MPAR Multifunction Phased Array Radar Multi-Purpose Airport Radar Good morning. Our support for MPAR analysis comes from the FAA so my talk is going to be focussed on their interests to a significant extent. 1 1

ATC History Communication, Navigation and Surveillance Automation 1970 1980 1990 2000 Discrete Address Beacon System Mode S Surveillance and Communications Microwave Landing System Beacon Collision Avoidance System TCAS UAS Moving Target Detector Communication, Navigation and Surveillance Airport Surface Detection Equipment ASR-9 Proc. Augmentation Card SLEP Parallel Runway Monitor GPS Applications Runway Status Lights ADS-B Mode S Surface Comms Airport Surface Traffic Automation GCNSS/SWIM Automation Terminal ATC Automation NASA ATM Research Storm Turbulence I put this chart in just to indicate that our involvement with the U.S. Air Traffic Control System dates back almost 40 years now, and that a major component of our efforts have involved understanding and enhancing the nation’s aircraft and weather suveillance systems and the applications that ride on top of these. Specifically: Mode-S, ASR-9, TCAS TDWR, ASR-9 WSP, FAA Nexrrad applications Point is that we understand surveillance requirements rather well! Terminal Doppler Weather Radar SLEP ASR-9 Wind Shear Processor NEXRAD Enhancements Weather Multi Function Phased Array Radar Integrated Terminal Weather System Aviation Weather Research Wake Vortex Corridor Integrated Weather System

ATC Real-Time Database Collision avoidance Radar GPS Flight plans update Radar Conflict resolution Track data Controller displays Restriction avoidance Real time database Autovoice advisory Terrain avoidance Weather status Pilot Terminal conditions Aircraft data

National Air Surveillance Infrastructure Today Future ASR-9 ASR-11 ARSR-3 TDWR ARSR-4 ASR-8 ARSR-1/2 NEXRAD ADS-B FAA transition to Automatic Dependent Surveillance Broadcast (ADS-B) dictates that the nation re-think its overall surveillance architecture. Needs: Weather (national scale and at airports) ADS-B integrity verification and backup Airspace situational awareness for homeland security MPAR So from an FAA perspective, decision to implement ADS-B as primary a/c surveillance system is watershed event and requires rethinking of surveillance architecture. In the wake of ADS-B, the current national networks of primary and secondary aircraft surveillance radars are clearly sub-optimal. What the next generation “non-cooperative” surveillance system needs to provide (and MPAR is part, but probably not the only part of that) is Weather ADS-B backup Airspace Security

Today’s Operational Radar Capabilities Function Maximum Range for Detection of 1m2 Target Required Coverage Range Altitude Angular Resol. Az El Waveform* Scan Period Terminal Area Aircraft Surveillance (ASR-9/11) 60 nmi 60 nm 20,000' 1.4 5o >18 pulses PRI ~ 0.001 sec 5 sec En Route Aircraft Surveillance (ARSR-4) 205 nmi 250 nm 60,000' 2.0 >10 pulses 12 sec Airport Weather (TDWR) 212 nmi 1 0.5 ~50 pulses 180 sec Nationwide Weather (NEXRAD) 225 nmi 250 nmi 50,000' >240 sec Jeff Herd showed this chart yesterday so I can be brief Key points in yellow box! Weather surveillance drives requirements for radar power and aperture size Aircraft surveillance functions can be provided “for free” if necessary airspace coverage and update rates can be achieved Active array radar an obvious approach, but only if less expensive and/or more capable than “conventional” alternatives

Required Surveillance Performance (RSP) Methodology Lincoln has been applying RSP methodology to understand whether alternative backup strategies, in particular MPAR, could provide the same level of service. This chart summarizes the RSP analysis. Basically involves a complete model of the surveillance chain including the sensor, date formats, and human display interface. Measured separation error PDFs associated with each of these stages are convolved to determine the end-to-end separation error distritubtion. Reference system approach used to establish that system under test, in this case MPAR, has an end-to-end separation error PDF that is at least as compact as currently accepted surveillance systems.

RSP Derived from En Route Radar Capabilities* Currently Acceptable (sliding window SSR) Latest Technology (monopulse SSR) Registration Errors Location Bias 200’ uniform any direction Azimuth Bias  0.3 uniform Range Errors Radar Bias  30’ uniform Radar Jitter  = 25’ Gaussian Azimuth Error Azimuth Jitter  = 0.230  = 0.068 Data Quant. (CD2 format) Range 760’ (1/8 NM) Azimuth 0.088 (1 ACP) Uncorrelated* Sensor Scan Time Error 10-12 sec Transponder Error Range Error (ATCRBS)  250’ uniform  = 144’ RSP Analysis Location Error  = 1.0 NM   0.30 NM Separation Errors (at 200 NM @ 600 kts)  = 0.8 NM  = 0.25 NM 90% <  1.4 NM 99% <  2.4 NM 99.9% <  3.3 NM 90% <  0.43 NM 99% <  0.76 NM 99.9% <  1.02 NM Summarizes RSP analysis for currently accepted sensors providing 5 nmi separation capability in en route a/c. Critical measurement parameters are azimuth accuracy and refresh rate. As you can see a separation error sigma of 0.8 nmi at full range is deemed acceptable for the currently defined ADS-B backup system. *Only applies for multiple sensors *Supports 5 nmi separation

