Showing papers on "Audio signal processing published in 1986"

Circuit breaker with solid-state trip unit with a digital processing system shunted by an analog processing system

Abstract: Solid-state trip unit having a unit (29, 50, 48) for digital processing of signals emitted by current sensors (16). The digital processing system provides the long delay, short delay and instantaneous tripping functions and delivers a tripping order to the relay (14). An analog processing unit (70) is connected parallel with the digital processing unit to transmit an instantaneous tripping order to the relay (14). When the digital processing unit operates, the analog unit pick-up level is higher than the digital instantaneous tripping pick-up and this pick-up is reduced to a lower or equal value, if the digital unit is inactive.

Audio and video digital recording and playback system

Abstract: A microcomputer system for converting an analog signal, such as an audio or video signal representative of sound or video into a digital form for storing in digital form in a highly condensed code and for reconstructing the analog signal from the coded digital form. The system includes reductive analytic means where the original digital data stream is converted to a sequential series of spectrograms, signal amplitude histrograms and waveform code tables. Approximately 100 times less storage space than previously required for the storage of digitized signals is thereby obtained. Additive synthesis logic interprets the stored codes and recreates an output digital data stream for digital to analog conversion that is nearly identical to the original analog signal.

Apparatus for generating an image from a digital video signal

Abstract: An apparatus for generating a high quality image from a digital video signal includes a system for gamma correcting the digital video signal with a digital look up table and for converting the resultant digital signal to an analog video signal. Another circuit generates a triangular wave reference pattern signal and a comparator compares the analog video signal with the triangular wave reference pattern signal to form a pulse-width-modulated signal. A raster scanning print engine producing, for example, a laser beam, scans over a recording medium in accordance with the pulse-width-modulated signal, thereby forming an image of high quality on the recording medium of a print engine. This apparatus can also be used with an analog video signal by first converting the analog video signal to a digital video signal with an analog to digital converter.

Method of and apparatus for recording and/or reproducing a picture signal and an associated audio signal in/from a record carrier

Abstract: Finite audio and video signals are subjected to a digitizing code format and converted into blocks of audio and video words respectively. For the transmission of these blocks via a record carrier (2), for example a compact disc, the words are arranged in frames, Each frame has a frame header (8.1) and a data field (8.2). Such a data field contains information words in the form of either audio words or video words. The header indicates whether the associated data field contains audio words or video words. At least two audio signals associated with a video signal are recorded on the record carrier. An example of this is a "slide show" in which the explanatory text is available in two or more languages (e for English, f for French). The frame header of the frames containing an encoded audio signal also indicate to which one of the two or more audio signals the information words in an audio frame belong. Further, reference signals and additional frames (6)are recorded in the record carrier. For each of the two or more audio signals associated with a picture (or video) signal the additional frames contain time information on the time interval between the instant of detection of a reference signal after reading and the instant at which a picture signal read is to be displayed on a monitor (50). An apparatus for recording or reproducing the above signals is described.

Digital transmisson including add/drop module

Abstract: In a transmission system, adding and/or dropping any one or more of a plurality of digital signals of one or more digital transmission bit rates is facilitated by employing a un- lque transmission signal in which data words associated with Individual digital signals are arranged in prescribed groups. The transmission signal data word groups are obtained by formatting the individual digital signals to be combined into a unique channel frame format common to all of the digital signals and by employing a unique one-step multiplexing process to insert digital words from the channel frames into the group of data word positions in the transmission signal associated with the particular signal being combined. Consequently, digital signals may be added to the transmission signal by formatting them into the common channel frame format and, then, inserting the digital words therefrom in the one-step multiplexing process into an associated group of data words positions in the transmission signal. Digital signals are dropped from the transmission signal by extracting associated groups of data words from the transmission signal, identifying the corresponding channel frames and deformatting the data bits from channel frames of corresponding digital signals being reconstructed.

