Harris and GPS Technology Evolving a Global Utility. James Phelan Harris Corporation

Transcription

1 Evolving a Global Utility James Phelan Harris Corporation

2 TABLE OF CONTENTS INTRODUCTION...2 Harris Payload Legacy and Expertise...2 GPS III MDU Capabilities...5 Digital Waveform Generator...6 Harris Payloads and GPS-Related Technology Development...9 Harris FPGA Technology...10 On-orbit Reprogrammable Technology...11 SUMMARY...12 LIST OF FIGURES Figure 1. Current GPS Vehicles...2 Figure 2. GPS Control and Monitor Stations...4 Figure 3. GPS Block IIR/IIRM Mission Data Unit (MDU)...5 Figure 4. GPS III MDU Design for MEO Orbit...5 Figure 5. First Operational Waveform Generator with M-Code (IIRM)...6 Figure 6. GPS III Mission Data Unit with Embedded Waveform Generator...7 Figure 7. FDWG Used in Pseudolite Demonstration...7 Figure 8. Small GPS Satellite Architecture with FDWG...8 Figure 9. Harris Program Waveform Generation...8 LIST OF TABLES Table 1. Historical Harris Technology in the GPS Program...3 Table 2. GPS IIIA MDU Code Generation Flexibility...6 Table 3. New Software Builds

3 Harris and GPS Technology Evolving a Global Utility INTRODUCTION Harris Corporation is a leading technology innovator, solving our customers toughest mission-critical challenges by providing solutions that connect, inform and protect. Harris supports customers in more than 125 countries and has 22,000 employees including 9,000 engineers and scientists worldwide. The company is organized into four business segments: Communication Systems, Space and Intelligence Systems, Electronic Systems, and Critical Networks. The Harris Clifton, N.J., facility has been providing integral technology for the Global Positioning System (GPS) Space Segment Navigation Payload since the program s inception. During the Labor Day weekend of 1973, military officers meeting at the Pentagon developed a GPS concept based on technologies developed under earlier missionspecific navigation programs. Between 1978 and 1985, ten prototype satellites were developed and launched to test the concept. The navigation signals these prototypes provided and all subsequent U.S. GPS satellites have consistently been furnished by high-signal-quality Harris Corporation transmitters. This paper documents Harris past, present, and future efforts to support United States dominance in this important global utility. In 2013 alone, GPS contributed more than $68 billion to the U.S. economy. From waveform generation to transmission, command, and control to precise timekeeping technology you ll learn how Harris continues to advance technologies that apply specifically to the GPS constellation. Harris Payload Legacy and Expertise Harris navigation payload technology has been present on every U.S. GPS satellite ever launched. Harris first contributed to GPS in the 1970s, supporting the transmission of L-Band navigation signals in the first Block I GPS satellites. At the time, our customers turned to Harris for our expertise with the Radio Frequency (RF) spectrum from our deep experience reaching back to World War II. For GPS Blocks I and II/IIA, Harris continued to provide RF payloads for 40 satellite systems delivered from the 1970s through the 1980s. Harris leveraged this experience when providing full navigation payloads to Lockheed Martin for the Block IIR program from 1988 through Harris also brought several innovations to the IIR program including improved time keeping, accuracy, and security for the nation s GPS satellites. Harris continued to improve GPS payload technologies for IIR, IIF, and today s GPS III modernization program. Harris provides the entire navigation payload as well as key elements of the Ultra High Frequency (UHF) Crosslink processing for most of the active constellation. In the remaining space vehicles, Harris provides the navigation L-Band transmission equipment. Figure 1 shows past and present GPS Satellite types while Table 1 lists the Harris navigation content within the various GPS Space Vehicle types. Vehicle Data GPS IIA GPS IIR GPS IIRM GPS IIF Signals L1 C/A, L1 and L2 P(Y) L1 C/A, L1 and L2 P(Y) L1 C/A, L1 and L2 P(Y), L2C, M-Code L1 C/A, L1 and L2 P(Y), L2C, M-Code L5 Design Life 7.5 Years 7.5 Years 7.5 Years 12 Years Launch Period Present Currently Active Figure 1. Current GPS Vehicles 2

