Swept-step radar system and detection method using same
First Claim
1. A method of detecting an object, comprising the steps of:
- (a) transmitting a frequency-modulated probe signal having a center frequency and a sweep bandwidth using an antenna;
(b) receiving a return signal resulting from the probe signal using the antenna;
(c) producing a difference signal using a reference signal related to the probe signal and the return signal;
(d) filtering the difference signal so as to suppress reflections from the antenna;
(e) storing magnitude and phase information of the difference signal corresponding to the object;
(f) shifting the center frequency;
(g) repeating steps (a) through (f) a predetermined number of times; and
(h) determining a range to the object using the stored magnitude and phase information.
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Accused Products
Abstract
An apparatus and method for detecting an object and determining the range of the object is disclosed. A transmitter, coupled to an antenna, transmits a frequency-modulated probe signal at each of a number of center frequency intervals or steps. A receiver, coupled to the antenna when operating in a monostatic mode or, alternatively, to a separate antenna when operating in a bistatic mode, receives a return signal from a target object resulting from the probe signal. Magnitude and phase information corresponding to the object are measured and stored in a memory at each of the center frequency steps. The range to the object is determined using the magnitude and phase information stored in the memory. The present invention provides for high-resolution probing and object detection in short-range applications. The present invention has a wide range of applications including high-resolution probing of geophysical surfaces and ground-penetration applications. The invention may also be used to measure the relative permittivity of materials.
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Citations
25 Claims
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1. A method of detecting an object, comprising the steps of:
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(a) transmitting a frequency-modulated probe signal having a center frequency and a sweep bandwidth using an antenna; (b) receiving a return signal resulting from the probe signal using the antenna; (c) producing a difference signal using a reference signal related to the probe signal and the return signal; (d) filtering the difference signal so as to suppress reflections from the antenna; (e) storing magnitude and phase information of the difference signal corresponding to the object; (f) shifting the center frequency; (g) repeating steps (a) through (f) a predetermined number of times; and (h) determining a range to the object using the stored magnitude and phase information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of detecting an object, comprising the steps of:
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(a) transmitting a frequency-modulated probe signal having a center frequency and a sweep bandwidth; (b) receiving a return signal resulting from the probe signal; (c) storing magnitude and phase information corresponding to the object derived by using the return signal; (d) shifting the center frequency; (e) repeating steps (a) through (d) a number of times; and (f) determining a range to the object using the stored magnitude and phase information. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A system for detecting a object, comprising:
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a transmitter, coupled to an antenna, that transmits a frequency-modulated probe signal having a center frequency and a sweep bandwidth; a receiver, coupled to the antenna, that receives a return signal resulting from the probe signal; a frequency selector that controls shifting of the probe signal center frequency to a number of center frequency values; a memory that stores magnitude and phase data of the return signal resulting from transmission of the probe signal at each of the center frequency values; and a processor, coupled to the memory, that computes a range to the object using the magnitude and phase data stored in the memory. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A system for detecting a object, comprising:
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an oscillator coupled to a waveform generator for generating a frequency-modulated probe signal having a center frequency and a sweep bandwidth; a controller that causes the oscillator to shift the center frequency to a number of center frequency values; an antenna that transmits the probe signal and receives a return signal resulting from the probe signal; a mixer coupled to the antenna and the oscillator for down-converting the return signal to a beat signal; a filter coupled to the mixer that receives the beat signal and suppresses reflections from the antenna; an amplifier coupled to the filter that amplifies the filtered beat signal; a data acquisition unit, coupled to the amplifier and a memory, that acquires magnitude and phase data of the filtered beat signal corresponding to the object resulting from transmission of the probe signal at each of the center frequency values, and stores the magnitude and phase data in the memory; and a processor, coupled to the memory, that computes a range to the object using the magnitude and phase data stored in the memory. - View Dependent Claims (23, 24, 25)
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Specification