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Multifunction phased array radar (MPAR) spectral usage analysis

July 24, 2012
  |
Project Report
Author:
John Y. Cho
…
Published in:
MIT Lincoln Laboratory Report ATC-395
Topic:
radar
R&D area:
R&D group:

Summary

This report addressed two technical risks associated with replacing current air traffic and weather surveillance radars with a single type of multifunction phased array radar (MPAR). The first risk is whether radio spectrum usage would increase with the MPAR network and whether the allocated band will have enough spectral space. This question is addressed in two steps. First, single-radar spectrum usage is estimated based on certain assumptions regarding the radar design. Second, locations based on a previous radar placement study are used together with a terrain-dependent propagation model to compute the number of frequency channels needed at each site. We conclude that the overall spectrum usage is likely to increase with MPAR, but that the targeted window in S band will be able to accommodate the occupancy at all sites. The second risk is whether self-interference will limit the ability of the MPAR to operate asynchronously and adaptively on different antenna faces. This question is addressed by employing a simple bistatic ground clutter model to characterize the interference between adjacent faces. We conclude that some interference is unavoidable, but it would likely only occur during times when a transmit beam is at its maximum off-broadside angle (~2% of the time).
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Summary

This report addressed two technical risks associated with replacing current air traffic and weather surveillance radars with a single type of multifunction phased array radar (MPAR). The first risk is whether radio spectrum usage would increase with the MPAR network and whether the allocated band will have enough spectral space...

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Multifunction phased array radar (MPAR) spectral usage analysis

Analytical workload model for estimating en route sector capacity in convective weather

June 14, 2011
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Conference Paper
Author:
John Y. Cho
…
Published in:
9th USA/Europe Air Traffic Management Research and Development Sem., ATM 2011, 14-17 June 2011.
Topic:
air traffic control
R&D area:
R&D group:

Summary

We have extended an analytical workload model for estimating en route sector capacity to include the impact of convective weather. We use historical weather avoidance data to characterize weather blockage, which affects the sector workload in three ways: (1) Increase in the conflict resolution task rate via reduction in available airspace, (2) increase in the recurring task load through the rerouting of aircraft around weather, and (3) increase in the inter-sector coordination rate via reduction in the mean sector transit time. Application of the extended model to observed and forecast data shows promise for future use in network flow models.
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Summary

We have extended an analytical workload model for estimating en route sector capacity to include the impact of convective weather. We use historical weather avoidance data to characterize weather blockage, which affects the sector workload in three ways: (1) Increase in the conflict resolution task rate via reduction in available...

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Analytical workload model for estimating en route sector capacity in convective weather

Analysis of ground-based radar low-altitude wind-shear detection in OEP terminal airspace for NextGen

December 2, 2010
  |
Project Report
Author:
Suilou Huang
…
Published in:
MIT Lincoln Laboratory Report ATC-375
Topic:
wind shear
R&D area:
R&D group:

Summary

To support the Next Generation Air Transportation System (NextGen), the Reduce Weather Impact Sensor RightSizing program is identifying and analyzing gaps in the current sensor network coverage relative to the Four-Dimensional Weather Data Cube Single Authoritative Source performance requirements. In this study, we look for shortfalls in low-altitude wind-shear sensing by ground-based radars and lidar in the NextGen super-density operations (SDO) terminal airspace. Specifically, 2D gridded wind-shear visibility (an upper bound to detection probability) data are generated for microbursts and gust fronts separately for different sensors, namely the Terminal Doppler Weather Radar, Next Generation Weather Radar, Airport Surveillance Radar-9 with Weather Systems Processor, and Doppler lidar.
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Summary

To support the Next Generation Air Transportation System (NextGen), the Reduce Weather Impact Sensor RightSizing program is identifying and analyzing gaps in the current sensor network coverage relative to the Four-Dimensional Weather Data Cube Single Authoritative Source performance requirements. In this study, we look for shortfalls in low-altitude wind-shear sensing...

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Analysis of ground-based radar low-altitude wind-shear detection in OEP terminal airspace for NextGen

Wind-shear system cost-benefit analysis

August 1, 2010
  |
Journal Article
Author:
Robert G. Hallowell
…
Published in:
Lincoln Laboratory Journal, Vol. 18, No. 2, August 20, pp. 47-68.
Topic:
aviation weather
R&D area:
R&D group:

Summary

Mitigating thunderstorm wind-shear threats for aircraft near the ground has been an important issue since the 1970s, when several fatal commercial aviation accidents were attributed to wind shear. Updating the knowledge base for airport wind-shear exposure and effectiveness of detection systems has become critical to the Federal Aviation Administration as they consider options for aging systems and evaluations of new systems.
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Summary

Mitigating thunderstorm wind-shear threats for aircraft near the ground has been an important issue since the 1970s, when several fatal commercial aviation accidents were attributed to wind shear. Updating the knowledge base for airport wind-shear exposure and effectiveness of detection systems has become critical to the Federal Aviation Administration as...

