Publications
Advanced signal processing for airport surveillance radars
June 11, 1977
Conference Paper
Published in:
IEEE Electronics and Aerospace Systems Convention, EASCON, 7-9 October 1974.
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Summary
The inclusion of airport surveillance radars (ASR) in an automated air traffic control system, such as the ARTS-III, has been limited by the present radar's capability to automatically reject ground clutter, weather clutter and angels while still maintaining good detectability on all aircraft within their coverage patterns. Analytical and experimental studies have been performed which indicate that new techniques can significantly enhance the automated capability of these radars. A special-purpose, hard-wired, digital signal processor has been designed, built and tested which provides near-optimum target detection over the entire ASR coverage out to 48 nmi. The processor which coherently integrates eight pulses has both a fine grained clutter map for optimal thresholding in high ground clutter environments and a mean-level thresholding scheme for filtering those Doppler cells which contain heavy precipitation. Because of the processor's ability to detect targets in a high ground clutter environment, the ASR's will be able to operate their antennas at lower elevation angles and, thus, have better coverage of low flying aircraft near the terminal. The processor is initially being tested on a highly modified, coherent S-band, FPR-18 radar. The stability of the klystron transmitter was improved so that it would not limit system performance and a new, wide dynamic range, linear receiver was provided.
Summary
The inclusion of airport surveillance radars (ASR) in an automated air traffic control system, such as the ARTS-III, has been limited by the present radar's capability to automatically reject ground clutter, weather clutter and angels while still maintaining good detectability on all aircraft within their coverage patterns. Analytical and experimental...
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Comparison of the performance of the moving target detector and the radar video digitizer
April 26, 1977
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-70
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Results of side by side simultaneous tests to compare the performance of the Moving Target Detector (MID) digital signal processor and that of a newly developed adaptive sliding window detector, the Radar Video Digitizer (RVD-4), are described. The MTD, used with a highly modified FPS-18, employs coherent linear doppler filtering, adaptive thresholding, and a fine grained clutter map which together reject all forms of clutter simultaneously. The RVD-4, which was used with an ASR-7, is a non-linear, non-coherent digital processor. The detection and false alarm performance of both processors in thermal noise was identical. Measured detection and sub-clutter visibility performance of the MTD on controlled aircraft flying in heavy rain, in heavy ground clutter, and at near-zero radial velocity is shown to be superior to that of the RVD-4. MID report data is also shown to be more accurate than the RVD-4 data resulting in improved ARTS-Ill tracker performance when using MID processed data.
Summary
Results of side by side simultaneous tests to compare the performance of the Moving Target Detector (MID) digital signal processor and that of a newly developed adaptive sliding window detector, the Radar Video Digitizer (RVD-4), are described. The MTD, used with a highly modified FPS-18, employs coherent linear doppler filtering...
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Description and performance evaluation of the moving target detector
March 8, 1977
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-69
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Under FAA sponsorship, MIT, Lincoln Laboratory has developed new techniques which significantly enhance automated aircraft detection in all forms of clutter. These techniques are embodied in a digital signal processor called the Moving Target Detector (MTD). This processor has been integrated into the ARTS-III system at the National Aviation Facilities Experimental Center, Atlantic City, New Jersey (NAFEC) and has undergone testing during the summer of 1975. This report contains a description of the MTD design and its evaluation tests. A detailed discussion of the significance of the results is also presented. The detection performance of the MTD was excellent in the clear, in rain and ground clutter, and false alarms were under complete control. The MTD processed range and azimuth data was very accurate, and the MTJI did not suffer from track dropouts as did the conventional MTI when the aircraft track became tangential to the radar. Performance was excellent on magnetron as well as klystron-type radars with the exception- of second-time-around clutter cancellation.
Summary
Under FAA sponsorship, MIT, Lincoln Laboratory has developed new techniques which significantly enhance automated aircraft detection in all forms of clutter. These techniques are embodied in a digital signal processor called the Moving Target Detector (MTD). This processor has been integrated into the ARTS-III system at the National Aviation Facilities...
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Automatic Reporting of Height (AROH) design and trade-off studies
November 1, 1976
Technical Report
Published in:
MIT Lincoln Laboratory Report TN-1976-42
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Application of MTD signal processing and state-of-the-art data processing can result in a completely automatic nodding beam height finder. The resulting savings in manpower are significant. Calculations show that such a system should have good sensitivity and adequate rejection of ground and weather clutter. Modification of an FPS-6 radar for this purpose is discussed.
Summary
Application of MTD signal processing and state-of-the-art data processing can result in a completely automatic nodding beam height finder. The resulting savings in manpower are significant. Calculations show that such a system should have good sensitivity and adequate rejection of ground and weather clutter. Modification of an FPS-6 radar for...
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New techniques applied to air-traffic control radars
June 1, 1974
Journal Article
Published in:
Proc. IEEE, Vol. 62, No. 6, June 1974, pp. 716-723.
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During the past two years a program has been carried out to show how new techniques can greatly improve the performance of radars used for air-traffic control. A survey of problems associated with presently used radars was undertaken. This survey indicates that primary radar in an automated air-traffic control system can be made significantly more effective by the use of new techniques. The radar's handling of extraneous reflections (clutter) is critical to its performance. Three types of interfering clutter were found to predominate: ground clutter, weather clutter, and angels. Angels are generally accepted to be radar returns from flocks of birds. In addition, second-time-around clutter is often troublesome. For each type of clutter, all known remedies for improving the signal-to-clutter ratio were studied and radar systems were configured using appropriate sets of remedies. Some specific solutions incorporated in the resulting radar systems are: a) the use of linear large dynamic range, near-optimum digital signal processors to filter signals from clutter, b) the use of electronically step-scanned antennas to improve the correlation of aircraft and clutter returns from pulse to pulse, c) the use of multiple PRF's instead of staggered PRF's together with coherent transmitters to keep second-time-around clutter returns well correlated while still overcoming blind speeds, d) the use of a fine grained ground clutter map to give superclutter visibility on tangential targets, and e) the use of lower operating frequencies to greatly reduce weather and angel returns. Two demonstration radar systems have been implemented, an S-band radar using a mechanically rotating antenna and a UHF radar using an electronically step-scanned cylindrical antenna. Experimental results are described.
Summary
During the past two years a program has been carried out to show how new techniques can greatly improve the performance of radars used for air-traffic control. A survey of problems associated with presently used radars was undertaken. This survey indicates that primary radar in an automated air-traffic control system...
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A high performance, low cost, air traffic control radar
February 15, 1973
Technical Report
Published in:
MIT Lincoln Laboratory Report TN-1973-12
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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.
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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An experimental UHF ground surveillance radar, volume II
October 12, 1972
Technical Report
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.
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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