Abstract: A method of creating an impression of sound from an imaginary source to a listener. The method includes the step of determining an acoustic matrix for an actual set of speakers at an actual location relative to the listener and the step of determining an acoustic matrix for transmission of an acoustic signal from an apparent speaker location different from the actual location to the listener. The method further includes the step of solving for a transfer function matrix to present the listener with an audio signal creating an audio image of sound emanating from the apparent speaker location.

Abstract: The invention is a method of creating an enlarged listening sweet spot for multiloudspeaker audio reproduction. The method employs a plurality of audio drivers displaced generally in a horizontal dimension for a vertically oriented head of a listener, the drivers operating over a plurality of different passbands. Higher frequency drivers are located closer to one another and displaced more towards a center line of the listening space than lower frequency drivers, thereby causing a smaller change in acoustic ear signals for listeners seated away from the designed-for listening position, but without causing increased low frequency signal capacity requirements for phantom images generally outside the array. Specially adapted signal processing accounting for the layout of the various drivers and their associated crossover networks is employed to create desired audio images.

Abstract: A method of creating an impression of sound from an imaginary source to a listener. The method includes the step of determining an acoustic matrix for an actual set of speakers at an actual location relative to the listener and the step of determining an acoustic matrix for transmission of an acoustic signal from an apparent speaker location different from the actual location to the listener. The method further includes the step of solving for a transfer function matrix to present the listener with an audio signal creating an audio image of sound emanating from the apparent speaker location.

Abstract: A stereo audio processing system for a stereo audio signal processing reproduction that provides improved source imaging and simulation of desired listening environment acoustics while retaining relative independence of listener movement. The system first utilizes a synthetic or artificial head microphone pickup and utilizes the results as inputs to a cross-talk cancellation and naturalization compensation circuit utilizing minimum phase filter circuits to adapt the head diffraction compensated signals for use as loudspeaker signals. The system provides for head diffraction compensation including cross-coupling while permitting listener movement by limiting the cross-talk cancellation and diffraction compensation to frequencies substantially below approximately ten kilohertz.

Abstract: A stereo audio processing system for a stereo audio signal processing reproduction that provides improved source imaging and simulation of desired listening environment acoustics while retaining relative independence of listener movement. The system first utilizes a synthetic or artificial head microphone pickup and utilizes the results as inputs to a cross-talk cancellation and naturalization compensation circuit utilizing minimum phase filter circuits to adapt the head diffraction compensated signals for use as loudspeaker signals. The system provides for head diffraction compensation including cross-coupling while permitting listener movement by limiting the cross-talk cancellation and diffraction compensation to frequencies substantially below approximately ten kilohertz.

Abstract: A stereo audio processing system for a stereo audio signal processing reproduction that provides improved source imaging and simulation of desired listening environment acoustics while retaining relative independence of listener movement. The system first utilizes a synthetic or artificial head microphone pickup and utilizes the results as inputs to a cross-talk cancellation and naturalization compensation circuit utilizing minimum phase filter circuits to adapt the head diffraction compensated signals for use as loudspeaker signals. The system provides for head diffraction compensation including cross-coupling while permitting listener movement by limiting the cross-talk cancellation and diffraction compensation to frequencies substantially below approximately ten kilohertz.

Abstract: A stereo audio processing system for a stereo audio signal processing reproduction that provides improved source imaging and simulation of desired listening environment acoustics while retaining relative independence of listener movement. The system first utilizes a synthetic or artificial head microphone pickup and utilizes the results as inputs to an equalization circuit with the outputs coupled to a cross-talk cancellation compensation circuit utilizing minimum phase filter circuits to adapt the head diffraction compensated signals for use as loudspeaker signals. The system provides for head diffraction compensation including equalization and cross-coupling while permitting listener movement by modifying the cross-talk cancellation and diffraction compensation at frequencies substantially above approximately ten kilohertz while maintaining substantially accurate equalization for the desired incidence angle.

Abstract: A stereo audio processing system for a stereo audio signal processing reproduction that provides improved source imaging and simulation of desired listening environment accoustics while retaining relative independence of listener movement. The system first utilizes a synthetic or artificial head microphone pickup and utilizes the results as inputs to an equalization circuit with the outputs coupled to a cross-talk cancellation compensation circuit utilizing minimum phase filter circuits to adapt the head diffraction compensated signals for use as loudspeaker signals. The system provides for head diffraction compensation including equalization and cross-coupling while permitting listener movement by modifying the cross-talk cancellation and diffraction compensation at frequencies substantially above approximately ten kilohertz while maintaining substantially accurate equalization for the desired incidence angle.

Abstract: A stereo audio processing system for a stereo audio signal processing reproduction that provides improved source imaging and simulation of desired listening environment acoustics while retaining relative independence of listener movement. The system first utilizes a synthetic or artificial head microphone pickup and utilizes the results as inputs to a cross-talk cancellation and naturalization compensation circuit utilizing minimum phase filter circuits to adapt the head diffraction compensated signals for use as loudspeaker signals. The system provides for head diffraction compensation including cross-coupling while permitting listener movement by limiting the cross-talk cancellation and diffraction compensation to frequencies substantially below approximately ten kilohertz.

Abstract: The signal to be classified is sampled and the samples are multiplied by weighting functions prior to performing discrete Fourier transforms, power calculations, and normalization thereon so that the preprocessor is essentially a plurality of channel bandpass filter stages, the k-th one of which has a frequency response approximating an ideal filter defined by ##EQU1## where k=O, .alpha., 2.alpha., 3.alpha., . . . , r.alpha..alpha.=constant, 1.ltoreq..alpha..ltoreq.N/2r+1=greatest integer in N/.alpha.This preprocessor transforms blocks of one dimensional data into spectra in such a way that data blocks coming from similar sources will have spectra that are close to one another in spectrum space. The discrete Fourier transform is modified to remove or reduce the phase dependency problem and to enhance the clustering of similar spectra by the weighting function above.

Abstract: A passive radiation bearing (azimuth) sensor including a member having a plurality of radiation detectors mounted in spaced apart relationship therearound and additional structure limiting the receiving field of each detector to a generally conical volume having its apex at the detector. The sensor further includes electronics for determining when the radiation being received has changed from a reference value and which detectors sensed the change, and for calculating from this information whether a transient object is in the field and, if so, its bearing.

Abstract: The purpose of the disclosed structure is to extract features from the emissions of quasi-periodic signal sources, such as piston engine powered vehicles and the like, after which pattern classification can proceed by any of a number of known methods. The structure consists of a phase locked loop, a bank of discrete-time filters, and a microcomputer. The filter bank is tuned by changing the clock rates, which are derived from the phase locked loop, which is locked to the signal fundamental frequency. The microcomputer is used to acquire the fundamental frequency and the filter tuning is such that each filter tracks a single harmonic.

Abstract: An E-scan, space fed antenna is realized using non-active radiation and excitation arrays and a reduced number of phase and amplitude shifters. The linear radiation array is coupled to the concave excitation array by a parallel plate lens. An optimization technique allows the choice of a subset of the excitation array and the calculation of the optimum complex weight for each activated element of the excitation array. An antenna design allowing 80.degree. of scan and providing a maximum sidelobe level of better than -40 dB is disclosed which requires only 16 high resolution digital phase shifters and amplitude settings.