# Presentation: 529367

## MPAR Trade Studies

**Mark Weber**
**12 October 2007**

**Notes:**
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.

## Lincoln Laboratory ATC Program History

**1970****	****	****           1980****	****	****	****1990****	****	****           2000**

**Discrete Address Beacon System**

**Mode S**

**Surveillance and Communications**

**Microwave Landing System**

**Beacon Collision Avoidance System        TCAS**

**Moving Target Detector**

**Airport Surface Detection Equipment **

**ASR-9**

**SLEP**

**Parallel Runway Monitor**

**GPS Applications**

**ADS-B**

**Mode S**
**Surface Comms**

**Airport Surface**
**Traffic Automation**

**Terminal ATC Automation**

**NASA ATM Research**

**Storm Turbulence**

**Terminal Doppler Weather Radar**

**SLEP**

**ASR-9 Wind Shear Processor**

**NEXRAD Enhancements**

**Multi Function Phased Array Radar**

**Integrated Terminal Weather System**

**Aviation Weather Research**

**Wake Vortex**

**GCNSS/SWIM**

**Communication,**
**Navigation and**
**Surveillance**

**Automation**

**Weather**

**UAS**

**Corridor Integrated Weather System**

**Runway Status Lights**

**Proc. Augmentation Card**

**Notes:**
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!

## National Air Surveillance Infrastructure

_**Today**_

_**Future**_

**National Air Surveillance Infrastructure**

- 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

**ADS-B**

**MPAR**

**Notes:**
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' | 
1.4 | 
2.0 | >10 pulses
PRI ~ 0.001 sec | 
12 sec |
| Airport Weather
(TDWR) | 212 nmi | 
60 nmi | 
20,000' | 
1 | 
0.5 | ~50 pulses
PRI ~ 0.001 sec | 
180 sec |
| Nationwide Weather
(NEXRAD) | 
225 nmi                                  | 
250 nmi | 
50,000' | 
1 | 
1 | ~50 pulses
PRI ~ 0.001 sec | 
>240 sec |

**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**

**Notes:**
Jeff Herd showed this chart yesterday so I can be brief

Key points in yellow box!

## Outline

**Perspectives on operational needs**
**A specific MPAR concept**
**Summary**

**Notes:**
Rest of my talk will pro vide top-down and bottom-up perspectives on MPAR

## Key Questions

**What are the operational driver’s for the “next generation” ground weather radar network?**
**Improved low altitude coverage, particularly at airports?**
**Volume scan update rate?**
**Capability to observe low-cross section phenomena (e.g clear air boundary winds)?**
**High integrity measurements, devoid of clutter, out-of-trip returns, velocity aliasing, etc.?**
**What are requirements for the ADS-B backup system?**
**Are additional non-cooperative aircraft surveillance capabilities needed to maintain airspace security?**

**Notes:**
These are some key “top down” questions we need to answers

Between Nexrad and the FAA en route route radars we really have very good coverage above 5000’ AGL.  FAA has spent a lot of money providing additional capabilities at airportss.  How much more do we need?  CASA of course very interested.

I’ll comment that I think we can put down pretty good first cut answsers to all of these questions now!  We don’t  need to spend 5 years defining requirements.

## U.S. Airport “Weather” Radars

**U.S. Airport “Weather” Radars**

**Current WSR-88D network does not provide the near-airport low altitude coverage or update rate (30 – 60 sec) needed by terminal ATC**

**Notes:**
This chart emphasizes that MPAR must consider the needs of terminal air traffic controllers and their customers for high quality weather radar data.  In addition to ~50 TDWRs, FAA controllers use weather channel data from 200+ ASRs to provide advisories to pilots in terminal airspace.

The WSR-88D network basically does not satisfy these requirements.   

## Airport Weather Radar Alternatives Analysis

**Wind Shear**
** ****Detection Probability **

**Notes:**
FAA has asked us to look at their near, mid and long-term requirements for airport weather radar observations, and to assess the costs and benefits associated with various sensor configurations.

