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Multiple-access considerations - a satellite example

Published in:
IEEE Transactions on Communications, Vol. 21, No. 5, May 1973, pp. 577-82.

Summary

Increased air traffic coupled with the proliferation of sophisticated avionics can be expected to stimulate increased demand for air traffic control (ATC) services over the next few decades. New challenges for the design of communication, surveillance, and navigation subsystems is an anticipated consequence. Since it is unlikely that significantly larger frequency bands will become available, it will be necessary to exploit more efficient multiple-access techniques. The design of a multiple-access technique for a particular application will depend on a broad range of system issues. A predetermined procedure based on general characteristics of the various techniques will have but limited value. An example of an ATC satellite surveillance system is used to illustrate some of the broad ranging systems issues that can be expected to influence the selection of the multiple access technique.
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Summary

Increased air traffic coupled with the proliferation of sophisticated avionics can be expected to stimulate increased demand for air traffic control (ATC) services over the next few decades. New challenges for the design of communication, surveillance, and navigation subsystems is an anticipated consequence. Since it is unlikely that significantly larger...

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The influence of surveillance system parameters on automated conflict detection and resolution

Author:
Published in:
MIT Lincoln Laboratory Report ATC-15

Summary

The effects of sensor accuracy, data rate, and message delivery delay upon automated conflict detection,and resolution processing is analyzed and particular considerations for DABS/IPC operation are discussed. Various options in the design of the algorithmic logic are enumerated and a particular logic is chosen for quantitative inspection. Performance sensitivity calculations for the conflict detection and command generation functions are then presented. The influence of algorithmic logic and traffic environment upon surveillance requirements is delineated.
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Summary

The effects of sensor accuracy, data rate, and message delivery delay upon automated conflict detection,and resolution processing is analyzed and particular considerations for DABS/IPC operation are discussed. Various options in the design of the algorithmic logic are enumerated and a particular logic is chosen for quantitative inspection. Performance sensitivity calculations...

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The effect of staggered PRF's on MTI signal detection

Published in:
IEEE Trans. Aerosp. Electron. Syst., Vol. 9, No. 4, July 1973, pp. 615-8.

Summary

Long-range surveillance radars use MTI techniques to detect moving targets in a clutter background. The transmitter PRF is usually staggered to eliminate the blind speeds due to aliasing of the target and clutter spectra. A spectral analysis of the target and clutter signals is performed for the case of nonuniform sampling, and it is shown that the clutter spectral density continues to fold over at the basic PRF, but the signal spectrum becomes dispersed in frequency, which means that an MTI radar will never be completely blind to moving targets.
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Summary

Long-range surveillance radars use MTI techniques to detect moving targets in a clutter background. The transmitter PRF is usually staggered to eliminate the blind speeds due to aliasing of the target and clutter spectra. A spectral analysis of the target and clutter signals is performed for the case of nonuniform...

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A theory for optimal MTI digital signal processing, supplement I

Published in:
MIT Lincoln Laboratory Report TN-1972-14-SUP-I

Summary

In the report, "A Theory for Optimal MTI Digital Signal Processing. Part I. Receiver Synthesis," (1), the problem of eliminating scanning ground clutter from an aircraft surveillance radar was examined from a statistical decision theoretical point of view. An optimum processor was derived which could be approximated by a clutter filter followed by a discrete Fourier transform (DFT). In this report, additional numerical work is documented that compares the performance of the pulse cancellers, pulse cancellers with feedback and the DFT with that of the optimum processor. The issue of coherent vs incoherent integration gain is considered by comparing the filters only on their ability to reject clutter. A clutter rejection improvement factor is defined and used to compare the various filters. It is shown that the pulse cancellers can be quite effective in rejecting clutter provided the input clutter power is not too large and that additional gains are possible using the DFT.
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Summary

In the report, "A Theory for Optimal MTI Digital Signal Processing. Part I. Receiver Synthesis," (1), the problem of eliminating scanning ground clutter from an aircraft surveillance radar was examined from a statistical decision theoretical point of view. An optimum processor was derived which could be approximated by a clutter...

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An experimental UHF ground surveillance radar, volume II

Published in:
MIT Lincoln Laboratory Report TR-497-II

Summary

This is Volume 2 of the final report summarizing two years of work on ground-based foliage-penetration radar. The design and implementation of a breadboard radar system and of a theoretical and experimental investigation of target and propagation phenomena specific to the foliage-penetration problem are described. Volume 1 comprises three main sections: a short introduction; an overall description of the radar; and detailed descriptions of the hardware and software subsystems in the radar. Volume 2 describes the use of the radar as a measurements system for studying targets and the clutter environment, in addition to its use for demonstrating the feasibility of radar detection of walking men in foliage. Investigations of target return spectra, clutter return spectra, and clutter return amplitude statistics are reported. Theoretical models relating clutter spectra to wind turbulence and tree resonances are presented and compared with experimental results. Similarly, a previous theoretical prediction of target return spectra is compared with experimental results. Clutter return amplitude statistics are measured and found to be Gaussian under certain conditions. Finally, Vol.2 contains some comments on the relationships between the subclutter visibility and various parameters of digital MTI systems.
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Summary

This is Volume 2 of the final report summarizing two years of work on ground-based foliage-penetration radar. The design and implementation of a breadboard radar system and of a theoretical and experimental investigation of target and propagation phenomena specific to the foliage-penetration problem are described. Volume 1 comprises three main...

