A Fregat booster successfully delivered a Glonass-K navigational satellite into its designated orbit, Russia’s Defense Ministry reported on Oct. 10. Glonass-K No. 17L is the fifth K satellite to join the constellation.
“A Soyuz-2.1b medium-class carrier rocket that blasted off at 05:52 a.m. Moscow time on October 10 from the Plesetsk spaceport in the Arkhangelsk Region successfully delivered a Russian Glonass-K navigational satellite into the target orbit at the designated time,” the ministry said in a statement.
Liftoff and the delivery into the designated orbit proceeded in normal mode, the ministry said, and the ground-based facilities of Russia’s Aerospace Forces assumed control.
“The Russian Glonass-K navigational space vehicle launched on Monday, October 10, from the Plesetsk spaceport by a combat team of the Space Troops of the Aerospace Forces was delivered into the target orbit at the designated time and placed under the control of the ground-based facilities of the Titov Main Testing Space Center of the Aerospace Forces’ Space Troops,” the statement said.
Stable telemetry communications have been established and are being maintained with the satellite. The space vehicle’s onboard systems are operating in normal mode, the ministry said.
The Glonass-K is a third-generation satellite of the Russian global navigation satellite system (Glonass). The satellite was engineered and manufactured by the Reshetnev Information Satellite Systems Company (part of Russia’s State Space Corporation Roscosmos). The satellite was developed to replace the Glonass-M family of space vehicles.
Figure 1. GLONASS high inclined space complex. (Image: Institute of Navigation Technology JSC)
The digital transformation of the global economy requires precise time synchronization and valid object position information. Global navigation satellite systems (GNSS) are the most accurate tool for such tasks.
This year will be 40th anniversary of the launch of the first GLONASS satellite, and we see that the quality of navigation services is driven by the characteristics of today’s satellite navigation signals.
The first fourth-generation Glonass-K2 #13L satellite is scheduled for launch in 2022. It will broadcast a full ensemble of navigation signals — both Frequency Division Multiple Access (FDMA) signals in the L1 and L2 bands and Code Division Multiple Access (CDMA) signals in the L1, L2 and L3 bands. This long-awaited launch will cap a 10-year effort and begin to provide a new platform by broadcasting all the CDMA signals through a single antenna array on the satellite’s geometric axis.
The FDMA antenna array is displaced by 0.9 m from this axis, but this arrangement is done on only two satellites. The next Glonass-K2 satellites, which will be launched beginning in 2024, will have a single antenna array for all navigation signals.
The final second-generation Glonass-M satellite, scheduled to be placed in orbit next year, will provide services by open FDMA signals in the traditional bands at 1.6 GHz and 1.25 GHz. This satellite will be the seventh Glonass-M vehicle able to broadcast GLONASS L3 CDMA signals. There are only two Glonass-K satellites broadcasting this signal now, but more satellites with such a signal will be activated by the end of testing of the GLONASS modernized ground control facility.
We expect the number of satellites able to provide this service to increase by two per year as we replace Glonass-M satellites with Glonass-K and Glonass-K2 satellites.
As of this writing, 15 satellites (62% of the constellation) are working past their guaranteed life times, limiting our ability to increase the system’s accuracy. For the last decade, the signal-in-space range error (SISRE) was 1.4 m, despite the fact that newly launched satellites provide a SISRE of about 0.8 m.
Glonass-K satellites will be launched to maintain the orbit constellation within the next three years, and the accuracy of their signals will be the same or even better. These satellites have a single antenna array for all three bands and could broadcast either FDMA or CDMA signals.
In 2022, the constellation orbits will increase to six satellites in three planes, as we aim to increase the navigation service accuracy and availability (FIGURE 1). See TABLE 1 for satellite orbit parameters. This constellation will make it possible to increase navigation accuracy in the Eastern Hemisphere by about 25% through decreasing the value of the geometric factor.
Additionally, this will greatly improve the availability of the GLONASS navigation service in difficult conditions, such as locations where current users can only receive navigation signals from satellites at least 25° above the horizon. New constellation satellites will be based on the Glonass-K platform, which has passed in-orbit qualification and proved it can provide SISRE at 0.3 m. The preliminary design proved that satellites on this platform could provide an in-orbit SISRE below 0.4 m with standard cesium on-board clocks. This signal-in-space accuracy level with valid ionospheric and tropospheric model data from the navigation signal will allow users to receive a position determination error below 2 m in the plane. Navigation services from these satellites will be provided by the CDMA signal in three frequency bands.
The new satellite will weigh about 1,000 kg and be launched into orbit from both Russian spaceports (northern Plesetsk and eastern Vostochny) by the highly reliable Soyuz-2 rocket. The first launch is scheduled for 2026.
One of GLONASS’ important tasks is to transmit the UTC (SU) national time scale to consumers. Over the past few years, significant results have been achieved in this area.
A complex of high-precision measuring instruments to compare the national coordinate timescale UTC (SU) with the GLONASS timescale was put into operation. These instruments include a transported quantum clock that provides timescale storage with an uncertainty of no more than 1 ns at an observation interval of one day, and with a transportation time of no more than 12 hours. It also provides duplex comparisons of timescales, comparing objects with the permissible uncertainty of ±1.5 ns.
