GEO Specification_draft.pdf

WAAS100232A

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WIDE AREA AUGMENTATION SYSTEM

Technical Specifications For

GEO 7 Service Lease

DATE (TBD)

July 2015 WAAS100232A

DOCUMENT CHANGE HISTORY

Process Version Issue Date Reason for Change Originator

01 01/11/2012 Initial Release G. Pazos

02 06/25/2013

Changed sign error in Short-Term Fractional Coherence Limitation between L1 & L5 Carriers equation. Updated Short-Term End-to-End Carrier Frequency Stability. Updated Min and Max User Received Signal Strengths.

J. Burn

03 03/03/2014 Made changes to clarify the Long- Term Frequency Stability requirement

J. Burn

04 07/06/2015

Removed Type-1 from GUST and SGST. Updated figures and references. Added clarification to the end-to-end requirements:

Added clarification to Maximum Frequency Translation Error;

Corrected the Phase Noise Density of the Frequency Offset for Carrier; and other editorial changes.

J. Burn

05 Incorporate changes from

Table of Contents

1 INTRODUCTION

1.1 PURPOSE AND SCOPE

1.2 SYSTEM OVERVIEW

1.3 WAAS GEO SATELLITE AND GUS PAIR

1.4 DOCUMENT OVERVIEW

2 APPLICABLE DOCUMENTS

2.1 GENERAL

2.2 GOVERNMENT DOCUMENTS ........................................................ ERROR! BOOKMARK NOT DEFINED.

2.2.1 SPECIFICATIONS, STANDARDS AND OTHERS ........................... ERROR! BOOKMARK NOT DEFINED.

2.2.1.1 Specifications

2.2.1.2 FAA Documents

2.2.1.3 Other Documents

3 TECHNICAL REQUIREMENTS

3.1 INTERFACE REQUIREMENTS

3.1.1 SGS/RFU INTERFACE

3.1.2 SCC/MCP INTERFACE

3.2 WAAS REQUIREMENTS

3.2.1 WAAS END-TO-END REQUIREMENTS

3.2.1.1 Code-Carrier Coherence (CCC) for L1 and L5

3.2.1.1.1 Short-Term CCC for L1 and L5 Signals

3.2.1.1.1.1 Short-Term CCC Limitation for L1 and L5 Signals

3.2.1.1.2 Long-Term CCC for L1 and L5 Signals

3.2.1.1.2.1 Long-Term CCC Limitation for L1 and L5 Signals

3.2.1.1.3 Steady State CCC for L1 and L5 Signals

3.2.1.1.3.1 Steady State CCC Limitation for L1 and L5 Signals

3.2.1.2 Fractional Coherence between L1 and L5 Carriers

3.2.1.2.1 Short-Term Fractional Coherence between L1 and L5 Carriers

3.2.1.2.1.1 Short-Term Fractional Coherence Limitation between L1 and L5 Carriers

3.2.1.2.2 Long-Term Fractional Coherence between L1 and L5 Carriers

3.2.1.2.2.1 Long-Term Fractional Coherence Limitation between L1 and L5 Carriers

3.2.1.3 Correlation Loss

3.2.1.4 Short-Term End-to-End Carrier Frequency Stability

3.2.1.5 User Received Signal Strength

3.2.1.5.1 Maximum User Received Signal Strength

3.2.1.5.1.1 Maximum User Received Signal Strength for L1

3.2.1.5.1.2 Maximum User Received Signal Strength for L5

3.2.1.5.2 Minimum User Received Signal Strength

3.2.1.5.2.1 Minimum User Received Signal Strength for L1

3.2.1.5.2.2 Minimum User Received Signal Strength for L5

3.2.1.6 Doppler Shift

3.2.1.7 Spectral Occupancy

3.2.1.7.1 L1 Spectral Occupancy

3.2.1.7.2 L5 Spectral Occupancy

3.2.1.8 Polarization

3.2.1.9 SIS Phase Noise

3.2.1.10 SIS L1/L5 Crosstalk

3.2.1.11 Radio Frequency (RF) Interference Rejection

3.2.1.11.1 In-Band

3.2.1.11.1.1 In-Band Rejection for Continuous Wave (CW) and Noise Interference

3.2.1.11.1.2 In-Band Rejection for Pulsed Interference

3.2.1.11.1.3 In-Band Rejection for Pulsed Interference – Verification

3.2.1.11.2 Out-of-Band

3.2.1.11.2.1 Out-of-Band Rejection for CW Interference

3.2.1.11.3 WAAS GEO Uplink Protection

3.2.1.12 Reliability, Maintainability and Availability (RMA)

3.2.1.12.1 Service Reliability

3.2.1.12.2 GUS Mean Time Between Failure

3.2.1.12.3 GUS Maintenance During Normal Operation

3.2.1.12.4 GUS Mean Time to Repair (MTTR)

3.2.1.12.5 GUS Antenna Actuator MTTR

3.2.1.12.6 GUS Periodic Maintenance Service Interruptions

3.2.1.12.7 GUS Periodic Maintenance Interval

3.2.1.12.8 GUS Periodic Maintenance Tasks

3.2.1.12.8.1 Manufacturer’s Recommended Periodic Maintenance

3.2.1.12.9 GUS Periodic Maintenance Cumulative Time

3.2.1.12.10 Off-line Equipment Verification

3.2.2 WAAS GEO SATELLITE NAVIGATION PAYLOAD REQUIREMENTS

3.2.2.1 WAAS GEO Satellite Capabilities

3.2.2.2 WAAS GEO Satellite Orbital Arc

3.2.2.3 Navigation Transponder Frequency Translation

3.2.2.3.1 Maximum Frequency Translation Error

3.2.2.3.2 Difference in Downlink Signals Frequency Translation Error

3.2.2.3.3 Navigation Transponder Carrier Frequency

3.2.2.3.4 Navigation Transponder Signal Spectrum

3.2.2.4 Navigation Transponder Mean Mission Duration

3.2.2.5 Navigation Transponder Spurious Transmission

3.2.2.6 Navigation Transponder Frequency Stability

3.2.2.6.1 Short Term Frequency Stability

3.2.2.6.2 Long Term Frequency Stability

3.2.2.7 Navigation Transponder Transmit Coverage

3.2.2.8 Navigation Transponder Antenna Gain Variation

3.2.2.9 Navigation Transponder Axial Ratio

3.2.2.10 Navigation Transponder Uplink Interference Protection

3.2.2.11 Navigation Transponder EIRP

3.2.2.11.1 Maximum Saturated EIRP at L1

3.2.2.11.2 Maximum Saturated EIRP at L5

3.2.2.11.3 Minimum Saturated EIRP at L1

3.2.2.11.4 Minimum Saturated EIRP at L5

3.2.2.11.5 EIRP Stability

3.2.2.11.5.1 Saturated EIRP Stability

3.2.2.11.5.2 Small Signal EIRP Stability

3.2.2.12 Uplink Receive Gain-to-noise Temperature ratio (G/T)

3.2.2.13 Navigation Transponder Phase Variation with Dynamic Range

3.2.2.13.1 Phase Variation, Peak-to-Peak (dB)

3.2.2.13.2 Overall Group Delay

3.2.2.13.3 Group Delay Stability

3.2.3 RFU SUBSYSTEM REQUIREMENTS

3.2.3.1 RFU Performance Requirements

3.2.3.2 Transmit Channel Characteristics

3.2.3.2.1 Transmit Channel Time Delay

3.2.3.2.1.1 Transmit Channel Time Delay Uncertainty