4 Table 1. Historical Harris Technology in the GPS Program GPS Navigation Payloads I II/IIA IIR/IIRM IIF III L1 XMTR L2 XMTR L3 XMTR L5 XMTR RAFS CAFS MDU Waveform Generator Fine Phase Meter VCXO and Code Loop TKS TRIPLEXER CROSSLINK L3 Filter On-orbit Support Payloads Produced TBD As of October 2015, there have been 71 GPS satellites launched. Today, there are 31 operational satellites in orbit. They continuously send signals to Earth to help receiving devices like smartphones and vehicles determine their location. Since the 1970s, GPS satellites have logged more than 750 years of cumulative, on-orbit operations, without a single failure due to Harris equipment. In fact, many of the satellites have outlived their expected operation by several years. For Block I, between 1978 and 1985, Rockwell International subcontracted to Harris to provide the navigational payloads for the first block of GPS satellites, which were intended solely for military use. For Block II and IIA, which launched between 1990 and 1997, Harris provided 28 flight payloads. Part of the payload Harris delivered for Blocks I and II was the signal conversion portion, which converted a digital signal generated by the satellite to radio frequency (RF) energy to be beamed to the ground. Harris saw its role expanded in the program for Block IIR from 1997 to 2004, when it teamed with new prime contractor Lockheed Martin to provide the entire navigation payload, including sophisticated atomic clocks, rather than just the signal conversion portion. Next came Block IIF, but with a new prime contractor, Boeing. Harris and Lockheed were concerned they would not be involved with this portion of the program. Instead, the customer decided to retrofit some IIR payloads several had yet to launch to upgrade that system with some capabilities from the IIF satellites, including a modernized, more powerful signal. The Air Force was impressed and the IIR Modernization, or IIRM program, was born. Harris engineers upgraded eight IIR payloads and delivered them to the Air Force before the first new IIF vehicle was even built. As a result, Boeing subcontracted Harris to work on the navigation payloads of the IIF program. Moving forward, the Harris-Lockheed team is working on eight navigational payloads for the next generation satellites of GPS: Block III. The advanced payload will deliver signals with three times more accuracy, provide dramatically improved anti-jamming capabilities, and extend satellite life to 15 years. For civilians, the signal will reach users more effectively. The newest signal will be capable of penetrating heavy tree cover to reach cars in wooded areas or pedestrians in an urban jungle. For the military, the signal will provide location accuracy down to sub-meter levels and be even more dependable due to improved anti-jam capabilities. 3

5 Harris has also continuously supported the GPS Constellation Health and Maintenance efforts since Those efforts include: Investigating orbit signal anomalies Determining the root cause Identifying work-arounds Making software changes Performing equipment switchovers Preparing anomaly reports Monitoring the health and performance of the IIR/IIRM Space Vehicles Ensuring that the GPS Constellation provides the required performance to both the civil and military communities Harris provides operational support, control, and maintenance for the current GPS Constellation (reference Figure 2), the GPS IIA and IIF satellites, and will also support the navigation payload for GPS III once it is launched. Finally, Harris is currently developing all of the GPS III Navigation Payload Control Software on the OCX Program (Next Generation Operational Control Segment). As a Raytheon subcontractor, Harris software efforts involve setting the stage for secure uploads that provide the precise ephemeris and timing required by the GPS space vehicles. Other responsibilities for OCX include: Developing the command software and data for the current waveform generator to produce the various signal structures Developing and producing Type 1 Mission Crypto and Monitor Station Receiver (OMSRE) Assessing overall performance and the software for generating uploads to the Mission Data Unit (MDU) payload Assisting Lockheed Martin in developing the Launch Checkout System that will provide early command and control capability prior to the formal validation of the OCX System Figure 2. GPS Control and Monitor Stations The GPS IIR/IIRM Mission Data Unit is shown in Figure 3. It is currently performing the navigation mission on the majority of the active GPS Satellites. This fully redundant system can operate through the natural radiation hazards in the Medium Earth Orbit (MEO). It is also hardened against manmade radiation effects. With this MDU, Harris initiated the on-orbit reprogrammable capability to updated software via the Master Control Segment. This technique has been used for 18 years to address anomalies and add new functionality to the GPS Constellation. The software code for this application was written in the ADA language to facilitate such modifications. 4