Digital audio synchronizing system with mute time switching function

Abstract: A digital audio synchronizing system resynchronizes the audio signal of a video signal by storing the audio signal in a memory and reading it out from the memory after a time period which is related to the time by which the video signal is delayed as a result of being synchronized to a reference video signal. In order to prevent a discontinuity in the audio signal waveform caused by variations in the video delay between the video signal and the reference signal, the digital audio signal is read out as a first and a second output from memory addresses which correspond to the previous video delay and to a new updated video delay value. A synchronized audio signal is obtained by switching from the first output to the second output when the muting times of the first and the second outputs are coincident with each other. When the both muting times are not coincident with each other within a predetermined time from the variation in the video delay, the first and the second outputs are cross-faded with each other over a predetermined time period and the cross-faded output is produced as the synchronized audio signal for the predetermined time period, and after cross-fade operation, the second output is produced as the synchronized audio signal.

Sound recording system for electronic still camera

Abstract: A sound recording system for an electronic still camera records video signals indicative of still pictures time-serially in a rotary magnetic recording medium. An audio signal having a duration equal to a first period of time is compressed in the time axis into an audio signal having a duration equal to a second period of time, which is shorter than the first. The compressed audio signal is written into the recording medium as a unit record of data. Such a time-axis compression and recording cycle is repeated to record audio signals in the recording medium as discrete unit record data, in association with the video signals recorded.

Optical sensing circuit for audio activation of toys

Abstract: A noise-generating toy includes first and second optical sensors to detect the intensity of light in first and second optical fields, respectively. The sensor signals serve as inputs to a comparator which provides as an output a differential signal indicative of the difference between the sensor outputs. The comparator output drives an oscillator which generates audio signals in response to the differential in the intensity of light. The oscillator drives one or more speakers with the audio signals, and the speakers use the audio signals to produce audible sound or noise.

Method and apparatus for substituting a higher quality audio soundtrack for a lesser quality audio soundtrack during reproduction of the lesser quality audio soundtrack and a corresponding visual picture

Abstract: For use with master reproducing apparatus which reproduces a visual signal and a corresponding first audio signal, apparatus for substituting a second higher quality audio signal reproduced by slave reproducing apparatus for the first audio signal during reproduction of the visual signal and the first audio signal, includes a synchronizer detector for detecting the amount of synchronization between the first and second audio signals in response to the first and second audio signals and for producing an error signal corresponding thereto; a controller for controlling the slave reproducing apparatus in response to the error signal, to bring the first and second audio signals into synchronization; and a switch for switching the first audio signal to a sound system when the first and second audio signals are out of synchronization, and for switching the second audio signal to the sound system when the first and second audio signals are in synchronization, in response to the controller, whereby the higher quality second audio signal is substituted for the first audio signal when synchronization is achieved between the second audio signal and the first audio signal.

The Texas Instruments TMS320C25 Digital Signal Microcomputer

Abstract: Capable of 10 million operations per second, the newest member of the TMS320 family can serve as an inexpensive alternative to bit-slice processors or custom ICs in digital signal processing applications.

Video and audio signal recording and/or reproducing apparatus

Abstract: A video and audio signal recording apparatus comprises a video block, a digital audio signal producing circuit, a modulating circuit for generating an n-value frequency modulated signal, where n is an integer greater than or equal to three, and a recording circuit for recording the n-value frequency modulating signal and a frequency division multiplexed signal from the video block. A video and audio signal recording and reproducing apparatus comprises a first video block, a digital audio signal producing circuit, a modulating circuit for generating an n-value frequency modulated signal, a recording and reproducing circuit, first and second demodulating circuits, a decoder, and a second video block for obtaining a reproduced video signal.

Automotive multi-speaker audio system with automatic echo-control feature

Abstract: An automotive audio system separates audio signals from an audio signal source into first and second components. The first component of the audio signal is sent directly to a first main amplifier through a first audio signal path and reproduced through a main speaker or speakers. On the other hand, the second component of the audio signal is sent to a second main amplifier through a second audio signal path. An echo system is provided with the second audio signal path, which echo system induces echos in the audio sound to be reproduced through the second main amplifier. The echo system is associated with a discriminator circuit which receives an audio signal output from the audio signal source and derives an echo system control signal on the basis of the audio signal. The echo signal control signal is fed to the echo system for controlling operation of the echo system.

