The second Russian SBAS satellite, Luch-5B, has now been positioned at its designated orbital slot of 16 degrees west longitude. The satellite had been in a drift orbit since its launch on November 2 at 21:04:00 UTC along with the domestic communications satellite Yamal-300K.
Tracking data from NORAD/JSpOC showed Luch-5B arriving at its geostationary position by about December 13. The footprint of the satellite is shown below with the elevation-angle contours at 30-degree intervals.
The Technische Universitaet Muenchen has reported that transmissions of the L1/E1 signal from Galileo satellite IOV-4 (FM-4) started at about 17:15:10 GPS Time December 12. The navigation signals of both of the recently launched in-orbit validation satellites have now been activated.
A number of stations in the Cooperative Network for GNSS Observation as well as some stations participating in the International GNSS Service’s Multi-GNSS Experiment are tracking IOV-4. The satellite is using PRN code E20.
If the commissioning schedule is similar to that of IOV-3, the E5 and E6 signals of IOV-4 should be switched on over the next few days.
The Delta 4 rocket’s cryogenic upper stage engine experienced a fuel leak that caused a low-thrust condition. Four-and-a-half minutes into the launch, after the first stage had shut down and separated, the trouble began as the RL10B-2 engine on the upper stage extended its nozzle and fired to life.
When the powerplant was igniting and reached its peak chamber pressure, a leak started above the narrow throat portion of the thrust chamber, setting off a chain of nail-biting events over the next three hours as the vehicle made its climb to the GPS constellation. The Delta 4 made autonomous adjustments, however. The onboard inertial guidance and flight control systems compensated for the lower thrust conditions. Its closed loop guidance system measured the decreased thrust in real time and revised the trajectory and burn durations to ensure the mission succeeded. The GPS IIF-3 satellite was delivered to the correct orbit as planned.
Leica Geosystems Inc. announced the launch of the e-commerce site for Leica Geosystems Solutions Centers. The grand opening of the Leica Geosystems Solutions Center is marked by an unprecedented online-only promotion.
Logo: Leica Geosystems
Providing 24/7 personalized access to the products essential to the surveying, engineering, and construction industries, the site is a resource for more than purchases. It also enables customers to compare thousands of products based on features, shipping options and availability, and to create wish lists.
The Leica Geosystems Solutions Centers e-commerce site offers a range of supplies, accessories and rentals, from paint and flagging, safety supplies, total stations and GPS systems for surveying, construction lasers and building layout systems. Relevant products and pricing are presented based on each customer’s unique profile, and subscription and quick-order capabilities make it easy to reorder frequently needed products.
“We are committed to continually delivering value to our customers, and it is exciting to respond to customer needs by bringing this e-commerce site to the market,” said Mike Strom, General Manager, Solutions Centers for Leica Geosystems. “Our customers are busy, and they often need to place orders outside of standard business hours. Our new e-commerce website provides customers a more convenient way to buy from us, and we will be offering online-only promotions on a regular basis – similar to the tremendous grand opening deals – so it’s easier than ever for customers to begin reaping the benefits of Leica Geosystems solutions.”
The Leica Geosystems Solutions Center is factory-owned and operated, which guarantees that customers will receive the quality products and service expected from Leica Geosystems. Additionally, because support is critical at every step of the way, even during the purchase process, the site features multiple avenues to online support: customers get real answers, from real factory-trained experts.
Leica Geosystems Inc. announced the launch of the e-commerce site for Leica Geosystems Solutions Centers. The grand opening of the Leica Geosystems Solutions Center is marked by an unprecedented online-only promotion.
Logo: Leica Geosystems
Providing 24/7 personalized access to the products essential to the surveying, engineering, and construction industries, the site is a resource for more than purchases. It also enables customers to compare thousands of products based on features, shipping options and availability, and to create wish lists.
The Leica Geosystems Solutions Centers e-commerce site offers a range of supplies, accessories and rentals, from paint and flagging, safety supplies, total stations and GPS systems for surveying, construction lasers and building layout systems. Relevant products and pricing are presented based on each customer’s unique profile, and subscription and quick-order capabilities make it easy to reorder frequently needed products.
“We are committed to continually delivering value to our customers, and it is exciting to respond to customer needs by bringing this e-commerce site to the market,” said Mike Strom, General Manager, Solutions Centers for Leica Geosystems. “Our customers are busy, and they often need to place orders outside of standard business hours. Our new e-commerce website provides customers a more convenient way to buy from us, and we will be offering online-only promotions on a regular basis – similar to the tremendous grand opening deals – so it’s easier than ever for customers to begin reaping the benefits of Leica Geosystems solutions.”
The Leica Geosystems Solutions Center is factory-owned and operated, which guarantees that customers will receive the quality products and service expected from Leica Geosystems. Additionally, because support is critical at every step of the way, even during the purchase process, the site features multiple avenues to online support: customers get real answers, from real factory-trained experts.