6 Figure 3. GPS Block IIR/IIRM Mission Data Unit (MDU) GPS III MDU Capabilities The Harris Mission Data Unit for GPS III is shown on the right side of Figure 4. It s a modular, fully redundant system that is radiation tolerant to both the MEO (Reference Figure 4, left) as well as manmade effects. The MDU is the main command and control center for the navigation mission. It provides precise timing, generates all GPS waveforms, and provides health and status messages via its S-Band serial telemetry link. The MDU accepts daily uploads from the GPS Control Segment, which provides all the military and civilian data required to generate GPS signals. Figure 4. GPS III MDU Design for MEO Orbit For GPS III, the U.S. Air Force envisioned an entirely new block of GPS satellites unlike any that had come before. They wanted the new Block III to include the ability to spiral in advanced technology as risk is reduced and therefore meet evolving warfighter needs. New modular technology within GPS Block III satellites enables this spiral development. Harris has enhanced the IIR/IIRM MDU to include both the Waveform Generator functions and the Synthesizer MOD/IPA functions. These two functions were assembled independently in the previous GPS design. The MDU also contains a more advanced microprocessor and memory than the original 1750A Silicon on Sapphire-based product. The modular design of GPS III satellites enables insertion of these advanced technologies. The GPS III MDU consists of individual circuit cards, which support Timekeeping (TKS), Waveform Generation (WG), Cryptography, I/O, and Peripheral functions. The Flight Software (resident on the SBC circuit cards) provides all the algorithms and data processing required for generating the User Navigation Data. It also includes the software logic required to support command, control, maintenance, integrity and telemetry functions. Spare Circuit Card Assembly (CCA) slots are allocated for accommodating future functional enhancements. 5

7 The GPS III MDU contains a flexible code generation and signal combining system which supports separate M-Code transmitters, the ability to move codes between transmitters, and the generation of new codes on-orbit using Flex Code generators as shown in Table 2. All codes and navigation data are generated by the MDU for transmission by the L-Band System. This includes the following codes and data, C/A, P(Y), L1-M, L2-M, L1CP, L1CD, L2C, L3, L5I, L5Q, NAV, MNAV, CNAV and CNAV-2 data. Table 2. GPS IIIA MDU Code Generation Flexibility Carrier Valid PRN Codes Per Carrier4 L1 EC C/A 3 P(Y) 2 L1M L1Cd L1Cp 2 Flexible 1 L1 MEC C/A 3 P(Y) 2 L1M L1Cd L1Cp L2 EC C/A 3 P(Y) 2 L2M L2C 2 Flexible 1 L2 MEC C/A 3 P(Y) 2 L2M L2C L5 EC L5I L5Q 2 Flexible 1 Notes: 1. T wo Flexible, On-Orbit Programmable Code Generators per carrier, which are shared between the EC and MEC transmit chains. 2. Single P(Y) code generator shared between L1 and L2 transmit chains. 3. Single C/A code generator shared between L1 and L2 transmit chains. 4. Codes on a specific carrier (L1, L2) can only be transmitted on one aperture (EC or MEC) at a time. Example: C/A code on L1 can only be transmitted on the L1 EC transmitter or the L1 MEC transmitter, not both simultaneously. Legend: Nominal Codes on Transmit Chain The GPS III MDU also contains a unique closed-loop timekeeping system that maintains accurate timing for precise positioning. For example, 1ns/1 billionth of a second represents one foot of navigation error. The GPS III MDU distributes this precise timing throughout the GPS Space Vehicle for use by other payloads. The Microsemi VCXO provides short-term stability while the Excelitas RAFS provides long term stability all under the guidance of a proprietary Harris Control Loop and Betting Logic algorithm. A sampling clock and an array of fine-phase meters complete the MDU components required for timekeeping. Finally, the MDU provides secure, encrypted functions to support the Navigation and Nuclear Detection Missions. Digital Waveform Generator Since GPS Block I was awarded in 1974, Harris has led next-generation GPS payload technology. Our ongoing investment in research and development has directly contributed to the extraordinary advancements seen in today s robust GPS constellation. Harris has researched and invested in digital payload technology for over a decade. In 2004, we demonstrated our first direct digital-to-rf waveform generator by successfully producing and receiving legacy GPS signals and Pseudo M-code. It was part of the GPS IIR/IIRM Program, which introduced L2C, M-Code and a demonstration L5 Signal to the GPS Constellation. Twelve GPS IIR s and eight GPS IIRM s were launched containing this waveform generation technology including the associated M-Code crypto algorithms (reference Figure 5). Then, in 2010, we used our second-generation digital waveform generator design to demonstrate the new L1C GPS signal. Figure 5. First Operational Waveform Generator with M-Code (IIRM) 6

8 In 2013, as part of the GPS III development program, Harris demonstrated digital signal capability for the navigation payload at a preliminary design level. The preliminary design was reviewed to the rigorous standards of a tailored military-standard process and included a formal study by our customers, clearly identifying the maturity of the navigation payload design. Harris customers documented the design s technical adequacy, risk resolution, approach, and technical risk. The GPS III payload Harris is now developing for the U.S. Air Force is the most capable navigation satellite payload ever produced. We believe the combination of our proven GPS heritage, our skill in the RF spectrum, satellite communications and reprogrammable payload, and our continued investment in research all uniquely qualify us to support the next generation of GPS satellites. Harris incorporated a more advanced Waveform Generator within the GPS III Mission Data Unit (MDU). This design iteration addresses the SS-SS-800 signal flexibility requirements imposed upon the GPS III program, specifically the flexibility for adding new codes and signals (reference Figure 6). During the development of the GPS III Program, Harris funded multiple programs to further digitize the waveform generator. We explored the available technology for supporting on-orbit reprogrammability and developed predistortion techniques for Figure 6. GPS III Mission Data Unit with Embedded Waveform Generator further improving signal quality. Harris is actively pursuing the potential use of its digital navigation waveform generation technology on numerous domestic and international platforms. Also in 2012, Harris utilized the Advanced Navigation Receiver (ANR) and Flexible Digital Waveform Generator (FDWG) to produce and monitor Pseudolite Navigation Signals for use in a flight demonstration over the Mojave Desert. Figure 7 shows the FDWG used during this successful pseudolite flight testing. Figure 7. FDWG Used in Pseudolite Demonstration 7

9 Figure 8. Small GPS Satellite Architecture with FDWG Harris continued to evolve the design of the FDWG during our Small GPS Satellite Study. The design iteration combined the GPS III Waveform Generator and Synthesizer/Modulator/Intermediate Power Amplifier (SMIL) functions within one CCA. The characteristics of this design are being leveraged further to improve this technology (Reference Figure 8). Leverages GPS III MDU Software Improves RF Performance and Signal Flexibility Combines Signals Efficiently Harris Waveform Generation Investment Harris GPS Program Waveform Generation Experience GPS IIR Waveform Generation On-Orbit QPSK C/A and P(Y) Code Generation Fully Programmable Modulation Techniques Up to 7 Codes Using Intervote Modulation Digital Waveform Generator ( ) GPS IIR-M Waveform Generation On-Orbit Interplex Signal Combining for C/A, P(Y), M-Code, and L2-C Code Generation Direct-to-L-Band Digital Waveform Generator includes Flexible Carrier Frequency, Single- Sideband Signal, Multiple Modulation Schemes All-Digital Waveform Generator ( ) GPS III MDU Development Advanced Waveform Generation Meeting GPS III Specifications Migrated the All-Digital Waveform Generator to a Space Qual Package Space-Based Digital Waveform Generator ( ) Fully Implemented and Demonstrated Waveform Generator Using POCET Combining, COPAC Combining Algorithm Developed and Implemented Combining Algorithm Investment Advanced Waveform Generation All-Digital DDS Based, Multiple GNSS Capable, Fully On-Orbit Reprogrammable Reduced SWAPC Flexible Power Consumption Figure 9. Harris Program Waveform Generation Figure 9 shows Harris previous developments in waveform generation. Ever since GPS IIR, Harris has continuously developed waveform generation and is combining algorithms to advance GPS navigation. We apply both our experience and signal quality test equipment to ensure new waveforms meet the latest in GPS signal-in-space requirements. Harris waveform generation research will enhance the on-orbit signal flexibility of GPS payloads. It will enable implementation of more modulation types such as *M-ary Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM). To further improve efficiency, the technology will support precise tuning of code power ratios and reduce spurious emissions. Finally, this research will support the implementation of more efficient signal combining techniques such as Aerospace s Phased Optimized Constant Envelope Transmission (POCET) algorithm, as well as others designed to reduce power loss. 8

