Publications

Refine Results

(Filters Applied) Clear All

Effects of RF power deviations on BCAS link reliability

June 7, 1977
  |
Project Report
Author:
William H. Harman III
Published in:
MIT Lincoln Laboratory Report ATC-76
Topic:
surveillance
R&D area:
R&D group:

Summary

In the design of BCAS there is some freedom in the choice of specifications for BCAS transmitter power and receiver MTL (Minimum Triggering Level). Transmitter power should be high enough to provide adequate link reliability while being low enough to prevent interference problems. The question of providing adequate link reliability for the DABS mode of BCAS is addressed in this study. The study makes use of aircraft antenna gain data resulting from a model measurement program, and is otherwise analytical. It is concluded that appropriate nominal design values are transmitter power = 500 watts and receiver MTL = -77 dBm (referred to the BCAS unit). It is shown that these values provide sufficient power margin, at the air-to-air ranges appropriate for BCAS, so as to allow for adverse power deviations that might result from aircraft antenna gains, antenna cabling, and the expected transmitter and receiver deviations due to manufacturing nonuniformities and aging.
READ LESS

Summary

In the design of BCAS there is some freedom in the choice of specifications for BCAS transmitter power and receiver MTL (Minimum Triggering Level). Transmitter power should be high enough to provide adequate link reliability while being low enough to prevent interference problems. The question of providing adequate link reliability...

READ MORE
Effects of RF power deviations on BCAS link reliability

Comparison of the performance of the moving target detector and the radar video digitizer

April 26, 1977
  |
Project Report
Author:
Robert M. O'Donnell
…
Published in:
MIT Lincoln Laboratory Report ATC-70
Topic:
surveillance
R&D area:
R&D group:

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, 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.
READ LESS

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...

READ MORE
Comparison of the performance of the moving target detector and the radar video digitizer

Air-to-air visual acquisition performance with Pilot Warning Instruments (PWI)

April 25, 1977
  |
Project Report
Author:
John W. Andrews
Published in:
MIT Lincoln Laboratory Report ATC-73
Topic:
surveillance
R&D area:
R&D group:

Summary

Subject pilot flight tests conducted at the M.I.T. Lincoln Laboratory have produced new data characterizing the ability of general aviation pilots to visually acquire portential collision hazards when aided by Pilot Warning Instruments (PWI). In this paper major issues in the design of Pilot Warning Instruments are reviewed. Visual acquisition performance is described in terms of a non-homogeneous Poisson process and results of previous experiments are reinterpreted in this light. It is shown that the major test results can be explained in terms of an acquisition rate which is proportional to the solid angle subtended by the target. Model parameters appropriate for Lincoln Laboratory flight test data are derived by maximum likelihood techniques. A statistical analysis of significance is performed for other factors which are not explicitly included in this model. Performance predictions for a wide variety of aircraft sizes, approach speeds, and visibility conditions are presented.
READ LESS

Summary

Subject pilot flight tests conducted at the M.I.T. Lincoln Laboratory have produced new data characterizing the ability of general aviation pilots to visually acquire portential collision hazards when aided by Pilot Warning Instruments (PWI). In this paper major issues in the design of Pilot Warning Instruments are reviewed. Visual acquisition...

READ MORE
Air-to-air visual acquisition performance with Pilot Warning Instruments (PWI)

Description and performance evaluation of the moving target detector

March 8, 1977
  |
Project Report
Author:
Lincoln Cartledge
…
Published in:
MIT Lincoln Laboratory Report ATC-69
Topic:
surveillance
R&D area:
R&D group:

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 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.
READ LESS

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...