3.2.3.2.2 Transmit Channel Coherency

3.2.3.2.3 Transmit Channel Harmonics

3.2.3.2.4 Transmit Frequency Accuracy

3.2.3.2.5 Transmit Amplitude Modulation (AM)/ Phase Modulation (PM) Conversion

3.2.3.2.6 RFU Transmit Phase Linearity

3.2.3.2.6.1 Phase Linearity at Uplink 1

3.2.3.2.6.2 Phase Linearity at Uplink 2

3.2.3.2.7 Uplink Nominal EIRP

3.2.3.2.7.1 EIRP Increase

3.2.3.2.7.2 Increase in Uplink EIRP

3.2.3.2.8 RFU Transmit Gain Flatness

3.2.3.2.8.1 Gain Flatness at Uplink 1

3.2.3.2.8.2 Gain Flatness at Uplink 2

3.2.3.2.9 Sidelobes

3.2.3.2.9.1 Sidelobe Peak

3.2.3.2.9.2 Sidelobe Peak Applicability

3.2.3.2.10 Antenna Sidelobe EIRP Density

3.2.3.2.10.1 EIRP Constraints

3.2.3.2.11 Transmit Phase Noise

3.2.3.2.11.1 Transmit Phase Noise Spectrum

3.2.3.2.11.2 Transmit Phase Noise Limitation

3.2.3.2.12 Transmit Signal Level

3.2.3.3 Receive L-Band Channel Characteristics

3.2.3.3.1 Receive L-Band Passband

3.2.3.3.1.1 Receive Passband at L1

3.2.3.3.1.2 Receive Passband at L5

3.2.3.3.2 Receive L-Band G/T

3.2.3.3.3 Receive L-band Antenna Pointing and Tracking

3.2.3.3.4 Receive Channel Time Delay

3.2.3.3.4.1 Receive Time Delay for L1

3.2.3.3.4.2 Receive Time Delay for L5

3.2.3.3.5 Receive Channel Coherency

3.2.3.3.6 Receive Phase Linearity

3.2.3.3.6.1 Receive Phase Linearity – L1

3.2.3.3.6.2 Receive Phase Linearity – L5

3.2.3.4 RFU Built-in-Test Capabilities

3.2.3.4.1 RF/IF Test Capabilities

3.2.3.4.2 Test Translator Requirement

3.2.3.4.3 Delay Calibration Requirement

3.2.4 OPERATIONAL REQUIREMENTS

3.2.4.1 GUS Maintenance During Normal Operation

3.2.4.1.1 GUS Average Logistics Delay Time

3.2.4.2 Uninterruptible Power

3.2.4.3 Standby Power

3.2.4.4 Human Engineering

3.2.4.5 Personnel Safety

3.2.4.6 Computer Resources

3.2.4.6.1 Computer Memory

3.2.4.6.1.1 Volatile Memory

3.2.4.6.1.2 Non-Volatile Memory

3.2.4.6.1.3 Memory Increase Capability

3.2.4.6.1.4 Computer Resource Reserve Capacity

3.2.4.6.2 Software Development Requirement

3.2.4.6.3 Fail-Safe Operation

3.2.4.6.4 Security Protection

4 VERIFICATION REQUIREMENTS

4.1 VERIFICATION METHODS

APPENDIX I: ACRONYMS

1 INTRODUCTION

1.1 PURPOSE AND SCOPE

This document establishes the functional and performance requirements for the Wide Area Augmentation System (WAAS) Geostationary Earth Orbit (GEO) Satellite Payload (GSP) Service Lease for the 7th WAAS GEO satellite.

1.2 SYSTEM OVERVIEW

The WAAS is a safety-critical system consisting of equipment and software that augments the Department of Defense (DoD) Global Positioning System (GPS) Standard Positioning Service (SPS). The primary mission of WAAS is to provide a means for air navigation for all phases of flight in the National Airspace System (NAS) from departure through en route and approach. WAAS augments GPS with:

a. A ranging function, which improves availability;

b. Differential GPS corrections, which improve accuracy; and

c. Integrity monitoring, which improves safety.

WAAS provides a Signal-in-Space (SIS) to WAAS certified avionics for FAA approved phases of flight. The SIS provides data corrections for the GPS and GEO satellites, and a ranging capability.

As shown in Figure 1-1, the main architectural components of WAAS are the Wide-area Reference Stations (WRSs), the Wide-area Master Stations (WMSs), the GEO Uplink Subsystems (GUSs), the GSPs, and the Terrestrial Communications Subsystem (TCS), which interconnects the WAAS components. Each GSP has, associated with it, two dedicated, geographically diverse GUSs. The two GUSs are functionally redundant and operate under coordinated control such that one GUS operates as the Primary uplink to the GSP, while the other operates as a Backup radiating into a dummy load.

Broadcasts from the GPS and GEO satellites are received and processed by widely-dispersed WRSs that are strategically located for optimum data collection within the WAAS service volume. Processed data from the WRSs is forwarded to WMSs for further processing to determine the integrity, differential corrections, and residual errors for each monitored satellite and for each predefined Ionosphere Grid Point (IGP).

Multiple WMSs are provided to eliminate single-point failures within the WAAS.

Although all WMSs send data to all GUSs, only data from the selected source WMS is accepted by the GUSs. The GUSs modulate the navigation message and transmit the GPS-like SIS to their respective GEO satellite that broadcasts the WAAS SIS to Users.

Figure 1-1 WAAS Overview

The WAAS User receiver processes (1) integrity data to ensure that the satellites being used are providing in-tolerance navigation data; (2) differential correction and ionospheric data to improve the accuracy of the User's position solution and (3) ranging data from one or more of the GEO satellites for use in user position determination. In addition to providing GPS integrity, WAAS verifies the integrity of its own data broadcast and takes any necessary action to ensure that the system meets the WAAS performance requirements.

1.3 WAAS GEO SATELLITE AND GUS PAIR

Figure 1-2 shows the architecture of a typical WAAS GEO satellite and its dedicated GUS pair – one operating in the Primary and the other in the Backup mode. The Contractor Furnished Equipment (CFE) (shown in broken, blue lines) consists essentially of a GSP and its associated pair of Radio Frequency Uplink (RFU) subsystems. The Government Furnished Equipment (GFE) consists of the Signal Generator Subsystem (SGS). Each GUS consists of an RFU subsystem and an SGS, including associated site-specific equipment and facilities.

