Spectrum analyzer using delta modulation encoding
First Claim
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1. Apparatus for developing a signal representative of the power at a preselected frequency of a predtermined time segment of a delta modulated signal comprising:
- first means for multiplying said delta modulated signal with a cosine signal having its argument dependent on said preselected frequency;
second means for multiplying said delta modulated signal with a sine signal having its argument identical to that of said cosine signal;
third means for accumulating said first means output signal;
sixth means for squaring said third means output signal;
fourth means for accumulating said second means output signal;
seventh means for squaring said fourth means output signal; and
fifth means for adding the output signals of said sixth and seventh means.
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Abstract
Disclosed are a method and apparatus for computing the power spectrum of an applied analog signal at a chosen frequency, by converting the analog signal into a binary sequence, by separately multiplying the binary sequence by a sequence of cosine and sine functions, by accumulating and squaring the resultant product signals, by adding the squared signals, and by multiplying the added signals with a constant signal which is a function of the chosen frequency.
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Citations
10 Claims
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1. Apparatus for developing a signal representative of the power at a preselected frequency of a predtermined time segment of a delta modulated signal comprising:
- first means for multiplying said delta modulated signal with a cosine signal having its argument dependent on said preselected frequency;
second means for multiplying said delta modulated signal with a sine signal having its argument identical to that of said cosine signal;
third means for accumulating said first means output signal;
sixth means for squaring said third means output signal;
fourth means for accumulating said second means output signal;
seventh means for squaring said fourth means output signal; and
fifth means for adding the output signals of said sixth and seventh means.
- first means for multiplying said delta modulated signal with a cosine signal having its argument dependent on said preselected frequency;
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2. The apparatus of claim 1, further comprising:
- a multiplier for multiplying the output signal of said fifth means with a constant signal of a magnitude that is a function of said preselected frequency.
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3. Apparatus for developing a signal representative of the power at a preselected frequency of a predetermined time segment of a delta modulated signal comprising:
- first means for multiplying said delta modulated signal with a trigonometric function comprising a difference of cosine signals having arguments dependent on said preselected frequency;
second means for multiplying said delta modulated signal with a trigonometric function comprising a difference of sine signals having arguments identical to those of said cosine signals;
third means for accumulating said first means output signal;
fourth means for accumulating said second means output signal;
fifth means for squaring said third means output signal;
sixth means for squaring said fourth means output signal; and
seventh means for adding the output signals of said first and sixth means.
- first means for multiplying said delta modulated signal with a trigonometric function comprising a difference of cosine signals having arguments dependent on said preselected frequency;
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4. Apparatus for developing a signal representative of the power at a preselected frequency of a predetermined time segment of a delta modulated signal comprising:
- first means, for generating a difference of cosine signals having arguments dependent on said preselected frequency;
second means, for generating a difference of sine signals having arguments identical to those of said cosine signals;
third means for developing a first product signal of said delta modulated signal with said first means output signal;
fourth means for developing a second product signal of said delta modulated signal with said second means output signal;
fifth means for accumulating said first product signal;
sixth means for accumulating said second product signal;
seventh means for squaring the output signal of said fifth means;
eighth means for squaring the output signal of said sixth means; and
ninth means for adding the output signals of said seventh and eighth means.
- first means, for generating a difference of cosine signals having arguments dependent on said preselected frequency;
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5. The apparatus of claim 4, further comprising a multiplier for multiplying the output signal of said means for adding with a constant signal of a magnitude that is a function of said preselected frequency.
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6. Apparatus for developing a signal representative of the power at a preselected frequency of a preselected time segment of an applied signal comprising:
- a linear delta modulator responsive to said applied signal for generating a binary delta modulated signal;
first means, for generating a difference of cosine signals having arguments dependent on said preselected frequency;
second means, for generating a difference of sine signals having arguments identical to those of said cosine signals;
a first multiplier for multiplying said delta modulated signals with said first means output signal;
a second multiplier for multiplying said delta modulated signal with said second means output signal;
a first accumulator for accumulating the output signal of said first multiplier;
a second accumulator for accumulating the output signal of said second multiplier;
third means for squaring the output signal of said first accumulator;
fourth means for squaring the output signal of said second accumulator;
fifth means for adding the output signals of said third and four means; and
a multiplier for multiplying the output signal of said fifth means for adding with a constant signal having a magnitude that is a function of said frequency.
- a linear delta modulator responsive to said applied signal for generating a binary delta modulated signal;
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7. The apparatus of claim 1 wherein said linear delta modulator'"'"''"'"'s binary output signal alternates between +1 and -1.
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8. Apparatus for developing a signal representative of the power at a selected frequency, f, of a predetermined time segment of an applied signal comprising:
- a linear delta modulator of input step size Delta , responsive to an NT seconds segment of an applied signal and to a clock signal having a period T, developing a binary signal br having values +1 and -1, where r indicates the time position of br and ranges from 1 to N;
a cosine generator providing a signal
- a linear delta modulator of input step size Delta , responsive to an NT seconds segment of an applied signal and to a clock signal having a period T, developing a binary signal br having values +1 and -1, where r indicates the time position of br and ranges from 1 to N;
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9. A spectrum analyzer tuned to a frequency f and responsive to an applied input signal of duration M seconds comprising:
- first means responsive to said applied input signal and to a clock signal having a period T seconds for developing a binary signal alternating between +1 and -1 where the integral of said binary signal forms a stepwise approximation of said applied input signal divided by a constant Delta ;
means for generating first trigonometric signals
- first means responsive to said applied input signal and to a clock signal having a period T seconds for developing a binary signal alternating between +1 and -1 where the integral of said binary signal forms a stepwise approximation of said applied input signal divided by a constant Delta ;
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10. The method of generating a power spectral estimate of an incoming signal at a preselected frequency comprising the steps of:
- converting a time segment of said incoming signal in accordance with linear delta modulation techniques into a sequence of N binary signals, br, having values + or - 1 at a rate of 1/T Hz, where r is a variable incrementing from 1 to N;
multiplying each of said binary signals by a difference of cosine signals whose arguments are dependent on said preselected frequency and on said r variable to develop a sequence of N first signals;
multiplying each of said binary signals by a difference of sine signals whose arguments are identical to those of said cosine signals to develop a sequence of N second signals;
accumulating said sequence of N first signals;
accumulating said sequence of N second signals;
independently squaring the resultant signals of said two accumulating steps;
adding said squared signals; and
multiplying said added signals with a constant signal having a magnitude that is a function of said preselected frequency.
- converting a time segment of said incoming signal in accordance with linear delta modulation techniques into a sequence of N binary signals, br, having values + or - 1 at a rate of 1/T Hz, where r is a variable incrementing from 1 to N;
Specification