READ MORE
Description and performance evaluation of the moving target detector

DABS monopulse summary

February 4, 1977
  |
Project Report
Author:
David Karp
…
Published in:
MIT Lincoln Laboratory Report ATC-72
Topic:
surveillance
R&D area:
R&D group:

Summary

Improved azimuthal resolution of proximate aircraft necessary to support ATC automation can be achieved by beacon surveillance systems employing monopulse angle estimation techniques described in this report. Included in the report are the results of beacon surveillance monopulse system analyses relating to off-boresight angle estimation using short (1/2 micro sec) pulses: the effects of specular and diffuse multipath signal return; the effects of overlapping ATCRBS fruit replies, and the problems of antenna pattern design. These topics have been studied in detail as part of the Lincoln Laboratory disign of the Discrete Address Beacon System (DABS). This report summarizes analytical results obtained. In general, it has been concluded that the ATC environment does not pose a serious problem to the use of the monopulse concept for beacon system direction finding and that sufficient direction finding accuracy can be obtained using a small number of narrow pulses for each scan.
READ LESS

Summary

Improved azimuthal resolution of proximate aircraft necessary to support ATC automation can be achieved by beacon surveillance systems employing monopulse angle estimation techniques described in this report. Included in the report are the results of beacon surveillance monopulse system analyses relating to off-boresight angle estimation using short (1/2 micro sec)...

READ MORE
DABS monopulse summary

Ionospheric scintillation

February 1, 1977
  |
Journal Article
Author:
Robert K. Crane
Published in:
Proc. of the IEEE, Vol. 65, No. 2, February 1977, pp. 180-199.
Topic:
radar
R&D area:
R&D group:

Summary

Available observations of ionospheric scintillation are analyzed to evaluate the adequacy of existing models used for the interpretation of scintillation data. The theoretical models are reviewed and the frequency and propagation geometry dependences predicted by the models are compared with the observations. The models were used to construct scintillation occurrence distribution functions which show that scintillation phenomena significantly affect the design of transionospheric radar or communication systems operating at frequencies below 1 GHz. Diversity schemes useful for mitigation of scintillation effects are considered. Mention is made of the geophysical processes thought to be responsible for scintillation.
READ LESS

Summary

Available observations of ionospheric scintillation are analyzed to evaluate the adequacy of existing models used for the interpretation of scintillation data. The theoretical models are reviewed and the frequency and propagation geometry dependences predicted by the models are compared with the observations. The models were used to construct scintillation occurrence...

READ MORE
Ionospheric scintillation

ATCRBS mode of DABS

January 31, 1977
  |
Project Report
Author:
Jeffrey L. Gertz
Published in:
MIT Lincoln Laboratory Report ATC-65
Topic:
surveillance
R&D area:
R&D group:

Summary

The Discrete Address Beacon System (DABS) has been designed to be an evolutionary replacement oth the third generation Air Traffic Control Radar Beacon System (ATCRBS). Although the ATCRBS returns processed by DABS will be identical to those currently being employed, the DABS processing system will not merely mimic the present system. Instead, it has been designed to surpass current performance levels even while reducing the number of interrogations transmitted per scan. This will be made possible by utilizing the availability of several new features introduced by the DABS sensor. In particular, the employment of monopulse antenna will permit both more accurate azimuth estimation with fewer replies per scan and improved decoding performance when garble is present. The ATCRBS portion of the DABS sensor has been designed to be a complete, self-contained package that performs all ATCRBS functions required for aircraft surveillance. The major tasks it implements are: 1. Determining the range, azimuth, and code of each received ATCRBS reply 2. Grouping replies from the same aircraft into target reports and discarding fruit replies 3. Identifying all false alarm target reports due to reflections, coincident fruit, splitting, or ringaround 4. Initiating and maintaining a track on all aircraft in the covered airspace The first function has been implemented in hardware while the remaining ones are performed in software. This report will discuss in detail only the software subsystems. The ATCRBS system described in this report has been implemented in the ATCRBS Monopulse Processing System (AMPS) built at Lincoln Laboratory. Although the AMPS design is based upon the specifications contained in the DABS Engineering Requirements (ER), there are two major differences between AMPS and the ER system. First, the design described here is for a standalone ATCRBS system; no capabilities are built in to send, receive, or employ information from other sensors, and no formal interfaces to other ATC functions are defined. Second, this system was not intended to be a production prototype, so no reliability features have been included.
READ LESS

Summary

The Discrete Address Beacon System (DABS) has been designed to be an evolutionary replacement oth the third generation Air Traffic Control Radar Beacon System (ATCRBS). Although the ATCRBS returns processed by DABS will be identical to those currently being employed, the DABS processing system will not merely mimic the present...