Figure 1-2 WAAS SIS Broadcast

1.4 DOCUMENT OVERVIEW

Section 2 lists the specifications, standards and orders referred to in this document.

Section 3 specifies the functional and performance requirements. Section 4 identifies requirements for test and verification that the Contractor must satisfy to be compliant with these Technical Specifications. Appendix I contains acronyms and definitions for the various terms used in this document.

The following terms used in this Specification carry the meaning defined below:

Must: identifies a mandatory requirement

Will: indicates a statement of intent or fact

2 APPLICABLE DOCUMENTS

2.1 GENERAL

This section and its subsections identify the specifications, handbooks, orders, standards, and drawings that form a part of the Technical Specifications and are applicable to the extent specified herein. The latest version of these documents as of the contract award date will apply. In the event of a conflict between the contents of this document and the references cited herein, the contents of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

2.2 LIST OF APPLICABLE DOCUMENTS

2.2.1.1 Specifications

a.

Document Number

Document Name Revision/ Date

Reference

Global Positioning Systems Standard Positioning Service Signal Specification

3.2.1

Global Positioning System Wide Area Augmentation System Performance Standard

31 October

IS-GPS-200 Global Positioning System Wing (GPSW) Systems Engineering and Integration Interface Specification

Revision E, 8 June 2010

IS-GPS-705 GPSW Interface Specification Revision A, 8 June 2010

International Telecommunications Union (ITU) Radio Regulations for RHCP and Left Hand Circular Polarization (LHCP), Article 1, Numbers 154 and 155

3.2.1.8

2.2.1.2 FAA Documents

a.

Document Number

Document Name Revision/ Date

Reference

FAA-STD-

026A

NAS Software Development June 2001

FAA-E-2892d System Specification for Wide Area Augmentation System

March 2012

FAA-G-2100H Electronic Equipment, General Requirements May 2005

WAAS100161 WAAS Radio Frequency Uplink (RFU)/Signal Generator Subsystem (SGS) Interface Control Document (ICD)

August 2014

WAAS100184 Satellite Control Center (SCC)/Message Control Processor (MCP) ICD

January

2.2.1.3 Other Documents

a. RTCA/DO-178B, Software Considerations in Airborne Systems and Equipment

Certification, December 1992

Document Number

Document Name Revision/ Date

Reference

RTCA/DO-

178B

Software Considerations in Airborne Systems and Equipment Certification

December

GNSS SARPS 3.2.1

3 TECHNICAL REQUIREMENTS

This section and its subsections specify the requirements that the Contractor and its subcontractors must satisfy.

Within the Technical Requirements section, clarifications are in italics.

3.1 INTERFACE REQUIREMENTS

3.1.1 SGS/RFU INTERFACE

All interface requirements of the WAAS RFU/SGS ICD must be satisfied.

3.1.2 SCC/MCP INTERFACE

All requirements of the SCC/MCP ICD must be satisfied.

3.2 WAAS REQUIREMENTS

“Objective” represents desired performance requirements and “threshold” represents minimum mandatory performance requirements.

3.2.1 WAAS END-TO-END REQUIREMENTS

The WAAS SIS performance requirements will be met under the following conditions:

a. the GPS satellite constellation is operational as defined by the Global Positioning Systems Standard Positioning Service Signal Specification;

b. the user equipment is within the service volume;

c. GPS satellite outage rates conform to the definition provided in FAA-E-

2892d, Appendix C.

d. The WAAS GEO satellite signal waveform distortions are as described in

GNSS SARPs, Amendment 85 of ICAO Annex 10, Vol. I. WAAS GEO satellite signal waveform distortions with parameters outside this range can be assumed not to occur; and

e. the avionics contribution to pseudorange error is assumed to be zero.

3.2.1.1 Code-Carrier Coherence (CCC) for L1 and L5

The SGS contains the SIS generation capability that will be tailored by the FAA for specific approaches for verification of the requirements.

3.2.1.1.1 Short-Term CCC for L1 and L5 Signals

The lack of coherence between the phase of the broadcast SIS carriers, L1 at 1575.42 Megahertz (MHz) and L5 at 1176.45MHz, and their respective codes must be limited in accordance with the equation in 3.2.1.1.1.1.

3.2.1.1.1.1 Short-Term CCC Limitation for L1 and L5 Signals

The root mean square (rms) over T seconds of the error due to a 10-second, carrier smoothing of the code-based pseudorange must be less than 0.15 meters for L1, and less than 0.2 meters for L5.

rms(T sec) ( ) ( )Li LiPR t PR t − < 0.15 m/0.2 m for L1/L5, respectively for i = 1 and 5, ( ) ( ) ( ) ( )( )1 1 ( ) 1Li Li Li Li Li

PR t MPR t PR t CR t CR t M M

− = + − + − − , t = 1,2,3,---

( )LiPR t is the Li pseudorange in meters that would be measured by a noiseless receiver, ( )LiPR t is the carrier-smoothed Li pseudorange, ( )LiCR t is the biased Li carrier range in meters that would be measured by a noiseless receiver, T = 3600 seconds (1 hour), and M = 10 seconds is the smoothing interval.

Short-Term CCC does not include code-carrier divergence due to ionospheric refraction in the downlink propagation path or error due to local effects such as multipath.

3.2.1.1.2 Long-Term CCC for L1 and L5 Signals

The lack of coherence between the phase of the broadcast SIS carriers, L1 and L5, and their respective codes must be limited in accordance with the equation in 3.2.1.1.2.1.

3.2.1.1.2.1 Long-Term CCC Limitation for L1 and L5 Signals

The rms over T seconds of the error due to a 100-second carrier smoothing of the code-based pseudoranges must be less than one carrier wavelength for L1 and L5 signals.

rms(T sec) ( ) ( )Li LiPR t PR t − < 0.19 m/0.255 m for L1/L5, respectively for i = 1 and 5.

, t = 1,2,3,---

( )LiPR t is the Li pseudorange in meters that would be measured by a noiseless receiver, ( )LiPR t is the carrier-smoothed Li pseudorange, ( )LiCR t is the biased Li carrier range in meters that would be measured by a noiseless receiver, T = 86,400 seconds (1 day), and M = 100 seconds is the smoothing interval.

Long-Term CCC does not include code-carrier divergence due to ionospheric refraction in the downlink propagation path or error due to local effects such as multipath.

3.2.1.1.3 Steady State CCC for L1 and L5 Signals

The lack of coherence between the broadcast SIS carriers’ (L1 and L5) phases and their respective code phases must be limited in accordance with the equation in 3.2.1.1.3.1.

