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Mode S installation and siting criteria

September 13, 1982
  |
Project Report
Author:
Ronald G. Sandholm
Published in:
MIT Lincoln Laboratory Report ATC-99,REV.A
Topic:
mode S data links
R&D area:
R&D group:

Summary

This paper provides information on site-associated phenomena that affect the proper operation of a Mode S sensor and therefore warrant serious consideration when siting a sensor. The Mode S related discussion is intended to be a supplement to the ATCRBS siting criteria presented in the FAA Primary/Secondary Terminal Radar Siting Handbook. The paper discusses siting criteria as they relate to the Mode S sensor antenna system, as opposed to the ATCRBS hogtrough antenna, and importantly, addresses those characteristics of the surrounding environment that are crucial to proper Mode S surveillance.
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Summary

This paper provides information on site-associated phenomena that affect the proper operation of a Mode S sensor and therefore warrant serious consideration when siting a sensor. The Mode S related discussion is intended to be a supplement to the ATCRBS siting criteria presented in the FAA Primary/Secondary Terminal Radar Siting...

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Mode S installation and siting criteria

The AMPS computer system: design and operation

September 9, 1982
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Project Report
Author:
Jeffrey L. Gertz
…
Published in:
MIT Lincoln Laboratory Report ATC-110
Topic:
surveillance
R&D area:
R&D group:

Summary

The Lincoln Laboratory Air Traffic Control Radar Beacon System (ATCRBS) Monopulse Processing System (AMPS) is a mobile, stand-alone, ATCRBS surveillance sensor for processing and disseminating target reports from transponder-equipped aircraft. AMPS is essentially the ATCRBS portion of the Mode Select Beacon System (Mode S), a system designed to be an evolutionary replacement for the present third generation ATCRBS. AMPS utilizes several new features introduced by the Mode S sensor concept. In particular, the use of monopulse angle estimation permits more accurate aircraft azimuth estimation with fewer replies per scan, and improved decoding (identification) performance when garble is present. This report provides a description of the details and philosophy of the AMPS computer system implementation and operation. In particular, specific and detailed descriptions of the interrelations between AMPS's several subsystems and subtasks are provided as well as a guide on how to run them.
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Summary

The Lincoln Laboratory Air Traffic Control Radar Beacon System (ATCRBS) Monopulse Processing System (AMPS) is a mobile, stand-alone, ATCRBS surveillance sensor for processing and disseminating target reports from transponder-equipped aircraft. AMPS is essentially the ATCRBS portion of the Mode Select Beacon System (Mode S), a system designed to be an...

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The AMPS computer system: design and operation

Implementation of 2-D digital filters by iterative methods

June 1, 1982
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Journal Article
Author:
Thomas F. Quatieri
…
Published in:
IEEE Trans. Acoust. Speech Signal Process., Vol. ASSP-30, No. 3, June 1982, pp. 473-87.
Topic:
signal processing
R&D area:
R&D group:

Summary

A two-dimensional (2-D) rational filter can be implemented by an iterative computation involving only finite-extent impulse response (FIR) filtering operations, provided a certain convergence criterion is met. In this paper, we generalize this procedure so that the convergence criterion is satisfied for any stable 2-D rational transfer function. One formulation which guarantees convergence invokes a relaxed form of the iterative computation along with prefiltering the numerator and denominator polynomials of the rational transfer function. This implementation may be applied with a frequency-varying relaxation parameter for increasing the rate of convergence. An alternative generalization uses several previously computed iterates, unlike our first modification which utilizes only the most recently computed iterate. This formulation can potentially guarantee convergence and also increase the convergence rate without the requirement of prefiltering. Another extension of the iterative computation incorporates constraints (e.g., positivity or finite extent) on the output of each iteration. Proof of convergence of such constrained iterations relies on the concept of a nonexpansive operator. In particular, the error introduced within the converging solution resulting from a finite-extent constraint is shown to satisfy a homogeneous partial difference equation. Finally, this error computation leads to an important link between our iterative implementation with constraints and an iterative solution to partial difference equations (e.g., Laplace's equation) with known boundary conditions.
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Summary

A two-dimensional (2-D) rational filter can be implemented by an iterative computation involving only finite-extent impulse response (FIR) filtering operations, provided a certain convergence criterion is met. In this paper, we generalize this procedure so that the convergence criterion is satisfied for any stable 2-D rational transfer function. One formulation...

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Implementation of 2-D digital filters by iterative methods

Signal reconstruction from the short-time Fourier transform magnitude

May 2, 1982
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Conference Paper
Author:
Jae S. Lim
…
Published in:
IEEE-ASSP Int. Conf., 2 May 1982.
Topic:
signal processing
R&D area:
R&D group:

Summary

In this paper, a signal is shown to be uniquely represented by the magnitude of its short-time Fourier transform (STFT) under mild restrictions on the signal and the analysis window of the STFT. Furthermore, various algorithms are developed which reconstruct signal from appropriate samples of the STFT magnitude. Several of the algorithms can also be used to obtain signal estimates from the processed STFT magnitude, which generally does not have a valid short-time structure. These algorithms are successfully applied to the time-scale modification and noise reduction problems in speech processing. Finally, the results presented here have similar potential for other applications areas, including those with multidimensional signals.
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Summary

In this paper, a signal is shown to be uniquely represented by the magnitude of its short-time Fourier transform (STFT) under mild restrictions on the signal and the analysis window of the STFT. Furthermore, various algorithms are developed which reconstruct signal from appropriate samples of the STFT magnitude. Several of...

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Signal reconstruction from the short-time Fourier transform magnitude

L-Band DME multipath environment in the microwave landing system (MLS) approach and landing region

April 13, 1982
  |
Project Report
Author:
James E. Evans
Published in:
MIT Lincoln Laboratory Report ATC-116
Topic:
surveillance
R&D area:
R&D group:

Summary

The multipath environment in the approach and landing region represents an important factor in the optimization and ultimate performance of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P). Various types of multipath are assessed in the context of the proposed DME/P implementation error characteristics to ascertain the principal challenges. It is shown (analytically and experimentally) that specular reflections from buildings represent a significant challenge, particularly at low altitudes (e.g., category II decision height and below) where terrain lobing can cause the effective multipath levels to exceed the effective direct signal level. However, the time delay discrimination capabilities of the proposed DME/P should effectively eliminate the bulk of such multipath. Limited S-band (3 GHz) measurements of diffuse reflections from nominally flat terrain indicated very low levels. However, specular reflections from bare, hilly terrain may present problems in some cases.
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Summary

The multipath environment in the approach and landing region represents an important factor in the optimization and ultimate performance of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P). Various types of multipath are assessed in the context of the proposed DME/P implementation error characteristics to ascertain the principal...

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L-Band DME multipath environment in the microwave landing system (MLS) approach and landing region

En route weather data extraction from ATC radar systems

March 11, 1982
  |
Project Report
Author:
David Karp
Published in:
MIT Lincoln Laboratory Report ATC-113
Topic:
radar
R&D area:
R&D group:

Summary

This report describes the results of phase I of the En Route Radar Weather Program. The objective of this effort was to develop techniques for generating accurate en route weather reflectivity estimates in the presence of ground clutter. A candidate weather data extraction processor is proposed for use with either the ASR-MTD or ARSR-MTD radar systems. Principal features of the candidate processor include: (1) an antenna port (to permit use of an appropriate polarization), front end (with R^-2 STC) and quadrature video sampling subsystem which are separate from that used for aircraft surveillance. (2) use of a ground clutter map to select the form of clutter rejection to be used in each individual range-azimuth cell to estimate various weather reflectivity levels, and (3) spatial /temporal smoothing of the cell reflectivity estimates. The key elements of the suggested signal processing techniques were evaluated using data from MTD tests in Bedford, VA, Burlington, VT, and Atlantic City, NJ; however, the full system has not as yet received design validation/refinement and operational evaluation by ATC controllers. In particular, methods for identifying second trip weather echos should be addressed in the full system validation program.
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Summary

This report describes the results of phase I of the En Route Radar Weather Program. The objective of this effort was to develop techniques for generating accurate en route weather reflectivity estimates in the presence of ground clutter. A candidate weather data extraction processor is proposed for use with either...

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En route weather data extraction from ATC radar systems

Air-to-air mode S surveillance algorithms

February 8, 1982
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Project Report
Author:
Patricia H. Mann
Published in:
MIT Lincoln Laboratory Report ATC-111
Topic:
surveillance
R&D area:
R&D group:

Summary

Lincoln Laboratory is assisting the Federal Aviation Administration in developing a beacon-based airborne collision avoidance system known as the Traffic Alert and Collision Avoidance System (TCAS). The version of TCAS intended for air carrier use is called TCAS II. It provides traffic and resolution advisories and operates in the highest traffic densities predicted for the end of the century. TCAS II extends and replaces an earlier system known as BCAS (for Beacon Collision Avoidance System). Mode S surveillance algorithms form the basis for TCAS algorithms now under development at Lincoln Laboratory.
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Summary

Lincoln Laboratory is assisting the Federal Aviation Administration in developing a beacon-based airborne collision avoidance system known as the Traffic Alert and Collision Avoidance System (TCAS). The version of TCAS intended for air carrier use is called TCAS II. It provides traffic and resolution advisories and operates in the highest...

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Air-to-air mode S surveillance algorithms

Classes of functions with explicit best uniform approximations

January 1, 1982
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Journal Article
Author:
Harold Z. Ollin
…
Published in:
J. Approx. Theory, Vol. 34, No. 3, 1982, pp. 264-276.
Topic:
algorithms
R&D area:
R&D group:

Summary

This paper concerns the construction of forms of the error function, en(x) = f(x)- p*n(x), where p*n is the best uniform polynomial approximation of degree n to a continuous function f on [-1, +l]. We show that it is always possible and, from the viewpoint of obtaining explicit results, expedient to write the error as en= a cos(n(Theta + phi), where x =cos Theta, |a|= En(f), the uniform norm of en(x), and the phase angle phi is a continuous function of Theta, depending on f and n. Our classes of explicit best approximations arise from a novel method of determining suitable phase angles in this representation of en(x).
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Summary

This paper concerns the construction of forms of the error function, en(x) = f(x)- p*n(x), where p*n is the best uniform polynomial approximation of degree n to a continuous function f on [-1, +l]. We show that it is always possible and, from the viewpoint of obtaining explicit results, expedient...

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Classes of functions with explicit best uniform approximations

Iterative techniques for minimum phase signal reconstruction from phase or magnitude

December 1, 1981
  |
Journal Article
Author:
Thomas F. Quatieri
…
Published in:
IEEE Trans. on Acoustics, Speech & Signal Processing, Vol. ASSP-29, No.6, Dec. 1981, pp.1187-1193.
Topic:
speech enhancement
R&D area:
R&D group:

Summary

In this paper, we develop iterative algorithms for reconstructing a minimum phase sequence from pthhea se or magnitude of its Fourier transform. These iterative solutions involve repeatedly imposing a causality constraint in the time domain and incorporating the known phase or magnitude function in the frequency domain. This approach is the basis of a new means of computing the Hilbert transform of the log-magnitude or phase of the Fourier transform of a minimum phase sequence which does not require phase unwrapping. Finally, we discuss the potential use of this iterative computation in determining samples of the unwrapped phase of a mixed phase sequence.
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Summary

In this paper, we develop iterative algorithms for reconstructing a minimum phase sequence from pthhea se or magnitude of its Fourier transform. These iterative solutions involve repeatedly imposing a causality constraint in the time domain and incorporating the known phase or magnitude function in the frequency domain. This approach is...

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Iterative techniques for minimum phase signal reconstruction from phase or magnitude

Moving Target Detector (Mod II) summary report

November 3, 1981
  |
Project Report
Author:
David Karp
…
Published in:
MIT Lincoln Laboratory Report ATC-95
Topic:
surveillance
R&D area:
R&D group:

Summary

Under FAA sponsorship, MIT/Lincoln Laboratory has developed a second generation, field operable Moving Target Detection System (MTD-II) which has been tested at operational FAA terminal and enroute radar sites, and serves as the basis for the ASR-9 MTD technical performance specifications. This summary report covers the period October, 1976 through September, 1979 in which design, development, field testing and system performance evaluation were carried out. Report No. FAA-RD-76-190, ATC-69, "Description and Performance Evaluation of the Moving Target Detector" dated 8 March 1977, serves as the technical foundation of this work. MTD-processing design modifications were effected to handle conditions of excessive ground clutter and moving ground traffic. The rationale for the modified algorithms is provided, and measured performance characteristics at several FAA field sites are discussed.
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Summary

Under FAA sponsorship, MIT/Lincoln Laboratory has developed a second generation, field operable Moving Target Detection System (MTD-II) which has been tested at operational FAA terminal and enroute radar sites, and serves as the basis for the ASR-9 MTD technical performance specifications. This summary report covers the period October, 1976 through...

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Moving Target Detector (Mod II) summary report
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