Apparatus and method for analyzing acoustical signals
First Claim
1. Apparatus for analyzing an acoustical signal having a plurality of signal components extending over a band of signal frequencies, comprising:
- means for separating an acoustical signal into a plurality of sub-bands;
means for measuring the time period between successive zero-crossings of signal components in each of said sub-bands;
reciprocal means for extracting the reciprocal of the zero-crossing time periods of signal components in each of said sub-bands;
display means for simultaneously displaying the time period reciprocals of signal components in each of said sub-bands; and
means for sequentially scanning each of said sub-bands for the presence of a signal component therein, for causing a zero-crossing time period measurement to be made if said signal component is present in the selected sub-band, and for advancing to the next sub-band if no such signal component is present.
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Abstract
A zero-crossing accoustical signal analyzer includes a plurality of parallel-connected adjacently tuned filter channels to separate an incoming accoustical signal into a plurality of adjacent sub-bands. Zero crossing analysis is provided for each of the sub-bands to determine the time period between successive zero crossings of signal components within each of the sub-bands. The reciprocal of the time periods from each sub-band is then simultaneously provided on a frequency vs. time display. Each filter channel also produces a signal proportional to the amplitude of signal frequency components within the respective sub-band for producing a frequency vs. amplitude display.
41 Citations
14 Claims
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1. Apparatus for analyzing an acoustical signal having a plurality of signal components extending over a band of signal frequencies, comprising:
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means for separating an acoustical signal into a plurality of sub-bands; means for measuring the time period between successive zero-crossings of signal components in each of said sub-bands; reciprocal means for extracting the reciprocal of the zero-crossing time periods of signal components in each of said sub-bands; display means for simultaneously displaying the time period reciprocals of signal components in each of said sub-bands; and means for sequentially scanning each of said sub-bands for the presence of a signal component therein, for causing a zero-crossing time period measurement to be made if said signal component is present in the selected sub-band, and for advancing to the next sub-band if no such signal component is present. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Time domain signal analyzing apparatus, comprising:
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(a) a plurality of filter channels, each responsive to a portion of the frequency spectrum of signals being analyzed, and each comprising; (i) a bandpass filter, (ii) means for producing zero-crossing control pulses designating zero-crossings of output signals from said bandpass filter, and (iii) means for producing an activation signal whenever the output signal from said bandpass filter exceeds a predetermined threshold; (b) a clock for producing a series of regular clock pulses; (c) a counter for producing a digital output signal proportional to the number of said clock pulses received at the input of said counter; (d) connecting means for supplying said clock pulses to said counter in response to said zero-crossing control pulses; (e) scanning means for sequentially connecting said filter channels to said connecting means such that a pair of said zero-crossing control pulses from a connected filter channel causes said connecting means to supply a number of said clock pulses to said counter proportional to the time period between zero-crossings of the output of the bandpass filter of said connected filter channel, said scanning means comprising a scan counter having a plurality of outputs each connected to one of said filter channels, said outputs being individually and selectively activated by pulses supplied to said scan counter, and a gate having an input connected to said clock, an output connected to said counter, and a control terminal connected to said activation signal means such that the presence of said activation signal blocks the flow of signals from said clock to said scan counter; (f) reciprocal means for providing a value proportional to the reciprocal of said counter digital output signal; and (g) display means for displaying the output of said reciprocal means. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for analyzing an acoustical signal having a plurality of signal components extending over a band of signal frequencies, comprising the steps of:
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separating an acoustical signal into a plurality of adjacent sub-bands; sequentially scanning each of said sub-bands for the presence of a signal component therein; causing a zero-crossing time period measurement to be made if said signal component is present in the selected sub-band; extracting the reciprocal of the zero-crossing time periods of signal components in each of said sub-bands; advancing to the next sub-band if no such signal component is present; and simultaneously displaying the time period reciprocals of signal components in each of said sub-bands.
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Specification