US 5,206,601 A · Order statistic signal processor for estimating values of signal parameters and demodulating amplitude-, phase-, and frequency-modulated signals

Abstract

The order statistic signal processor obtains continuing estimates of amplitude, phase, or frequency of an input signal based on order statistics. By way of definition, the P'th order statistic for a set of samples from a continuously distributed process is the P'th largest of the samples. Where a signal parameter fluctuates with time as a result of contamination by noise and interference and where the noise fluctuation rate is much greater than the rate at which changes in a signal parameter occur, an order statistic associated with a set of signal parameter samples can serve as an estimate of the signal parameter. The order statistic signal processor is based on an iterative process whereby the prior estimate of a signal parameter, i.e. amplitude or phase, is subtracted from each of a plurality of signal parameter samples obtained over a period of time. The differences are converted to quantities of fixed magnitude with signs corresponding to the differences. The converted differences are summed, the sum is biased, and the biased sum is then integrated to provide a new estimate of the signal parameter. The signal parameter estimate obtained in this way corresponds to a particular order statistic for the signal parameter sample set that is obtained each time the process repeats. A particular order statistic is selected by adjusting the bias level.

Claims18

Dependent claims

An order statistic signal processor for estimating the values of signal parameters and demodulating amplitude-, phase-, and frequency-modulated signals, said processor being adapted to receive an input signal and producing an output signal at a processor output terminal, said input signal being characterized by a plurality of parameters, one of said parameters being selected for processing, said processor comprising:

a means for generating a parameter reference;
a means for subtracting at successively-occurring times said parameter reference from each of a plurality of delayed versions of said selected signal parameter thereby obtaining differences;
a means for limiting the magnitudes of said differences to a predetermined value and preserving the algebraic sign of said differences;
a means for adding said limited differences together thereby obtaining said output signal.

1 more element

A process for estimating a parameter of a target electrical signal by measuring a statistic for a plurality of samples of said parameter, said process comprising the steps:

(a) entering an initial estimate of said statistic for said plurality of signal parameter samples in a saved-estimate memory device, the contents of said saved-estimate memory device being known as the saved estimate;
(b) sampling a parameter of said signal at a plurality of successively-occurring times thereby obtaining a plurality of signal parameter samples;
(c) generating a signal parameter reference, said parameter reference being the integral over time of said saved estimate if said selected parameter is signal amplitude, said parameter reference being the integral over time of said saved estimate excluding any time-invariant component of said output signal if said selected parameter is the phase of a periodic signal;
(d) subtracting at successively-occurring times said parameter reference from each of a plurality of delayed versions of said selected signal parameter thereby obtaining differences;
(e) limiting the magnitudes of said differences to a predetermined value and preserving the algebraic sign of said differences thereby obtaining limited differences;
(f) adding said limited differences together to obtain a sum;
(g) adding a bias voltage to said sum thereby obtaining a biased sum;
(h) entering said biased sum into said saved-estimate memory device;
(i) repeating steps (b) through (h) indefinitely, said saved estimate being an estimate of signal amplitude as a function of time if said selected parameter is amplitude, said saved estimate being an estimate of frequency as a function of time if said selected parameter is phase and said target signal is frequency modulated, the integral of said saved estimate excluding any zero-frequency component being phase as a function of time if said selected parameter is phase and said target signal is phase modulated.

6 more elements

A process for estimating a parameter of a target electrical signal by measuring a statistic for a plurality of samples of said parameter, said process yielding a process signal, said process comprising the steps:

(a) generating a plurality of object signals, said object signals being either delayed replicas of said target signal or square-wave signals, said replicas being subject to different delays, said square-wave signals having amplitudes at any particular time corresponding to a plurality of prior samples of the amplitude of said target signal;
(b) multiplying each of said object signals by a weight thereby obtaining weighted object signals;
(d) generating a reference signal, said reference signal being equal to the integral of said process signal if said selected parameter is signal amplitude, said reference signal being a phase-continuous sinusoid having an instantaneous frequency linearly related to said process signal if said selected parameter is the phase of a periodic signal;
(e) subtracting said reference signal from each of said object signals if said selected parameter is signal amplitude, multiplying said reference signal by each of said object signals and lowpass-filtering the products if said selected parameter is the phase of a periodic target signal, thereby obtaining converted signals;
(f) limiting the magnitudes of said converted signals to a predetermined value and preserving the algebraic sign of said converted signals thereby obtaining limited signals;
(g) weighting said limited signals thereby obtaining weighted limited signals;
(h) adding said weighted limited signals together to obtain a sum signal;
(i) adding a bias voltage to said sum signal thereby obtaining a biased sum signal;
(j) limiting the magnitude of said biased sum signal to a predetermined value and preserving the algebraic sign of said biased sum signal thereby obtaining a process signal, said process signal being an estimate of signal amplitude as a function of time if said selected parameter is amplitude, said process signal being an estimate of frequency as a function of time if said selected parameter is phase and said target signal is frequency modulated, the integral of said process signal excluding any zero-frequency component being phase as a function of time if said selected parameter is phase and said target signal is phase modulated.

6 more elements

Dependencies are inferred from the claim text.

Order statistic signal processor for estimating values of signal parameters and demodulating amplitude-, phase-, and frequency-modulated signals

Life of this patent

Order statistic signal processor for estimating values of signal parameters and demodulating amplitude-, phase-, and frequency-modulated signals

Life of this patent

Abstract

Claims18