RSP Derived from Terminal Radar Capabilities* Currently Acceptable (sliding window SSR) Intermediate (primary radar) Latest Technology (monopulse SSR) Registration Errors Location Bias 200’ uniform any direction Azimuth Bias  0.3 uniform Range Errors Radar Bias  30’ uniform Radar Jitter  = 25’ Gaussian  = 275’ Azimuth Error Azimuth Jitter  = 0.230  = 0.160  = 0.068 Data Quant. (CD2 format) Range 95’ (1/64 NM) Azimuth 0.088 (1 ACP) Uncorrelated* Sensor Scan Time Error 4-5 sec Transponder Error Range Error (ATCRBS)  250’ uniform  = 144’ N/A RSP Analysis Location Error  = 0.20 NM   0.15 NM   0.10 NM Separation Errors (at specified range @ 250 kts)  = 0.16 NM at 40 nm  = 0.12 NM  = 0.08 NM at 60 nm 90% <  0.28 NM 99% <  0.49 NM 99.9% <  0.65 NM 90% <  0.20 NM 99% <  0.35 NM 99.9% <  0.46 NM 90% <  0.13 NM 99% <  0.23 NM 99.9% <  0.32 NM Corresponding analysis for terminal airspace where 3 nmi separation criteria are enforced. In this case, separation error of 0.16 nmi is needed to establish RSP equivalent to today’s defined ADS-B backup system. *Only applies for multiple sensors *Supports 3 nmi separation

MPAR RSP Analysis 20:1 Monopulse For MPAR, the most stressing RSP requirement in terms of system cost is azimuth accuracy, that is beamwidth, which of course relates to antenna size. This chart just confirms my earlier point that an MPAR sized to provide angular resolution equivalent to today’s weather radars can easily meet the RSP requirements for maintaining current separation standards in the event of an ADS-B failure. Note that we’ve assumed the active array will be used to develop monopulse patterns which allow for 20:1 improvement on angular resolution for discrete targets. 4.4 antenna beamwidth meets Terminal RSP Separation Error 4.6 antenna beamwidth meets En Route RSP Separation Error

Concept MPAR Parameters Active Array (planar, 4 faces) Diameter: 8 m TR elements/face: 20,000 Dual polarization Beamwidth: 0.7 (broadside) 1.0 (@ 45) Gain: > 46 dB Transmit/Receive Modules Wavelength: 10 cm (2.7–2.9 GHz) Bandwidth/channel: 1 MHz Frequency channels: 3 Pulse length: 30 s Peak power/element: 2 W Architecture Overlapped subarray Number of subarrays: 300–400 Maximum concurrent beams: ~160 Aircraft Surveillance Non cooperative target tracking and characterization I won’t go through this in any detail other than to point out that we’ve laid down a very specific design concept that’s based on Lincoln Laboratory’s 40 years of experience with ATC and weather surveillance needs. We would be very happy offline to go through the rational for each and every number on this chart and the backup documents that we’ve put out. Weather Surveillance 334 MPARS required to duplicate today’s airspace coverage. Half of these are scaled “Terminal MPARS”

Concept MPAR Capability Summary Airspace coverage equal to today’s operational radar networks. Angular resolution, minimum detectible reflectivity and volume scan update rate equal or exceed today’s operational weather radars Ancillary benefits from improved data integrity and cross-beam wind measurement Can easily support 3-5 nmi separation standards required for ADS-B backup Can provide non-cooperative aircraft surveillance data of significantly higher quality that today’s surveillance radars Altitude information Substantially lower minimum RCS threshold Because our concept is very specific, we can substantiate these assertions.

SLS

3.1.1.5 INTERROGATOR AND CONTROL TRANSMISSION CHARACTERISTICS (INTERROGATION SIDE-LOBE SUPPRESSION) The radiated amplitude of P2 at the antenna of the transponder shall be: a) equal to or greater than the radiated amplitude of P1 from the side-lobe transmissions of the antenna radiating P1; and b) at a level lower than 9 dB below the radiated amplitude of P1, within the desired arc of interrogation. Within the desired beam width of the directional interrogation (main lobe), the radiated amplitude of P3 shall be within 1 dB of the radiated amplitude of P1.

3. 1. 1. 6 REPLY TRANSMISSION CHARACTERISTICS Framing pulses 3.1.1.6 REPLY TRANSMISSION CHARACTERISTICS Framing pulses. The reply function shall employ a signal comprising two framing pulses spaced 20.3 microseconds as the most elementary code. Information pulses. Information pulses shall be spaced in increments of 1.45 microseconds from the first framing pulse. The designation and position of these information pulses shall be as follows:

Special position identification pulse (SPI) Special position identification pulse (SPI). In addition to the information pulses provided, a special position identification pulse shall be transmitted but only as a result of manual (pilot) selection. When transmitted, it shall be spaced at an interval of 4.35 microseconds following the last framing pulse of Mode A replies only. Reply pulse shape. All reply pulses shall have a pulse duration of 0.45 plus or minus 0.1 microsecond, a pulse rise time between 0.05 and 0.1 microsecond and a pulse decay time between 0.05 and 0.2 microsecond. The pulse amplitude variation of one pulse with respect to any other pulse in a reply train shall not exceed 1 dB.

Code nomenclature. The code designation shall consist of digits between 0 and 7 inclusive, and shall consist of the sum of the subscripts of the pulse numbers employed as follows:

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