Air-traffic regulating systems

Claim 2

In an air-traffic-control system which (1) comprises an aircraft with a secondary radar beacon, having (1a) means for giving secondary radar returns in response to interrogations, and (1b) auxiliary measuring means for measuring a heading-related air-derivable quantity, and (1c) reporter means for emitting a stream of reports representing a succession of such measurements, and which (2) comprises a ground-based control equipment, having (2a) a secondary radar for periodically interrogating said beacon and receiving its returns, and (2b) tracking means for deriving from said returns a succession of noisy fixes on said aircraft, and (2c) report-handling means for receiving said reports and deriving therefrom a stream of heading-related auxiliary values, and (2d) predicting means to compute for said aircraft a position extrapolated (on the basis of said fixes and said auxiliary values and other information) to a future time, the improvement defined by the following characteristics: I. that said auxiliary measuring means comprise a modest-cost heading-variation sensor capable of usefully sensing only shorter-term variations of the aircraft''s heading rather than its absolute heading, II. that said reporting means consist of means for emitting (as said stream of reports) reports derived solely from said sensor, III. that due to the source from which they are derived (recited just above) said stream of reports has substantial information content re variations of heading but negligible information content re absolute flight-heading IV. that said control equipment also has IVA. means for storing a first string of data representing an extensive but limited sequence of said fixes spanning a specific time interval, and IVB. means for storing a second string of data representing an extensive but limited sequence of said auxiliary values covering approximately the same time interval, V. that said predicting means comprise means for applying to said computation all the more significant ones of said stored first string of data and all the more significant ones of said second string of data.

Claim 3

In a system according to claim 1 the improvement according to claim 1 further limited by the requirement that ''''the more significant ones of said stored first string'''' shall in every case include at least the data representing the first and last fixes of said limited sequence of fixes and the data representing a few last ones of said fixes, and by the further requirement that ''''the more significant data of said stored second string'''' shall in every case include at least the data necessary to represent the overall heading change during said time interval.

Claim 4

In an air-traffic-control system which (1) comprises an aircraft with a secondary radar beacon, having (1a) means for giving secondary radar returns in response to interrogations, and (1b) auxiliary measuring means for measuring a heading-related air-derivable quantity, and (1c) reporter means for emitting a stream of reports representing a succession of such measurements, and which (2) comprises a ground-based control equipment, having (2a) a secondary radar for periodically interrogating said beacon and receiving its returns, and (2b) tracking means for deriving from said returns a succession of noisy fixes on said aircraft, and (2c) report-handling means for receiving said reports and deriving therefrom a stream of heading-related auxiliary values, and (2d) predicting means to compute for said aircraft a position extrapolated (on the basis of said fixes aNd said auxiliary values and other information) to a future time, the improvement defined by the following characteristics: I. that said auxiliary measuring means comprise a modest-cost heading-variation sensor capable of usefully sensing only shorter-term variations of the aircraft''s heading rather than its absolute heading, II. that said reporter means consist of means for emitting (as said stream of reports) reports derived solely from said sensor in an effectively filtered form with an effective delay of D seconds, III. that due to the source from which they are derived (recited just above) said stream of reports has substantial information content re variations of heading but negligible information content re absolute flight-heading IV. that said control equipment also has IVA. means for storing a first string of data representing an extensive but limited sequence of said fixes spanning a specific time interval, and IVB. means for storing a second string of data representing an extensive but limited sequence of said auxiliary means covering approximately the same time interval, V. that said predicting means comprise VA. computation means effectively applying to the estimation of latest flight-heading an ''''important'''' fraction of all the following available information content: VAa. the information content re mean absolute flight-heading averaged over said time interval which is inherent in said first string of data, VAb. the information content re the angular relations between the headings existing at different instants within said specific time interval which is inherent in said second string of data VB. the criterion of importance of the effectively applied fraction being that the resulting estimated latest flight-heading pass the following two tests: VBa. the fix-noise-attributable uncertainty in such estimated latest flight-heading shall be comparable with that of an ideal mean heading optimally derived from all the fixes represented by said first string of data. VBb. the departure from perfect currency of such estimated latest flight-heading shall be closely comparable with D seconds VC. and also comprise means for predicting the aircraft''s future position based on said estimated latest flight-heading, and on a present position derived from at least the last two of said sequence of fixes, and on other information.

Claim 5

In an air-traffic-control system which (1) comprises an aircraft with a secondary radar beacon, having (1a) means for giving secondary radar returns in response to interrogations, and (1b) auxiliary measuring means for measuring a heading-related air-derivable quantity, and (1c) reporter means for emitting a stream of reports representing a succession of such measurements, and which (2) comprises a ground-based control equipment, having (2a) a secondary radar for periodically interrogating said beacon and receiving its returns, and (2b) tracking means for deriving from said returns a succession of noisy fixes on said aircraft, and (2c) report-handling means for receiving said reports and deriving therefrom a stream of heading-related auxiliary values, and (2d) predicting means to compute for said aircraft a position extrapolated (on the basis of said fixes aNd said auxiliary values and other information) to a future time, the improvement defined by the following characteristics: I. that said auxiliary measuring means comprise a modest-cost heading-variation sensor capable of usefully sensing only shorter-term variations of the aircraft''s heading rather than its absolute heading, II. that said reporter means consist of means for emitting (as said stream of reports) reports derived solely from said sensor in an effectively filtered form with an effective delay of D seconds, III. that due to the source from which they are derived (recited just above) said stream of reports has substantial information content re variations of heading but negligible information content re absolute flight-heading IV. that said control equipment also has IVA. means for storing a first string of data representing an extensive but limited sequence of said fixes spanning a specific time interval, and IVB. means for storing a second string of data representing an extensive but limited sequence of said auxiliary means covering approximately the same time interval, V. that said predicting means comprise VA. computation means effectively applying to the estimation of latest flight-heading an ''''important'''' fraction of all the following available information content: VAa. the information content re mean absolute flight-heading averaged over said time interval which is inherent in said first string of data, VAb. the information content re the angular relations between the headings existing at different instants within said specific time interval which is inherent in said second string of data VB. the criterion of importance of the effectively applied fraction being that the resulting estimated latest flight-heading pass the following two tests: VBa. the fix-noise-attributable uncertainty in such estimated latest flight-heading shall be comparable with that of an ideal mean heading optimally derived from all the fixes represented by said first string of data. VBb. the departure from perfect currency of such estimated latest flight-heading shall be closely comparable with D seconds VC. and also comprise means for predicting the aircraft''s future position based on said estimated latest flight-heading, and on a present position derived from at least the last two of said sequence of fixes, and on other information.

Claim 6

In an air-traffic-control system with (1) comprises an aircraft with a secondary radar beacon, having (1a) means for giving secondary radar returns in response to interrogatons, and (1b) auxiliary measuring means for measuring a heading-related air-derivable quantity, and (1c) reporter means for emitting a stream of reports representing a succession of such measurements, and which (2) comprises a ground-based control equipment, having (2a) a secondary radar for periodically interrogating said beacon and receiving its returns, and (2b) tracking means for deriving from said returns a succession of noisy fixes on said aircraft, and (2c) report-handling means for receiving said reports and deriving therefrom a stream of heading-related auxiliary values, and (2d) predicting means to compute for said aircraft a position extrapolated (on the basis of said fixes and said auxiliary values and other information) to a future time F seconds after the latest of said fixes, The improvement defined by the following characteristics: I. that said auxiliary measuring means comprise a modest-cost heading-variation sensor capable of usefully sensing only shorter-term variations of the aircraft''s heading rather than its absolute heading, II. that said reporting means consist of means for emitting (as said stream of reports) reports derived solely from said sensor in an effectively filtered form with an effective delay of D seconds, III. that due to the source from Which they are derived (reciated just above) said stream of reports has substantial information content re variations of heading but negligible information content re absolute flight-heading IV. that said control equipment also has IVA. means for storing a first string of data representing an extensive but limited sequence of said fixes spanning a specific time interval, and IVB. means for storing a second string of data representing an extensive but limited sequence of said auxiliary values covering approximately the same time interval, V. that said predicting means for computing a position extrapolated on the basis of said fixes and said auxiliary values) comprise VA. computation means effectively applying to the estimation of said extrapolated position an ''''important'''' fraction of all the following available information content: VAa. the information content re absolute mean flight-heading (averaged over said time interval) which is inheret in said first string of stored data, VAb. the information content re angular relation between changing headings over said time interval which is inherent in said second string of stored data, VAc. the information content re recent aircraft position which is inherent in an average of at least the last three of said fixes, VB. the criterion of ''''importance'''' of the effectively applied fraction being that the resulting extrapolated position shall pass the following two tests (VBa and VBb): VBa. that the fix-noise-attributable uncertainty of the extrapolated position shall be comparable with the sum of VBa1. the uncertainty (in radians) of an ideal mean heading (optimally derived from all the fixes of said sequence) multiplied by the distance flown by the aircraft in F seconds plus VBa2. the position uncertainty of an average of three fixes VBb. that in the absence of such fix noise the error in the extrapolated position due to the aircraft''s recent turn rate shall be closely comparable to that which would result from a final flight-heading error of the following value VBb1. D times the aircraft''s mean turn-rate averaged over the last D seconds.

Claim 7

In an air-traffic-control system with (1) comprises an aircraft with a secondary radar beacon, having (1a) means for giving secondary radar returns in response to interrogatons, and (1b) auxiliary measuring means for measuring a heading-related air-derivable quantity, and (1c) reporter means for emitting a stream of reports representing a succession of such measurements, and which (2) comprises a ground-based control equipment, having (2a) a secondary radar for periodically interrogating said beacon and receiving its returns, and (2b) tracking means for deriving from said returns a succession of noisy fixes on said aircraft, and (2c) report-handling means for receiving said reports and deriving therefrom a stream of heading-related auxiliary values, and (2d) predicting means to compute for said aircraft a position extrapolated (on the basis of said fixes and said auxiliary values and other information) to a future time F seconds after the latest of said fixes, The improvement defined by the following characteristics: I. that said auxiliary measuring means comprise a modest-cost heading-variation sensor capable of usefully sensing only shorter-term variations of the aircraft''s heading rather than its absolute heading, II. that said reporting means consist of means for emitting (as said stream of reports) reports derived solely from said sensor in an effectively filtered form with an effective delay of D seconds, III. that due to the source from Which they are derived (reciated just above) said stream of reports has substantial information content re variations of heading but negligible information content re absolute flight-heading IV. that said control equipment also has IVA. means for storing a first string of data representing an extensive but limited sequence of said fixes spanning a specific time interval, and IVB. means for storing a second string of data representing an extensive but limited sequence of said auxiliary values covering approximately the same time interval, V. that said predicting means for computing a position extrapolated on the basis of said fixes and said auxiliary values) comprise VA. computation means effectively applying to the estimation of said extrapolated position an ''''important'''' fraction of all the following available information content: VAa. the information content re absolute mean flight-heading (averaged over said time interval) which is inheret in said first string of stored data, VAb. the information content re angular relation between changing headings over said time interval which is inherent in said second string of stored data, VAc. the information content re recent aircraft position which is inherent in an average of at least the last three of said fixes, VB. the criterion of ''''importance'''' of the effectively applied fraction being that the resulting extrapolated position shall pass the following two tests (VBa and VBb): VBa. that the fix-noise-attributable uncertainty of the extrapolated position shall be comparable with the sum of VBa1. the uncertainty (in radians) of an ideal mean heading (optimally derived from all the fixes of said sequence) multiplied by the distance flown by the aircraft in F seconds plus VBa2. the position uncertainty of an average of three fixes VBb. that in the absence of such fix noise the error in the extrapolated position due to the aircraft''s recent turn rate shall be closely comparable to that which would result from a final flight-heading error of the following value VBb1. D times the aircraft''s mean turn-rate averaged over the last D seconds.