Holonomically constrained (tethered) spin-around locator
First Claim
1. An enhanced distance and direction locator system, comprising:
- an electronic tag including an RF transponder operative to coherently send and receive complex signal sequences in response to interrogations from an electronic locator unit;
an electronic locator unit including an antenna and an RF transmitter and receiver operative to send and receive complex signal sequences to and from the tag through the antenna;
a tether having a length;
wherein the locator antenna spins on the tether in response to an applied force so as to approximate a continuous, circular path having a nominal radius;
a processor at the locator unit operative to perform the following correlation and post-correlation beam-steering functions;
receive successive complex signal sequences from the tag;
calculate complex circular correlation functions of the successively received complex signal sequences with respect to a reference signal to generate a set of correlation results as the antenna rotates,determine time delays and phase rotations associated with the successively received complex signal sequences based upon the set of correlation results,use the rotating antenna as a virtual circular phased array antenna by performing time alignment and summation of the correlation results that are geometrically consistent with a set of target azimuth values,define a peak trial azimuth position as the greatest coherent summed correlation result;
identify a peak trial azimuth position as tag direction, anddetermining tag distance as the round-trip time delay divided by twice the speed of light plus the tether length.
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Accused Products
Abstract
An improved two-way tagging tracking and locating system uses time of arrival (TOA), Doppler, and angle of arrival (AOA) in conjunction with remote tags and a locator. The locator'"'"'s antenna is tethered to a central point, and moved in a constrained motion so that it describes a roughly circular horizontal path. The locator transmits and receives sets of complex radio sequences to/from the tag(s) so that the tag(s) emit signals which are phase, chip, and symbol coherent with the received locator signals. This enables the locator to determine the distances and Doppler shifts between itself and the tag(s) at various positions in its path such that, by post correlation processing of complex captured signal sequences, aims a virtual phased array antenna at the tag(s), resulting in enhanced distance and direction measurements. The angular position of the orbiting locator'"'"'s antenna may be measured using an electronic compass packaged with the antenna.
8 Citations
20 Claims
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1. An enhanced distance and direction locator system, comprising:
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an electronic tag including an RF transponder operative to coherently send and receive complex signal sequences in response to interrogations from an electronic locator unit; an electronic locator unit including an antenna and an RF transmitter and receiver operative to send and receive complex signal sequences to and from the tag through the antenna; a tether having a length; wherein the locator antenna spins on the tether in response to an applied force so as to approximate a continuous, circular path having a nominal radius; a processor at the locator unit operative to perform the following correlation and post-correlation beam-steering functions; receive successive complex signal sequences from the tag; calculate complex circular correlation functions of the successively received complex signal sequences with respect to a reference signal to generate a set of correlation results as the antenna rotates, determine time delays and phase rotations associated with the successively received complex signal sequences based upon the set of correlation results, use the rotating antenna as a virtual circular phased array antenna by performing time alignment and summation of the correlation results that are geometrically consistent with a set of target azimuth values, define a peak trial azimuth position as the greatest coherent summed correlation result; identify a peak trial azimuth position as tag direction, and determining tag distance as the round-trip time delay divided by twice the speed of light plus the tether length. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification