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| Speech communication apparatus having an echo canceler |
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| Method of and device for echo cancellation |
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| Acoustical echo canceller having an adaptive filter with passage into the frequency domain |
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| Method and apparatus for equallization in an asymmetric digital aubscriber line communications system |
| OF THE DRAWINGS Generally, the present invention provides an adaptive equalizer in an ADSL system ... |
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| Method and apparatus for inhibiting echo in a channel of a communication system |
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| Full-duplex speakerphone circuit including a control interface |
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| Frequency domain stereophonic acoustic echo canceller utilizing non-linear transformations |
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Method and apparatus for detecting, locating, and identifying microwave transmitters and receivers at distant locations
| Details |
Inventors: Holly, Sandor;
Assignee: The Boeing Company (Chicago, IL)
Primary Examiner: Sotomayor; John B.
Assistant Examiner:
Attorney, Agent or Firm: Alston & Bird LLP
Methods and apparatuses for detecting, locating, and identifying microwave transmitters and receivers at distant locations are disclosed. First and second electromagnetic beams at first and second frequencies, respectively, are transmitted in first and second directions. The second frequency is offset from the first frequency to define an interference difference frequency. As such, the first and second electromagnetic beams interfere at a far field distance corresponding to an intersection of the first and second electromagnetic beams. In the far field the beams interfere with microwave devices that reradiate a return radiation at the difference frequency. The methods and apparatuses detect the return radiation at the difference frequency, such as by way of a receiver, and locate the interference zone to determine the location of the microwave device, such as by a processor. |
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DETAILED DESCRIPTION That which is claimed: 1.
A method of detecting, locating, and identifying at least one of microwave transmitters or microwave receivers at a distant location, comprising: transmitting a first electromagnetic beam at a first frequency and in a first direction; transmitting a second electromagnetic beam at a second frequency and in a second direction, wherein the second frequency is offset from the first frequency to define an interference difference frequency, and the first and second electromagnetic beams interfere at a far field distance corresponding to an intersection of the first and second electromagnetic beams; detecting a return radiation at the difference frequency produced by interference with a microwave device in the intersection, locating the interference zone to determine the location of the microwave device; and identifying the microwave device according to the return radiation at the difference frequency.
2.
The method according to claim 1, wherein the step of locating comprises locating the interference zone azimuthally based upon the direction of at least one of the first or second directions.
3.
The method according to claim 1, wherein the step of locating comprises locating the interference zone based upon triangulation of the first and second directions.
4.
The method according to claim 1, wherein the step of identifying the microwave device comprises determining a cut-off frequency from the return radiation at the difference frequency.
5.
The method according to claim 4, further comprising comparing the cut-off frequency with cut-off frequencies of microwave devices to determine the type of microwave device.
6.
The method according to claim 1, wherein the step of identifying the microwave device comprises spectrally analyzing the return radiation at the difference frequency.
7.
The method according to claim 6, further comprising comparing the spectral analysis to characteristics of other microwave devices to determine the type of microwave device
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Telecommunications 
