ADS-B RECEIVER SYSTEM WITH MULTIPATH MITIGATION
First Claim
1. A method comprising:
- at a plurality of receivers,receiving a plurality of signals from a plurality of diversity antennas;
at a device in communication with the plurality of receivers,simultaneously processing the plurality of signals to detect the reception of an ADS-B message in the presence of short delay and long delay multipath signals to produce a signal that is free of interference from the short delay multipath signals;
removing interference from the long delay multipath signals from the produced signal; and
outputting an ADS-B message based on the produced signal that is free of short delay interference signals with the removed interference from long delay multipath signals.
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Accused Products
Abstract
Systems and methods for receiving ADS-B messages in environments where multipath propagation corrupts the messages or blocks the reception of the messages. An exemplary system combines RF signal processing and digital signal processing techniques to make it possible to receive ADS-B messages in the presence of multipath reflections from nearby structures and/or farther out structures. The system uses an array of horizontally spaced antennas. The RF signals from the antennas are combined by the receiver so as to form a set of beams with different azimuth antenna patterns to increase the probability that the multipath does not combine destructively with the line-of-sight path in at least one of the beams. This effectively removes multipath reflections where the delay of the multipath relative to the line-of-sight path is less than 100-200 nanoseconds. The system is also configured to remove multipath reflections with greater delays relative to the line-of-sight path.
36 Citations
19 Claims
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1. A method comprising:
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at a plurality of receivers, receiving a plurality of signals from a plurality of diversity antennas; at a device in communication with the plurality of receivers, simultaneously processing the plurality of signals to detect the reception of an ADS-B message in the presence of short delay and long delay multipath signals to produce a signal that is free of interference from the short delay multipath signals; removing interference from the long delay multipath signals from the produced signal; and outputting an ADS-B message based on the produced signal that is free of short delay interference signals with the removed interference from long delay multipath signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system comprising:
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a plurality of diversity antennas configured to receive a plurality of signals; a plurality of receivers configured to receive the plurality of signals from the plurality of diversity antennas; a device in communication with the plurality of receivers, the device configured to; simultaneously process the plurality of signals to detect the reception of an ADS-B message in the presence of short delay and long delay multipath signals to produce a signal that is free of interference from the short delay multipath signals; remove interference from the long delay multipath signals from the produced signal; and output an ADS-B message based on the produced signal that is free of short delay interference signals with the removed interference from long delay multipath signals. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A system comprising:
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a means for receiving a plurality of signals from a plurality of diversity antennas, wherein the diversity antennas are at least one of spaced horizontally on a vehicle by a plurality of ADS-B signal wavelengths or each of the diversity antennas produces a different azimuth antenna pattern; and a means for simultaneously processing the plurality of signals to detect the reception of an ADS-B message in the presence of short delay and long delay multipath signals to produce a signal that is free of interference from the short delay multipath signals; removing interference from the long delay multipath signals from the produced signal; and outputting an ADS-B message based on the produced signal that is free of short delay interference signals with the removed interference from long delay multipath signals.
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Specification