Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
112 words
A system for cancelling unwanted sound and noise from outside a well defined area comprising: (a) two directional microphones, each microphone being placed a distance away from a user and having a predetermined beam pattern; (b) preamplifier means electrically connected to each microphone. (c) multiplexer means connected to said preamplifier means for leading signals amplified by said preamplifier means into an A/D converter means; (d) said A/D converter means supplying digital signals to a microcomputer; (e) said microcomputer being programmed to subject said digital signals to fast Fourier transformation from a time domain to a frequency domain; and (f) said microcomputer being further programmed to cancel unwanted aspects of said digital signals.
Claim 2
Independent Claim
112 words
A system for cancelling unwanted sound and noise from outside a well defined area comprising: (a) two directional microphones, each microphone being placed a distance away from a user and having a predetermined beam pattern; (b) preamplifier means electrically connected to each microphone. (c) multiplexer means connected to said preamplifier means for leading signals amplified by said preamplifier means into an A/D converter means; (d) said A/D converter means supplying digital signals to a microcomputer; (e) said microcomputer being programmed to subject said digital signals to fast Fourier transformation from a time domain to a frequency domain; and (f) said microcomputer being further programmed to cancel unwanted aspects of said digital signals.
Claim 3
Dependent Claim
84 words
The invention of claim 1, wherein the system further comprises: (a) a third directional microphone placed a predetermined distance away from the user and having an overlapping beam pattern with respect to said two directional microphones; (b) further preamplifier means electrically connected to said third microphone and to said multiplexer means and A/D converter means; (c) said microcomputer being further programmed to subject digital signals received from said third microphone to said fast Fourier transformation and to cancel unwanted aspects of said digital signals.
Claim 4
Dependent Claim
82 words
The invention of claim 1, wherein the system further comprises: (a) said microcomputer being programmed after said unwanted aspects have been cancelled to subject remaining signals to inverse fast Fourier transformation from said frequency domain to said time domain; (b) D/A converter means enabling conversion of said remaining signals from digital signals into analog signals; (c) amplifier means for amplifying said remaining signals in analog form to a predetermined level; and (d) speaker means for converting said remaining signals to sound waves.
Claim 5
Dependent Claim
92 words
The invention of claims 1, 2 or 3, wherein said area comprises overlapping portions of all of said beam patterns, said microcomputer being programmed to cancel static noise by setting a static noise level to an average amplitude of the signals upon activation of the system, the system then continuously measuring amplitude levels, and finding a new static noise level if changes in one or both signals are less than a predetermined amplitude level for a predetermined time, the signals being modified to a controlled static noise level by a simple subtraction.
Claim 6
Dependent Claim
75 words
The invention of claims 1, 2 or 3, wherein said area comprises overlapping portions of all of said beam patterns, said microcomputer being programmed to cancel dynamic noise, said system including a low pass and a high pass filter which are operative to manipulate the signals in said frequency domain by simple window function multiplication whereby signals subjected to said high pass filter are averaged and subtracted from signals subjected to said low pass filter.
Claim 7
Dependent Claim
58 words
The invention of claims 1, 2 or 3, wherein said area comprises overlapping portions of all of said beam patterns, said microcomputer being programmed for area cancellation of different frequency components, whereby signals are compared for each frequency component and are adjusted so that the frequencies which are not present in all signals are cancelled from all signals.
Claim 8
Dependent Claim
41 words
The invention of claim 5, wherein said microcomputer includes means for phase adjustment compensation of said signals in a frequency domain, by finding a most common absolute amplitude difference between the signals and compensating one of said signals with said difference.
Claim 9
Dependent Claim
57 words
The invention of claims 1, 2 or 3, wherein said area comprises overlapping portions of all of said beam patterns, said system further including control means for dynamically controlling gain of incoming signals by testing to see whether incoming amplitude should be adjusted up or down via setting of a variable amplifier operatively connected into said system.