Demodulation system and method for recovering a signal of interest from an undersampled, modulated carrier
First Claim
1. A method of recovering at least one signal of interest D cos ω
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h (t) from at least one undersampled, modulated carrier (f(t)), wherein the signal of interest is detected by at least one sensor and modulates a carrier signal (ω
c (t)) to form the undersampled, modulated function (f(t)) having the form f(t)=A+B sin(C cos(ω
c (t)+Phc)+D cos(ω
h (t))+Phi (t)) where;
A, B=detection factors,C=amplitude of the carrier signal,ω
c =the carrier signal frequency (2π
f),Phc =phase of the carrier signal relative to the sensor,D=amplitude of the signal of interest,ω
h =radian frequency of the signal of interest, andPhi (t)=environmentally induced phase noise;
said method comprising the steps of;
receiving the undersampled, modulated carrier;
orthogonally demodulating said undersampled, modulated carrier by multiplying said undersampled, modulated carrier by cos(ω
c (to)) to extract an even harmonic component of said signal of interest and multiplying said undersampled, modulated carrier by sin(ω
c (to)) to extract an odd harmonic component of said signal of interest; and
further demodulating said even harmonic component and said odd harmonic component of said signal of interest to recover said signal of interest.
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Abstract
A demodulation system and method is used in a sensor system, such as a fi optic sensor system, that senses optical signals and modulates a phase generated carrier having a carrier frequency ωc to form a modulated carrier. The modulated carrier is preferably undersampled at three times the carrier frequency (3ωc), thereby maximizing the sensors'"'"' demodulated bandwidth relative to the sensors'"'"' sampling frequency. The undersampled, modulated carrier is orthogonally demodulated by multiplying the undersampled, modulated carrier by cos(ωc (to)) and sin(ωc)(to)) to extract even and odd harmonic components of the signal of interest. The even and odd harmonic components of the signal of interest are further demodulated by taking the square root of the sum of squares of the even and odd harmonic components, normalizing the even and odd harmonic components, and differentiating, cross-multiplying and differencing the normalized even and odd harmonic components to recover the signal of interest.
103 Citations
15 Claims
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1. A method of recovering at least one signal of interest D cos ω
-
h (t) from at least one undersampled, modulated carrier (f(t)), wherein the signal of interest is detected by at least one sensor and modulates a carrier signal (ω
c (t)) to form the undersampled, modulated function (f(t)) having the form f(t)=A+B sin(C cos(ω
c (t)+Phc)+D cos(ω
h (t))+Phi (t)) where;A, B=detection factors, C=amplitude of the carrier signal, ω
c =the carrier signal frequency (2π
f),Phc =phase of the carrier signal relative to the sensor, D=amplitude of the signal of interest, ω
h =radian frequency of the signal of interest, andPhi (t)=environmentally induced phase noise; said method comprising the steps of; receiving the undersampled, modulated carrier; orthogonally demodulating said undersampled, modulated carrier by multiplying said undersampled, modulated carrier by cos(ω
c (to)) to extract an even harmonic component of said signal of interest and multiplying said undersampled, modulated carrier by sin(ω
c (to)) to extract an odd harmonic component of said signal of interest; andfurther demodulating said even harmonic component and said odd harmonic component of said signal of interest to recover said signal of interest. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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h (t) from at least one undersampled, modulated carrier (f(t)), wherein the signal of interest is detected by at least one sensor and modulates a carrier signal (ω
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11. A system for recovering at least one signal of interest D cos ω
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h (t) from at least one undersampled, modulated carrier (f(t)), wherein the signal of interest is detected by at least one sensor and modulates a carrier signal (ω
c (t)) to form said undersampled, modulated carrier (f(t)) having the form;
f(t)=A+B sin(C cos(ω
c (t)+Phc)+D cos(ω
h (t))+Phi (t)) where;A, B=detection factors, C=amplitude of the carrier signal, ω
c =the carrier signal frequency (2π
f),Phc =phase of the carrier signal relative to the sensor, D=amplitude of the signal of interest, ω
h =radian frequency of signal of interest, andPhi (t)=environmentally induced phase noise; said system comprising; means for receiving the undersampled, modulated carrier; means for multiplying said undersampled, modulated carrier by cos(ω
c (to)) to extract an even harmonic component of said signal of interest;means for multiplying said undersampled, modulated carrier by sin(ω
c (to)) to extract an odd harmonic component of said signal of interest; andmeans for further demodulating said even harmonic component and said odd harmonic component of said signal of interest to recover said signal of interest. - View Dependent Claims (12, 13, 14, 15)
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h (t) from at least one undersampled, modulated carrier (f(t)), wherein the signal of interest is detected by at least one sensor and modulates a carrier signal (ω
Specification