Timescale storage complexes of secondary and working standards of time and frequency VET1-5 (Irkutsk), VET 1–19 (Novosibirsk), VET 1–7 (Khabarovsk) and RET1-1 (Petropavlovsk-Kamchatsky) were modernized and put into operation, providing an overall uncertainty of 3 · 10-15 and with a maximum permissible shift of the timescale of the complex relative to the national timescale UTC (SU) of ± 10 ns.
An optical ground-based frequency reference on cold strontium atoms was developed with an uncertainty of reproduction of the frequency unit and time of no more than 1 · 10-17 .
A keeper of time and frequency units was developed on the basis of a “fountain” of rubidium atoms having a frequency instability of no more than 2 · 10-16 for equipping the standards of time and frequency units and subsequent transmission of more accurate time-frequency information to precision ground and onboard equipment and GLONASS systems.
A developmental prototype of the national timescale storage complex of the Russian Federation was developed on the basis of a new generation of hydrogen keepers.
The application of the newly developed technical equipment made it possible to significantly reduce the maximum displacement of the national timescale relative to the International Coordinated Time Scale (UTC), which in 2020 was less than ± 3 ns (FIGURE 2). The UTC (SU) timescale ranks among the best national implementations of UTC, according to the International Bureau of Weights and Measures (BIMP).
Figure 2. Displacement of national timescales relative to Universal Coordinated Time (UTC). (Image: VNIIFTRI FSUE)
Many important events are coming for GLONASS users in 2022. They will improve the user characteristics and lay the foundation for further development of the system.
Sergey Karutin is general designer of the Russian GNSS program GLONASS.
Nicolay Testoedov is CEO of JSC Information Satellite Systems Reshetnev (ISS JSC), a Russian satellite manufacturing company.
Sergey Donchenko is general director of the Federal State Unitary Enterprise, Russian metrological institute of technical physics and radio engineering, VNIIFTRI FSUE.
By Yury Urlichich, first deputy director general of Roscosmos State Space Corporation Sergey Karutin, designer general of GLONASS Nikolay Testoedov, director general, Information Satellite Systems JSC
Sergey Koblov, director general, Central Research Institute of Machine Building JSC
The year 2020 heralds the end of another 10-year stage of development of the Russian GLObal NAvigation Satellite System (GLONASS). Reconstruction of our orbital constellation, started in 2006, is bearing its fruit. Today, it is hard to imagine one’s daily life without the continuous artificial radio-navigation field provided to users globally by the GLONASS orbital constellation since 2011.
GLONASS signals are employed to perform a wide range of tasks, such as
Saving lives in road accidents
Air, ground and naval traffic monitoring and control
Network synchronization of mobile cellular communications
Monitoring and enabling the energy grid, road travel, agricultural equipment operation, and more.
Our orbital constellation is built upon a base of second-generation spacecraft (SC) — Glonass-M SC — that was developed in 2003 and has demonstrated outstanding operational capacity: 14 SC are already operating well beyond their expected lifetimes, and four SC celebrate their 13th birthday in orbit this year. Activities focused on improving GLONASS accuracy have not stopped for a single day.
If we go back to 2014, the SC-based ranging offset (which specialists refer as equivalent ranging deviation) was 1.4 m. We managed to achieve 0.9 m offset on Jan. 30, 2020, and during the same week the offset did not exceed 1.15 m. Furthermore, the penultimate series-produced Glonass-M SC (Cosmos-2545), which was launched on March 30, demonstrated basic service ranging accuracy of 0.38 m on a daily interval and 0.63 m accuracy on the “best week” interval.
Glonass-K No. 15 was launched into orbit on Oct. 25. (Photo: Roscosmos)
It was Glonass-M SC development that enabled users around the world to gain access to the first dual-frequency navigation service, which is necessary for decreasing the effects of the ionosphere on navigation accuracy.
The third generation of GLONASS SC — Glonass-K — was successfully launched from the Plesetsk launch site on Oct. 25. This SC will provide users with a broader range of capabilities — and a more accurate and informative signal in the L3 frequency band. Further gradual rejuvenation of the GLONASS constellation will ensure the ever-improving quality of our navigation services.
Two Glonass-K2 SC are planned for the launch campaign in 2021, and all the experience accumulated during the development of third-generation GLONASS SC (Glonass-K) will be implemented in the fourth-generation SС. Glonass -K2 is a unique SC: It will provide users with five navigation signals, its accuracy will be within 0.3–0.5 m, and its assured expected lifetime will be at least 10 years.
High-Orbit Space Complex
GLONASS developers remain focused on user requirements. Recent surveys show a growing demand for high-quality navigation services in difficult conditions where the SC is visible at more than 25° above the horizon. To satisfy these needs with the implementation of new CDMA signals, development of the GLONASS High-Orbit Space Complex (HOSC) will begin in 2021. Its first SC will be launched in 2025, and complete deployment of the constellation including six SC in three or six planes will be finished by the end of 2027.
As a result, the accuracy and availability of navigation in difficult conditions will improve in the Eastern Hemisphere. But the major anticipated outcome of the HOSC implementation is assured two-fold coverage of the Northeastern segment of the globe with high-accuracy differential navigation data by GLONASS and other GNSS.
HOSC implementation will ensure 25% navigation accuracy improvement over the Eastern hemisphere. Glonass-K SC will be used as a base platform for HASC deployment due to its excellent record.
Ground Control at the Titov Main Test Space Center established a stable telemetry connection with the new satellite shortly after launch. (Photo: Roscosmos)
User Interface Harmony
One of the most important tasks for the year 2020 is harmonization of the GLONASS user interface. As we already mentioned, the signal propagation environment has a strong effect on navigation accuracy; therefore, new issues of GLONASS Interface Control Documents (ICD) are being prepared for publication.
We anticipate that GLONASS end-user accuracy improvement will be achieved through introducing additional information into reserve bits of navigation frames, including relevant parameters of an ionospheric model.
The ICD will contain operating methods with parameters of the ionospheric model and definite recommendations designed for compensation of ionospheric delays by both single-frequency and dual-frequency receivers, as well as generalized methods for compensating for tropospheric delays.
Changes in the ICD concerning FDMA and CDMA signals will ensure backward compatibility and uninterrupted operation for the existing range of user navigation equipment.
Russia launched a new-generation Glonass-K satellite, number 15, into orbit Oct. 25. Unlike its Glonass-M predecessors, Glonass-K satellites carry two types of navigation signals — frequency-separated and code-separated. The satellites emit additional code-division L2 navigation signals.
In addition to their main functions, Glonass-K satellites will transmit information from the Cospas-Sarsat international search-and-rescue system. Additional Glonass-K satellites are in production at ISS Reshetnev, all with a domestic electronic component base.
Russia’s Aerospace Forces (VKS) Space Forces launched the satellite aboard a Soyuz-2 rocket from the Plesetsk cosmodrome in the Arkhangelsk region. The launch of the carrier rocket and the maneuvering of the spacecraft into the orbit took place under normal operating conditions, according to Roscosmos.
Two minutes after the launch, the ground-based automated control complex of the Titov Main Testing Space Center acquired the Soyuz-2. On schedule, the Glonass-K satellite was injected into the target orbit by the Fregat upper stage and taken over by the ground-based facilities of the VKS Space Forces.
Photo: Roscosmos
A stable telemetric connection has been established and maintained with spacecraft. The onboard systems of the Glonass-K spacecraft are operating normally.
GLONASS consists of 28 spacecraft, with 24 active, two in reserve, and one Glonass-K undergoing flight tests. Another spacecraft is temporarily out for maintenance.
Glonass-M satellites form the basis of the system’s orbital grouping. Replacing the orbital constellation with Glonass-K spacecraft will ensure the stable operation of the Russian navigation system and increase the accuracy of its navigation determinations up to tens of centimeters.
According to Roscosmos, Glonass-K spacecraft are constructed in an unpressurized design, have a guaranteed period of active existence in orbit increased to 10 years, reduced energy consumption, and significantly lower weight.
Russia has launched another GLONASS-M satellite, according to Roscosmos, the Russian State Space Corporation.
A Soyuz-2.1b launch vehicle successfully carried the satellite to its planned orbit from the Plesetsk cosmodrome. The launch took place on schedule on March 16.
Ground-based facilities of the G.S. Titov Space Forces VKS immediately took control of the satellite. A stable telemetry connection has been established and maintained with the satellite. The onboard systems of the spacecraft are operating normally.
The launch used a Fregat booster block produced by NPO Lavochkin, part of the Roscosmos State Corporation. The satellite was manufactured by ISS, also part of Roscosmos State Corporation.
The Soyuz-2.1b launch vehicle with encapsulated GLONASS-M satellite is transported to the launchpad. (Screenshot: Russian Ministry of Defense video)
For the GLONASS constellation, a full complement of 24 satellites are set healthy. In addition, four satellites previously in the constellation are classified as spares, in maintenance or in test.
The just-launched satellite is expected to replace a currently operational GLONASS-M satellite, specifically GLONASS 735 in orbital slot 24). Of the 24 healthy satellites, one is a K1; the rest are Ms. The satellite in test is also a K1 (the first K1 to be launched).
Artist’s rendering of a Glonass-K satellite. (Image: ISS-Reshetnev)
ISS-Reshetnev Company — the primary GLONASS contractor — has a backlog of orders for navigation satellites up to 2025, according to General Director Nikolay Testoyedov.
Testoyedov discussed GLONASS production on Dec. 30, 2019, at a meeting hosted by ISS-Reshetnev Company for Russia’s Science and Technical Council.
“Within the Federal Target Program, GLONASS ISS-Reshetnev Company is tasked with the production of 27 navigation satellites,” Testoyedov said. “Taking all things together, we plan to double the number of satellites launched in 2020 compared to 2019.”
The orders require production at full capacity at the company’s facilities. At any given time, about 50 satellites are in varying stages of production, including 12 ground spares. Some of them are slated for launch in 2020.
In 2019 eight satellites designed and built by the company were launched into various orbits. As of today, 104 ISS-Reshetnev-made satellites are in space, or two-thirds of Russia’s entire orbital fleet of satellites. ISS-Reshetnev also successfully completed several projects for the manufacture of satellite onboard systems and instruments, including the international ExoMars-2020 program slated to launch this year.
A joint team of experts representing ISS-Reshetnev Company and the operating organization successfully completed all procedures moving the Glonass-M satellite to its proper orbital position, and switched on its main instruments. To this date, all the required data has been received from the satellite, which allowed it to be commissioned into service.
The new Glonass-M replaced a retired satellite of the GLONASS constellation that had surpassed its designed life expectancy by seven years.
Yury Urlichich, First Deputy Director General, Roscosmos. (Photo: Roscosmos)
By Yury Urlichich First Deputy Director General, Roscosmos State Space Corporation
The year 2019 will bring GLONASS users many new opportunities. Improving navigation services specifically at the user level, primarily assessed in terms of signal accuracy and availability, is our primary goal. Improving navigation accuracy is based on space system development, including both the orbital constellation (space segment) and ground control segment.
CDMA Signal
A Glonass-K2 spacecraft (SC) launch followed by flight testing will be the most important event in space segment development. This SC will enable navigation not only using legacy FDMA signals available for users for more than 35 years, but simultaneously with a full row of CDMA signals in all GLONASS frequency bands: L1, L2 and L3.
Currently the major navigation error contributors are the radio signal trajectory and the user terminal receiving environment. The new signals will allow lowering the hardware-dependent SC-user ranging error by an order of magnitude, reducing the influence of signal reflections from buildings, constructions and landscape (multipath effect), thus enabling their effective use for high-precision navigation with real-time errors below 0.1 m.
We are also finalizing in 2019 the newest edition of the GLONASS Interface Control Document containing recommended models for evaluation of tropospheric and ionospheric delays. Our forecasts show two times navigation accuracy improvement for users of these models.
High-Orbit GLONASS
Improving signal availability is equally important. As large urban areas demonstrate growing use of navigation technologies, these users experience difficulties receiving signals from SC flying below the elevation angle of 25°. To provide a navigation solution in such environments, we will begin development of High-Orbit GLONASS in 2019.
High-Orbit GLONASS will consist of six SC distributed among the three orbital planes and forming two SC ground traces with 64.8° orbit inclination, eccentricity of 0.072, revolution period of 23.9 hours, geographical longitude of the ascendant angle – 60°, 120° (See figure below).
High-Orbit GLONASS — ground track in red. (Image: Roscosmos)
The new generation space segment will be populated with Glonass-B satellites designed on the proven Glonass-K platform, successfully providing services since 2012. Users will be offered the full spectrum of new CDMA signals in all three GLONASS frequency bands.
The first Glonass-B is planned for launch in 2023, with the full constellation of six SC to be deployed by the end of 2025, increasing by 25% the navigation accuracy in the Eastern hemisphere.
The satellite mass below 1,000 kg allows Angara-A5, the new Russian heavy launch vehicle, to perform a dual launch from either Plesetsk or Vostochny launch sites.
Much attention is being paid to the signal characteristics’ stability throughout the whole system lifecycle. For this purpose, ROSCOSMOS developed the GLONASS Monitoring and Performance Assessment System for civil users, including the distributed network of monitoring stations abroad, and dedicated radio telescopes capable of analyzing the navigation signal structure and power on the Earth’s surface.
Currently the planned user range error (URE) for signal in space is 1.4 m. Feb. 26, with URE of 1.13 m, became the best day of the ten-month long monitoring in 2018. Moreover, this value tends to decrease as Glonass-M satellites operating beyond their guaranteed life period are being replaced. For instance, on Nov. 3, Glonass-M satellite No. 57 launched, replacing No. 16 after almost 12 years of operation in orbit.
As already mentioned, the Glonass-K2 is planned for launch in 2019. Compared to Glonass-M and Glonass-K satellites, Mission Definition Requirements for Glonass-K2 define URE to be 0.3 m, qualitatively improving GLONASS user performance.
The new on-board frequency standard based on passive hydrogen maser (PHM) will also contribute to better performance. This PHM is undergoing its ground tests and will be installed onboard the SC by the end of the year. Its relative 24-hour stability of better than 5×10-15 ensures the required URE.
A review of the history of the GLONASS program, its current status and an overview of the plans for the immediate future of the satellite constellation, its navigation signals and the ground support network.
English versions of the GLONASS CDMA interface control documents are now available. See Further Reading.
Richard Langley
On Oct. 12, 1982, the Soviet Union launched the first GLONASS satellite. Whether in reaction to the development of GPS or simply to fulfill the requirement for a system with similar capabilities for its armed forces, the Soviet Union began the development of the Global’naya Navigatsionnaya Sputnikovaya Sistema or Global Navigation Satellite System in 1976 just three years after the start of the GPS program. The first test satellite, code-named Kosmos 1413, was accompanied by two dummy or ballast satellites with the same approximate mass since the Soviet Union was already planning to launch three GLONASS satellites at a time with its powerful rockets to save on launch costs.
But because of launch failures and the characteristically brief lives of the satellites, a further 70 satellites were launched before a fully populated constellation of 24 functioning satellites (providing full operational capability or FOC) was achieved in early 1996. Unfortunately, the full constellation was short-lived. Russia’s economic difficulties following the dismantling of the Soviet Union hurt GLONASS. Funds were not available, and by 2002 the constellation had dropped to as few as seven satellites, with only six available during maintenance operations! But Russia’s fortunes turned around, and with support from the Russian hierarchy, GLONASS was reborn. Longer-lived satellites were launched, as many as six per year, and slowly but surely a full constellation of 24 satellites returned. And on Dec. 8, 2011, FOC was again achieved and has been subsequently more or less maintained — the system has even operated sometimes with in-orbit spares.
While GLONASS-only and survey-grade dual-system GPS/GLONASS receivers have been around for more than a decade, manufacturers took notice of GLONASS’s rebirth and began producing chips and receivers with GLONASS capability for the consumer market. In 2011, Garmin released handheld receivers supporting both GPS and GLONASS. In the same year, various cell-phone manufacturers started offering GLONASS capability with their embedded positioning modules. The early GPS/GLONASS receivers paved the way for the multi-GNSS receivers we have today, with their capability to track not just GPS and GLONASS satellites but those of the European Galileo and Chinese BeiDou systems, as well as those of the Japanese Quasi-Zenith Satellite System (not to mention the satellites of the satellite-based augmentation systems).
I documented the development of GLONASS in this column back in July 1997, and a team of authors from the Joint Stock Company Russian Space Systems discussed the plans for modernizing GLONASS in an April 2011 article. An update is overdue. So, in this article, I will briefly review the history of the GLONASS program, discuss its current status, and overview the plans for the immediate future of the satellite constellation, its navigation signals and the ground support network.
EARLY YEARS, PRESENT DAY
During the Cold War, information about GLONASS was scarce. Apart from the general characteristics of the satellite orbits and the frequencies used for transmitting the navigation signals, the Ministry of Defence of the Soviet Union revealed little else. However, sleuthing by Professor Peter Daly and his students at the University of Leeds provided some details about the signals’ structure. With the advent of glasnost and perestroika, and the eventual demise of the Soviet Union, information about GLONASS became more readily available. Eventually, the Russians released the Interface Control Document (ICD). This document, similar in structure to the Navstar GPS Space Segment/Navigation User Interfaces ICD-GPS-200, describes the system, its components, and the structure of the signal and the navigation message intended for civil use. Its latest version was published in 2016, but so far this version is only publicly available in Russian.
Satellites and Signals. Six models of GLONASS satellites (also known as Uragan, Russian for Hurricane) have been launched so far. Russia (actually the former Soviet Union) launched the first 10 satellites, called Block I, between October 1982 and May 1985. It sent up six Block IIa satellites between May 1985 and September 1986 and 12 Block IIb satellites between Apri1 1987 and May 1988, of which six were lost because of launch-vehicle-related failures. The fourth model was the Block IIv (v is the English transliteration of the Russian alphabet’s third letter). By the end of 2005, the Russians had deployed 60 Block IIvs. Each subsequent satellite generation contained equipment enhancements and also achieved longer lifetimes.
A prototype GLONASS-M (for Modernized) satellite was launched on Dec. 1, 2001, along with two Block IIvs with the first two production GLONASS-M satellites included in the triplet launches of Dec. 10, 2003, and Dec. 26, 2004. Two GLONASS-M satellites were included in the triplet launch of Dec. 25, 2005. The new design offered many improvements, including better onboard electronics, a longer lifetime, an L2 civil signal, and an improved navigation message. Like earlier versions, the GLONASS-M spacecraft still used a pressurized, hermetically sealed cylinder for the electronics.
FIGURE 1. Image from Reshetnev Information Satellite Systems, manufacturer of the GLONASS satellites, celebrating the 35th anniversary of the launch of the first GLONASS satellite in 1982 (“35 years of service to the world”).
All GLONASS satellites launched since December 2005 have been GLONASS-M satellites with the exception of two GLONASS-K1 (sometimes referred to as just GLONASS-K) satellites, launched on Feb. 26, 2011, and Nov. 30, 2014. GLONASS-K1 satellites are markedly different from their predecessors. They are lighter, use an unpressurized housing (similar to that of GPS satellites), have improved clock stability and a longer, 10-year design life. They also include, for the first time, code-division-multiple-access (CDMA) signals on a third frequency accompanying the legacy frequency-division-multiple-access signals (I’ll discuss these shortly). All of the GLONASS satellites have been manufactured by the Joint Stock Company Reshetnev Information Satellite Systems, located in Zheleznogorsk near Krasnoyarsk in central Siberia, and named after Mikhail Fyodorovich Reshetnev, the founding general director and chief designer. The Reshetnev company was formerly known as the Scientific Production Association of Applied Mechanics (Nauchno Proizvodstvennoe Ob”edinenie Prikladnoi Mekaniki or NPO PM). The Roscosmos State Corporation for Space Activities (formerly the Federal Space Agency), commonly known as Roscosmos, is the governmental body responsible for GLONASS.
FIGURE 1 includes artist’s images of the initial GLONASS, GLONASS-M and GLONASS-K1 satellites.
GLONASS satellite orbits are arrayed in three planes, separated from one another in right ascension of ascending node by 120 degrees, with eight satellites in each plane. The satellites within a plane are equally spaced, separated in argument of latitude by 45 degrees. Satellites in adjoining planes are shifted in argument of latitude by 15 degrees. The satellites are placed into nominally circular orbits with a target inclination of 64.8 degrees and semimajor axis of approximately 25,510 kilometers, giving them an orbital period of about 675.8 minutes. These satellites have ground tracks that repeat every 17 orbits or eight sidereal days. The GLONASS orbit planes are numbered 1–3 and contain orbital slots 1–8, 9–16 and 17–24, respectively.
FIGURE 2 shows the status of the constellation on Oct. 17, 2017. The orbital slot number (also called almanac slot) and frequency channel (discussed below) are given in parentheses. The recently launched GLONASS 752 was set healthy on Oct. 16, 2017, resulting in a fully operational 24-satellite constellation. All of the satellites are standard GLONASS-M satellites except for GLONASS 755, which includes a transmitter for the new third frequency, and GLONASS 701K and 702K. These last two are GLONASS-K1 satellites, with 702K operational while 701K is undergoing flight tests. The “K” isn’t part of the official GLONASS number but has been added to avoid ambiguity. A GLONASS-M satellite launched on Dec. 10, 2003, was also called GLONASS 701. Similarly, the International GNSS Service (IGS) refers to GLONASS 701K and 702K as 801 and 802, respectively. IGS also designates GLONASS 751 as GLONASS 851 to prevent confusion with Kosmos 2080, a GLONASS-IIv satellite launched on May 19, 1990, and also called GLONASS 751. And it designates GLONASS 753 as GLONASS 853 to prevent confusion with Kosmos 2140, a GLONASS-IIv satellite launched on April 14, 1991, and also called GLONASS 751.
FIGURE 2. Status of GLONASS constellation on Oct. 17, 2017. A green square identifies the location of a healthy satellite and orange, a test satellite. Orbital slot numbers and frequency channels are given in parentheses.
The satellites have been traditionally launched three at a time by Proton boosters from the Baikonur Cosmodrome near Leninsk in Kazakhstan. However, starting with the launch of the first GLONASS-K1 satellite, several GLONASS satellites have been launched singly on Soyuz rockets from the Plesetsk Cosmodrome north of Moscow.
Unlike GPS and the other GNSSs, GLONASS uses FDMA rather than CDMA for its legacy signals. Originally, the system transmitted the signals within two bands: Ll, 1602.0–1615.5 MHz, and L2, 1246.0–1256.5 MHz, at frequencies spaced by 0.5625 MHz at L1 and by 0.4375 MHz at L2:
L1k = 1602. + 0.5625k (MHz)
L2k = 1246. + 0.4375k (MHz)
This arrangement provided 25 channels, so that each satellite in the full 24-satellite constellation could be assigned a unique frequency (with the remaining channel reserved for testing). Some of the GLONASS transmissions initially caused interference to radio astronomers, who study very weak natural radio emissions in the vicinity of the GLONASS frequencies. Radio astronomers use the frequency bands of 1610.6–1613.8 and 1660–1670 MHz to observe the spectral emissions from hydroxyl radical clouds in interstellar space, and the International Telecommunication Union (ITU) has afforded them primary user status for this spectrum space. Also, ITU has allocated the 1610–1626.5-MHz band to operators of low-Earth-orbiting mobile communications satellites. As a result, the GLONASS authorities decided to reduce the number of frequencies used by the satellites and shift the bands to slightly lower frequencies.
The system now uses only 14 primary frequency channels with k values ranging from –7 to +6, including two channels for testing purposes (currently –5 and –6). (The +7 channel has also been used in the past for testing purposes.) How can 24 satellites get by with only 14 channels? The solution is for antipodal satellites — satellites in the same orbit plane separated by 180 degrees in argument of latitude — to share the same channel. This approach is quite feasible because a user at any location on Earth will never simultaneously receive the signals from such a pair of satellites. The move to the new frequency assignments started in September 1993.
Like the legacy GPS signals, the GLONASS signals include two pseudorandom noise (PRN) ranging codes: ST (for Standartnaya Tochnost or Standard Precision) and VT (for Visokaya Tochnost or High Precision) similar to the GPS C/A- and P-codes, respectively (but at half the chipping rates), modulated onto the L1 and L2 carriers.
As with GPS, GLONASS transmits the high-precision code on both L1 and L2. But, unlike the GPS satellites, the GLONASS standard-precision code has also been transmitted on the L2 frequencies beginning with the GLONASS-M satellites. (A separate civil code, L2C, has been added to the GPS L2 signal transmitted by Block IIR-M and subsequent satellites.) The GLONASS ST code is 511 chips long with a rate of 511 kilochips per second, giving a repetition interval of 1 millisecond. The VT-code is 33,554,432 chips long with a rate of 5.11 megachips per second. The code sequence is truncated to give a repetition interval of 1 second. Unlike GPS satellites, all GLONASS satellites transmit the same codes. They derive signal timing and frequencies from one of the onboard atomic frequency standards (AFSs) operating at 5 MHz. The various GLONASS satellite series since Block II through to the GLONASS-M series have three cesium AFSs on each satellite. The transmitted signals are right-hand circularly polarized, like GPS signals, and have comparable signal strengths.
Navigation Message. Like GPS and the other GNSSs, the GLONASS signals also contain navigation messages providing satellite orbit, clock and other information. Separate 50-bits-per-second navigation messages are modulo-2 added to the ST- and VT-codes. The ST-code message includes satellite clock epoch and rate offsets from GLONASS System Time; the satellite ephemeris given in terms of the satellite position, velocity and acceleration vectors at a reference epoch; and additional information such as synchronization bits, data age, satellite health, offset of GLONASS System Time from Coordinated Universal Time (UTC) as maintained by the National Metrology Institute of the Russian Federation UTC(SU) as part of the State Time and Frequency Service, and almanacs (approximate ephemerides) of all other GLONASS satellites. Note that, unlike GPS System Time, for example, GLONASS System Time has no integer offset from UTC and so leap-second jumps are added to GLONASS System Time simultaneously with those added to UTC. Note, however, that GLONASS System Time is offset by a constant three hours to match Moscow Standard Time (MSK, an abbreviation for Moscow).
The full message lasts 2.5 minutes, and is continuously repeated between ephemeris updates (nominally once every 30 minutes), but the ephemeris and clock information is repeated every 30 seconds.
The GLONASS authorities have not published, at least publicly, details of the VT-code navigation message. It is known, however, that the full message takes 12 minutes and that the ephemeris and clock information are repeated every 10 seconds.
Geodetic System. GLONASS ephemerides are referenced to the Parametry Zemli 1990 (PZ-90 or, in English translation, Parameters of the Earth 1990, PE-90) geodetic system. PZ-90 replaced the Soviet Geodetic System 1985, SGS 85, used by GLONASS until 1993. PZ-90 is a terrestrial reference system with its coordinate frame defined in the same way as that of the International Terrestrial Reference Frame (ITRF). The initial realization of PZ-90 had an accuracy of one or two meters.
However, in an effort to bring the system closer to the ITRF (and GPS’s WGS 84 geodetic reference system), two updates to PZ-90 were carried out. The first update, resulting in PZ-90.02 (referring to 2002), was adopted for GLONASS operations on Sept. 20, 2007, and brought the frame of the broadcast orbits (and hence derived receiver coordinates) closer to ITRF and WGS 84. Another realization, PZ-90.11, adopted on Dec. 31, 2013, reportedly reduced the differences to the sub-centimeter level.
TABLE 1 lists the defining constants and parameters of PZ-90.
TABLE 1. Fundamental geodetic constants and some of the parameters of the PZ-90 geodetic system as used by GLONASS.
The new GLONASS-K satellites transmit additional signals. GLONASS-K1 transmit a CDMA signal on a new L3 frequency (1202.025 MHz), and GLONASS-K2, in addition, will feature CDMA signals on the L1 and L2 frequencies.
FIGURE 3. Circular reflector array on a GLONASS-K1 satellite, surrounding navigation signal inner antenna elements. Photo from Reshetnev Information Satellite Systems.
Control Segment. Similar to GPS and other GNSSs, GLONASS requires a network of ground stations for monitoring and maintaining the satellite constellation and for determining the orbits of the satellites and behavior of their operating AFSs. The tracking network uses stations only within the territory of the former Soviet Union, supplemented with satellite laser ranging stations to help with orbit determination since all GLONASS satellites contain laser reflectors (see FIGURE 3).
Having a non-global network of tracking stations for determining the satellite orbits and AFS behavior results in slightly degraded GLONASS signal-in-space range error (SISRE). Recently, a number of tracking stations overseas have been established in conjunction with the development of the Russian satellite-based augmentation system (SBAS), the System for Differential Correction and Monitoring (SDCM). SDCM will function in a similar fashion to the Wide Area Augmentation System or WAAS, the U.S. SBAS, and the other SBASs in operation. The addition to the tracking network of the overseas SDCM stations, which already includes stations in Antarctica and South America with more stations coming, could help improve SISRE. Roscosmos also uses a global network of IGS and other tracking stations to monitor the health of the GLONASS constellation (see FIGURE 4).
FIGURE 4. Roscosmos global GLONASS satellite health monitoring network with 22 reporting stations on Oct. 18, 2017, between 13:00 and 14:00 MSK.
Performance. SISRE has improved over the years and is currently at the level of about 1 to 2 meters. In part, this is due to the better performance of the on-board AFSs carried by the latest GLONASS-M satellites compared to the first GLONASS-M satellites. Their relative one-day stability has improved from 10-13 to 2.4 × 10-14. FIGURE 5 shows a time series of recent values of SISRE determined by the Information and Analysis Center for Positioning, Navigation and Timing. These error levels can result in pseudorange-based positioning errors using GLONASS broadcast orbits and clocks about a factor of two worse than those provided by GPS — although, at any given instant, positioning accuracy will also be impacted by atmospheric effects and multipath and these could dominate the signal-in-space errors.
FIGURE 5. GLONASS daily root-mean-square signal-in-space range error in meters as determined by the Information and Analysis Center for Positioning, Navigation and Timing.
Much higher positioning accuracies can be obtained using GLONASS orbits and clocks provided by the IGS and its participating analysis centers. This is particularly true if carrier-phase measurements are used instead of or as a supplement to pseudorange measurements. A combination of appropriately weighted GPS and GLONASS measurements has shown to be beneficial in terms of availability, accuracy and efficiency, especially for high-accuracy positioning carried out using the real-time kinematic or RTK approach. Furthermore, the precise point positioning (PPP) technique, based on real-time or post-processing of dual-frequency carrier-phase measurements with precise satellite ephemeris and clock data, has demonstrated that kinematic decimeter-level accuracy is possible using GLONASS data or GLONASS data in combination with GPS data. GLONASS-only static PPP solutions over 24 hours have achieved accuracies at the millimeter level.
Users. The initial uptake of GLONASS by both civil and military users in the former Soviet Union and subsequently in Russia, not to mention outside Russia, was minimal. Prototype GLONASS-only receivers were developed for the military, and foreign GPS/GLONASS receivers were developed by several manufacturers for scientific and other advanced applications. The IGS added a set of GLONASS-tracking receivers to its network in 1998 and has continuously increased the number of such receivers since then. However, consumer use of GLONASS both within and outside Russia has only recently taken off with the development of GLONASS-only and combined GPS/GLONASS chipsets. Such chipsets are now featured in many mobile phones and in handheld GNSS receiver and vehicle navigation units.