According to RIA Novosti, the launch of Russia’s second GLONASS-K satellite has been delayed until 2013 from its end-of-year launch date, Defense Ministry spokesman Col. Alexey Zolotukhin said on Monday.
“The launch has been postponed due to technical flaws in the Fregat booster made by the Lavochkin space company,” Zolotukhin said. The new date for the launch will be set at a state commission meeting on spacecraft testing after all the flaws have been fixed, Zolotukhin said.
A Soyuz-2.1b launch vehicle had previously been scheduled to lift off from the Plesetsk space center in northern Russia by the end of 2012.
The satellite will be tested in orbit through 2015 before it becomes operational.
Four Galileo In-Orbit Validation satellites in medium-Earth orbit, the minimum number needed to perform a navigation fix. (Credits: ESA – P. Carril)
According to a report from the Technische Universitaet Muenchen, transmissions of the L1/E1 signal from the recently launched Galileo satellite IOV-3 (FM-3) started at about 13:55:20 GPS Time December 1. Transmissions from IOV-3 of the E5 signal began December 2. By December 4, all three Galileo bands, including E6, were being broadcast, according to the European Space Agency (ESA).
Several stations of the Cooperative Network for GNSS Observation as well as some stations participating in the International GNSS Service’s Multi-GNSS Experiment are tracking IOV-3. The satellite is using PRN code E19.
The Galileo In-orbit Validation (IOV) satellites were launched on October 12 (Flight Model 3 and 4). Now that FM3’s payload has been activated, FM4 is set to begin transmitting test navigation signals later this month. The first two satellites have already passed their in-orbit testing.
Galileo is designed to provide highly accurate timing and navigation services to users around the world, ESA said, so the testing is being carried out in addition to the standard satellite commissioning to confirm that the critical navigation payloads have not been degraded by the violence of launch.
While the satellites are run from Galileo’s Oberpfaffenhofen Control Centre near Munich in Germany and their navigation payloads are overseen from Galileo’s Mission Control Centre in Fucino, Italy, a separate site is used for the in-orbit testing. Located in the heart of Belgium’s Ardennes forest, Redu is specially equipped for Galileo testing, with a 15-m diameter S-band antenna to upload commands and receive telemetry from the satellite, and a 20-m diameter L-band dish to monitor the shape and quality of navigation signals at high resolution.
“This marked the very first time that a Galileo payload was activated directly from ESA’s Redu centre in Belgium,” explained Marco Falcone, overseeing the campaign effort as Galileo’s System Manager. “We have now established an end-to-end setup in Redu that allows us to upload commands generated from Fucino’s Galileo Control Centre to the satellite payload whenever the satellite passes over the station, while at the same time directly receiving the resulting navigation signal through its main L-band antenna.
“The result is our operations are much more effective, shortening the time needed for payload in orbit testing.”
Operating at an altitude of 23,222 km, the Galileo satellites take about 14 hours to orbit Earth, typically coming into view of Redu for between three to nine hours each day.
One of the GNSS controversies of the past year ended, not with a bang nor with a whimper, but like the fog, silently creeping away on its little cat feet. The UK patent applications against the interoperative GPS/Galileo signal design appear to have been dropped.
Vague rumblings emerged throughout spring and summer this year that two British technologists, backed by the U.K. Ministry Defense, had filed patents on the future interoperable GPS and Galileo binary-offset carrier signal designs. If granted and enforced, the patents would have severely disrupted modernization plans for both systems and levied unexpected costs upon receiver manufacturers. A company called Ploughshare Innovations Ltd. started contacting manufacturers and asking for payment of royalties, based on the patent filings.
After significant uproar and negotiations before and behind the scenes, it now appears that the initiative has been quietly scuttled. The U.S. Patent Office file on application number 11/774,412, Modulation Signals for a Satellite Navigation System, on the Patent Office’s website, now reads “Expressly Abandoned — During Examination.” The status is dated September 16, 2012, some time ago, but none of the parties involved, whether as filers or negotiators, has made any public announcement about it.
Both Sides Now. Checking the European Patent Office and its registry — which is no trivial task of website navigation — turns up a note, dated September 24, under the docket for EP1830199, Modulations Signals for a Satellite Navigation System. The note states “Patent surrendered.” A few days later, another note: “Lapsed in a contracting state announced via postgrant inform. From Nat. Office to EPO,” with further information to the effect of “lapse because of failure to submit a translation or the description or to pay the fee within the prescribed time limit.”
For good measure, a final docket note on October 3: “Lapsed due to resignation by the proprietor.”
Lockheed Martin Logs Enviro OK on GPS III Sat
The Lockheed Martin team developing the U.S. Air Force’s GPS III satellites has completed thermal vacuum testing for the Navigation Payload Element (NPE) of the GPS III Non-Flight Satellite Testbed (GNST). The milestone is one of several environmental tests verifying the navigation payload’s quality of workmanship and increased performance compared to the current generation of satellites.
