Accession Number : ADA137999

Title :   Voice Preprocessing System Incorporating a Real-Time Spectrum Analyzer with Programmable Switched-Capacitor Filters.

Descriptive Note : Final rept.,

Corporate Author : MITRE CORP BEDFORD MA

Personal Author(s) : Knapp,G

PDF Url : ADA137999

Report Date : Jan 1984

Pagination or Media Count : 52

Abstract : As part of a speaker verification program for BISS (Base Installation Security System), a test system is being designed with a flexible preprocessing system for the evaluation of voice spectrum/verification algorithm related problems. The main part of this report covers the design, construction, and testing of a voice analyzer with 16 integrating real-time frequency channels ranging from 300 Hz to 3 KHz. The bandpass filter response of each channel is programmable by NMOS switched capacitor quad filter arrays. Presently, the accuracy of these units is limited to a moderate precision by the finite steps of programming. However, repeatability of characteristics between filter units and sections seems to be excellent for the implemented fourth-order Butterworth bandpass responses. We obtained a 0.1 dB linearity error of signal detection and measured a signal-to-noise ratio of approximately 70 Db. The proprocessing system discussed includes preemphasis filter design, gain normalizer design, and data acquisition system design as well as test results. (Author)

Descriptors :   *Voice communications, *Preprocessing, *Systems engineering, *Spectrum analyzers, Real time, Data acquisition, Bandpass filters, Response, Signal processing, Signal to noise ratio, Capacitors, Filters, Speech, Preamplifiers, Threshold effects, Equalization, Algorithms

Subject Categories : Administration and Management
      Voice Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE