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Accuracy limitations of range-range (spherical) multilateration systems

October 11, 1973
  |
Technical Report
Author:
Harry B. Lee
Published in:
MIT Lincoln Laboratory Report TN-1973-43
Topic:
surveillance
R&D area:
R&D group:

Summary

This report presents a novel procedure for determining the accuracy of range-range (or spherical) multilateration systems. The procedure is a generalization of one previously described for hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of inertia matrix of a simple mass configuration. The insight afforded by this fact is used to resolve a number of questions relating to accuracy. Specific questions addressed include the following: 1. How does accuracy depend upon the number of receivers? 2. How does accuracy depend upon the deployment of receivers? 3. What is the maximum accuracy that can be obtained from N receivers? How should the receivers be deployed to maximize accuracy? 4. How do altitude errors compare to horizontal errors in satellite-based systems? In ground-based systems?
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Summary

This report presents a novel procedure for determining the accuracy of range-range (or spherical) multilateration systems. The procedure is a generalization of one previously described for hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of...

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Accuracy limitations of range-range (spherical) multilateration systems

An optimum interference detector for DABS monopulse data editing

September 26, 1973
  |
Technical Report
Author:
Robert J. McAulay
…
Published in:
MIT Lincoln Laboratory Report TN-1973-48
Topic:
air traffic control
R&D area:
R&D group:

Summary

In the application of the Discrete Address Beacon System (DABS) concept to Air Traffic Control (ATC) surveillance, estimates of aircraft position must be made using as few replies as possible, preferably one. This requires the use of monopulse techniques. Since the beacon system provides high signal-to-noise ratios (SNR), the fundamental limitation to direction finding (DF) performance is due to externally generated interference from multipath signals and from the present Air Traffic Control Radar Beacon System (ATCRBS). Since there are many bits in any one DABS reply it should be possible to generate an accurate azimuth estimate if those that bear interference could be detected and deleted from the sample. In this report, the generalized likelihood ratio test is used to derive an optimum interference statistic. The detector performance is then analyzed in detail with respect to its dependence on SNR, interference-to-signal ratio (ISR) and on the relative phase between the target and interfering signals. It is shown that good detection performance can be obtained if the phase difference between the target and interference signals are either in- or out-of-phase.
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Summary

In the application of the Discrete Address Beacon System (DABS) concept to Air Traffic Control (ATC) surveillance, estimates of aircraft position must be made using as few replies as possible, preferably one. This requires the use of monopulse techniques. Since the beacon system provides high signal-to-noise ratios (SNR), the fundamental...

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An optimum interference detector for DABS monopulse data editing

The effects of interference on monopulse performance

August 1, 1973
  |
Technical Report
Author:
Robert J. McAulay
Published in:
MIT Lincoln Laboratory Report TN-1973-30
Topic:
air traffic control
R&D area:
R&D group:

Summary

The first and second moments of the monopulse azimuth estimates are used to characterize the estimator performance in a background of mainbeam or sidelobe multipath or ATCRBS interference. An exact expression for the bias error is obtained that not only accounts for the bias due to targets separated in azimuth but also demonstrates the effect of fading or signal cancellation. For a target signal at a 20 dB signal-to-noise ratio, it is shown that the fading effect produces negligible bias unless the signal-to-interference ratio is between ±2.5 dB. A first order expression for the variance is obtained that demonstrates that an increase in the random error will occur due to the target separation in azimuth and due to signal fades. The exact nature of the bias and variance depend strongly on the relative phase between the target and interference signals with the poorest performance being obtained at the in- and out-of-phase conditions. It is knowledge of this behavior that is essential in evaluating the idea of azimuth estimation data editing.
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Summary

The first and second moments of the monopulse azimuth estimates are used to characterize the estimator performance in a background of mainbeam or sidelobe multipath or ATCRBS interference. An exact expression for the bias error is obtained that not only accounts for the bias due to targets separated in azimuth...

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The effects of interference on monopulse performance

Recent advances in air traffic control radars

June 26, 1973
  |
Conference Paper
Author:
Charles E. Muehe
Published in:
IEEE Northeast Electronic Research and Engineering Meeting, NEREM, 8 November 1973.
Topic:
air traffic control
R&D area:
R&D group:

Summary

This paper describes recent improvements in microwave radars used for air traffic control. These improvements have been designed to increase the target-to-clutter ratio so that adaptive thresholding can be used to give a very low false alarm rate and high probability of detection even when the aircraft target is in the presence of strong clutter. Studies show that detection suffers when three types of clutter returns are strong; namely, ground clutter, weather clutter or angels. Angels have been almost universally identified as bird flocks. Under certain terrain and propagation conditions, second-time-around clutter can also be a problem. Here ground returns from the second to last transmitted pulse are received from targets beyond the nonambiguous range. These may be from mountains or from the ground when anomalous propagation conditions occur. Meaningful improvements in this class of radar can be conveniently grouped as shown in Table I. We will briefly discuss each of the three classes listed.
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Summary

This paper describes recent improvements in microwave radars used for air traffic control. These improvements have been designed to increase the target-to-clutter ratio so that adaptive thresholding can be used to give a very low false alarm rate and high probability of detection even when the aircraft target is in...

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Recent advances in air traffic control radars

Dual lane runway study, final report

May 22, 1973
  |
Project Report
Author:
Victor S. Dolat
…
Published in:
MIT Lincoln Laboratory Report ATC-17
Topic:
air traffic control
R&D area:
R&D group:

Summary

The issues in the dual lane runway problem were investigated via computer real time (man in the loop) and fast time (no human input during the simulation run) simulations in order to identify a dual lane runway configuration and determine operation strategies. The real time experiments were conducted using experienced ATC controllers and a pilot to observe the situation at interactive graphics CRT displays. Headsets and microphones were utilized to permit the normal controller/pilot interchanges. Flight strips as used in control tower cabs were employed to further simulate controller workload. Based on information gained during early real time controller experiments, a programmed controller concept (fast time) was adopted. A series of dual lane runway computer simulation experiments were performed to investigate the pertinent dual lane issues: centerline spacing, arrival/departure preference, parallel taxiway, threshold stagger, and hiqh speed exits. In addition, time was spent analyzing operational high density airport terminal facilities. Airport administrative and operations personnel were interviewed to obtain their views on high density operations and the dual lane concept. Peak rush hour periods were sought out to detenTIine control strategies employed indirecting peak period traffic. Air crews utilizing these high density airport terminals were interviewed in the course of their operations into and out of these major hub airports.
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Summary

The issues in the dual lane runway problem were investigated via computer real time (man in the loop) and fast time (no human input during the simulation run) simulations in order to identify a dual lane runway configuration and determine operation strategies. The real time experiments were conducted using experienced...

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Dual lane runway study, final report

Accuracy limitations of hyperbolic multilateration systems

March 22, 1973
  |
Technical Report
Author:
Harry B. Lee
Published in:
MIT Lincoln Laboratory Report TN-1973-11
Topic:
air traffic control
R&D area:
R&D group:

Summary

This report is an analysis of the accuracy limitations of hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of inertia matrix of a simple mass configuration. The insight afforded by this fact is used to resolve a number of questions relating to accuracy. Specific questions addressed include the following. 1. How does accuracy depend upon the number of receivers? 2. How does accuracy depend upon the deployment of receivers? 3. What is the maximum accuracy that can be obtained from N receivers? How should the receivers be deployed to maximize accuracy? 4. How do altitude errors compare to horizontal errors in satellite based systems? In ground based systems? 5. How is accuracy impacted by dropout of any particular receiver?
READ LESS

Summary

This report is an analysis of the accuracy limitations of hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of inertia matrix of a simple mass configuration. The insight afforded by this fact is used to...

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Accuracy limitations of hyperbolic multilateration systems

Concepts for improvement of airport surveillance radars

February 26, 1973
  |
Project Report
Author:
Charles E. Muehe
…
Published in:
MIT Lincoln Laboratory Report ATC-14
Topic:
radar
R&D area:
R&D group:

Summary

This report reviews the performance of operational ASR's, discusses each type of clutter with which the target must compete, examines presently employed methods of overcoming clutter and several state-of-the-art techniques which have not found their way into the ASR's for one reason or another. It concludes by describing two radars, one at S-band and one at UHF, which are believed to come closest to fulfilling ASR requirements in advanced ARTS facilities. The major improvements in performance will be derived from the use of linear optimum signal processing. Further gains will be achieved through the use of adaptive thresholds. STC will combat bird clutter. The radar will incorporate proper shaping of the antenna pattern so that aircraft off the peak of the antenna elevation beam will not be at a disadvantage compared to moving clutter at the peak. The recommended radar concepts also include radial velocity determination by Doppler measurement. This should prove of value in maintaining target tracks and in discrimination against ground vehicles.
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Summary

This report reviews the performance of operational ASR's, discusses each type of clutter with which the target must compete, examines presently employed methods of overcoming clutter and several state-of-the-art techniques which have not found their way into the ASR's for one reason or another. It concludes by describing two radars...

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Concepts for improvement of airport surveillance radars

A high performance, low cost, air traffic control radar

February 15, 1973
  |
Technical Report
Author:
Charles E. Muehe
…
Published in:
MIT Lincoln Laboratory Report TN-1973-12
Topic:
air traffic control
R&D area:
R&D group:

Summary

Recent improvements in the technology of electronically switched antennas and digital signal processing make possible a relatively high performance, low cost, surveillance radar. The radar described employs an electronically step-scanned, cylindrical antenna together with an advanced digital signal processor to give superior MTI performance at an estimated cost of less than half the present S-band ASRs. The radar output consists of narrow band, digital target reports free of false alarms, suitable for transmission over telephone lines. Remote radar operation using digital, bright, scan-history displays becomes practical as does easy incorporation of beacon and direction finder outputs along with digitally generated video maps. The complete absence of moving parts, the low power transmitter and the largely solid-state construction will provide high reliability and low maintenance costs. These techniques are most easily and economically implemented in the UHF band, but a similar L-band radar can be designed with somewhat increased complexity and cost. The techniques and background studies employed in the design of the proposed radar evolved over a period of three or four years as a result of work for the Air Force under Contract F19628-73-C-0002. Some of these techniques are being applied to improve the MTI performance of the ASR under FAA Contract DOT-FA71WAI-242.
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Summary

Recent improvements in the technology of electronically switched antennas and digital signal processing make possible a relatively high performance, low cost, surveillance radar. The radar described employs an electronically step-scanned, cylindrical antenna together with an advanced digital signal processor to give superior MTI performance at an estimated cost of less...

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A high performance, low cost, air traffic control radar

A maximum-likelihood multiple-hypothesis testing algorithm, with an application to monopulse data editing

February 9, 1973
  |
Technical Report
Author:
Edward J. Kelly
Published in:
MIT Lincoln Laboratory Report TN-1973-7
Topic:
air traffic control
R&D area:
R&D group:

Summary

A simple algorithm for multiple-hypothesis testing, based on a generalization of likelihood ratio testing between pairs of hypotheses, is developed and applied to a specific problem. The problem arises in connection with an amplitude comparison monopulse system in an Air Traffic Control application. In particular, it is desired to measure target azimuth in a beacon system in the presence of interference and multipath. The multiple hypotheses relate to the presence or absence of a desired signal, with or without either of two kinds of interfering signal. The analysis leads to a new technique of data editing, or processing, to detect the presence of interference.
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Summary

A simple algorithm for multiple-hypothesis testing, based on a generalization of likelihood ratio testing between pairs of hypotheses, is developed and applied to a specific problem. The problem arises in connection with an amplitude comparison monopulse system in an Air Traffic Control application. In particular, it is desired to measure...

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A maximum-likelihood multiple-hypothesis testing algorithm, with an application to monopulse data editing

A decision-directed adaptive tracker

January 1, 1973
  |
Journal Article
Author:
Robert J. McAulay
…
Published in:
IEEE Trans. Aerosp. Electron. Syst., Vol. AEM-9, No. 2, March 1974, p. 229-236.
Topic:
air traffic control
R&D area:
R&D group:

Summary

In the design of a tracking filter for air traffic control (ATC) applications, a maneuvering aircraft can be modelled by a linear system with random noise accelerations. A Kalman filter tracker, designed on the basis of a variance chosen according to the distribution of the potential maneuver accelerations, will maintain track during maneuvers and provide some improvement in position accuracy. However, during those portions of the flight path where the aircraft is not maneuvering, the tracking accuracy will not be as good as if no acceleration noise had been allowed in the tracking filter. In this paper, statistical decision theory is used to derive an optimal test for detecting the aircraft maneuver: a more practical suboptimal test is then deduced from the optimal test. As long as no maneuver is declared, a simpler filter, based on a constant-velocity model, is used to track the aircraft. When a maneuver is detected, the tracker is reinitialized using stored data, up-dated to the present time, and then normal tracking is resumed as new data arrives. In essence, the tracker performs on the basis of a piecewise linear model in which the breakpoints are defined on-line using the maneuver detector. Simulation results show that there is a significant improvement in tracking capability using the decision-directed adaptive tracker.
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Summary

In the design of a tracking filter for air traffic control (ATC) applications, a maneuvering aircraft can be modelled by a linear system with random noise accelerations. A Kalman filter tracker, designed on the basis of a variance chosen according to the distribution of the potential maneuver accelerations, will maintain...

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A decision-directed adaptive tracker
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