During thermal vacuum testing, the navigation payload’s performance was proven in a vacuum environment at the extreme hot and cold temperatures it will experience on orbit to ensure it will operate as planned once in space. Following the test, the NPE will now be integrated with the GNST for final satellite level testing.
The GNST is a full-sized prototype of a GPS III satellite used to identify and solve development issues prior to integration and test of the first space vehicle. The approach significantly reduces risk, improves production predictability, increases mission assurance and lowers overall program costs. Following integration and test at Lockheed Martin’s GPS Processing Facility (GPF) near Denver, the GNST will be shipped to Cape Canaveral Air Force Station, Florida, for risk reduction activities at the launch site.
Lockheed Martin is on contract to deliver the first four GPS III satellites for launch. The Air Force plans to purchase up to 32 GPS III satellites.
Galileo IOV Satellites in Position
The Galileo In-Orbit Validation (IOV) satellites launched on October 12 (Flight Model 3 and 4), have now been positioned in their designated orbits, according to tracking data from the U.S. Joint Space Operations Center. A plot of the IOV constellation is now available at http://gge.unb.ca/test/Galileo.argper.690.432000.pdf.
The four IOV satellites are in two orbital planes separated by about 120 degrees. Within each plane, the satellites are separated by about 40 degrees. This orbital arrangement will allow the four satellites to be simultaneously tracked for periods of time by GNSS monitoring stations, permitting positioning tests using only IOV data to be carried out. However, no signals from FM3 or FM4 have yet been detected by stations of the International GNSS Service.
Activities of the European Navigation Support Office
Headshot: Werner Enderle
By Werner Enderle
The European Space Operations Centre (ESOC) in Darmstadt, Germany operates spacecraft on behalf of the European Space Agency (ESA) and maintains the ground facilities and expertise for ESA and other institutional and commercial customers. ESOC is composed of two departments: the Mission Operations Department and the Ground Systems Engineering Department, of which the Navigation Support Office is an integral part. The main objectives of the Navigation Support Office (NSO)are the provision of expertise for high-accuracy navigation, satellite geodesy, and the generation of related products and services for all ESA missions and for third-party customers, as well as supporting the European GNSS Programmes: Galileo and EGNOS.
In 2013, the NSO will conduct a number of projects and activities, described here.
European GNSS
The Navigation Office provides support in the area of data processing and analysis, performance analysis. It performs operational orbit predictions for the International Satellite Laser Ranging Service (ILRS), operational precise/rapid orbit and clock determination, computation of antenna patterns, and provides support to Galileo Sensor Stations (GSS) site deployment and to Ranging and Integrity Monitoring Station (RIMS) deployment. It also provides consultancy on modeling and data processing, mission analysis for the constellation, orbit validation activities for orbits and clocks, ionosphere, group delays, and intersystem biases, and is involved in the generation of the Galileo Geodetic Reference Frame. Furthermore, the Office participated in European Commission studies for the Galileo Commercial Service.
Earth Observation Missions
A number of European and American missions have been equipped with radar altimeter instruments that observe the level of the sea surface from space. To do this, the height component of the satellite orbits needs to be determined with centimeter-accuracy, matching the accuracy of the altimeter observations. The NSO provides support to Precise Orbit Determination (POD), evaluation, analysis and improvement of models and standards, as well as instrument calibration (radar altimeter and GNSS antenna).
Examples of missions already supported include ERS, Envisat, Cryosat, GOCE and also non-ESA missions JASON 1&2. Solutions with multiple simultaneous data types (GNSS, SLR, DORIS, altimetry, S-band range, Doppler, and angle tracking) are typically performed, allowing the alignment of different reference frames and estimation of inter-system and instrument biases. Based on all these capabilities, the NSO is one of the leading institutions for low-Earth orbiting (LEO) satellite POD activities and very well suited for supporting the upcoming European programme for Earth Observation, called Global Monitoring for Environment and Security (GMES) and its related Sentinel satellite missions.
Automated Transfer Vehicle
The Automated Transfer Vehicle (ATV) is part of the European contribution to the International Space Station (ISS) program. The main tasks of the ATV are to provide logistics supply, station re-boost and ISS waste retrieval. The rendezvous of the ATV and ISS is based on a real-time on-board relative navigation concept, using GPS data from receivers of ISS and ATV. The NSO conducts in this context simulations before the flight and also post facto performance analysis of the relative orbit determination accuracy to support the ATV missions.
Space Situation Awareness
An important atmospheric application of GNSS data is the monitoring of ionospheric activity (total electron content or TEC). Dual-frequency GNSS signals enable direct measurement of this parameter, and by merging the data from hundreds of globally distributed GPS receivers, detailed maps of the TEC and its evolution as a function of time can be constructed. Such maps have been computed routinely for many years. FIGURE 1 shows an example. The importance of these products lies in the fact that high solar activity leads to high TEC values, which can seriously disturb satellite communications. The NSO provides ionospheric TEC maps to the scientific community.