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Wind-shear system cost-benefit analysis

OEP terminal and CONUS weather radar coverage gap identification analysis for NextGen

May 19, 2010
  |
Project Report
Author:
John Y. Cho
Published in:
MIT Lincoln Laboratory Report ATC-369
Topic:
air traffic control
R&D area:
R&D group:

Summary

The initial results of a weather radar coverage analysis in support of the Reduce Weather Impacts (RWI) Sensor RightSizing program are presented. The main impetus behind this study is to identify gaps in the radar network relative to the Next Generation Air Transportation System (NextGen) end-state performance requirements. Because detailed performance requirements are currently available only for super-density terminal airspace, we focused on this domain. We also analyzed, to a lesser extent, the contiguous United States (CONUS) airspace as an approximation to the en route airspace. Significant gaps were uncovered in the following requirement areas. (1) Vertical resolution. The current weather radar network (and any future radar network of reasonable cost) will not meet the 4D weather cube single authoritative source (4D WxSAS) vertical resolution requirements for both super-density terminal and en route airspace domains. (2) Vertical accuracy. Accurate determination of the radar beam height is difficult due to the natural variability of the vertical refractivitiy gradient in the atmosphere. (3) Update period for convective weather. The current weather radars have volume scan update periods that are substantially longer than the required times. (4) Horizontal resolution. This requirement is met in only some parts of the super-density terminal and en route airspaces (5) Low-altitude coverage. The current weather radars are generally spaced too far apart to provide seamless coverage of the boundary layer. (6) Overall terminal airspace weather radar coverage is significantly diminished due to terrain blockage at a handful of major airports.
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Summary

The initial results of a weather radar coverage analysis in support of the Reduce Weather Impacts (RWI) Sensor RightSizing program are presented. The main impetus behind this study is to identify gaps in the radar network relative to the Next Generation Air Transportation System (NextGen) end-state performance requirements. Because detailed...

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OEP terminal and CONUS weather radar coverage gap identification analysis for NextGen

Terminal Doppler Weather Radar enhancements

May 10, 2010
  |
Conference Paper
Author:
John Y. Cho
…
Published in:
IEEE Radar Conf., 10 May 2010, pp. 1245-1249.
Topic:
algorithms
R&D area:
R&D group:

Summary

The design of an open radar data acquisition system for the Terminal Doppler Weather Radar is presented. Adaptive signal transmission and processing techniques that take advantage of the enhanced capabilities of this new system are also discussed. Results displaying data quality improvements with respect to problems such as range-velocity ambiguity and moving clutter are shown.
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Summary

The design of an open radar data acquisition system for the Terminal Doppler Weather Radar is presented. Adaptive signal transmission and processing techniques that take advantage of the enhanced capabilities of this new system are also discussed. Results displaying data quality improvements with respect to problems such as range-velocity ambiguity...

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Terminal Doppler Weather Radar enhancements

Signal processing algorithms for the Terminal Doppler Weather Radar: Build 2

April 30, 2010
  |
Project Report
Author:
John Y. Cho
Published in:
MIT Lincoln Laboratory Report ATC-363
Topic:
signal processing
R&D area:
R&D group:

Summary

As a new radar data acquisition system (RDA) was developed for the Terminal Doppler Weather Radar (TDWR), enhanced signal processing algorithms taking advantage of its increased capabilities were also developed. The primary goals of protecting the base data estimates from range-aliased signals and providing reliable velocity dealiasing were achieved through multiple pulse repetition interval (PRI) and phase coding methods. An innovative radial-by-radial adaptive selection process was used to take full advantage of the different techniques, the first time such an approach has been implemented for weather radars. Improvement in clutter filtering was also achieved. This report discusses in detail these new RDA signal processing algorithms.
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Summary

As a new radar data acquisition system (RDA) was developed for the Terminal Doppler Weather Radar (TDWR), enhanced signal processing algorithms taking advantage of its increased capabilities were also developed. The primary goals of protecting the base data estimates from range-aliased signals and providing reliable velocity dealiasing were achieved through...

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Signal processing algorithms for the Terminal Doppler Weather Radar: Build 2

Comment on "Reinterpreting aircraft measurement in anisotropic scaling turbulence" by Lovejoy et al. (2009)

January 1, 2010
  |
Journal Article
Author:
E. Lindborg
…
Published in:
Atmos. Chem. Phys., Vol. 10, No. 3, 2010, pp. 1401-1402.
Topic:
aircraft
R&D area:
R&D group:

Summary

Recently, Lovejoy et al. (2009) argued that the steep ~k-3 atmospheric kinetic energy spectrum at synoptic scales (>~1000km) observed by aircraft is a spurious artefact of aircraft following isobars instead of isoheights. Without taking into account the earth's rotation they hypothesize that the horizontal atmospheric energy spectrum should scale as k?5/3 at all scales. We point out that the approximate k?3- spectrum at synoptic scales has been observed by a number of non-aircraft means since the 1960s and that general circulation models and other current models have successfully produced this spectrum. We also argue that the vertical movements of the aircraft are far too small to cause any strong effect on the measured spectrum at synoptic scales.
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Summary

Recently, Lovejoy et al. (2009) argued that the steep ~k-3 atmospheric kinetic energy spectrum at synoptic scales (>~1000km) observed by aircraft is a spurious artefact of aircraft following isobars instead of isoheights. Without taking into account the earth's rotation they hypothesize that the horizontal atmospheric energy spectrum should scale as...