Secure television signal encoding and decoding system

Abstract: A television signal encoding and decoding system providing a line-spin scrambled video signal with substantially reduced amplitude gaps and line tilt and a digitally-encrypted audio signal that can be transmitted within the bandwidth limitations of a conventional NTSC television signal. The television signal encoding system, located at a television transmitter, includes a video and an audio encoder. The video encoder selectively line spin scrambles, reverses and inverts certain video lines or video line segments to generate a line-spin scrambled video signal having amplitude gaps less than some desired value. The audio encoder digitally encrypts the audio signal and modulates the encrypted audio signal with a three-level partial response waveform to generate and encrypted audio signal that can be transmitted within the bandwidth limitations of a conventional NTSC television signal. The television signal decoding system, located at a television receiver, includes a video and an audio decoder. The video decoder applies line tilt compensation to the received line-spin scrambled video signal and then unscrambles the compensated scrambled video signal. The audio decoder demodulates and decrypts the received audio signal.

Method for supervising and controlling the traffic in digital transmission networks

Abstract: For monitoring and controlling the traffic in a transmission network of a multiplex hierarchy stage comprising circuit switching devices connected via digital signal sections, all digital signals to be fed in are supplied at their source with an identification character for a desired digital signal connection. The identification character is communicated to all involved circuit switching devices so that the same can be tracked along the digital signal connection and the circuit switching devices are correspondingly controlled. Idle digital signal sections can be maintained active with an alternate signal which contains an alternate signal identification character. Given a disturbance of a digital signal section, an alternate circuit can be switched.

Universal listening device

Abstract: A listening device for detecting audio frequency sounds and presenting them at increased sound levels to a user's ears. The listening device comprises a lighweight housing with a sound port disposed on a front wall and containing audio processing components for detecting input sound waves, amplifying them, and transferring them to bi-aural sound transfer means coupled to the housing. The bi-aural transfer means directs amplified sound to both ears of a device user simultaneously. The listening device is very lightweight and very compact, with the main housing being less than about 1 cubic inch in volume The listening device employs an acoustical connector on the front wall to allow efficient transfer of sound waves from a series of acoustical adapters, generators, and probes. One such probe is highly useful for automotive engine analysis and another is highly useful for medical applications.

Multiple input silent audio switch

Abstract: A silent audio switch provides switching between multiple audio sources while eliminating the "pop" caused by switching spikes Two internal buses are used for each visible external bus, whereby a new audio signal is first switched to an off-air bus opposite an on-air bus, any switching spike is allowed to subside, and then a fast mix is made between the two buses to derive the new audio signal as the switch output signal

Programmed audio controller

Abstract: Controller for use at a listening station in an audio distribution system for selecting a channel of audio programming. The controller has input attenuators for reducing the level of the audio signals, an output amplifier, and a controlled analog switch connected between the attenuators and the amplifier for passing the attenuated audio signal from a selected channel to the output amplifier. The amplifiers have a relatively high imput impedance, and the amplifiers in the distribution system operate at a relatively low power level. The attenuated audio signals are impressed upon a voltage centered in the operating range of the analog switch. In the disclosed embodiment, the analog switch comprises a multiplexer, a counter connected to the address inputs of the multiplexer, and a channel selection switch for applying clock pulses to the counter to step the multiplexer through the audio channels in a predetermined sequence.

Digital Signal Processing Technology For R-DAT

Abstract: As one of consumer audio equipment, the CD (Compact Disc) player has come into wide use since its commercialization of 1982 for its high quality sound, easy operation and low price. The Direct Broadcasting Satellite (DBS) service has started in Japan in 1984. On the other hand, the Digital Audio Tape recorder (DAT) which has both recording and reproducing function and easy recording from these digitalized audio sources, is expected to be a next-generation audio product.

A multiprocessor digital signal processing system for real-time audio applications

Abstract: This paper describes the design and application of a multiprocessor digital signal processing system. Incorporating six VLSI digital signal processors, the fully programmable system is a powerful laboratory instrument that provides real-time digital signal processing to facilitate speech and audio research. The system capabilities include: up to 15 million 16-bit multiply-accumulate operations per second; two analog input channels sampled and converted to 16-bit values each at the rate of up to 50 kHz; and two 16-bit digital-to-analog output channels with conversion rates to 50 kHz. The implementation of a four-channel hearing aid is described to provide an understanding of a typical application to which this system is well suited.

