A voiceband codec with digital filtering
Abstract
A description is presented of the design of an oversampled per-channel codec suitable for efficient large-scale integration. This codec converts between analog signals and a uniform PCM code with signal-to-noise ratios more than 15 dB above typical digital channel bank objectives. The resolution for small signals is greater than 15 bits. Such performance allows for the presence of out-of-band energy at the modulator input and will permit more extensive use of digital processing for purposes such as gain, management, equalization, conferencing, and echo cancellation. The various sections of the oversampled codec are discussed. The encoder consists of modulator, decimator, low-pass filter, and high-pass filter. The components of the decoder include low-pass filter, interpolator, and demodulator.
- Publication:
-
IEEE Transactions on Communications
- Pub Date:
- June 1981
- Bibcode:
- 1981ITCom..29..815C
- Keywords:
-
- Data Converters;
- Decoding;
- Digital Filters;
- Signal Encoding;
- Signal Processing;
- Voice Communication;
- Demodulators;
- Echo Suppressors;
- Equalizers (Circuits);
- High Pass Filters;
- Large Scale Integration;
- Low Pass Filters;
- Pulse Code Modulation;
- Signal To Noise Ratios;
- Voice Data Processing;
- Communications and Radar