Multiple frequency through-the-wall motion detection and ranging using a difference-based estimation technique
First Claim
1. A method for detecting range to a moving object, comprising the steps of:
- projecting continuous wave energy simultaneously at two different frequencies from a single antenna towards the moving object; and
,estimating range from the antenna to the moving object based on the phase difference between outgoing and reflected waves of the two frequencies at the antenna, the phase difference between the outgoing and reflected waves being used to establish respective temporal waveforms in the estimating step, the range estimation based on the relative phase relationship between the temporal waveforms.
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Abstract
A multi-tone CW radar (14) is used to project signals from an antenna (22) and to receive returns with the same antenna. The phase differences between the outgoing signals and the returns are analyzed to determine the existence of motion and the range to a moving object (10). A model is made which has range as its major parameter. A waveform associated with the phase difference between outgoing signals and returns for one of the tones is compared to templates produced by the model to determine which has a range that most closely matches. By varying the range parameters, when a match is detected the range to the object can be obtained even if its motion is pseudorandom. If the range is measured with multiple units it is possible to measure the location of the object. This can be done assuming a grid and algorithmically combining the ranges from the units.
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Citations
14 Claims
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1. A method for detecting range to a moving object, comprising the steps of:
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projecting continuous wave energy simultaneously at two different frequencies from a single antenna towards the moving object; and
,estimating range from the antenna to the moving object based on the phase difference between outgoing and reflected waves of the two frequencies at the antenna, the phase difference between the outgoing and reflected waves being used to establish respective temporal waveforms in the estimating step, the range estimation based on the relative phase relationship between the temporal waveforms. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for estimating the range to a non-uniformly-moving object, comprising the steps of:
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simultaneously projecting from a single antenna continuous wave energy simultaneously at two different frequencies towards the moving object which reflects incident wave energy back to the antenna; and
,estimating the range to the non-uniformly-moving object based on the phase difference between outgoing and reflected waves of the two frequencies reflected by the object to the antenna, the range estimation step including the step of generating waveforms corresponding to the phase differences between outgoing and reflected waves, and further including from waveforms associated with a first one of said frequencies generating a set of range-dependent waveform templates corresponding to the second of the frequencies and comparing a waveform at the second frequency derived from measured data with each of the range-dependent waveform templates to ascertain by matching techniques which template is closest, and thus the estimated range to the non-uniformly-moving object.
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11. Apparatus for the estimation of the range to a moving object, comprising:
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a two-tone radar for generating continuous wave energy simultaneously at two different frequencies; a single antenna coupled to said radar for simultaneously projecting continuous wave energy therefrom; a pair of mixers coupled to said antenna and said radar for generating waveforms corresponding respectively to the phase difference between outgoing and reflected energy at said antenna for each of said two different frequencies; and
,a range estimation unit coupled to said pair of mixers for estimating range to said moving object, said range estimation unit including a predictor for generating from a temporal waveform corresponding to the phase difference between outgoing and reflected energy at the second of said frequencies a series of range dependent waveforms corresponding to an expected temporal phase difference of returned continuous wave energy at a first one of said frequencies, and a waveform matching unit for establishing a match between one of said range-dependent waveforms and the output of the mixer associated with said first one of said frequencies. - View Dependent Claims (12, 13, 14)
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Specification