Showing papers on "Audio signal processing published in 1969"
Patent•
23 Jun 1969
TL;DR: In this article, a voice annunciating system having an electronic memory for storing digital data representative of the analog audio signal of a plurality of predetermined sound components, selected series of said data being applied from said memory to a digital to analog converter adapted to produce an audio signal corresponding to the digital data applied thereto, by means of a control logic.
Abstract: A voice annunciating system having an electronic memory for storing digital data representative of the analog audio signal of a plurality of predetermined sound components, selected series of said data being applied from said memory to a digital to analog converter adapted to produce an audio signal corresponding to the digital data applied thereto, by means of a control logic. The control logic is operative in response to an actuating signal associated with the desired message. Substantially all redundancy is eliminated from the digital data stored in the memory, said control logic being adapted to repetitively apply individual sound components or series of sound components to the digital to analog converter for reconstructing the desired message.
66 citations
Patent•
01 Jul 1969
TL;DR: In this article, a circuit for efficiently coupling an amplified audio signal to a transducer is described, where two 180* out-of-phase audio signals are respectively applied to first and second comparators which compare the audio signals with a reference signal to produce two pulsewidth-modulated signals.
Abstract: A circuit for efficiently coupling an amplified audio signal to a transducer is disclosed. In the form herein described, two 180* out-of-phase audio signals are respectively applied to first and second comparators which compare the audio signals with a reference signal to produce two pulse-width-modulated signals. The latter signals are applied to switching semiconductors connected in the two arms of a bridge which includes the transducer.
24 citations
Patent•
14 Nov 1969
TL;DR: In this article, an audio frequency amplifier, useful to DC in which a pulsewidth modulated signal is formed from the audio frequency signal, is described, where each excursion of the pulse-width signal is cut in half with respect to time by an appropriately timed square wave and plural logic gates.
Abstract: An audio frequency amplifier, useful to DC in which a pulsewidth modulated signal is formed from the audio frequency signal. Each excursion of the pulse-width signal is cut in half with respect to time by an appropriately timed square-wave and plural logic gates. The resulting waveforms are passed without distortion by pulse transformers. Plural rectifiers and low-pass filters re-form the pulse-width modulated signal. This signal is impressed upon switching power transistors. These give a greatly amplified power output, which is the same type of amplitudevarying waveform as the input audio signal, upon the current flowing through a small choke to the load. The load may have any phase angle without incurring distortion of the output waveform. Half-bridge, quarter-bridge, full-bridge, and plural phase embodiments are described.
13 citations
TL;DR: In this paper, the results of some field trials of a sonar system which uses a digital signal processing unit are presented mainly in the form of the system range/bearing display and these indicate that the system is suitable to detect mid-water fish shoals and to study their behaviour.
1 citations