( ) ( ) ( ) ( )( )1 1 ( ) 1Li

Li Li Li Li

PR t MPR t PR t CR t CR t M M

3.2.1.1.3.1 Steady State CCC Limitation for L1 and L5 Signals The difference between the Code Minus Carrier corrected for the Ionosphere (CMCI) at a given time and the value of CMCI smoothed over a two-day period must not exceed the following mask.

( ) ( ) 910 , 1 14400 14400Li Li tt t m tρ ρ− ≤ − ≤ ≤

144001 0.5 , 14400 86400 72000 t m t− ≤ − < ≤

0.5 , 86400m t≤ > for i = 1, 5 where t is the number of seconds since the most recent GUS Switchover, for t = 1,2,3,---and where

( ) ( ) ( )Li Li Lit PR t CR tρ = −

Li Li t j t j t ρ ρ

= ∑ , t = 1,2,3,---, M

( ) ( ) ( )1 1Li Li Li t Mt t M M ρ ρ ρ−

= + − , t > M

( )LiPR t is the Li pseudorange in meters at time t that would be measured by a noiseless receiver, ( )LiCR t is the biased Li carrier range in meters at time t that would be measured by a noiseless receiver, ( )Li tρ is the Li CMCI in meters at time t, ( )Li tρ is the smoothed Li CMCI in meters at time t, and M = 172800 seconds (2 days).

As in the definitions of ( )LiPR t and ( )LiCR t in Sections 3.2.1.1.1.1 and 3.2.1.1.2.1 above, it is assumed that these waveforms have been corrected for ionospheric refraction in the downlink propagation path, or equivalently, that they have been measured at the Space Vehicle (SV) and thus need no such correction.

3.2.1.2 Fractional Coherence between L1 and L5 Carriers

3.2.1.2.1 Short-Term Fractional Coherence between L1 and L5 Carriers The lack of coherence between the broadcast SIS L1 carrier phase and the L5 carrier phase must be limited in accordance with the equation in 3.2.1.2.1.1.

3.2.1.2.1.1 Short-Term Fractional Coherence Limitation between L1 and L5 Carriers

The rms over T seconds of the error due to 10-second differential carrier smoothing of the pseudorange-based ionospheric delay estimates at L1 must be less than 0.20 meters.

rms(T sec) ( ) ( )I t I t − <

0.2 m where

1 5

L L

L

L

PR t PR tI t f f

111ˆ1ˆˆ

L

L

LLLL

f f tCRtCRtCRtCRtI M

M M tItI , for t = 1,2,3,--

At t=0, raw measurements should be used.

1( )LPR t , 5 ( )LPR t , 1( )LCR t , 5 ( )LCR t are defined above, ( )I t is the pseudorange-based

L1 ionospheric delay estimate, ( )I t is the smoothed pseudorange-based L1 ionospheric delay estimate, 1Lf is the L1 carrier frequency, 5Lf is the L5 carrier frequency, T = 3600 seconds (1 hour), and M = 10 seconds is the smoothing interval.

3.2.1.2.2 Long-Term Fractional Coherence between L1 and L5 Carriers The lack of coherence between the broadcast SIS L1 carrier phase and the L5 carrier phase must be limited in accord with the equation in 3.2.1.2.2.1.

3.2.1.2.2.1 Long-Term Fractional Coherence Limitation between L1 and L5 Carriers

The rms over T seconds of the error due to a 100-second differential carrier smoothing of the pseudorange-based ionospheric delay estimates at L1 must be less than 0.255 meters (L5 wavelength).

rms(T sec) ( ) ( )I t I t − <

0.255 m where ( )I t and ( )I t are defined above, T = 86,400 seconds (1 day), and M = 100 seconds is the smoothing interval.

3.2.1.3 Correlation Loss

The correlation loss resulting from SIS signal generation, modulation, transmission imperfections and filtering in the WAAS GEO satellite payload must be less than 1 decibel (dB).

3.2.1.4 Short-Term End-to-End Carrier Frequency Stability

Including uplink propagation effects, the threshold additive short-term stabilities of the L1 and L5 carrier frequencies (square root of the Allan Variance) at the input of the User antenna must be better than 5.0E-11 and 6.7E-11, respectively, and the objective values must be better than 1.0E-12 and 1.34E-12, respectively, over 1 to 10 seconds. This does not include downlink propagation effects due to the ionosphere, Doppler and multipath.

3.2.1.5 User Received Signal Strength

3.2.1.5.1 Maximum User Received Signal Strength

3.2.1.5.1.1 Maximum User Received Signal Strength for L1

The maximum received signal strength at L1 at the output of a 3-dBil User antenna at its best orientation must be less than or equal to -152.5 decibels relative to 1 Watt (dBW) for the WAAS GEO satellites.

This requirement limits the spread between maximum and minimum User received signal strength to 6 dB (see Section 3.2.1.5.2.1 below). ‘Best’ orientation is defined as the linearly polarized User antenna aligned with the major axis of the received signal polarization ellipse.

3.2.1.5.1.2 Maximum User Received Signal Strength for L5

The maximum received signal strength at L5 at the output of a 3-dBil User antenna at its best orientation must be less than or equal to -151.0 dBW.

3.2.1.5.2 Minimum User Received Signal Strength

3.2.1.5.2.1 Minimum User Received Signal Strength for L1

The minimum received signal strength at L1 at the output of a 3-dBil User antenna at its worst orientation must be greater than or equal to -158.5 dBW within the SIS coverage (User elevation angle ≥ 5 degree elevation angle).

‘Worst’ orientation is defined as the linearly polarized User antenna aligned with the minor axis of the received signal polarization ellipse.

3.2.1.5.2.2 Minimum User Received Signal Strength for L5

The minimum received signal strength at L5 at the output of a 3-dBil User antenna at its worst orientation must be greater than or equal to -157.0 dBW within the SIS coverage.

3.2.1.6 Doppler Shift

The Doppler shift of the SIS, as perceived by a stationary User, must be less than 40 meters per second in the worst case.

“Worst case” is expected to be at the End-of-Life (EOL) of the WAAS GEO satellite.

3.2.1.7 Spectral Occupancy

3.2.1.7.1 L1 Spectral Occupancy

The 3-dB bandwidth for the L1 SIS must be greater than or equal to 20 MHz.

3.2.1.7.2 L5 Spectral Occupancy

The 3-dB bandwidth for the L5 SIS must be greater than or equal to 20 MHz.

3.2.1.8 Polarization

The SIS must accommodate Right Hand Circular Polarization (RHCP) in accordance with the sense of polarization defined in the International Telecommunications Union (ITU) Radio Regulations for RHCP and Left Hand Circular Polarization (LHCP), Article 1, Numbers 154 and 155.

3.2.1.9 SIS Phase Noise

The end-to-end SIS single-sided phase noise for corresponding frequency offsets from the nominal frequency must be equal to or less than the values shown in Table 3-1.

Table 3-1 End-to-End SIS Phase Noise

Frequency Offset from Carrier (Hertz(Hz)) Phase Noise (dBc/Hz)

1 -22

5 -50

10 -55

100 -69

1000 -77

10K -88

100K -93

300K -93

> 1000K -95

3.2.1.10 SIS L1/L5 Crosstalk

Crosstalk measured on L1 due to L5 must be equal to or less than –30 dB. Crosstalk measured on L5 due to L1 must be equal to or less than –30 dB.

3.2.1.11 Radio Frequency (RF) Interference Rejection

The requirements stated below assume an RF environment in which unintentional interference above the stated rejection levels are absent due to:

a) Appropriate antenna site selection;

b) Suitable filtering of emissions by offending interference sources; and/or

c) Regulatory mandates to curtail offending interference sources.

3.2.1.11.1 In-Band

In-band must include all frequencies between 1166.45 MHz and 1237.6 MHz for the GPS L2-P(Y) and GPS/WAAS L5 signals and between 1565.42 MHz and 1585.42 MHz for the GPS L1-C/A and WAAS L1 signals. For purposes of verification relative to the paragraphs below, multiple interferers must be at the same elevation angle.

3.2.1.11.1.1 In-Band Rejection for Continuous Wave (CW) and Noise Interference

3.2.1.11.1.1.1 In-Band Rejection for CW and Noise Interference – Operating Environment

After initial signal acquisition and steady-state operation has commenced, a WAAS antenna/receiver must operate in the presence of a single CW or noise interferer with an interference to signal power ratio of 30 dB for GPS and 24 dB for WAAS.

3.2.1.11.1.1.2 In-Band Rejection for CW and Noise Interference – Verification For purposes of verification, the interference signal must be relative to the minimum WAAS signal levels stated in 3.2.1.5.2.1 and 3.2.1.5.2.2.

3.2.1.11.1.2 In-Band Rejection for Pulsed Interference

3.2.1.11.1.2.1 In-Band Rejection for Pulsed Interference – Operating Environment After initial signal acquisition and steady-state operation has commenced, a WAAS antenna/receiver must operate in the presence of a single pulsed interferer with characteristics identified in Table 3-2.

Table 3-2 In-band Rejection Characteristics for Pulsed Interference

Signal WAAS GPS Only

Peak Power +10 dBm +10 dBm

Pulse Width 125 μsec 1 ms

Pulse Duty Cycle 10% 10%

3.2.1.11.1.3 In-Band Rejection for Pulsed Interference – Verification For purposes of verification, the interference signal must be relative to the minimum WAAS signal levels stated in 3.2.1.5.2.1 and 3.2.1.5.2.2 and only interference signal bandwidths greater than 100 Kilohertz (kHz) are applicable.

3.2.1.11.2 Out-of-Band

Out-of-band must include all frequencies less than 1166.45 MHz, all frequencies between

1237.6 MHz and 1565.42 MHz, and all frequencies greater than 1585.42 MHz.

3.2.1.11.2.1 Out-of-Band Rejection for CW Interference

3.2.1.11.2.1.1 Out-of-Band Rejection for CW Interference – Operating Environment

After initial signal acquisition and steady-state operation has commenced, a WAAS antenna/receiver must operate in the presence of a single CW interferer with characteristics identified in Table 3-3 (see Figure 3-1 also).

Table 3-3 Out-of-band Rejection Characteristics for CW Interference

Interference Frequency, f (MHz) Interference to Signal Power Ratio (dB) f ≤ 1106.45 ≥150

1106.45 < f ≤ 1166.45 +150 – 2*(f-1106.45)

1237.6 < f ≤ 1297.6 +30 + 2*(f–- 1237.6)

1297.6 < f ≤ 1505.42 ≥150

1505.42 < f ≤ 1565.42 +150–- 2*(f-1505.42)

1585.42 < f ≤ 1645.42 +30 + 2*(f–- 1585.42)

1645.42 < f ≥150

Figure 3-1 Out-of-Band Rejection Characteristics for CW Interference

3.2.1.11.2.1.2 Out-of-Band Rejection for CW Interference – Verification For purposes of verification, the interference signal must be relative to the minimum WAAS signal levels stated in 3.2.1.5.2.1 and 3.2.1.5.2.2.

3.2.1.11.3 WAAS GEO Uplink Protection

The WAAS GEO uplinks must be protected from RF interference causing Hazardously Misleading Information (HMI).

3.2.1.12 Reliability, Maintainability and Availability (RMA)

3.2.1.12.1 Service Reliability

Service reliability is defined as the WAAS providing a SIS to Users, assuming the WMS is operating fault-free.

The end-to-end SIS service reliability for the GEO satellite and associated GUS pair must be greater than 0.9995 in any one hour interval including all outages due to GUS failures or scheduled GUS maintenance.

The service reliability must be determined using Mean Time Between Failure (MTBF) and outage rate data with the assumption that software reliability is 1.0 and GUS switchover time is zero.

3.2.1.12.2 GUS Mean Time Between Failure

Each GUS must have a minimum Critical Mean Time Between Failure (CMTBF) of at least 3000 hours and a minimum Series Mean Time Between Failure (SMTBF) of at least 2190 hours.

3.2.1.12.3 GUS Maintenance During Normal Operation

The GUS must be capable of operation in the normal state without additional degradation of WAAS service during all periods that corrective maintenance is being performed on the other GUS.

3.2.1.12.4 GUS Mean Time to Repair (MTTR)

The GUS MTTR must be less than or equal to 60 minutes, including the time required for manual fault isolation, repair, test and restoration. The GUS MTTR includes active corrective maintenance tasks but excludes maintenance task times for repairs that are not controlled by system design such as GPS acquisition time or warm up and initialization times.

MTTR begins when the maintenance technician arrives at the equipment and ends when the maintenance technician has turned the repaired equipment over to an FAA certifying authority.

3.2.1.12.5 GUS Antenna Actuator MTTR

The MTTR for the GUS antenna actuator must be less than or equal to 12 hours, exclusive of the time required to have a crane on site.

3.2.1.12.6 GUS Periodic Maintenance Service Interruptions

Periodic maintenance of the GUSs requiring removal of the affected GUS from an operational state must be coordinated to prevent WAAS SIS interruption. Periodic maintenance of the GUSs must not require WAAS SIS interruption.

3.2.1.12.7 GUS Periodic Maintenance Interval

The periodic maintenance interval for each GUS must be greater than 2,190 hours (three months).

3.2.1.12.8 GUS Periodic Maintenance Tasks

Periodic maintenance of the GUSs must be limited to cleaning, inspecting, adjusting and replacing parts in accordance with their service life expectancy or as found necessary during inspection.

3.2.1.12.8.1 Manufacturer’s Recommended Periodic Maintenance

The periodic maintenance requirements must be established for each of the equipment items from manufacturer’s or vendor’s requirements.

3.2.1.12.9 GUS Periodic Maintenance Cumulative Time

Periodic maintenance must not cause more than eight (8) hours outage per GUS per year.

The antenna is excluded from this requirement for the maintenance period(s) required for painting of the antenna.

3.2.1.12.10 Off-line Equipment Verification

The RFU must support verification of GUS operation in an off-line mode which does not jeopardize WAAS operation after the faulty equipment has been replaced, or the software has been re-initialized or reloaded.

3.2.2 WAAS GEO SATELLITE NAVIGATION PAYLOAD REQUIREMENTS

3.2.2.1 WAAS GEO Satellite Capabilities

The WAAS GEO must:

a) Receive the generated WAAS message from the RFU; and

b) Broadcast the WAAS message to the User.

3.2.2.2 WAAS GEO Satellite Orbital Arc

WAAS GEO satellites must be located in the orbital arc of 115°West Longitude (WL) – 137°WL (threshold), 119°WL – 129°WL (objective).

3.2.2.3 Navigation Transponder Frequency Translation

The navigation transponder must be a dual-channel transponder that translates the uplink signals to the downlink L-band (L1 and L5) navigation signals.

3.2.2.3.1 Maximum Frequency Translation Error

The Maximum Frequency Translation Error from each uplink frequency to the associated downlink frequency must be less than 1 part in 1.0E+7. The maximum peak-to-peak diurnal frequency deviation about the translation error on each downlink frequency must not exceed 1.1 Hz per day.

3.2.2.3.2 Difference in Downlink Signals Frequency Translation Error The difference in the frequency translation error between the downlink signals must not exceed 1 part in 1.0E+8 over the GSP service life.

3.2.2.3.3 Navigation Transponder Carrier Frequency

The WAAS broadcast must consist of two independent carrier frequencies of 1575.42 MHz (GPS L1) and 1176.45 MHz (GPS L5).

3.2.2.3.4 Navigation Transponder Signal Spectrum

Ninety-nine percent (99%) of the broadcast signal power for each signal must be in a 41- MHz bandwidth centered at the respective L1 and L5 carrier frequencies.

3.2.2.4 Navigation Transponder Mean Mission Duration

The navigation transponder must be configured to provide performance in accordance with the performance requirements herein for a minimum of 10 years.

3.2.2.5 Navigation Transponder Spurious Transmission

For single-carrier illumination at a power level that is sufficient to drive the transponder amplifier to saturation, in-band spurious transmissions must be at least 40 dB below the unmodulated carriers over all frequencies when the carriers are modulated with the appropriate Pseudo Random Noise (PRN) code.

This requirement must be met with a single-carrier illumination at a power level sufficient to drive the power amplifier to saturation, at frequencies anywhere within the navigation channel and for any number of RF channels of the communications subsystem.

3.2.2.6 Navigation Transponder Frequency Stability

3.2.2.6.1 Short Term Frequency Stability

Over a period of 1 to 10 seconds, the contribution to downlink frequency stability (square root of the Allan variance) from the conversion oscillator (includes reference oscillator, multiplier Phase Lock Loop (PLL) and mixer) must be better than 4.0E-11 (threshold), 1.0E-12 (objective) for L1 and better than 5.36E-11 (threshold), 1.34E-12 (objective) for L5.

3.2.2.6.2 Long Term Frequency Stability

Over the service life of the WAAS GEO satellite, the deviation of the frequency of the L1/L5 conversion oscillator (includes reference oscillator, multiplier PLL and mixer) due to deterministic effects must be less than 1.4E-07 times the nominal frequency of the L1/L5 conversion oscillator.

3.2.2.7 Navigation Transponder Transmit Coverage

The SIS coverage (User elevation angle ≥ 5 degrees) must be achieved for all static and dynamic satellite pointing errors in normal operations including during station keeping and in eclipse.

3.2.2.8 Navigation Transponder Antenna Gain Variation

The antenna gain variation from any location within the SIS coverage (User elevation angle ≥ 5 degrees), resulting from all sources including three-sigma pointing error, must not exceed 3.5 dB (threshold), 1.0 dB (objective).

3.2.2.9 Navigation Transponder Axial Ratio

The axial ratio must be less than 2 dB within the SIS coverage (User elevation angle ≥ 5 degrees) and over the full operational bandwidth for L5 and for L1.

3.2.2.10 Navigation Transponder Uplink Interference Protection The navigation transponder must satisfy all requirements in the presence of RF interference that is less than or equal to 10 dB above the nominal uplink Effective Isotropic Radiated Power (EIRP).

3.2.2.11 Navigation Transponder EIRP

3.2.2.11.1 Maximum Saturated EIRP at L1

The EIRP at L1 for single-carrier saturated operation must be less than or equal to 34.7 dBW for the WAAS GEO satellites.

3.2.2.11.2 Maximum Saturated EIRP at L5

The EIRP at L5 for single-carrier saturated operation must be less than or equal to 34.0 dBW.

3.2.2.11.3 Minimum Saturated EIRP at L1

The EIRP at L1 for single-carrier saturated operation must be greater than or equal to

32.0 dBW within the SIS coverage.

3.2.2.11.4 Minimum Saturated EIRP at L5

The EIRP at L5 for single-carrier saturated operation must be greater than or equal to

31.5 dBW within the SIS coverage.

3.2.2.11.5 EIRP Stability

The change in EIRP, at any location in the SIS coverage, due to all causes, including antenna thermal distortion, attitude instabilities, one sigma pointing errors, filter characteristics, and power amplifier characteristics, must not exceed 1.2 dB peak-to-peak for 24 hours and 1.9 dB peak-to-peak over the service life.

3.2.2.11.5.1 Saturated EIRP Stability

The change in saturated EIRP due to all causes, except antenna pointing error, must not exceed 0.5 dB peak-to-peak diurnally and 1.0 dB peak-to-peak over the service life of the satellite.

3.2.2.11.5.2 Small Signal EIRP Stability

The change of small signal levels, including antenna effects, must not exceed ±2 dB over any twenty-four (24) hour period and ±3 dB over service life.

3.2.2.12 Uplink Receive Gain-to-noise Temperature ratio (G/T) The minimum G/T at any frequency within either of the transmission channels and in the directions of the associated GUSs must not be less than -11 decibel (dB)/Kelvin (K).

3.2.2.13 Navigation Transponder Phase Variation with Dynamic Range

3.2.2.13.1 Phase Variation, Peak-to-Peak (dB)

The phase variation for signals operating over a 20 dB dynamic range below the specified operating point EIRP must be less than 20 degrees, peak-to-peak for the L-band navigation transponders.

3.2.2.13.2 Overall Group Delay

Turn-around calibration accuracy in the navigation transponder group delay prior to launch and during in-orbit testing must be better than 10 nanoseconds, one sigma.