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Comment on "Reinterpreting aircraft measurement in anisotropic scaling turbulence" by Lovejoy et al. (2009)

Moving clutter spectral filter for Terminal Doppler Weather Radar

October 6, 2009
  |
Conference Paper
Author:
John Y. Cho
Published in:
34th Conf. on Radar Meteorology, 5-9 October 2009.
Topic:
algorithms
R&D area:
R&D group:

Summary

Detecting low-altitude wind shear in support of aviation safety and efficiency is the primary mission of the Terminal Doppler Weather Radar (TDWR). The wind-shear detection performance depends directly on the quality of the data produced by the TDWR. At times the data quality suffers from the presence of clutter. Al-though stationary ground clutter signals can be removed by a high-pass filter, moving clutter such as birds and roadway traffic cannot be attenuated using the same technique because their signal power can exist any-where in the Doppler velocity spectrum. Furthermore, because the TDWR is a single-polarization radar, polarimetry cannot be used to discriminate these types of clutter from atmospheric signals. The moving clutter problem is exacerbated at Western sites with dry microbursts, because their low signal-to-noise ratios (SNRs) are more easily masked by un-wanted moving clutter. For Las Vegas (LAS), Nevada, the offending clutter is traffic on roads that are oriented along the radar line of sight near the airport. The radar is located at a significantly higher altitude than the town, improving the visibility to the roads, and giving LAS the worst road clutter problem of all TDWR sites. The Salt Lake City (SLC), Utah, airport is located near the Great Salt Lake, which is the biggest inland staging area for migrating seabirds in the country. It, therefore, suffers from bird clutter, which not only can obscure wind shear signatures but can also mimic them to trigger false alarms. The TDWR "dry" site issues are discussed in more detail by Cho (2008). In order to mitigate these problems, we developed a moving clutter spectral filter (MCSF). In this paper we describe the algorithm and present preliminary test results.
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Summary

Detecting low-altitude wind shear in support of aviation safety and efficiency is the primary mission of the Terminal Doppler Weather Radar (TDWR). The wind-shear detection performance depends directly on the quality of the data produced by the TDWR. At times the data quality suffers from the presence of clutter. Al-though...

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Moving clutter spectral filter for Terminal Doppler Weather Radar

Redeployment of the New York TDWR - technical analysis of candidate sites and alternative wind shear sensors

September 14, 2009
  |
Project Report
Author:
Suilou Huang
…
Published in:
MIT Lincoln Laboratory Report ATC-351
Topic:
wind shear
R&D area:
R&D group:

Summary

The John F. Kennedy International Airport (JFK) and LaGuardia Airport (LGA) are protected from wind shear exposure by the New York Terminal Doppler Weather Radar (TDWR), which is currently located at Floyd Bennet Field, New York. Because of a September 1999 agreement between the Department of the Interior and the Department of Transportation, this location is required to be vacated no later than January 2023. Therefore, a study based on model simulations of wind shear detection probability was conducted to support future siting selection and alternative technologies. A total of 18 candidate sites were selected for analysis, including leaving the radar where it is. (The FAA will explore the feasibility of the latter alternative; it is included in this study only for technical analysis.) The 18 sites are: Six candidate sites that were identified in the initial New York TDWR site-survey studies in the 1990s (one of which is the current TDWR site), a site on Staten Island, two Manhattan skyscrapers, the current location of the WCBS Doppler weather radar in Twombly Landing, New Jersey, and eight local airports including JFK and LGA themselves. Results clearly show that for a single TDWR system, all six previously surveyed sites are suitable for future housing of the TDWR. Unfortunately, land acquisition of these sites will be at least as challenging as it was in the 1990s due to further urban development and likely negative reaction from neighboring residents. Evaluation results of the on-airport siting of the TDWR (either at JFK or at LGA) indicate that this option is feasible if data from the Newark TDWR are simultaneously used. This on-airport option would require software modification such as integration of data from the two radar systems an dimplementation of "overhead" feature detection. The radars on the Manhattan skyscrapers are not an acceptable alternative due to severe ground clutter. The Staten Island site and most other candidate airports are also not acceptable due to distance and/or beam blockage. The existing Airport Surveillance Radar (ASR-9) Weather Systems Processor (WSP) at JFK and the Bookhaven (OKX) Weather Surveillance Radar 1988-Doppler (WSR-88D, commonly known as NEXRAD) on Long Island cannot provide sufficient wind shear protection mainly due to limited wind shear detection capability and/or distance.
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Summary

The John F. Kennedy International Airport (JFK) and LaGuardia Airport (LGA) are protected from wind shear exposure by the New York Terminal Doppler Weather Radar (TDWR), which is currently located at Floyd Bennet Field, New York. Because of a September 1999 agreement between the Department of the Interior and the...

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Redeployment of the New York TDWR - technical analysis of candidate sites and alternative wind shear sensors
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