The architecture, instruction set and development support for the WE ® DSP32 digital signal processor

Abstract: The WE®DSP32 Digital Signal Processor is a general purpose programmable single chip digital signal processor with 32-bit floating point arithmetic. The device can be cost effectively used in a wide variety of complex digital signal processing applications such as speech recognition, high speed modems, low bit rate voice coders, multi-channel signaling systems and signal processing workstations. This paper reviews the DSP32 architecture, presents its full instruction set, two complete program examples, and a description of the software and hardware support tools.

Digital audio scrambling system with pulse amplitude modulation

Abstract: In a system for scrambling an audio signal for transmission with a video signal having non-video information intervals, an analog audio signal is converted into a scrambled compressed digital audio signal; individual bits from the scrambled compressed digital audio signal are combined to provide 2-bit digital words; each digital word is converted into an 8-bit digital PAM data signal having a binary value bearing a predetermined relationship to the binary value of the converted 2-bit digital word; the 8-bit digital PAM data signal is converted into a 4-level PAM analog signal; and the PAM analog signals are inserted into the non-video information intervals of the video signal for transmission. A descrambling system descrambles the 4-level PAM analog signals by a complementary scheme.

Method and apparatus for PCM recording and reproducing an audio signal having an asynchronous relation between the sampling frequency for the audio signal and the rotation frequency of a rotary head scanner

Abstract: A PCM audio signal recording and reproducing apparatus samples an audio signal with a sampling frequency having an asynchronous relation to a field frequency of a video signal; converts it to a PCM signal, adds error detection/correction data to a predetermined number of PCM data, forms a data frame by those signals, modulates it in accordance with a predetermined modulation system, and records the audio signal together with the video signal or just the audio signal on a record medium by using a rotary head type scanner which is controlled so as to have a synchronous relation to the field frequency of the video signal. A digital signal processing circuit having a memory of a predetermined capacity is provided, and the number of digital data to be recorded in one data frame is varied in accordance with a difference between the number of input data of the digital audio signal to the digital signal processing circuit and the number of output data supplied to the record medium for recording. In the recording mode, the PCM audio signal is sectioned into blocks, a data block address signal is added to each block to indicate a relative order of a block to the other blocks and is completely added in one track, certain number of blocks are combined to form a block set for processing signals, and an identification signal completing in the block and an interleave block address signal for indicating a relative order to other blocks are added to each block.

Pcm audio signal reproducing apparatus

Abstract: In an apparatus for reproducing either a video signal or a PCM (pulse code modulated) audio signal from a record medium, the existence of a PCM audio signal recorded on the record medium is detected in response to an identifying pilot signal recorded together with the PCM audio signal, and, when a video signal is being reproduced, detection of a PCM audio signal is obviated. Thus, even if the identifying pilot signal and a portion of the video signal are superposed upon each other on a frequency axis, erroneous assumption of the presence of a recorded PCM audio signal can be avoided to prevent incorrect reproducing operation.

Method and apparatus for pcm recording and reproducing audio signal

Abstract: A PCM audio signal recording and reproducing apparatus samples an audio signal accompanying with a video signal, converts it to a PCM signal, adds an error detection correction data to a predetermined number of PCM data, forms a data frame by those signals, modulates it in accordance with a predetermined modulation system, and records the audio signal together with the video signal or singly on a record medium by using a rotary head type scanner. A digital signal processing circuit having a memory of a predetermined capacity is provided, and the number of digital data to be recorded in one data frame is varied in accordance with a difference between the number of input data of the digital audio signal to the digital signal processing circuit and the number of output data supplied to the record medium for recording. In the recording mode, the PCM audio signal is sectioned into blocks, a data block address signal is added to each block to indicate a relative order to other blocks and complete in one track, certain number of blocks are combined to form a block set for processing signals, and an identification signal completing in the block and an interleave block address signal for indicating a relative order to other blocks are added to each block.

Apparatus with liquid crystal display panel, for recording/playing back television signal by utilizing digital audio tape recorder system

Abstract: A television video signal is compressed to the number of digital video signals sufficient for display of an image on a liquid crystal display. A television audio signal is also sampled and digitized. The television video and audio signals are combined to produce a digital television signal. The audio signal is sampled and digitized to produce the digital audio signal. The rotational speed of a rotary drum having record/playback heads in the digital television signal record/playback mode is different from that in the digital audio signal record/playback mode. By utilizing a digital audio tape recorder (DAT), the digital television and audio signals can be selectively recorded or played back.