3.2.2.13.3 L1/L5 Differential Group Delay

The differential group delay variation between the navigation transponder channels must be less than 5 nanoseconds in any 24-hour period.

3.2.3 RFU SUBSYSTEM REQUIREMENTS

The RFU configuration items and functional relationships are shown in Figure 3-2.

Figure 3-2 RFU Functional Drawing

3.2.3.1 RFU Performance Requirements

The RFU Subsystem must:

a) Receive and convert the 70 MHz Intermediate Frequency (IF) signals from the

SGS.

b) Transmit Uplink 1 for L1 Downlink and Uplink 2 for L5 Downlink signals to the

GSP.

c) Receive L1 and L5 signals from the GSP and provide to the SGS.

d) Provide status information of the RFU Lowest Replaceable Units (LRUs).

3.2.3.2 Transmit Channel Characteristics

3.2.3.2.1 Transmit Channel Time Delay

The Uplink 1 and Uplink 2 transmit channel time delay must be less than 1 millisecond at each of the following nine frequency points within each of the 20 MHz passbands: f0, f0±2 MHz, f0±5 MHz, f0±10 MHz, f0±20 MHz. The channel time delay shall be measured a minimum of 20 times over a two second period, and the peak-to-peak variation must not exceed 5 nanoseconds.

3.2.3.2.1.1 Transmit Channel Differential Group Delay

The differential group delay variation between Uplink 1 and Uplink 2 must be less than 5 nanoseconds in any 24-hour period.

3.2.3.2.1.2 L1/L5 Group Delay Stability

The transmit channel time delay must have an uncertainty of less than 1 nanosecond rms, over time periods of less than 2 seconds.

3.2.3.2.1.3 Transmit Channel Time Delay Uncertainty

The transmit channel time delay must have an uncertainty of less than 1 nanosecond rms, over time periods of less than 2 seconds.

3.2.3.2.2 Transmit Channel Coherency

The transmit channel local oscillators must be phase-locked to the frequency reference in the SGS.

3.2.3.2.3 Transmit Channel Harmonics

The total EIRP of any harmonic signal below 40 Gigahertz (GHz) generated by the navigation carriers must not exceed 20 dBW.

3.2.3.2.4 Transmit Frequency Accuracy

The transmit frequency of the navigation signals must be within ±100 Hz of the required frequency, in the absence of the closed loop Doppler compensation.

3.2.3.2.5 Transmit Amplitude Modulation (AM)/ Phase Modulation (PM) Conversion

The total AM/PM conversion must not exceed 2.5 degrees per dB at the operational output power of the RFU.

3.2.3.2.6 RFU Transmit Phase Linearity

3.2.3.2.6.1 Phase Linearity at Uplink 1

Centered at the nominal Uplink 1 operating frequency, the phase linearity must be less than ± 0.1 radian over 20 MHz, centered at the nominal Uplink 1 operating frequency.

3.2.3.2.6.2 Phase Linearity at Uplink 2

Centered at the nominal Uplink 2 operating frequency, the phase linearity must be less than ± 0.1 radian over 20 MHz, centered at the nominal Uplink 2 operating frequency.

3.2.3.2.7 Uplink Nominal EIRP

The nominal Uplink 1 and Uplink 2 EIRP values in the direction of the satellite must be sufficient to operate with the associated WAAS GEO G/T and transponder design to establish required ‘nominal’ power levels at the L1 and L5 transmit antenna inputs.

Nominal power levels are defined as those sufficient for producing the required L1 and L5 saturated EIRP.

3.2.3.2.7.1 EIRP Increase

The RFU must provide an increase in the transmit EIRP of up to 10 dB from the nominal

EIRP.

3.2.3.2.7.2 Increase in Uplink EIRP

Upon receipt of the appropriate command from the SGS, the RFU must be capable of increasing the uplink EIRP.

3.2.3.2.8 RFU Transmit Gain Flatness

3.2.3.2.8.1 Gain Flatness at Uplink 1

Centered at the nominal Uplink 1 operating frequency, the gain flatness must be less than ±1 dB over 20 MHz, centered at the nominal Uplink 1 operating frequency.

3.2.3.2.8.2 Gain Flatness at Uplink 2

Centered at the Uplink 2 operating frequency, the gain flatness must be less than ±1 dB over 20 MHz, centered at the nominal Uplink 2 operating frequency.

3.2.3.2.9 Sidelobes

3.2.3.2.9.1 Sidelobe Peak

At angles greater than 1o from the main beam axis, and at any frequency within the transmit pass band, no more than 10% of the sidelobe peaks must exceed an envelope described by the following expressions (Reference ITU-R Recommendation 465-2):

G = 32-25 log10 θ dBi (1 < θ < 48)

G = -10 dBi (θ > 48)

G is the antenna gain in dB relative to isotropic at angleθ , in degrees, from the main beam axis.

3.2.3.2.9.2 Sidelobe Peak Applicability

The sidelobe peak requirement must apply to sidelobes occurring within ±5 degrees of the geostationary arc with the antenna pointed towards any location on the geostationary arc visible to the GUS.

3.2.3.2.10 Antenna Sidelobe EIRP Density

3.2.3.2.10.1 EIRP Constraints

The EIRP density in any direction within 3 degrees of the geostationary satellite orbital arc, at the indicated off-axis angle, must satisfy Table 3-4 (Reference ITU-R Rec. 524-2).

In the calculation of this EIRP density, the PRN modulated signal density in 4 kHz is -24 dB from the total EIRP.

Table 3-4 Antenna Sidelobe EIRP Constraints Off-axis angle - degrees EIRP - dBW per 4 kHz

2.5 < θ < 7 32 – 25 log10 θ

7 < θ < 9.2 +11

9.2 < θ < 48 35 – 25 log10 θ

48 < θ < 180 -7

3.2.3.2.11 Transmit Phase Noise

3.2.3.2.11.1 Transmit Phase Noise Spectrum

The total phase noise induced on an unmodulated uplink test carrier transmitted by the RFU must have a single sided power density spectrum in which each sideband, above and below the carrier, must be equal to or less than the values in Table 3-5.

3.2.3.2.11.2 Transmit Phase Noise Limitation

If any discrete phase noise components are present, at a level which exceeds the mask, the sum of the discrete phase noise components and continuous spectral component integrated over a bandwidth of ±10 Hz on either side of the discrete component must not exceed the phase noise mask.

Table 3-5 Transmit Phase Noise

Frequency Offset for Carrier (Hz) Phase Noise Density (dBc/Hz)

1 -27

5 -54

10 -57

100 -75

1000 -84

10K -95

100K -98

300K -98

> 1000K -100

3.2.3.2.12 Transmit Signal Level

Under typical weather conditions prevailing at the RFU location, the EIRP of any transmitted signal in the direction of the satellite must be maintained to within ±0.7 dB of the value specified with a probability of 0.95.