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A theory for optimal MTI digital signal processing, part II. signal design

Published in:
MIT Lincoln Laboratory Report TN-1972-14-II

Summary

In Part I of this report the optimum MTI receiver was derived and analyzed for the case in which the radar pulses were emitted from the transmitter equally spaced in time. For typical long range ATC surveillance radars , aliasing of the target and clutter spectra results in detection blind speeds at multiples of approximately 70 knots. It is well known operationally that these blind speeds can be eliminated by staggering the transmitter PRF. Heretofore, there has been no thorough theoretical analysis of the effect of staggered PRF on the spectral distribution of the target and clutter signals. It is shown in Part II that the clutter spectral density continues to fold over at the PRF, but that the signal spectrum becomes dispersed in frequency, somewhat like an anti-jam signal. The effect that this phenomenon has on the performance of the optimum processor is evaluated in terms of the signal-to-interference ratio (SIR) criterion that was derived in Part I. It is further noted that even when the target Doppler shifts are more than one PRF apart, the spectra are distinguishable, suggesting that unambiguous Doppler estimation may be possible. This concept is explored in detail using the MTI ambiguity function. It is shown that good SIR performance can be obtained by choosing the stagger parameters to minimize the height of the subsidiary Doppler side-lobes. The resulting design problem is noted to be similar to that of obtaining good antenna patterns for arrays having non-uniformly spaced elements.
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Summary

In Part I of this report the optimum MTI receiver was derived and analyzed for the case in which the radar pulses were emitted from the transmitter equally spaced in time. For typical long range ATC surveillance radars , aliasing of the target and clutter spectra results in detection blind...

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Dual lane runway study, interim report, Project 082-421-214

Published in:
Project Report ATC-11, MIT Lincoln Laboratory

Summary

An overview of the issues involved in the design of dual lane runways is presented. These issues include: centerline spacing, parallel taxiway, high speed exits, midpoint versus end point crossing, threshold stagger, and departure/arrival runway preference. An interactive graphics simulation was developed on the TX-2 computer. The simulation provides the capability for an airport designer to easily input dual lane runway configurations. ATC controllers were employed for over 100 hours to control and direct simulated traffic to various dual lane configurations. A set of preliminary criteria for dual lane runway configurations are presented along with recommendations for future work.
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Summary

An overview of the issues involved in the design of dual lane runways is presented. These issues include: centerline spacing, parallel taxiway, high speed exits, midpoint versus end point crossing, threshold stagger, and departure/arrival runway preference. An interactive graphics simulation was developed on the TX-2 computer. The simulation provides the...

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Comparison of immunity to garbling for three candidate modulation schemes for DABS

Published in:
MIT Lincoln Laboratory Report ATC-12

Summary

The performance of three candidate modulation schemes for DABS is analyzed in this report and a comparison on the basis of probability of error per bit is made. The three types of modulation are PAM, DPSK, and FSK. The results show that, at a given level of interference and signal-to-noise ratio, DPSK and FSK have a lower P(e)/bit than PAM and this difference is significant in most cases. In addition to P(e)/bit, however, the choice of modulation and message format depends on the capacity required, bandwidth occupancy, and cost of implementation. This list consideration is especially important with regard to the transponder.
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Summary

The performance of three candidate modulation schemes for DABS is analyzed in this report and a comparison on the basis of probability of error per bit is made. The three types of modulation are PAM, DPSK, and FSK. The results show that, at a given level of interference and signal-to-noise...

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Parallel approach surveillance

Published in:
MIT Lincoln Laboratory Report ATC-13

Summary

This report investigates the requirements imposed on a surveillance system for supporting independent approaches to closely spaced parallel runways. Based on a proposed procedure for monitoring aircraft approach paths and controlling deviations from proper approach paths, the required spacing between runway centerlines is derived as a function of surveillance system characteristics and other parameters. Potential trade-offs between the surveillance system characteristics are then investigated to determine whether the DABS sensor might be utilized for position measurement and/or communication in such a surveillance system. The results indicate that the required runway spacing is more sensitive to delays and data update intervals than to position measurement accuracies, and that, if DABS is to perform the communication function in the system, it should probably be used for position measurement as well.
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Summary

This report investigates the requirements imposed on a surveillance system for supporting independent approaches to closely spaced parallel runways. Based on a proposed procedure for monitoring aircraft approach paths and controlling deviations from proper approach paths, the required spacing between runway centerlines is derived as a function of surveillance system...

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Surveillance aspects of the Advanced Air Traffic Management System

Published in:
MIT Lincoln Laboratory Report ATC-10

Summary

Three topics with impact on the performance of Air-to Satellite-to-Ground Systems for Air Traffic Control Surveillance are addressed in detail: 1) vulnerability to intentional jamming; 2) performance degradation due to the multiple access noise which results from uncoordinated aircraft transmissions, and 3) tracking techniques for improved surveillance accuracy and reduced short-term outages.
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Summary

Three topics with impact on the performance of Air-to Satellite-to-Ground Systems for Air Traffic Control Surveillance are addressed in detail: 1) vulnerability to intentional jamming; 2) performance degradation due to the multiple access noise which results from uncoordinated aircraft transmissions, and 3) tracking techniques for improved surveillance accuracy and reduced...

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