READ MORE
ATCRBS mode of DABS

Automatic Reporting of Height (AROH) design and trade-off studies

November 1, 1976
  |
Technical Report
Author:
Lincoln Cartledge
…
Published in:
MIT Lincoln Laboratory Report TN-1976-42
Topic:
air traffic control
R&D area:
R&D group:

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 this purpose is discussed.
READ LESS

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...

READ MORE
Automatic Reporting of Height (AROH) design and trade-off studies

The PMP, a programmable radar signal processor

October 7, 1976
  |
Conference Paper
Author:
Bruce G. Laird
…
Published in:
Monthly Mtg. of Boston IEEE, Mitre Corp, Bedford, Ma 13 October 1976.
Topic:
signal processing
R&D area:
R&D group:

Summary

During the last few years, the Radar Techniques Group at Lincoln Laboratory has been applying digital processing techniques to the problem of automatic detection of moving vehicles in the presence of ground and weather clutter. An outgrowth of this effort is the development of a real-time radar signal processor, the Parallel Microprogrammable Processor, or PMP. Conceptually the PMP consists of a single control unit and an array of identical processing modules. The control unit sequences through a program stored in its control memory, providing identical instructions to each processing module, so that all modules are performing the same operation in parallel, each on its own set of data. The talk will focus on the motivation for, and advantages of such a parallel architecture, as presently implemented with TTL medium-scale integrated circuits. Some examples of parallel computation will be illustrated as well as more general issues relating to programmability of the PMP. Much of the information in the talk will be based on experience with an operational prototype, which has a control unit and one processor module.
READ LESS

Summary

During the last few years, the Radar Techniques Group at Lincoln Laboratory has been applying digital processing techniques to the problem of automatic detection of moving vehicles in the presence of ground and weather clutter. An outgrowth of this effort is the development of a real-time radar signal processor, the...

READ MORE
The PMP, a programmable radar signal processor

Radar detection of thunderstorm hazards for air traffic control volume II: radar systems

October 7, 1976
  |
Project Report
Author:
Steven M. Sussman
Published in:
MIT Lincoln Laboratory Report ATC-67,II
Topic:
weather
R&D area:
R&D group:

Summary

Radar systems are investigated for the acquisition of weather data to support detection and forecasting of hazardous turbulence associated with individual storm cells. Utilization of the FAA Airport Surveillance Radar (ASR) is explored. The issues of antenna polarization and Sensitivity Time Control (STG) that impact on shared operation for aircraft and weather detection are addressed. Candidate system configurations employing a common RF channel and dual orthogonal polarization channels are discussed. Ground clutter discrimination by coherent Doppler and noncoherent (Doppler spread) processing methods is described. An interim procedure is suggested for obtaining fixed reflectivity contour data from a Moving Target Detector for use in the all-digital ARTS. A preliminary design is presented for a new joint-use, long-range weather radar to support enroute air traffic controllers and to meet the data requirements of the National Weather Service and the Air Weather Service.
READ LESS

Summary

Radar systems are investigated for the acquisition of weather data to support detection and forecasting of hazardous turbulence associated with individual storm cells. Utilization of the FAA Airport Surveillance Radar (ASR) is explored. The issues of antenna polarization and Sensitivity Time Control (STG) that impact on shared operation for aircraft...

READ MORE
Radar detection of thunderstorm hazards for air traffic control volume II: radar systems
2131-2140 of 2265