International GNSS Services
ESA/ESOC was one of the founding members of the IGS, and at the time the NSO was implemented at ESOC, all of the IGS activities were transferred to the NSO. ESA Analysis Centre products are among the best products available from the individual IGS analysis centres. Secondly, the ESA products are among the few multi-constellation GNSS products. ESA was the first IGS analysis centre to provide a consistent set of orbit and clock products for all available GNSS satellites. These products constituted the very first products that have been used for true GNSS precise point positioning.
The sampling rate of the ESA final GPS+GLONASS clock product is 30 seconds. FIGURE 2 shows the statistics of a kinematic PPP analysis using the ESA GNSS clocks for three different cases. The ESA/ESOC IGS Analysis centre contributes to all of the core IGS analysis centre products: Final GNSS (GPS+GLONASS) products provided weekly based on 24-hour solutions using 150 stations from true GNSS solutions simultaneously and fully consistently processing GPS and GLONASS measurements for a total of around 55 satellites, consisting of orbits, clocks, coordinates, ionosphere, and Earth-orientation parameters (EOPs). Also Rapid GNSS (GPS+GLONASS) products (available within 3 hours after the end of the observation day) and Ultra-Rapid GNSS (GPS+GLONASS) products (4 times per day, available within 3 hours after the end of the observation interval) are provided. These products are publicly available to the scientific community, being published at several data servers, such as the CDDIS at NASA’s Goddard Space Flight Center. They are also finding very frequent application in testing of experimental and commercial applications, and have become the standard reference for all high-precision GNSS applications.
Figure 2. Kinematic PPP analysis using ESA GNSS clocks: GLONASS-only PPP (red); GPS-only, (green), and a truee GNSS-PP (blue).
Third-Party Activities
Different customers have different needs. One important customer for the Navigation Facility is the Metop mission operated by EUMETSAT. For the exploitation of its GNSS Receiver for Atmospheric Sounding (GRAS) payload, which delivers atmospheric profiles to the European Met offices, EUMETSAT requires GPS products with a guarantee on accuracy, availability and latency. To deliver this service, the Navigation Facility now hosts the operation of the GRAS Ground Support Network (GSN), which is a dedicated network of 45 stations. It has been operating successfully for five years, delivering products with a latency of only 45 minutes, and an availability of better than 99 percent. Based on these, EUMETSAT delivers a daily set of more than 500 atmospheric profiles (and double that number as soon as Metop-2 will be operational) to the European Met offices, a data set that has already become one of the key elements in numerical weather prediction.
Real-Time Processing
Over the last 10 years, ESOC has embarked on a program to build a Real Time GNSS software infrastructure. The main justification for this effort is the realization that the delivery of precise GNSS products in real-time processing will become increasingly more important for the user community. ESOC needs to be at the forefront of these developments, particularly with respect to products related to Galileo. The system for REal TIme NAvigation (RETINA) has been modelled after ESOC’s experience in real-time satellite control systems and includes many of the elements for data processing, archiving, and visualization that are common to such systems. In particular, it implements a specially designed circular filing system for streaming data, allowing maintenance-free operations for processing and archiving of data and products, and seamless transitions from historical to live data processing.
The investment in GNSS software and receiver infrastructure has enabled ESOC to participate in the IGS Real Time Pilot Project, assuming the roles of Real Time Analysis Centre and Analysis Centre Coordinator. In the latter role, ESOC has been generating and disseminating the IGS Real Time Combination stream after processing the real-time solutions from up to ten analysis centres. Included in these solutions are two streams generated by the ESOC Real Time Analysis Centre.
Standardization Activities
Participation in the IGS Real Time activities has stimulated ESOC’s involvement in the development of standards and formats for GNSS data and products. ESOC has been instrumental in the decision of the IGS to join the Radio Technical Commission for Maritime Services (RTCM), which is the primary standards setting organisation for real-time GNSS services. ESOC is now one of two agencies that represent the IGS at the RTCM meetings.
Work with the RTCM focuses on:
development of standards and formats for transmission of multi-constellation observations in real time (RTCM-MSM);
development of standards and formats for the transmission of real-time orbit and clock products (RTCM-SSR);
Further development of the RINEX standard for generation of multi-GNSS batch observation files.
Expertise and Areas of Activities
To comply with the main objectives of the NSO, the main pillars of expertise and areas of activities can be summarized as:
Precise orbit determination at centimeter-level accuracy for satellites in low-Earth orbits such as Earth observation missions, and satellites in medium-Earth orbits, typically GNSS satellites.
Development of state-of-the-art models and algorithms for high-precision orbit and clock determination, based on the capability to process all geodetic data types, namely GNSS, satellite laser ranging, Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), altimetry, and S-band tracking data.
Realization of Geodetic Reference Frame.
Operation of global distributed real-time sensor stations and networks, based on remote control of GNSS receivers.
The capability to operate complex navigation software infrastructure to generate operational products and services for a wide variety of applications.
Involvment in several international organized and coordinated activities. Besides being an IGS analysis center, ESOC’s NSO is also an analysis centre for the IDS and ILRS services.
Operational Facility
ESOC’s ESOC’s Navigation Facility (see FIGURE 3) provides a fully operational environment, compliant with ESA’s ECSS ground segment standards. The Navigation Facility consists of a control room including secure operational LAN (ESACERT against intruders from outside) with two physically separated computer and data centres for redundancy purposes and a globally distributed operational real time sensor station network (see FIGURE 4). An operational system availability of more than 99.9 percent on a 24/7 basis measured over the last 5 years (products delivered every 15 minutes) has been demonstrated.
Currently the sensor station network consists of 12 sites, but ESOC is extending the global network to at least 25 sites. Negotiations with new sites are currently ongoing or near completion. The objective is to deploy a homogeneous (all sites will have the same receiver and same antenna type) sensor station network by the third quarter of 2013. The deployment of new equipment on existing sites began in April 2012, and first results are very promising. The new type of geodetic quality GNSS receiver has been chosen, based on an internal selection process, and deployment is under way. Each receiver has 264 physical channels, is capable of multi-signal, multi-frequency and multi-constellation tracking and will be remotely controlled from the Navigation Facility at ESOC.
Software Packages
The NSO develops, maintains and operates a range of software packages and tools for high-precision orbit- and clock determination and prediction. The software capability also includes the estimation of station coordinates, Earth-orientation parameters, model parameters (radiation pressure, drag, and so on), ionosphere, troposphere, instrument biases, intersystem biases, ambiguities and antenna phase-centre variations based on state-of-the-art models and standards (for example, IERS, ITRF).
The main software packages used within the NSO are:
NAPEOS, which is the ESOC standard for high-precision navigation tasks. NAPEOS is used for almost all projects and is compliant with the highest navigation accuracy requirements, based on batch processing techniques with the capability to process different types of geodetic observations.
RETINA, the NSO’s real time software package for GNSS based precise navigation. This software is based on Kalman Filter techniques and has a closely coordinated interface to NAPEOS.
IONMON, processing GNSS data and producing ionosphere information and TEC map predictions.
In this context it is important to mention that ESA owns all the intellectual property rights to these software packages and that licences for operationally qualified software can be released on request to European companies, universities and R&D 0rganisations (currently only NAPEOS).
Summary and Outlook
The Navigation Support Office offers a combination of different capabilities, namely highest quality software, tools for real-time and batch processing ( the Office is the only analysis centre capable of processing three different geodetic techniques within a single software package), operation of own global GNSS sensor station network and demonstrated operational experience for mission support and provision of services. Operations are conducted in a controlled environment, fully in accordance with ESA safety and security standards.
The Navigation Support Office is ready for multi-frequency, multi-signal and multi constellation GNSS data processing. The Office is involved and strongly committed to support Galileo and EGNOS. In this context, the Office will soon become the consortium leader for the provision of the Galileo Geodetic Reference Frame.
Concerning the participation to international GNSS activities like IGS, ICG and GNSS standardisation aspects, the Navigation Support Office intends to continue its support for the foreseeable future.
In the area of LEO POD, the Navigation Support Office offers POD capability for all types of LEO satellites. For this reason, the Office intends to play a major role in the precise orbit determination activities for the European GMES Sentinel satellite missions.
Finally, the Navigation Support Office also intends to increase its capabilities related to navigation concepts for high-precision satellite formation flying and satellite constellations, via specific research and development activities. The aim is to maintain and expand its capabilities as a very attractive partner with cutting edge know-how and technology for the support of ESA activities and European industry.
Werner Enderle is the head of the Navigation Support Office at ESA\ESOC. Previously, he worked at the European GNSS Authority (GSA) as the Head of System Evolutions. He also worked for the European Commission, in charge of the procurement for the Galileo Ground Control Segment. He holds a doctoral degree in aerospace engineering from the Technical University of Berlin, Germany.
Co-authors: Rene Zandbergen, Tim Springer, and Loukis Agrotis.
CYGNSS, Others Deliver Now and in Future for Global Weather Forecast
Editor’s Note: This article reproduces the acceptance speeches given by the winners of GPS World’s 2012 Leadership Awards, at the Leadership Dinner in Nashville in September. The Leadership Dinner was sponsored by Lockheed Martin and Deimos Space.
Martin Unwin, Surrey Satellite Technology Limited; Principal GNSS Engineer, winner in the Satellites category. He is a key member of the team that built the GIOVE-A satellite (recently retired) and is now working on the Galileo FOC satellites. He is also recognized for his work on space-borne receivers.
Headshot: Martin Unwin, Surrey Satellite Technology, winner in the Satellites category.
