TDOA/FDOA technique for locating a transmitter
First Claim
1. A process for locating a transmitter, said process comprising the steps of:
- receiving at a first receiver a signal transmitted by said transmitter;
analog to digital converting the signal received by said first receiver to yield a first digital signal;
compressing the first digital signal or another digital signal derived from said first digital signal;
receiving at a second receiver the signal transmitted by said transmitter, wherein there is relative motion between said first or second receiver and said transmitter;
analog to digital converting the signal received by said second receiver to yield a second digital signal;
transmitting the compressed signal to a cross-correlation unit local to said second receiver and coupled also to receive said second digital signal or another digital signal derived from said second digital signal;
using said cross-correlation unit to generate and solve a cross-correlation function based on said compressed signal and said second digital signal or other digital signal derived from said second digital signal; and
determining, locally to said first receiver, correction factors for the solution to the cross-correlation function, and transmitting said correction factors to a correction unit which applies said correction factors to the solution of said cross-correlation function.
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Accused Products
Abstract
A process for locating a transmitter in which the signal is received by first and second receivers and then processed by respective analog to digital converters and filtered to yield first and second digital signals. There is relative motion between at least one of the receivers and the transmitter. A compression process local to the first receiver compresses the first digital signal. The result of the compression process is transmitted to a cross-correlation unit which is local to the second receiver and coupled also to receive the second digital signal. Locally to the first receiver, correction factors for the solution to the cross-correlation function are determined and transmitted to a correction unit at the second receiver site which applies the correction factors to the solution of the cross-correlation function. The location of the transmitter is determined based on time difference of arrival and frequency difference of arrival results output from the correction unit. If there is no relative motion between the transmitter and any receiver, then three receivers are necessary to locate the transmitter. The outputs are analog to digital converted and filtered to yield first, second and third digital signals. A compression process at the first receiver site compresses the first digital signal. The compressed signal data is transmitted to convolution units local to the second and third receivers and convolved with the second and third digital signals, respectively. Then correction factors for both convolution units are determined local to the first receiver and transmitted to correction units at both the second and third receiver sites. The location of the transmitter is then determined based on two time difference of arrival results.
215 Citations
35 Claims
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1. A process for locating a transmitter, said process comprising the steps of:
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receiving at a first receiver a signal transmitted by said transmitter; analog to digital converting the signal received by said first receiver to yield a first digital signal; compressing the first digital signal or another digital signal derived from said first digital signal; receiving at a second receiver the signal transmitted by said transmitter, wherein there is relative motion between said first or second receiver and said transmitter; analog to digital converting the signal received by said second receiver to yield a second digital signal; transmitting the compressed signal to a cross-correlation unit local to said second receiver and coupled also to receive said second digital signal or another digital signal derived from said second digital signal; using said cross-correlation unit to generate and solve a cross-correlation function based on said compressed signal and said second digital signal or other digital signal derived from said second digital signal; and determining, locally to said first receiver, correction factors for the solution to the cross-correlation function, and transmitting said correction factors to a correction unit which applies said correction factors to the solution of said cross-correlation function. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A process for locating a transmitter, said process comprising the steps of:
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receiving at a first receiver a signal transmitted by said transmitter; analog to digital converting the signal received by said first receiver to yield a first digital signal; compressing said first digital signal or another digital signal derived from said first digital signal; receiving at a second receiver the signal transmitted by said transmitter; analog to digital converting the signal received by said second receiver to yield a second digital signal; receiving at a third receiver a signal transmitted by said transmitter; analog to digital converting the signal received by said third receiver to yield a third digital signal; transmitting the compressed signal to a convolution unit local to said second receiver and convolving said compressed signal with said second digital signal or another digital signal derived from said second digital signal; transmitting said compressed signal to a convolution unit local to said third receiver and convolving said compressed signal with said third digital signal or another digital signal derived from said third digital signal; determining, locally to said first receiver, correction factors for the solution to both convolution units, transmitting said correction factors to a correction unit local to said second receiver which applies said correction factors to an output of the convolution unit local to said second receiver, and transmitting said correction factors to a correction unit local to said third receiver which applies said correction factors to an output of the convolution unit local to said third receiver. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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33. A system for locating a transmitter, said system comprising:
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a first receiver for receiving a signal transmitted by said transmitter; a first analog to digital converter for converting the signal received by said first receiver to yield a first digital signal; means for compressing the first digital signal or another digital signal derived from said first digital signal; a second receiver for receiving the signal transmitted by said transmitter, wherein there is relative motion between said first or second receiver and said transmitter; a second analog to digital converter for converting the signal received by said second receiver to yield a second digital signal; a cross-correlation unit local to said second receiver and coupled to receive said second digital signal or another digital signal derived from said second digital signal; means for transmitting the compressed signal to said cross-correlation unit, said cross-correlation unit generating and solving a cross-correlation function based on said compressed signal and said second digital signal or other distal signal derived from said second digital signal; a correction unit; and means for determining, locally to said first receiver, correction factors for the solution to the cross-correlation function, and transmitting said correction factors to said correction unit which applies said correction factors to the solution of said cross-correlation function. - View Dependent Claims (35)
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34. A system for locating a transmitter, said system comprising:
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a first receiver for receiving a signal transmitted by said transmitter; a first analog to digital converter for converting the signal received by said first receiver to yield a first digital signal; means for compressing said first digital signal or another digital signal derived from said first digital signal; a second receiver for receiving the signal transmitted by said transmitter; a second analog to digital converter for converting the signal received by said second receiver to yield a second digital signal; a third receiver for receiving a signal transmitted by said transmitter; a third analog to digital converter for converting the signal received by said third receiver to yield a third digital signal; a first convolution unit local to said second receiver; means for transmitting the compressed signal to said first convolution unit and convolving said compressed signal with said second digital signal or another digital signal derived from said second digital signal; a second convolution unit local to said third receiver; means for transmitting said compressed signal to said second convolution unit and convolving said compressed signal with said third digital signal or another digital signal derived from said third digital signal; a first correction unit local to said second receiver; a second correction unit local to said third receiver; means for determining, locally to said first receiver, correction factors for the solution to both convolution units, transmitting said correction factors to said first correction unit which applies said correction factors to an output of said first convolution unit and transmitting said correction factors to said second correction unit which applies said correction factors to an output of said second convolution unit.
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Specification