Publications
Data traffic performance of an integrated circuit and packet-switched multiplex structure
Summary
Summary
Results are developed for data traffic performance in an integrated multiplex structure which includes circuit-switching for voice and packet-switching for data. The results are obtained both through simulation and analysis, and show that excessive data queues and delays will build up under heavy loading conditions. These large data delays occur...
The tradeoff between delay and TASI advantage in a packetized speech multiplexer
Summary
Summary
A packetized speech multiplexer differs from a circuit-switched TASI system in that the presence of a packet buffer allows a tradeoff where the TASI advantage can be increased at a cost in packet delay. This tradeoff is investigated via a simulation. Results are presented to show the relations between TASI...
A phrase recognizer using syllable-based acoustic measurements
Summary
Summary
A system for the recognition of spoken phrases is described. The recognizer assumes that the input utterance contains one of a known set of allowable phrases, which may be spoken within a longer carrier sentence. Analysis is performed on a syllable-by-syllable basis with only the strong syllables considered in the...
A linear prediction vocoder with voice excitation
Summary
Summary
A speech bandwidth compression system, which employs voice excitation in conjunction with a Linear Predictive Coding (LPC) parameterization of the vocal tract filter, is described. To generate the excitation signal, the transmitted speech baseband is broadened at the receiver with a nonlinear distorter, and spectrally flattened by means of an...
A system for acoustic-phonetic analysis of continuous speech
Summary
Summary
A system for acoustic-phonetic analysis of continuous speech is being developed to serve as part of an automatic speech understanding system. The acoustic system accepts the speech waveform as an input and produces as output a string of phoneme-like units referred to as acoustic phonetic elements (APEL'S). This paper should...
Effects of finite register length in digital filtering and the fast Fourier transform
Summary
Summary
When digital signal processing operations are implemented on a computer or with special-purpose hardware, errors and constraints due to finite word length are unavoidable. The main categories of finite register length effects are errors due to A/D conversion, errors due to roundoffs in the arithmetic, constraints on signal levels imposed...
A theory of multiple antenna AMTI radar
Summary
Summary
This note presents a detailed mathematical analysis of a multiple-antenna AMTI radar system capable of detecting moving targets over a significantly wider velocity range than is achievable with a single-antenna system. The general system configuration and signaling strategy is defined, and relationships among system and signaling parameters are investigated. A...
Predictive coding in a homomorphic vocoder
Summary
Summary
Application of a type of predictive coding to the channel signals of a homomorphic vocoder has produced sizable bit rate reductions. With only slight degradation in speech quality, reduction (for the spectral envelope information) from 7800 to 4000 bits/s was achieved. A technique for obtaining the formant frequencies from the...
Quantization effects in digital filters
Summary
Summary
When a digital filter is implemented on a computer or with special-purpose hardware, errors and constraints due to finite word length are unavoidable. These quantization effects must be considered, both in deciding what register length is needed for a given filter implementation and in choosing between several possible implementations of...
Roundoff noise in floating point fast Fourier transform computation
Summary
Summary
A statistical model for roundoff errors is used to predict output noise-to-signal ratio when a fast Fourier transform is computed using floating point arithmetic. The result, derived for the case of white input signal, is that the ratio of mean-squared output noise to mean-squared output signal varies essentially as v...