I feel privileged and honored to receive this award from GPS World, and I am truly sorry now that I chose this year not to attend the ION-GNSS conference to receive it!
With respect to the achievements in GIOVE-A and Galileo, I cannot claim this award on behalf of myself, but I will claim it on behalf of the people in Surrey Satellite Technology Limited (SSTL) who made the projects possible, and to those in the team here who have been working tirelessly to make the payloads and satellites happen. We are of course partnered with others in Europe that have been laboring equally hard, so it has been a true team effort.
With respect to the spaceborne GPS and GNSS activities, my achievements have only been possible thanks to the top-class staff we have in the receivers team, and thanks are also due to the support we have had from the rest of SSTL.
In the 20 years I have been in the company, Surrey Satellite Technology Ltd has grown from a small university-based department to a major player in the international space scene, and I am immensely proud to have been part of this story.
A Few Words for the Future
Whilst it cannot quite match the early heady days of GPS, I still think nevertheless we are entering an exciting time in the GNSS world. We have two operational systems, and within a few years, we will be seeing two more reaching operational capability. Dual- and even triple-frequency civil signals will soon become operationally available, and some very wide bandwidth signals will be sent down, in particular, by Galileo. There is bound to be a steep learning curve in understanding how to exploit these new signals, with a few crevasses to be negotiated during the climb. But these new signals are bound to lead to an expanded vista of increased accuracy and robustness, and undoubtedly some unexpected destinations.
Taking perhaps the highest perspective, spaceborne remote sensing is a good example that has surprising relevance to the rest of us still on the ground. In this case, GNSS satellites are used as radar sources, and all that is required on a low-Earth orbiting (LEO) satellite to change the world is a GNSS receiver. GPS radio-occultation measurements from low-Earth orbit are now already the third most important data source for our global weather forecasts, thanks to the like of the COSMIC and MetOp satellites.
Furthermore, a new constellation of satellites called CYGNSS has recently announced by NASA that will be using ocean-reflected GPS signals to probe inside hurricanes and typhoons, and for the first time will enable the sensing of the wide-scale ocean roughness, leading to improved global wind and wave knowledge. By adding to this spaceborne receiver the ability to accommodate signals from GLONASS, Galileo, and Compass, plus any other available GNSS-type signals, the number of measurements is instantly quadrupled, and a new capability in sensing the atmosphere, waves, and even ice and land is likely to be seen. Meteorologists already view GPS as an emerging utility for weather and climate sensing, but I think this new role for GNSS will be reinforced and expanded into yet another area where GNSS incontrovertibly, if indirectly, makes such a significant difference to our daily lives.
As with many other applications where GNSS has become important or even critical to our modern world, this is, at the same time, both a blessing and a matter for some caution.
Fully Operational System Modernizes for the Multi-GNSS World
Headshot: Vitaly Davydov and Sergey Revnivykh
By Vitaly Davydov and Sergey Revnivykh
Since December 2011, the GLONASS system has been fully operational, providing worldwide service with 100 percent global availability and acceptable accuracy for most users. The system is globally accepted by many users, and most leading manufacturers include GLONASS in their devices.
This fact became a reality due to the successful completion in December 2011 of the Russian Federal Mission Oriented Program dedicated to GLONASS restoration, under the under permanent supervision and control of the President of the Russian Federation and Russian Government, Vladimir Putin.
It may have seemed back in 2002 that very few people outside the GLONASS team believed in the success of the Program, when the constellation was composed of six operational satellites with only a 3-year lifetime. But now the GLONASS constellation consists of 24 modernized operational Glonass-M satellites and in-orbit spares. Further, the new generation GLONASS-K satellite flight tests have begun.
The GLONASS Program obtained significant support in May 2007 when the famous Decree of the President of the Russian Federation was issued. The President made commitments to sustain the GLONASS system and provide its open service free of charge and available for all users worldwide without any restrictions. At the same time, the President charged the Government to prepare and approve the new GLONASS Program for 2020. The new Federal Mission Oriented Program ,designated GLONASS maintenance, development and use for 2012–2020, was approved by the Government of the Russian Federation on March 3, 2012 with a dedicated article in the State Budget Law. That means that the President’s commitments are supported by real financial resources for the next decade, and the situation of the mid-1990s will never occur to GLONASS again.
The new Program has three major tasks:
To keep GLONASS in full operational mode.
To significantly improve GLONASS performance and service quality.
To provide conditions for worldwide use.
The tasks to make GLONASS an integral component of the global GNSS infrastructure, providing worldwide service for all users, are challenging. At the same time, the primary goal of GLONASS as a dual-use system is to serve national security interests.
What the Future Brings
GLONASS development in the near future is foreseen in a few key directions.
Space Segment. Modernization of the GLONASS core, called the Space Complex, undertakes the development of new spacecraft with enhanced performance. This means more stable on-board clocks, new code-division multiple-access (CDMA) signals, and intersatellite link for orbit, clock update, and range measurements. The GLONASS-K satellite will be the new generation spacecraft, applying advanced technologies.
