Reference beacon methods and apparatus for TDOA/FDOA geolocation
First Claim
1. A method of determining bias error in a geolocation system, comprising:
- transmitting from a transmitter a reference beacon signal containing position information including at least one of a position of the transmitter at a time of fix and an estimate of the position of the transmitter at a time of trans mission of the reference beacon signal, wherein the reference beacon signal contains motion information relating to the transmitter;
receiving the reference beacon signal at a plurality of collection platforms;
determining a position measurement of the transmitter based on at least one of a time of arrival and a frequency of arrival of the reference beacon signal at the plurality of collection platforms;
determining a first bias error based on the position measurement of the transmitter and the position information contained in the reference beacon signal;
determining a velocity measurement of the transmitter based on a frequency of arrival of the reference beacon signal at each of the plurality of collection platforms; and
determining a second bias error based on the velocity measurement of the transmitter and the motion information contained in the reference beacon signal.
1 Assignment
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Accused Products
Abstract
A method and apparatus for estimating bias errors in a time-difference-of-arrival/frequency-difference-of-arrival (TDOA/FDOA) geolocation system using a reference signal transmitter in which position and/or motion information of the reference signal transmitter is encoded into the reference signal. The motion information may include the velocity and/or acceleration of the reference signal transmitter. The reference signal is received by multiple collection platforms operating in conjunction with a geolocation system and a reference correction processing system. The reference correction processing system receives, via the multiple collection platforms, the position and/or motion information, which is immediately and unambiguously associated with specific reference signal transmissions. The geolocation system estimates the position and/or velocity of the reference signal transmitter using conventional TDOA/FDOA techniques. The estimated position and/or velocity of the reference signal transmitter is compared to the information contained in the reference signal to estimate bias errors.
20 Citations
37 Claims
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1. A method of determining bias error in a geolocation system, comprising:
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transmitting from a transmitter a reference beacon signal containing position information including at least one of a position of the transmitter at a time of fix and an estimate of the position of the transmitter at a time of trans mission of the reference beacon signal, wherein the reference beacon signal contains motion information relating to the transmitter; receiving the reference beacon signal at a plurality of collection platforms; determining a position measurement of the transmitter based on at least one of a time of arrival and a frequency of arrival of the reference beacon signal at the plurality of collection platforms; determining a first bias error based on the position measurement of the transmitter and the position information contained in the reference beacon signal; determining a velocity measurement of the transmitter based on a frequency of arrival of the reference beacon signal at each of the plurality of collection platforms; and determining a second bias error based on the velocity measurement of the transmitter and the motion information contained in the reference beacon signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of determining bias error in a geolocation system, comprising:
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transmitting from a transmitter a reference beacon signal containing position information including at least one of a position of the transmitter at a time of fix and an estimate of the position of the transmitter at a time of transmission of the reference beacon signal; receiving the reference beacon signal at a plurality of collection platforms; determining a position measurement of the transmitter based on at least one of a time of arrival and a frequency of arrival of the reference beacon signal at the plurality of collection platforms; determining a first bias error based on the position measurement of the transmitter and the position information contained in the reference beacon signal; measuring a time of arrival of the reference beacon signal at each of the plurality of collection platforms; determining an expected difference between the times of arrival of the reference beacon signal at two of the plurality of collection platforms based on the position information contained in the reference beacon signal; and determining a timing bias error based on the measured times of arrival of the reference beacon signal at the two collection platforms and the expected difference between the times of arrival of the reference beacon signal at the two collection platforms. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A method of determining bias error in a geolocation system, comprising:
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transmitting from a transmitter a reference beacon signal containing position information including at least one of a position of the transmitter at a time of fix and an estimate of the position of the transmitter at a time of transmission of the reference beacon signal, wherein the reference beacon signal contains motion information relating to the transmitter; receiving the reference beacon signal at a plurality of collection platforms; determining a position measurement of the transmitter based on at least one of a time of arrival and a frequency of arrival of the reference beacon signal at the plurality of collection platforms; determining a first bias error based on the position measurement of the transmitter and the position information contained in the reference beacon signal; measuring a frequency of arrival of the reference beacon signal at each of the plurality of collection platforms; determining an expected frequency difference of arrival of the reference beacon signal at the plurality of collection platforms based on the motion information contained in the reference beacon signal; and determining a frequency bias error based on the measured frequency of arrival of the reference beacon signal at each of the plurality of collection platforms and the expected frequency difference of arrival of the reference beacon signal at the plurality of collection platforms. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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33. A method of determining bias error in a geolocation system, comprising:
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transmitting from a transmitter a reference beacon signal containing position information including at least one of a position of the transmitter at a time of fix and an estimate of the position of the transmitter at a time of transmission of the reference beacon signal; receiving the reference beacon signal at a plurality of collection platforms; determing a position measurement of the transmitter based on at least one of a time of arrival and a frequency of arrival of the reference beacon signal at the plurality of collection platforms determining a first bias error based on the position measurement of the transmitter and the position information contained in the reference beacon signal; measuring a frequency of arrival of the reference beacon signal at each of the plurality of collection platforms; determining an expected frequency difference of arrival of the reference beacon signal at the plurality of collection platforms based on the position information contained in the reference beacon signal; and determining a frequency bias error based on the measured frequency of arrival of the reference beacon signal at each of the plurality of collection platforms and the expected frequency difference of arrival of the reference beacon signal at the plurality of collection platforms. - View Dependent Claims (34, 35, 36, 37)
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Specification