US 4,237,343 AGranted

Digital delay/ambience processor

OwnerStephen L. Kurtin, Edward C. Kelminventors

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Abstract

A processor for audio program material which synthesizes simulated reflection and reverberation signals for use in creating the illusion of a specific modeled listening environment. A preferred embodiment of the processor accepts stereophonic audio signals and simulates the multiple reflections of an acoustically modeled environment by recirculating the signals through a pair of digital signal delays which have different delay times. The analog input signals are sampled and converted to digital form by first attenuating the signals with a digitally controlled step attenuator and then encoding the amplitude of the attenuated signal using a ramp comparison technique. The encoded amplitude signals, and a code representative of the attenuator position, are stored in a random access memory and are retrieved after the desired delay. The retrieved digital data are converted back to analog signals by reversing the encoding process, using the same ramp voltage generator. A stack comprised of a counter and two registers connected in a loop generates three addresses during each sample period for use in writing in new data and retrieving previously stored data.

Claims26

Dependent claims

A signal processor which comprises:

(a) means for coupling a pair of analog input signals to the inputs of a corresponding pair of channels:
(b) means for converting analog signals coupled to the input of each of said channels into digital form;
P1 (c) random access memory means for storing each of said digital signals at a different one of a plurality of addresses;
(d) means for retrieving said stored signals from said memory at said addresses after predetermined periods of time, said periods of time not being the same for all channels;
(e) means for generating said addresses for storing and retrieving said digitized signals in said memory which comprises:
(i) a stack in a loop circuit comprised of a counter and a plurality of registers, each of said registers being coupled to the next higher register in said stack, the highest register in said stack being coupled to said counter, said counter being coupled to the lowest register in said stack;
(ii) pulsing means for advancing said counter;
and
(iii) means for coupling a transfer pulse to each of said registers and said counter after said counter has advanced a predetermined number of counts, said transfer pulse causing said information in said stack and loop circuit to recirculate;
(f) means for converting said stored signals retrieved from said memory into analog amplitudes;
(g) means for coupling amplitudes proportional to said analog amplitudes derived from signals coupled to the input of each of said channels to the input of the corresponding channel;
and
(h) means for coupling amplitudes proportional to said analog amplitudes derived from signals coupled to the input of at least one of said channels to the input of the other of said channels.

10 more elements

Electronic apparatus for generating simulated ambience signals which comprises:

(a) a pair of signal input circuits for coupling a stereophonic input signal to two channels;
(b) means for generating digital codes representative of the instantaneous values of signals coupled to each of said channels;
(c) random access memory means for storing each of said digital codes at a different one of a plurality of addresses;
(d) means for retrieving the digital codes stored in said memory at the addresses which correspond to the addresses of signal values from one of said channels entered into said memory at a first time prior to retrieval;
(e) means for retrieving the digital codes stored in said memory at the addresses which correspond to the addresses of signal values from the second of said channels entered into said memory at a second time prior to retrieval;
(f) means for generating said addresses for storing and retrieving said digital codes in said memory which comprises:
(i) a stack and loop circuit comprised of a counter and a plurality of registers, each of said registers being coupled to the next higher register in said stack, the highest register in said stack being coupled to said counter, said counter being coupled to the lowest register in said stack;
(ii) pulsing means for advancing said counter;
and
(iii) means for coupling a transfer pulse to each of said registers and said counter after said counter has advanced a predetermined number of counts, said transfer pulse causing information in said stack and loop circuit to circulate.

7 more elements

Electronic apparatus for delaying signals which comprises:

(a) means for sampling input signals at a predetermined rate;
(b) means for attenuating each of said samples to a level below a predetermined level;
(c) means for generating digital codes representative of the amounts of said attenuation;
(d) means for generating digital codes representative of the amplitudes of said attenuated samples;
(e) random access memory means for storing each of said digital codes representative of the amounts of said attenuation and the amplitudes of said attenuated samples at a different one of a plurality of addresses;
(f) means for retrieving said digital codes representative of the amounts of said attenuation and the amplitudes of said attenuated samples from said addresses a predetermined time after said digital codes are stored in said memory;
(g) means for generating said addresses for storing and retrieving said digital codes in said memory which comprises:
(i) a stack and loop circuit comprised of a counter and a plurality of registers, each of said registers being coupled to the next higher register in said stack, the highest register in said stack being coupled to said counter, said counter being coupled to the lowest register in said stack;
(ii) pulsing means for advancing said counter;
and
(iii) means for coupling a transfer pulse to each of said registers and said counter after said counter has advanced a predetermined number of counts, said transfer pulse causing information in said stack and loop circuit to circulate;
(h) means for converting the digital codes representative of said signal amplitudes retrieved from said memory into signal amplitudes;
and
(i) means for altering the amplitudes of said converted signal amplitudes responsive to the digital codes retrieved which are representative of said amounts of attenuation whereby the amplitudes of said altered converted signals will be proportional to the amplitudes of the corresponding input signal samples.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/876,540Filed 9 Feb 1978
Granted: 2 Dec 1980
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04S 1/007
Two-channel systems: in which the audio signals are in digital form
G10K 15/12
Arrangements for producing a reverberation or echo sound: using electronic time-delay networks
H04S 5/02
Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or…: of…
H04S 7/305
Control circuits for electronic adaptation of the sound field: electronic adaptation of stereophonic audio signals to reverberation of the…