Pilot warning system
First Claim
1. A system to alert the pilot of an aircraft of a collision threat and of the direction in which to look for that threat, said system comprising:
- (a) antenna means to receive, directly from a source, pulse signals that are on a carrier having a certain wavelength λ and
were transmitted from a source located at a certain direction from the antenna means, the antenna means comprising a ground plane and a first element extending from the ground plane by a distance giving the first element an effective length of the first antenna means having first and second modes of operation characterized, respectively, by first and second directivity conditions resulting in a first gain for signals from said certain direction when the antenna means is in the first mode and a second gain for signals from said certain direction when the antenna means is in the second mode;
(b) receiving means comprising an input circuit connected to the antenna means to receive the pulse signals therefrom to produce a first response to the signals received when the antenna means is in the first mode and a second response to the signals received when the antenna is in the second mode; and
(c) first analytical means associated with the receiving means to make a comparison between the first and second responses and to produce an angle-indicating signal based on the comparison;
(d) second antenna means to receive the pulse signals directly from the source, the second antenna means being connected to the receiving means, one of the antenna means being on an upper surface of the aircraft and the other antenna means on a lower surface of the aircraft directly below the one antenna means; and
(e) second analytical means associated with the receiving means to compare the relative times of arrival of the signals at the first and second antenna means to determine the altitude of the source relative to the altitude of the aircraft.
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Accused Products
Abstract
This invention relates to a system to alert an aircraft pilot of the presence and general location of other aircraft that might constitute a collision threat to the pilot'"'"'s aircraft. A first and second antenna on the upper paid lower surfaces of the aircraft each operate in first and second modes characterized by respective first and second directivity conditions. The first and second antennas directly receive pulse signals from a source in order to determine the relative time of arrivals and thus the relative altitude of the source to the aircraft. Analysis means compares amplitudes of responses in the first and second modes to provide an angle indicating signal without having to generate radio signals other than those already being generated by equipment in the other aircraft in response to ground ATC interrogation.
57 Citations
54 Claims
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1. A system to alert the pilot of an aircraft of a collision threat and of the direction in which to look for that threat, said system comprising:
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(a) antenna means to receive, directly from a source, pulse signals that are on a carrier having a certain wavelength λ and
were transmitted from a source located at a certain direction from the antenna means, the antenna means comprising a ground plane and a first element extending from the ground plane by a distance giving the first element an effective length of the first antenna means having first and second modes of operation characterized, respectively, by first and second directivity conditions resulting in a first gain for signals from said certain direction when the antenna means is in the first mode and a second gain for signals from said certain direction when the antenna means is in the second mode;(b) receiving means comprising an input circuit connected to the antenna means to receive the pulse signals therefrom to produce a first response to the signals received when the antenna means is in the first mode and a second response to the signals received when the antenna is in the second mode; and (c) first analytical means associated with the receiving means to make a comparison between the first and second responses and to produce an angle-indicating signal based on the comparison; (d) second antenna means to receive the pulse signals directly from the source, the second antenna means being connected to the receiving means, one of the antenna means being on an upper surface of the aircraft and the other antenna means on a lower surface of the aircraft directly below the one antenna means; and (e) second analytical means associated with the receiving means to compare the relative times of arrival of the signals at the first and second antenna means to determine the altitude of the source relative to the altitude of the aircraft. - 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, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. The method of determining, in an aircraft that has first and second vertically spaced antenna means, the location of a pulse signal source relative to the aircraft, the first antenna means being characterized by first and second modes of directivity, said method comprising the steps of:
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(a) receiving at least a first part of the pulse signal directly from the source by way of the first antenna means and with the first antenna means in the first mode; (b) receiving at least said first part of the pulse signal directly from the source by way of the second antenna means; (c) comparing the time of arrival of the first part of the pulse signal by way of the first antenna means with the time of arrival of the same first part of the pulse signal by way of the second antenna means to produce relative altitude information indicating, from the compared times of arrival, whether or not the source is within a predetermined range of altitudes relative to the altitude of the aircraft; (e) switching the first antenna means from the first mode to the second mode; (f) receiving a second part of the pulse signal with the first antenna means in the second mode; (g) comparing a ratio of one of the parts to the other part with a table of entries of such ratios, each entry being correlated with a direction; and (h) generating a direction-indicating signal according to the entry that corresponds to the ratio of one of the first and second parts to the other of the first and second parts. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49)
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41. The method of claim '"'"'in which the first mode is omnidirectional and the second mode is directional.
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50. In a system to alert a pilot flying in a first aircraft to the presence of a second aircraft when radio signals in response to radar interrogation are being transmitted from the second aircraft on a standard response frequency and in the form of at least first and second pulses, each having a standard waveform and a predetermined time between leading edges of each of the pulses, the invention comprising:
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(a) antenna means on the first aircraft, said antenna means comprising; (i) a conductive ground plane, (ii) a parasitic antenna element having an effective length of about at the standard frequency and extending perpendicularly to the ground plane and having a location on it coplanar with the ground plane, (iii) a plurality n of antenna elements, each having an effective length of about at the standard frequency and being angularly spaced apart around the parasitic element and being located at a distance of about to about from the parasitic element; (b) receiving circuit means comprising n input sections, each connected to a respective one of the antenna elements and tuned to receive the signals from the second aircraft; (c) controllable short-circuiting means connected in series between the ground plane and said one end of the parasitic element to short-circuit said one end to the ground plane when the short-circuit means is actuated; and (d) control means connecting the receiving circuit means to the controllable short-circuiting means to actuate the short-circuiting means at a predetermined time after the start of one of the pulses. - View Dependent Claims (51, 52, 53)
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54. In a system to alert a pilot flying in a first aircraft to the presence of a second aircraft when radio signals in response to radar interrogation are being transmitted from the second aircraft on a standard response frequency and in the form of at least first and second pulses, each having a standard waveform and a predetermined time between the leading edges of the pulses, the invention comprising:
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(a) antenna means on the first aircraft, said antenna means comprising; (i) a conductive ground plane, (ii) a parasitic antenna element having an effective length of at the standard frequency and extending perpendicularly to the ground plane and having one end of the effective length substantially coplanar with the ground plane, (iii) four antenna elements, each having a length of at the standard frequency and being spaced 90°
apart around the parasitic element and being located at a distance of from the parasitic element;(b) receiving circuit means comprising four input sections and an output section, each of the input sections being connected to a respective one of the antenna elements and tuned to receive the signals received by that element; (c) controllable short-circuiting means connected to the output section to be actuated by a signal therefrom in response to the radio signals transmitted from the second aircraft and received by any of the antenna elements, the short-circuiting means being connected in series between the ground plane and said one end of the effective length of the parasitic element to short-circuit said one end to the ground plane when the short-circuit means is actuated; and (d) means connecting the output section of the receiving circuit means to the controllable short-circuiting means to actuate the short-circuiting means at a predetermined time after the start of one of the pulses.
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Specification