This chart alludes to an analysis of options for wind shear detection services and other terminal weather services focused on capacity enhancement.  As an example, the pictures here show an analysis of contribution of TDWR to ITWS TWINDS which has very high benefits in congested terminals in aircraft merging/sequencing operations during high wind conditions.  

## Preliminary Findings

**Easy to make the case for high capability airport weather radar at pacing airports (e.g. NYC, ORD, ATL, DFW, ....)**
**Large delay aversion benefits associated with high quality measurements of adverse winds and precipitation (>$10M per year per airport)**
**Business case for “TDWR-like” capability at smaller airports less convincing**
**Alternative solutions may provide adequate safety margin**
**Weather related delay benefits small**
**Implications for MPAR**
**Scalability key to realizing cost-effective solutions**
**Airport-specific integrated observation system configurations will be appropriate in some cases (e.g. western U.S. “dry sites”)**

**Notes:**
Key implication for MPAR is that “one size fits all” mentality is not appropriate.  Highest value to customer will occur if observation system is matched to specific operational needs of individual airport.

## ADS-B Backup Separation Services Map

**Notes:**
Let me turn to the ADS-B backup need.  As was mentioned by Jim Williams yesterday, FAA has defined a near-time strategy for ADS-B backup that involves maintaining legacy primary and secondary radars.  This chart summarizes the capabilities provided by that system 

## Required Surveillance Performance (RSP) Methodology

**Notes:**
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 |

***Only applies for multiple sensors**

***Supports 5 nmi separation**

**Notes:**
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.

## 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’ 
Gaussian |  = 25’ 
Gaussian |
| 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 |  250’ uniform
 = 144’  |
| 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
at 40 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 |

***Only applies for multiple sensors**

***Supports 3 nmi separation**

**Notes:**
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.

## MPAR RSP Analysis

***4.4*********** a*****ntenna beamwidth meets Terminal RSP Separation Error***
***4.6*********** a*****ntenna beamwidth meets En Route RSP Separation Error***

**20:1 Monopulse**

**Notes:**
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.

## Enhanced Regional Situation AwarenessSystem Elements

**Elevated**
**Sentinel Radars**

**FAA Radars**
**And Data Bases**

***Wide Area***

***3-D***

**NORAD**
**TADIL-J**

***Visual***

**Hi-Res **
**EO Sites**

**Mode-S**
**RCVR**

**Redundant Networks**

***USERS***

***FUSION***

***SENSORS***

**Air Situation Decision Support Display and Camera Control**

**Fan-out to Multiple Users**

**Redundant Networks**

**Primary Facility**
**Fusion and Aggregation**

**Evidence Accrual and**
**Decision Support**

**Portable**
**Air Situation Display**

**Lincoln facilities provided infrastructure for rapid system development**
**  ****Radar and camera sites**
**  ****FAA data feeds and fusion**
**  ****Network connectivity**
**Lincoln developed Integrated Air Picture, Decision Support, ID, and Visual Warning deployed for operational use in NCR**

**Notes:**
Finally, I want to briefly touch on Lincoln Laboratory’s perspectives on surveillance requirements for manned aircraft in interior US airspace.

This chart summarizes the ERSA system developed under NORAD sponsorship post-9/11 to improve airspace situational awareness in the NCR.
Three layers– sensors (ATC, special 3D radars– some elevated, cameras cued by the radrs and a laser warning systgem.

Data fusion layer where these sensor information are processed to sort out targets of possible interest from the very high volume of routine civil operations.

User interface layer.

All connected via a network based information management system.

## Lincoln Perspectives on Role of FAA Surveillance Systems

**Current primary/secondary radars “as is” will provide an essential backbone to homeland air picture and decision support system**
**Enhancement recommendations**
**“****Network compatible interface”**
**External access to unfiltered target detections (amplitude, Doppler velocity, ...)**
**Target height information would be very valuable**
**DoD/DHS will deploy ancillary sensor as necessary to meet specific operational needs**

**Notes:**
Very high level comments on the perspectives we’ve gleaned from this activity.

Sensors “as is” provide very valuable input to such systems.

