Frequency estimation system
First Claim
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1. An electronic measurement instrument comprising:
- input means for receiving an analog waveform;
signal processing means for converting said analog waveform into digital data sequences corresponding to real and imaginary components of the waveform at a number of points therealong;
means for determining from said real and imaginary data sequences a phase datum at a number of points along the analog signal; and
means for performing a linear regression fit on said number of phase data to determine a best estimate of the phase rate of change of the analog waveform;
wherein the phase datum is a cumulative phase of the analog signal waveform.
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Abstract
A signal of interest is periodically sampled and the samples decomposed into quadrature components. The signal'"'"'s phase angle at each sample is computed from the ratio of the real to imaginary parts. A linear regression analysis is then performed on the sampled phase data to obtain a best estimate of the signal'"'"'s phase rate of change. From this estimate, the signal frequency is determined. In superheterodye instruments, the frequency of an input signal can be deduced by analyzing an intermediate frequency signal using this technique and factoring out the frequency of intervening local oscillator(s).
27 Citations
11 Claims
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1. An electronic measurement instrument comprising:
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input means for receiving an analog waveform; signal processing means for converting said analog waveform into digital data sequences corresponding to real and imaginary components of the waveform at a number of points therealong; means for determining from said real and imaginary data sequences a phase datum at a number of points along the analog signal; and means for performing a linear regression fit on said number of phase data to determine a best estimate of the phase rate of change of the analog waveform; wherein the phase datum is a cumulative phase of the analog signal waveform. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for determining the frequency of a signal input to a superheterodyne instrument, the method comprising the steps:
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processing an intermediate frequency signal in said instrument to periodically quantify the real and imaginary parts thereof and to produce arrays of first and second data corresponding thereto, respectively; computing, for each of a plurality of said first and second data pairs, the quotient of one of said data divided by the other; determining from each of said quotients a phase of the intermediate frequency signal to yield an array of sampled phase data; examining the progression of sampled phase data with time and adding 2π
thereto as necessary to unwrap the sampled phases;performing a linear regression analysis on the unwrapped array of sampled phase data to estimate the phase rate of change; and computing from said phase rate of change and frequencies of one or more local oscillator signals the frequency of the signal input to the instrument.
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9. A method for determining the frequency of a signal input to a superheterodyne instrument, the method comprising the steps:
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processing an intermediate frequency signal in said instrument to periodically quantify the real and imaginary parts thereof and to produce a pair of first and second data corresponding thereto, respectively; determining from each of said pairs a phase datum related thereto; performing a linear regression analysis on the phase data to estimate the intermediate frequency signal'"'"'s phase rate of change; and computing from said phase rate of change and frequencies of one or more local oscillator signals the frequency of the signal input to the instrument. - View Dependent Claims (10, 11)
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Specification