This tolerance includes all factors such as transmitter RF power level-setting accuracy and instability, antenna transmitting gain instability, antenna beam pointing error, and antenna gain variation caused by tracking.

3.2.3.3 Receive L-Band Channel Characteristics

3.2.3.3.1 Receive L-Band Passband

3.2.3.3.1.1 Receive Passband at L1

The 3-dB receive passband must be at least 20 MHz centered at the nominal L1 frequency of 1575.42 MHz.

3.2.3.3.1.2 Receive Passband at L5

The 3-dB receive passband must be at least 20 MHz centered at the nominal L5 frequency of 1176.45 MHz.

3.2.3.3.2 Receive L-Band G/T

The L1 and L5 G/T in the direction of the satellite over the entire receive passband under clear sky and average wind conditions must provide a pre-detection Carrier to Noise ratio (C/No) of at least 62 dB-Hz. The minimum C/No must be met with the transmitter operating over the complete range of output power, including losses due to pointing errors and antenna polarization misalignment.

3.2.3.3.3 Receive L-band Antenna Pointing and Tracking

The antenna must be capable of pointing to a satellite nominally at any location in the geostationary arc visible to the uplink antenna.

3.2.3.3.4 Receive Channel Time Delay

3.2.3.3.4.1 Receive Time Delay for L1

The L1 receive channel time delay must be less than 1 millisecond with an uncertainty of less than 1 nanosecond root mean square, over time periods of less than 2 seconds.

3.2.3.3.4.2 Receive Time Delay for L5

The L5 receive channel time delay must be less than 1 millisecond with an uncertainty of less than 1 nanosecond root mean square, over time periods of less than 2 seconds.

3.2.3.3.5 Receive Channel Coherency

The L band receive channel local oscillators must be phase-locked with the frequency reference from the SGS.

3.2.3.3.6 Receive Phase Linearity

3.2.3.3.6.1 Receive Phase Linearity – L1

The receive phase linearity must be less than ± 0.1 radian over a 20-MHz bandwidth centered at the nominal L1 frequency.

3.2.3.3.6.2 Receive Phase Linearity – L5

The receive phase linearity must be less than ± 0.1 radian over a 20-MHz bandwidth centered at the nominal L5 frequency.

3.2.3.4 RFU Built-in-Test Capabilities

3.2.3.4.1 RF/IF Test Capabilities

The RFU must be equipped with suitable test access points to allow measurement of at least the following signal parameters:

a) Absolute carrier power (Received carrier power level represented by C/No estimate);

b) Center frequency of received L-band signals; and

c) C/No of received L-band signals.

3.2.3.4.2 Test Translator Requirement

The RFU must include a Test Translator which converts the Uplink 1 and Uplink 2 signals to L1 and L5, respectively, to verify operation of the RF uplink and to aid in subsystem maintenance and repair.

3.2.3.4.3 Delay Calibration Requirement

The path transmission delays for both the Uplink 1and Uplink 2 transmit and L-band receive paths must be accurate to 1 nanosecond rms. The calculation of path transmission delays for the transmit and L-band receive paths must use the appropriate installation and manufacturer's data and measurements.

3.2.4 OPERATIONAL REQUIREMENTS

3.2.4.1 GUS Maintenance During Normal Operation

During Normal Operations, corrective maintenance performed on backup GUS in maintenance mode, must not degrade WAAS Service.

3.2.4.1.1 GUS Average Logistics Delay Time

With the exception of the RFU antenna reflector, the GUS average logistics delay time must be less than or equal to 2 hours.

3.2.4.2 Uninterruptible Power

Facilities that support GUS equipment must provide sufficient uninterruptible power to permit all GUS equipment to operate within the nominal operating range for each equipment type. Uninterruptible power must sustain GUS operations for up to 30 minutes during the loss of commercial power without interruption of GUS operations.

3.2.4.3 Standby Power

The GUS facility must have a backup generator to replace the loss of commercial power.

The backup generator must be capable of supplying required power for at least 24 hours.

The backup power generator must be capable of being refueled without interruption of power to the GUS. Restoration of commercial power to the GUS facility must not cause interruption of the SIS services.

3.2.4.4 Human Engineering

In the selection of hardware and the design of software, the GUS design must conform to the applicable human engineering requirements of FAA-G-2100H, paragraph 3.3.6

3.2.4.5 Personnel Safety

All RFU LRUs, including Commercial-Off-The-Shelf (COTS) units, must conform to the applicable personnel safety requirements of FAA-G-2100H, paragraph 3.3.5.

3.2.4.6 Computer Resources

3.2.4.6.1 Computer Memory

3.2.4.6.1.1 Volatile Memory

Under worst case loading conditions, no more than 50% of the total addressable, populated memory locations must be used during execution of any program to hold instructions or data.

3.2.4.6.1.2 Non-Volatile Memory

Non-volatile memory includes such items as programmable read-only memory, electrically programmable read-only memory, and non-volatile random access memory.

Non-volatile memory embedded in the RFU subsystem or equipment must be capable of expansion within industry limits with no effect on form, fit, or interface factors.

3.2.4.6.1.3 Memory Increase Capability

Each type of memory must be expandable by 100%.

3.2.4.6.1.4 Computer Resource Reserve Capacity

Processing resource requirements for each element of the RFU must be in accordance with FAA-STD-026A.

3.2.4.6.2 Software Development Requirement

Software is defined as computer programs, procedures, rules, and associated documentation and data pertaining to the operation of the WAAS. Software for RFU must be developed in accordance with FAA-STD-026A and RTCA/DO-178B.

3.2.4.6.3 Fail-Safe Operation

RFU equipment must meet the fail-safe and fail-soft requirements of FAA-G-2100H, paragraphs 6.2.4 and 6.2.5.

3.2.4.6.4 Security Protection

The RFU must be designed to maintain the WAAS closed network architecture, accessible only locally and by operator personnel. If remote monitoring outside of the GUS site is incorporated, the design must provide for secure, one-way (output only) access to monitoring information.

4 VERIFICATION REQUIREMENTS

The Verification Requirements Matrix (VRM) in Table 4-1 correlates the requirements in Section 3 with the General Testing and Quality Assurance Requirements specified in the VRM. The VRM must be used to determine compliance to the Technical Specifications.

Verification is an activity involving test, demonstration, analysis (including computer simulation) or inspection, either singularly or in combination, to establish that design and/or performance satisfies the Technical Requirements.

4.1 VERIFICATION METHODS

The verification methods that are used to establish how a given requirement is verified are defined as follows:

a. Test - Verification that is accomplished through systematic exercising of the application item under appropriate conditions, with or without instrumentation, and the collection, analysis, and subsequent evaluation of quantitative data. This Verification Method (VM) differs from the others in that the system must be running but analysis of observed/measured results after test execution completes is required to determine success.

b. Demonstration - Verification that is accomplished by operation, adjustment or reconfiguration of items…