Redacted Version Cleared for Public Release · PDF file Redacted Version Cleared for Public...

Click here to load reader

  • date post

    19-Apr-2020
  • Category

    Documents

  • view

    6
  • download

    0

Embed Size (px)

Transcript of Redacted Version Cleared for Public Release · PDF file Redacted Version Cleared for Public...

  • Redacted Version Cleared for Public Release

    Redacted Version Cleared for Public Release

    U. S. DEPARTMENT OF TRANSPORTATION

    FEDERAL AVIATION ADMINISTRATION

    STATUS REPORT: ASSESSMENT OF COMPATIBILITY OF PLANNED LIGHTSQUARED ANCILLARY TERRESTRIAL COMPONENT TRANSMISSIONS IN THE 1526-1536 MHZ

    BAND WITH CERTIFIED AVIATION GPS RECEIVERS

    Redacted Version Cleared for Public Release

    JANUARY 25, 2012

  • Redacted Version Cleared for Public Release

    Redacted Version Cleared for Public Release

    i

    This Page intentionally left blank.

  • Redacted Version Cleared for Public Release

    Redacted Version Cleared for Public Release

    ii

    Executive Summary The Federal Aviation Administration (FAA) has worked with LightSquared since August 2011 to evaluate the compatibility of certified aviation receivers with the planned LightSquared ancillary terrestrial component (ATCt) network using a signal broadcast in the 1526-1536 MHz band.

    The assessment in this report is based on FAA performance standards. Unlike most other GPS devices, certified aviation GPS receivers have interference rejection requirements specified by the FAA and harmonized internationally. Aircraft antenna characteristics are also specified. The use of these specifications precludes the need to individually test every aviation device, and allows the assessment to be accomplished through analysis which estimates the LightSquared interference present at the aircraft GPS receiver, and then compares that level to the specified rejection limits.

    To predict the interference at the aircraft, the FAA has developed a set of propagation models that build upon testing conducted by the mobile satellite services and cellular communications industries for terrestrial applications. Unfortunately, aircraft operate at altitudes where no significant research on propagation has been conducted. Addressing this gap has been the primary focus of the FAA and LightSquared activities though several technical issues remain unresolved, which would require additional resources. While variations in the FAA and LightSquared models affect the scope of impact, they do not affect our fundamental conclusions.

    Two primary conclusions can be drawn from the analysis work done to-date: Conclusion 1

    The incompatibility is primarily focused at lower altitude aviation operations, including impacts to navigation and automatic dependent surveillance – broadcast (ADS-B) for fixed-wing aircraft and helicopters. Of special concern is the impact to terrain awareness and warning systems (TAWS) used by the fixed-wing and helicopter communities to reduce the risk of controlled flight into terrain. This technology uses GPS position in conjunction with a database of terrain to alert the flight crew of potentially unsafe trajectories and was mandated for commercially-operated turbine aircraft with 6 seats or more after the Cali, Columbia accident. TAWS is considered by many in the airplane safety community as the single most important safety device introduced to prevent commercial fatal accidents in the last 20 years. This technology has also been voluntarily adopted in general aviation as part of GPS-based navigation systems. This technology has particular advantage for helicopter operations at low altitudes and outside of FAA- established routes. Many operators of helicopters have voluntarily installed it, and the FAA has proposed mandating it for certain helicopter operations.

    : The proposed ATCt network is not compatible with FAA requirements for operations dependent on GPS receivers at low altitudes in the vicinity of the ATCt transmitters.

    Conclusion 2

    LightSquared has proposed to address this issue through a combination of site-by-site tailoring of their network density and operating parameters plus neutral third-party

    : The variations in local propagation environments preclude adoption of any readily-implementable mitigation for this interference.

  • Redacted Version Cleared for Public Release

    Redacted Version Cleared for Public Release

    iii

    verification. Prior to initiating any attempt to implement such a solution, site-by-site analyses to account for differences in signal blockage and reflections would be required and the remaining technical issues on the specific propagation models would need to be resolved. If, however, these conditions could be accomplished, maintaining the in-air power level limit presents a severe challenge, as the surrounding environment, LightSquared’s network, and aviation operations are all dynamic and continue to change (e.g., helicopter MediVac or search-and-rescue need to be able to operate anywhere, or an adjacent building is constructed which creates a new signal reflection).

    Therefore, the FAA believes that the LightSquared approach will not ensure the current safety levels and has significant concerns in ensuring the efficacy of modulating density and power levels on a site-by-site basis while reacting to future changes in LightSquared’s deployment or aviation operations. In addition, the FAA must maintain oversight and surveillance of critical national airspace equipment and operations and the FAA resources needed to perform this function do not exist.

    This Report represents the FAA views on the progress and outcome of the joint analysis. In the interest of transparency, LightSquared was provided with draft copies of the report and were provided an opportunity to comment or otherwise present their analysis and conclusions. That reaction is provided in its entirety as an Appendix to this report. However, it must be stressed that the views in that Appendix are those of LightSquared and its contractors, and its inclusion does not represent concurrence by the FAA.

  • Redacted Version Cleared for Public Release

    Redacted Version Cleared for Public Release

    iv

    Table of Contents Executive Summary ............................................................................................................ ii 1. Scope and Requirements .................................................................................... 10

    1.1 LightSquared Configuration ............................................................................... 10 1.2 Certified Aviation Receivers .............................................................................. 10 1.3 Tracking and Acquisition Thresholds ................................................................ 11 1.4 Area of Aviation Operation ................................................................................ 13

    2. Transmitter and Receiver Component Assumptions for Analysis ..................... 22 2.1 Transmit Antenna ............................................................................................... 22 2.2 Network Density/Arrangement .......................................................................... 24 2.3 LightSquared Transmit Power ........................................................................... 25 2.4 Network Loading ................................................................................................ 26 2.5 Receiver Antenna ............................................................................................... 26

    3. Analysis Models, Methods, and Results ............................................................ 28 3.1 Path Loss Models ............................................................................................... 28 3.1.1 Deterministic Models ......................................................................................... 28 3.1.2 Probabilistic Models ........................................................................................... 33 3.1.2.1 Probabilistic Model Background ...................................................................... 34 3.1.2.2 General “Extended Suzuki” Model Scenario Dependent Parameters .............. 35 3.1.3 Aggregate Interference Assessment ................................................................... 37 3.2 LAKIE Scenario Description, Analysis, and Results ......................................... 38 3.2.1 LAKIE Scenario Selection and Description ....................................................... 38 3.2.2 LAKIE Scenario-Specific Path Loss Model Parameters .................................... 39 3.2.3 LAKIE Scenario Aggregate Interference Analysis and Results ........................ 40 3.3 DCA Approach Scenarios Description, Analysis, and Results .......................... 44 3.3.1 DCA Runway 19 Approach Scenario Description ............................................. 44 3.3.2 DCA Scenario Site-Specific Path Loss Model Parameters ................................ 47 3.3.3 DCA Scenario Aggregate Interference Analysis and Results ............................ 48 3.3.4 Sensitivity of Monte Carlo Results to Model Parameters .................................. 54 3.4 Other Approach Scenarios and Landing/Surface Operations ............................ 57 3.4.1 United Medical Center, Washington, DC .......................................................... 57 3.4.2 LaGuardia Airport .............................................................................................. 58 3.4.3 Teterboro Airport ............................................................................................... 61 3.5 TAWS, HTAWS and Low Altitude Operations ................................................. 61 3.6 LightSquared Proposed Propagation Model ............................................