10 Harris is committed to continuing our legacy of innovation in GPS navigation payloads and will keep investing in digital technology, ensuring we are positioned to meet evolving GPS program and warfighter needs. Harris GPS-Related Technology Development Harris continues to pursue these GPS-related topics: New Signal Combining Techniques - Harris is exploring and validating constant envelope signal combining techniques Advanced Timekeeping - Harris has a multi-year program to explore advanced timekeeping capabilities for positioning, navigation, and timing (PNT) systems. The project explores advanced timekeeping and integrity monitoring algorithms to produce enhanced signal stability, plus anomaly detection and correction Higher Gain GaN Amplifiers To Reduce DC Power Consumption - Reduces out-of-band emission profile - Supports regional military protection requirements Enhanced Waveform Technology - Reduces spectral bandwidth - Improves transmitter efficiency - Reduces out-of-band emissions Phased Array Antenna Technology - Alternative technology for navigation signal transmission - Alternative technology for regional military protection requirements Harris FPGA Technology Harris is advancing waveform generation through innovative and unique (constant envelope) signal combining and wave-shaping algorithms. We are currently developing elements for a single card design that will provide all waveform generation and cryptographic functions, plus authenticate and process encrypted uploads. Harris is leveraging previous GPS waveform generation through the use of On-Orbit Reprogrammable Technology. These advancements will improve GPS through: The miniaturization of the waveform generator and full digital implementation, which will enable improvements in many critical PNT signal characteristics such as group delay, signal coherence, quadrature phase error, phase noise, and correlation loss The use of a radiation hardened on-orbit reprogrammable technology, in conjunction with new processors, provides a higher degree of on-orbit flexibility The addition of new ranging codes and frequencies (e.g. L5) in the past has taken 10 years or more to go from conception to broadcasting in space. This technology will allow new signals to be dynamically added Harris investment in these technologies will lead to an affordable, small-size, low-weight-and-power design that can be readily programmed on-orbit to produce any of the various pre-defined navigation signals (GPS, Glonass, Galileo, Beidou, etc.), as well as to accommodate future waveforms. The architecture will also support U.S Cryptographic algorithms necessary for producing GPS waveforms. 9

11 On-orbit Reprogrammable Technology Harris Corporation pioneered the introduction of on-orbit reprogramming in the GPS Block IIR series of Space Vehicles. All GPS Block IIR/IIRM Space Vehicles can be reprogrammed while on-orbit. This unique feature has enabled diagnostic activity, lessons learned and new enhancements. Indeed, the GPS Block IIR processor software design has evolved under the GPS Phase IIC Program, addressing a large list of user enhancements as well as providing workarounds for unforeseen events affecting IIR/IIR-M performance. New Software Versions (6 thru 14) that have been successfully uploaded to the IIR/IIRM Space Vehicles are shown in Table 3. Harris continues to invest in the evolution of this technology, including research in new processors, non-volatile memory, and radiation hardened devices and processes. Harris has extensive experience in dealing with natural and manmade radiation effects. We understand, quantify, and mitigate the mission impacts for various mission durations and orbits. We have successfully put ASICs and FPGAs to work for space applications, including the use of OTP FPGAs on the GPS IIR/M and GPS III Programs. Table 3. New Software Builds Mission Processor Operational Build Date Pre- or Post- Launch OB 1 03/25/1996 Pre-Launch OB 2 05/08/1996 Pre-Launch OB 3 05/22/1996 Pre-Launch OB 4 03/31/1997 Pre-Launch OB 5 04/15/1997 Pre-Launch OB 6 03/15/1998 Post Launch Upload OB /15/1998 Post Launch Upload OB 7 06/23/1998 Post Launch Upload OB 8 06/25/2000 Post Launch Upload OB /15/2000 Post Launch Upload OB 9 04/04/2001 Post Launch Upload OB 10 05/20/2002 Post Launch Upload OB 10.1A 11/30/2004 Post Launch Upload OB 11 06/12/2006 Post Launch Upload OB /23/2008 Post Launch Upload OB 12 06/15/2009 Post Launch Upload OB 13 12/09/2011 TBD SUMMARY Harris Corporation is constantly improving GPS navigation payload technology. We have proven this commitment many times through our contributions to past and present GPS program missions. We continually commit significant internal funding to research and development. Harris also supports AFRL and related small-business research efforts to improve GPS technology through the SBIR Program and others. We are currently investing in all areas pertinent to the navigation payload: Digital Waveform Generation Timekeeping System and Atomic Frequency Standards L-Band Transmission and Filter Technology High Speed Radiation Hardened Processors and Memory These efforts all pertain to the long term goal of providing high accuracy (currently 16 M Spherical Error Probable) for users in all circumstances and conditions. 10

12 Harris is a registered trademark of Harris Corporation. Trademarks and tradenames are the property of their respective companies Harris Corporation 02/02/16 d0808 mv