The first-phase GLONASS-K satellite is already passing flight tests, transmitting new CDMA signal in L3 band in addition to the existing set of FDMA signals. The GLONASS-K of the second modernization phase will transmit the full set of new CDMA signals in L1, L2 and L3 bands.
At the same time, all new GLONASS satellites will continue transmitting the existing set of frequency-division multiple-access (FDMA) signals, providing backward compatibility with existing user equipment. Implementation of the CDMA signals in L5 and in L1 (1575.42 MHz) bands is also in line with the Signal Modernization Concept. This task is undergoing study to optimize the power and mass budget of future satellites and to consider benefits for users. Finally, new CDMA signals will provide better accuracy, better protection to interference and better service for users.
GLONASS modernization foresees extending the number of operational satellites in constellation available for users. Presently navigation message enables maximum 24 satellites for users. Activities in order to get more operation satellites available, assumes modernization of the existing FDMA almanac. New almanac of CDMA signals has no limitations.
Ground Segment. Ground-control segment modernization will produce a monitoring-station network extension to provide global coverage, extension of the uplink-station network to provide more frequent updates of orbit and clock, and system clock modernization to make the system time scale more stable and better synchronized with UTC.
The new geodesy reference PZ-90.11 is already coordinated with the International Terrestrial Reference Frame (ITRF) at the centimeter level and shall be introduced soon.
Augmentation. The System for Differential Correction and Monitoring (SDCM) space-based augmentation system is dedicated to improving navigation services, providing integrity data and better accuracy for users. As a first phase, the service area of SDCM is over the Russian territory. For SBAS signal re-transmission, the three GEO communication satellites of the Luch system are equipped with navigation transponders. The first Luch-5A is already in orbit. The other two are scheduled for launch. Eventually the SDCM system will provide a global navigation service, transmitting precise orbit and clock data to users and introducing precise-point positioning (PPP) technique.
Performance Improvements. The GLONASS modernization plan foresees step-by-step performance improvement of all system components. By 2020, the GLONASS system in stand-alone mode will provide sub-meter accuracy for users with an open signal. Augmented by SBAS, the GLONASS system will provide user positioning accuracy at the decimeter level and better.
In the coming Multi-GNSS world, the GLONASS system must be one of the key components to benefit all users with reliable and accurate navigation, positioning, and timing services. To reach that goal, the international cooperation between system providers with feedback from all group of users is a mandatory condition. All global and regional navigation satellite systems must be compatible and interoperable. The International Committee on GNSS, established according to UN recommendation, plays a significant role for international cooperation aimed at achieving synergy in the navigation environment.
2013 is very important for GLONASS to demonstrate stability with improvement for all users around the world. All the necessary resources to achieve this are available, based on the long-term Federal Mission Oriented Program supported by the President and the Government of the Russian Federation.
Vitaly Davydov is the deputy head of the Federal Space Agency, Coordinator of the Program for GLONASS Sustainment, Development, and Use. He graduated from the Dzerzhinsky Military Academy and from the Russian Presidential Academy of National Economy and Public Administration with a Master‘s degree in Public and Municipal Administration. From 1997 to 2004 Vitaly Davydov supported the Russian Federation Security Council’s Office. Prior to that from 1975 to 1997 he occupied various positions in Russian Department of Defense’s Space Forces.
Sergey Revnivykh is deputy director general of the Central Research Institute of Machine Building, leading institute of Federal Space Agency, Head of PNT (Positioning, Navigation and Time) Analysis and Information Center. He is a member of the management of the Federal GLONASS Program. He received his Ph.D. degree from the Moscow Aviation Institute.
GPS Directorate: Receivers Will Operate in Environments Impossible Today
By Col. Bernie Gruber
Headshot: Col. Bernie Gruber
I believe the future of global navigation satellite systems (GNSS) and particularly GPS will only be limited by our ingenuity and imagination. In terms of economic benefit, GPS contributes $60 billion to our economy, and that’s no stretch considering the positive and real advantages GPS affords us every day through fuel savings, transportation optimization, banking transactions, recreational activities, and certainly the defense of our great nation.
GPS consists of three segments — space, ground and user equipment — all contributing synchronistically to provide the world positioning, navigation, and timing (PNT). Having joined the GPS program office (for the first time) in 1992, I was privileged to lead the very first Foreign Military Sales contracts and the development of the Selective Availability Anti-Spoofing module (SAASM) — both focused within the realm of user equipment. As program director of GPS reflecting back on the monumental change of the past 20 years, I am encouraged and look forward to seeing the fruition of the projects and plans we have already set in motion for the next 20. This is why:
Space Segment. The launch and handover of the third GPS IIF satellite on October 4 proves once again our commitment to mission success. We have exceeded our published worldwide accuracy standard since 1993, and the NavStar GPS constellation remains robust with 31 satellites currently available.
