Chirp-based method and apparatus for performing phase calibration across phased array antenna
First Claim
1. For use with an electrical apparatus employing a signal transport path having a first node coupled with a reference frequency signal source that is operative to generate a reference frequency signal that propagates along said signal transport path to a second node, said signal transport path imparting a variable delay of said reference frequency signal employed by said apparatus to operate electrical devices at said nodes, as a result of temperature variation along said signal transport path, a method of providing a measure of delay through said signal transport path between said first node and said second node, said method comprising the steps of:
- (a) injecting a chirp signal into said signal transport path from said second node of said signal transport path, so that said chirp signal is transmitted over said signal transport path, is reflected from said first node and returned to said second node of said apparatus;
(b) receiving said reflected chirp signal at said second node of said apparatus;
(c) correlating energy contained in said reflected chirp signal received in step (b) with energy in an auxiliary chirp signal, delayed with respect to that of the chirp signal injected into said signal transport path in step (a); and
(d) adjusting said auxiliary chirp signal to maximize the result of correlating in step (c) and thereby provide an output representative of delay through said signal transport path.
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Abstract
A chirp-based method and apparatus measures phase variation through a reference frequency transport cable for a phased array antenna. A chirp is injected into the a signal transport path from a remote transmit/receive portion of the antenna, so that the chirp is conveyed over the signal path, reflected from an upstream bandpass filter at a local transmit/receive portion of the antenna, and returned to a remote transmit portion of the antenna. Energy in the returned chirp is extracted by a downstream bandpass filter and correlated in a delay lock loop with energy in an auxiliary chirp signal, that is delayed relative to the injected chirp. The delay of the auxiliary chirp is adjusted to maximize the correlation output and provide an indication of the delay through the signal path.
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Citations
13 Claims
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1. For use with an electrical apparatus employing a signal transport path having a first node coupled with a reference frequency signal source that is operative to generate a reference frequency signal that propagates along said signal transport path to a second node, said signal transport path imparting a variable delay of said reference frequency signal employed by said apparatus to operate electrical devices at said nodes, as a result of temperature variation along said signal transport path, a method of providing a measure of delay through said signal transport path between said first node and said second node, said method comprising the steps of:
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(a) injecting a chirp signal into said signal transport path from said second node of said signal transport path, so that said chirp signal is transmitted over said signal transport path, is reflected from said first node and returned to said second node of said apparatus;
(b) receiving said reflected chirp signal at said second node of said apparatus;
(c) correlating energy contained in said reflected chirp signal received in step (b) with energy in an auxiliary chirp signal, delayed with respect to that of the chirp signal injected into said signal transport path in step (a); and
(d) adjusting said auxiliary chirp signal to maximize the result of correlating in step (c) and thereby provide an output representative of delay through said signal transport path. - View Dependent Claims (2, 3, 4, 5)
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6. An arrangement for providing a measure of phase delay through a signal transport path for a reference frequency signal that is conveyed thereover between first and second nodes of an electrical apparatus, comprising:
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a chirp signal generator which is operative to inject an upstream-directed chirp signal into said signal transport path from said second node of said apparatus, so that said chirp signal is transmitted over said signal transport path, is reflected from said first node, and returns to said second node;
a reflected chirp signal receiver coupled with said second node, and being operative to extract energy in said chirp signal that has reflected from said first node, and returned to said second node;
a correlator that is operative to correlate energy contained in said reflected chirp signal with energy in an auxiliary chirp signal, delayed with respect to that of the RF chirp signal injected into said signal transport path; and
an auxiliary chirp signal adjustment unit, which is operative to adjust said auxiliary chirp signal to maximize the output of said correlator and thereby provide an output representative of delay through said signal transport path. - View Dependent Claims (7, 8, 9)
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10. For use with a phased array antenna having a signal transport path between transmit/receive array portions of said antenna, said signal transport path being subject to a variable delay therethrough, of a reference frequency signal employed by said antenna to operate said transmit/receive array portions thereof, as a result of temperature variations along said signal transport path, a method of providing a measure of said variable delay through said signal transport path comprising the steps of:
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(a) at said remote portion of said antenna, injecting a chirp signal into said signal transport path so that said chirp signal is transmitted over said signal transport path and is reflected from said local transmit/receive portion of said antenna;
(b) extracting said reflected chirp signal at said receive portion of said antenna and correlating energy contained in said reflected chirp signal with energy in an auxiliary chirp signal that is delayed with respect to that of the chirp signal injected into said signal transport path in step (a);
(c) adjusting said auxiliary chirp signal to maximize its correlation with said reflected chirp signal and producing an output representative of phase delay of said reference frequency signal through said signal transport path. - View Dependent Claims (11, 12, 13)
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Specification