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 transmitter position information and transmitter motion information, wherein the transmitter motion information includes at least one of a velocity and an acceleration of the transmitter;
receiving the reference beacon signal at a plurality of collection platforms;
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 transmitter position information contained in the reference beacon signal;
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;
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 transmitter 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.
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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.
14 Citations
17 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 transmitter position information and transmitter motion information, wherein the transmitter motion information includes at least one of a velocity and an acceleration of the transmitter; receiving the reference beacon signal at a plurality of collection platforms; 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 transmitter position information contained in the reference beacon signal; 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; 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 transmitter 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 (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification