delta modulator, where a 1-bit data stream results. The 1-bit data stream is then reverse processed through a signal reconstructor, which sends its output through a cheap, low-pass filter. The output is the analog reconstruction of the original filtered signal. code by Richard Schreier with modifications by Kurt Sanner