A Voiceband Codec with Digital Filtering

摘要: Oversampling and digital filtering have been used to design a per-channel voiceband codec with resolution that exceeds the typical transmission system requirement by more than 15 dB. This extended dynamic range will allow for use of processing in management signal levels characteristics many telecommunication applications. Digital contained provides rejection out-of-band inputs smoothing analog output is sufficient eliminate need most telephone Some may be required only maintain expanded cases where there danger large amounts energy on input impairing modulator. The encoder portion oversampled comprises an interpolating modulator samples at 256 kHz followed produces 16-bit PCM code sample rate 8 kHz. In decoder, raise sampling 1 MHz prior demodulation 17-level demodulator. circuits are designed suitable large-scale integration. Component matching tolerances order ± percent, While can implemented fewer 5000 gates delays 0.1 μs. this paper response described mathematically results confirmed measurements experimental breadboard models.