Range and bearing tracking system with multipath rejection
DCFirst Claim
Patent Images
1. A method for determining the direction with respect to a receiver of a source of a radiated radiofrequency (RF) signal, comprising the steps of:
- (a) receiving a multipath signal which has been transmitted by a remote transmitter;
(b) correlating the received multipath signal into plural path signals;
(c) determining the time of arrival of each of the plural path signals;
(d) determining the direction of the remote transmitter from the path signal having the earliest determined time of arrival.
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Abstract
A system and method for tracking a remote RF transmitter with reduced susceptibility to the effects of multipath in which the distance and direction of an arriving RF chirp signal are determined with respect to the earliest arriving portion of the signal which is presumed to be the direct path signal. The received chirp signals, including the direct and multipath signals, from a remote transmitter are correlated into plural path signals, and the direction and distance to the transmitter is determined from the earliest arriving path signal.
64 Citations
32 Claims
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1. A method for determining the direction with respect to a receiver of a source of a radiated radiofrequency (RF) signal, comprising the steps of:
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(a) receiving a multipath signal which has been transmitted by a remote transmitter; (b) correlating the received multipath signal into plural path signals; (c) determining the time of arrival of each of the plural path signals; (d) determining the direction of the remote transmitter from the path signal having the earliest determined time of arrival. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for determining the direction from which a received multipath signal was transmitted, comprising:
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plural receiving channels, each channel comprising; RF signal receiving means for receiving a RF signal and converting said RF signal to a received signal; bandpass filtering means for filtering said received signal; a chirp mixer to mix the filtered electrical signal with a chirp signal to produce an intermediate frequency ("IF") signal; IF filtering means for filtering said IF signal; a quadrature downconverter to downconvert said filtered IF signal to baseband quadrature signals; and
,an analog-to-digital converter to convert the baseband quadrature signals to digital signals; digital signal processing means operatively connected to receive and determine the power spectrum of each of said digital signals from said plural receiving channels; control means for determining the time of arrival of each of said digital signals and for determining the angle of arrival of the digital signal having the earliest time of arrival. - View Dependent Claims (27, 28, 29)
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12. A method for determining the distance between a receiver of a radiated radiofrequency (RF) signal and a transmitter of said signal, comprising the steps of:
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(a) receiving a multipath signal which has been transmitted by a remote transmitter; (b) correlating the received multipath signal into plural path signals; (c) determining the time of arrival of each of the plural path signals; (d) determining the distance of the remote transmitter from the path signal having the earliest determined time of arrival. - View Dependent Claims (13, 14, 15, 16)
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17. A system for determining the direction to a remote transmitter from which a chirp signal was transmitted, comprising:
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a receiver for receiving a first chirp signal and any multipath chirp signals related thereto; a chirp generator for providing a locally generated chirp signal; a mixer for combining the locally generated chirp signal with each of the received chirp signals to generate plural sinusoidal signals whose frequencies are related to the arrival times of the received chirp signals; a signal processor operatively connected to receive the sinusoidal signals and for determining a power spectrum of the sinusoidal signals; and a control means for determining from the power spectrum the relative times of arrival of the received chirp signals and for determining the angle of arrival of one of the received chirp signals having the earliest time of arrival. - View Dependent Claims (18, 19, 20, 30)
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21. A method of determining the direction to a remote transmitter of an RF chirp signal, comprising the steps of:
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(a) receiving plural RF chirp signals resulting from a remotely transmitted RF chirp signal; (b) generating a local RF chirp signal; (c) mixing the local RF chirp signal with each of the received RF chirp signals to generate a set of sinusoidal signals whose frequencies are related to the arrival times of the received chirp signals; (d) correlating the sinusoidal signals into plural path signals; (e) determining which one of the plural path signals arrives first; and (f) determining the direction to the remote transmitter using the earliest arriving one of the plural path signals. - View Dependent Claims (22, 23, 24, 25, 31)
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26. A method of determining the distance to a remote transmitter of an RF chirp signal, comprising the steps of:
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(a) receiving a multipath RF chirp signal resulting from the remotely transmitted signal; (b) correlating the multipath RF chirp signal into plural path signals; (c) determining the time of arrival of the first arrived one of the path signals; and (d) determining the distance of the remote transmitter using the first arrived one of the path signals. - View Dependent Claims (32)
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Specification