Some mods would be nice, specifically height resolution.

Don’t sweat their requirements – they’ll take what we give them and add to it fullfill their mission requirements.

## Outline

**Perspectives on operational needs**
**A specific MPAR concept**
**Summary**

**Notes:**
So in summary, I think we have some pretty good understanding of the operational needs of the aviation weather community, the ATC surveillance community and perhaps the airspace security community.

Let me conclude with just a couple of charts reminding you of the specific MPAR concept we put out in the JAG report.

##  Concept MPAR Parameters

** ****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**

**Weather Surveillance**

- 334 MPARS required to duplicate today’s airspace coverage.  Half of these are scaled “Terminal MPARS”

**Notes:**
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.

## 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**

**Notes:**
Because our concept is very specific, we can substantiate these assertions.

## 2W Dual Mode T/R Module Parts Costs

**2W Dual Mode T/R Module Parts Costs**

**Parts costs driven by SP2T switches and multi-layer PC board fabrication**
**Packaging / test costs not included**

_**Item      Quantity     Unit Cost    Total Cost**_
**HPA****	****   2****	****   $2.37****	****       $4.74**
**SP2T****	****   3****	****   $4.00****	****       $12.00**
**LNA            1****	****   $1.69****	****       $1.69**
**BPF            1****	****   $3.00****	****       $3.00**
**Diplx****	****   1****	****   $1.50****	****       $1.50**
**Vect Mod****	****   3****	****   $2.14****	****       $6.42**
**Load****	****   1****	****   $2.00****	****       $2.00**
**Board****	****   1****	****   $20.00****	****       $20.00              **
**                                        **
** ****	****	****           ****Total = $51.35**

- v

**Notes:**
And again, because our concept is very specific, we can and have gone ahead and proceeded to develop explicit component designs which in turn allow for realistic tabulation of parts costs.

This example is for the T/R module.

## Preliminary Parts Cost Estimates

| Component | Pre-Prototype | Full Scale MPAR |
| --- | --- | --- |
| Antenna Element | $1.25 | $1.25 |
| T/R Module | $115.00* | $51.00** |
| Power, Timing and Control | $18.00 | $18.00 |
| Digital Transceiver | $12.50 | $6.25 |
| Analog Beamformer | $186.00*** | $55.00**** |
| Digital Beamformer | $18.00 | $8.00 |
| Mechanical/Packaging | $105.00 | $25.00 |

***Equivalent Cost per Element - Parts Only***

**$455.75**

**$164.50**

**Totals:**

*** ****Assumes 8W module incl RF board with sequential polarization**
**** Assumes 2W module and sequential polarization (updated 18 Sept 2007)**
***** Assumes standard beamformer in azimuth**
****** Assumes hybrid tile/brick architecture with RFIC overlapped subarray beamformer**

**Notes:**
Jeff Herd and his colleagues have gone ahead and extended that detailed design exercise to all the components of the concept MPAR and provided these estimates of the amortized per module parts cost of a preprototype and full-scale MPAR.  

$13M per radar parts but remember that half of the MPARS would be much smaller terminal systems providing airport weather services.

Next step, clearly is to understand what the NRE and manufacturing costs that ride on top of these component costs are. So I think, next step is to put out an RFI to industry to undersatnd costs.

## Summary 

**As a community, we are making substantial progress in exposing requirements for the Next Generation surveillance radar network**
**Multifunction, active array (MPAR) approach continues to be a leading candidate**
**Low cost is the key to success of MPAR**
**‘****Commercial’ approach needed to achieve extremely low cost goals**
**We are ready to solicit input from industry on specific design concepts and cost**
**Need to sell concept to policy makers**
**Compelling operational application demonstration**
**Business case substantiating agency cost savings**

**Notes:**
FAA and Lincoln doing a good job of understanding ATC requirements.  Our colleagues here at NSSL and OU are doing corrsponding yeoman’s work in exposing in NWS requirements.

It’s got to be cheap!

We really to find a way to engage the operational community!  Prototyping!