Showing papers on "Bandwidth expansion published in 1976"

System for the transmission of speech signals

Abstract: A speech bandwidth compression system uses a first set of filters to separate the speech signal into baseband (300-800 hz) and highband (800-3200 hz) signals. The baseband (first formant or fundamental pitch frequency) is transmitted directly, and is also rectified to form harmonics which are mixed with the highband signals in a second set of (paired digital) filters which form sine and cosine forms (amplitude and phase information) of the harmonic components, which are then multiplexed for transmission to a receiver which provides the corresponding bandwidth expansion system to reconstruct the original speech signal.

Discrete Estimation of Continuous Angle-Modulated Signals Over Multipath Channels for Aeronautical Communication

Abstract: The multipath channel for communication between an aerospace vehicle and a ground terminal is modeled by a multiplicative first-order Markov process. The multiplicative process is treated as a component of the message model and the discrete-time demodulation algorithms using the extended Kalman nonlinear estimation technique are developed for continuous-time angle-modulated signals. The equivalent baseband form of the demodulator structure is derived. Two examples of the message process are discussed for an FM system. The simulation results are presented for various values of the bandwidth expansion ratio and the additive SNR. The performance of the baseband algorithms is discussed.

The Berkeley Communication Laboratory

Abstract: The Berkeley Communication Laboratory consists of a number of stand-alone work stations, each one containing all necessary experimental equipment for two terms of experiments. By front-panel switching, the work station can be configured into a number of AM, FM, and PCM systems whose parameters can be varied. Waveforms, spectra, and signal-to-noise ratios (SNR's) at various points in these sysfems can be measured. Through use of the work station, the student is able empirically to investigate such concepts as spectral analysis, bandwidth expansion in modulation systems, sampling, aliasing, quantization, bandwidth/SNR tradeoffs, thresholds, etc. The underlying philosophy of the Laboratory, and some results of experiments with the work station are presented in this paper.