Abstract: A code excited linear predictive coder and decoder well suited to speech recording, transmission and reproduction, especially in voice messaging systems, provides backward adaptive gain control of stored codevectors to be applied to a synthesis filter prior to being compared with sequences of input speech signals. Simplified linear predictive parameter quantization using efficient table lookup procedures, efficient codevector storage and search all contribute in an illustrative embodiment to high quality coding and decoding with reduced computational complexity.

Abstract: A geometric vector quantizer coding technique is illustrated in the context of a full motion video coder based on a three-dimensional sub-band framework. The original image data is decomposed into different spatial-temporal frequency bands and based on the data in each, different quantization strategies are applied to the bands. The lowest spatial-temporal frequency band is coded using a traditional three-dimensional switched predictor and optimum scaler quantizer. The non-dominant sub-bands are coded using the vector quantization approach to efficiently encode the images while appropriately exploiting the sparse, highly structured nature of the data to design the codebooks. Variable resolution is achieved using these techniques and no training is needed to establish or maintain the codebook.

Abstract: A method is disclosed for determining estimates of the perceived noise masking level of audio signals as a function of frequency. By developing a randomness metric related to the euclidian distance between (i) actual frequency components amplitude and phase for each block of sampled values of the signal and (ii) predicted values for these components based on values in prior blocks, it is possible to form a tonality index which provides more detailed information useful in forming the noise masking function. Application of these techniques is illustrated in a coding and decoding context for audio recording or transmission. The noise spectrum is shaped based on a noise threshold and a tonality measure for each critical frequency-band (bark).

Abstract: A binaural sound recording and reproduction system which utilizes a recording mannequin equipped with an electroacoustic model of the human auditory tract to thereby record the sound pressure which would be incident on a listener's eardrum and also utilizes a headset with in-ear transducers or receivers which exhibit a flat frequency response as measured at the listener's eardrums is described. The receiver units utilize acoustic impedance matching to the listener's ear canal to effect the flat frequency response characteristic. An electrical equalizer circuit to facilitate the use of the subject in-ear receivers with conventionally recorded sound is also disclosed.

Abstract: A two-dimensional planar display device includes a plurality of plasma discharge shift registers positioned along rows of a display matrix. An additional shift register positioned along one column at the edge of the display matrix causes a plasma discharge to be transferred to the beginning of each successive row shift register. By transferring a discharge along each position in successive rows, a discharge is propagated in a two-dimensional scanned manner over the face of the display matrix. By suitably modifying the level of the propagating signals in accordance with an applied video signal, the brightness of the scanned discharge is modulated to produce a variable gray scale image.

Abstract: A two-dimensional planar display device includes a plurality of plasma discharge shift registers positioned along rows of a display matrix. Each resolution element along a row includes two stable discharge locations, a first of which is optically masked. Modulating the duration of propagation signals associated with the second discharge location, the duration for propagation signals for the entire resolution element being constant, permits the generation of continuously variable brightness levels. In a preferred embodiment, glow discharges propagating down an additional one or more column shift registers are sequentially coupled to row shift registers to permit rapid scanning over the entire two-dimensional array.

Abstract: A light pen tracking system and method particularly adapted for use with a plasma panel in which a first plurality of display sites on a display device are sequentially excited in such manner as to generate a signal which may be detected by a light pen. Upon detection of a first light signal, a second set of display sites centered at a location identified by the first signal and having smaller area than the first scanned area is then scanned. Because a relatively small area is scanned in the second scanning mode, and because the center of this smaller area has been localized by the previous signal detection, it is possible to more closely track rapid movements of a light pen on a display surface.

Abstract: A light pen tracking system and method particularly adapted for use with a plasma panel in which a first plurality of display sites on a display device are sequentially excited in such manner as to generate a signal which may be detected by a light pen. Upon detection of a first light signal, a second set of display sites centered at a location identified by the first signal and having smaller area than the first scanned area is then scanned. Because a relatively small area is scanned in the second scanning mode, and because the center of this smaller area has been localized by the previous signal detection, it is possible to more closely track rapid movements of a light pen on a display surface.

Abstract: Ideally, when a signal is quantized, the range of the quantizer should be matched to the power of the signal. Disclosed herein is adaptive quantizer apparatus which utilizes a particular quantizing scheme for those communications where the power of the signal to be quantized is unknown, but remains constant for the duration of a communication. The amplitude range of an adaptive quantizer is adjusted during an initial training period to a value appropriate to the power of the applied input signal. This is accomplished by successively altering the amplitude range by a multiplicative quantity that depends upon the amplitude of the quantizer output signal and upon the time elapsed since the onset of the training period.