In regards to the satellite systems, next-generation Block IIF and III satellites are in various states of test, integration, or production in an effort to improve the average user range error (URE) from 0.9 meters, achieved and maintained for the last 3 years, to a root-mean-squared URE of 0.5 meters by 2016. Along with increased civil and military signals, I also envision digital waveform generation (that is, the ability to change on-orbit signals in space via software) as an integral part of our architecture. Digital waveform generation coupled with an augmentation of the GPS III constellation for affordability and resiliency will pave our way to the future.
Ground Segment. Along with a host of additional satellite capabilities and signals, we will correspondingly modernize our ground segment. Our Next-Generation Operational Control System (OCX) is designed to command and control our modernized secondary civil signal L2C, safety-of-life signal L5, and the internationally compatible signal L1C. In fact, users such as John Deere and NavCom are already accessing the currently broadcast L1 C/A and L2C (with a default code) for dual-frequency ionospheric correction to improve upon accuracy. As the modernized signals become operational, users will see faster signal acquisition, enhanced reliability, and a greater operating range. The information assurance, expandability, and service-oriented architecture will afford users and operators with security and information they simply don’t have today.
User Segment. All that said, I am thrilled to look at the future of user equipment. We need to take advantage of the use of civil GPS. Apple and Android have shown the way to interface with and use applications, displays, and packaging; Google Map overlays, smart phone apps, time-to-first-fix augmentations from cell towers, and multi-GNSS international coverage are already in use, with the growth of apps, users will only get smarter and more sophisticated in their GPS expectations.
To that end, the Air Force is augmenting its pilots with digital maps and starting to integrate GPS with the digi-maps beginning with the C-130J. The Army is paving the way with an app store for military use and beginning to integrate GPS with its equipment, such as the use of a GPS integrated wind app for calibrating bullet trajectories.
Security, authentication, integrity, and the ability to operate in almost any environment is vital to our warfighters. The Department of Defense is posturing to operate in an anti-access area denial (A2AD) environment. Make no mistake; the list of potential adversaries also includes a list of known attacks on GPS — along with use of GPS and other GNSS systems against us. For that purpose, the modernized GPS is working on better and improved items like key management, M-Code power and cryptography, and Blue Force Electronic Attack (BFEA). In this area too, I see the commercial market burgeoning with new ideas to protect the calculation of GPS PNT solutions.
In the selective-availability anti-spoofing module, we introduced positive control and resiliency to the military GPS receivers. Now with M-Code we are taking it one step further. M-code will leverage the National Security Agency (NSA) Key Management Infrastructure and augment it with more tools to ensure only authorized users have access to M-Code. This provides greater protection from spoofing, ensures that keys are readily available to the United States and her Coalition partners, and that security cost drives for our user equipment are minimized.
With more signal power, almost every aspect of GPS is better. While the 6–10 dB of additional power in GPS III will not in itself defeat known threats, more power complements anti-jam techniques as well as improves operation under foliage and in the presence of pervasive unintentional interference. We’re going to see receivers that operate in navwar environments that would be impossible today. Similarly, I see us having the flexibility to operate with other GNSS systems in benign environments, but the ability to also operate in hostile or contested environments.
Blue Force Electronic Attack was always a principle driver for GPS modernization. It is embodied in the White House Directives and Title 10 U.S.C [Title 10 of the United States Code outlines the role of armed forces in the U.S. Code, a compilation and codification of the general and permanent federal laws of the United States — Ed.] Today’s Block II systems do not have enough spectral separation for effective BFEA. As M-Code becomes readily available, along with the additional filtering available in military GPS user equipment (MGUE), we are providing Joint Task Force Commanders with options to deny GPS; options that they don’t have today.
The future of GPS is bright indeed! From the originators of GPS to present day men and women who work tirelessly to deliver and operate it, we are all striving to improve and enhance this magnificent capability. The economic benefits of a system that, in reality, pays for itself guarantees the world’s desire to see improvements and growth in the overall GPS system. The Air Force is a proud steward of the GPS system, but it is our collective job to proliferate new ideas to use it and secure it.
Colonel Bernie J. Gruber is director, Global Positioning Systems (GPS) Directorate, Space and Missile Systems Center, Air Force Space Command, Los Angeles Air Force Base, California. He is responsible for a multiservice, multinational systems directorate which conducts development, acquisition, fielding and sustainment of all GPS space segment, satellite command and control (ground) and military user equipment. The $32 billion GPS program, with a $1 billion annual budget, maintains the largest satellite constellation and the largest avionics integration and installation program in the Department of Defense. He has served in key positions at Major Command, Air Staff, Joint Staff and Defense Agency levels. Prior to assuming his current position, Colonel Gruber was Chief, Space Superiority and Global Integrated Intelligence, Surveillance and Reconnaissance Division, Directorate of Programs, Deputy Chief of Staff, Strategic Plans and Programs, Headquarters, United States Air Force, Washington, D.C.