NEW AND IMPROVED
As previously mentioned, the GLONASS-K1 satellites include a CDMA signal accompanying the legacy FDMA signals on a new L3 frequency of 1202.025 MHz. The ranging-code chipping rate for the CDMA signal is 10.23 megachips per second with a period of 1 milliseconds. It is modulated onto the carrier using quadrature phase-shift keying (QPSK), with an in-phase data channel and a quadrature pilot channel. The set of possible ranging codes consists of 31 truncated Kasami sequences. (Kasami sequences, introduced by Tadao Kasami, a noted Japanese information theorist, are binary sequences of length 2m – 1 where m is an even integer. These sequences have good cross-correlation values approaching a theoretical lower bound. The Gold codes used in GPS are a special case of Kasami codes.) The full length of these sequences is 214 – 1 = 16,383 symbols, but the ranging code is truncated to a length of N = 10,230 with a period of 1 milliseconds.
The associated navigation message symbols are transmitted at a rate of 100 bits per second with half-rate convolution coding. The so-called navigation message superframe (2 minutes long) will consist of 8 navigation frames (NFs) for 24 regular satellites in the GLONASS first modernization stage and 10 NFs (lasting 2.5 minutes) for 30 satellites in the future. Each NF (15 seconds long) includes 5 strings (3 seconds each). Every NF has a full set of ephemerides for the current satellite and part of the system almanac for three satellites. The full system almanac is broadcast in one superframe.
The lighter, unpressurized K1 satellites feature two cesium and two rubidium AFSs. The relative daily stability of one of the rubidium AFSs on a K1 satellite is reported to be 4 ×10-14. As a result, the SISRE for this satellite is about 1 meter. Plans call for adding a CDMA signal to L2 on future versions of the K1 satellites, dubbed K1+ (see below).
GLONASS-K2 Satellites. These satellites will be heavier than the K1 and K1+ satellites with greater capabilities including a CDMA signal at the GPS/Galileo L1/E1 frequency. Reshetnev ISS will initially build two K2 satellites before going into mass production. It had been planned to transition to the K2 satellites much sooner, only launching the two K1 satellites now in orbit. But apparently plans changed because of the sanctions restricting the delivery of radiation-resistant electronic components from the West.
Now, Reshetnev ISS will build an additional nine GLONASS-K1 satellites. It’s not clear how many of these might be of the K1+ variety. The GLONASS-K1 satellites will now be transition satellites between the existing GLONASS-M satellites (including the half-dozen or so that have been manufactured and stored on the ground for future launch as needed) and the future GLONASS-K2 satellites.
One of the first K2 satellites will host a passive hydrogen maser (PHM) AFS. The PHM has been under development for about a decade, and multiyear ground tests displayed a reliability and one-day stability of 5 × 10-15. It is expected to contribute to future 0.3-meter SISRE.
According to a recent report, GLONASS-K2 satellites will begin flight tests in 2018, with mass production of GLONASS-K2 satellites to begin in the 2019–2020 time frame.
Improved Tracking Networks. The development of the SDCM and its associated tracking network has already been mentioned. The SDCM network stations are equipped with combined GPS/GLONASS dual-frequency receivers, hydrogen maser atomic clocks and direct communication links for real-time data transfer. As mentioned earlier, GLONASS authorities are looking at whether additionally using the SDCM stations for GLONASS orbit and clock determination would significantly enhance the accuracy of the broadcast data.
CONCLUSION
GPS, the oldest GNSS, is continuing to modernize and will soon launch the first Block III or GPS III satellite. Already, GPS Block IIR-M and Block IIF satellites are transmitting new signals. Galileo is fielding modern satellites right from the get go, and BeiDou is about to start launching the operational version of its BeiDou-3 satellites. GLONASS is not to be outdone. It has provided useful positioning, navigation and timing services since at least 1996. While at times the service level has dropped below acceptable levels, it is now a dependable system and, with announced improvements, will be a contender in the future world of multi-GNSS.
FURTHER READING
Official GLONASS Update
“GLONASS Programme Update” by I. Revnivykh presented at the 11th Meeting of the International Committee on Global Navigation Satellite Systems, Sochi, Russia, Nov. 6–11, 2016.
In-depth Description of GLONASS
“GLONASS” by S. Revnivykh, A. Bolkunov, A. Serdyukov and O. Montenbruck, Chapter 8 in Springer Handbook of Global Navigation Satellite Systems, edited by P.J.G. Teunissen and O. Montenbruck, published by Springer International Publishing AG, Cham, Switzerland, 2017.
“GLONASS: Developing Strategies for the Future” by Y. Urlichich, V. Subbotin, G. Stupak, V. Dvorkin, A. Povalyaev and S. Karutin in GPS World, Vol. 22, No. 4, April 2011, pp. 42–49.
“GLONASS: Review and Update” by R.B. Langley in GPS World, Vol. 8, No. 7, July 1997, pp. 46–50. Correction: GPS World, Vol. 8, No. 9, Sept. 1997, p. 71. Available on line:
“GLONASS Spacecraft” by N.L. Johnson in GPS World, Vol. 5, No 11, Nov. 1994, pp. 51–58.
Sergey Karutin, GLONASS designer general (left); Nikolay Testoyedov, director general, SC Information Satellite Systems (center); and Andrey Tyulin, director general, SC Russian Space Systems.
By Sergey Karutin, Nikolay Testoyedov and Andrey Tyulin
Currently, Global Navigation Satellite Systems (GNSS) are widely used in transportation, power systems, agriculture, communication, banking and the service sector. Humankind has very rapidly realized the benefits of GNSS use and therefore its dependence on the “artificial navigation field” is constantly growing. That is why at the present stage of GLONASS development, the major research and development foci include not only activities aimed at enhanced accuracy, availability and integrity of navigation, but also theoretical and practical efforts focused at ensuring resilience of navigation (interference mitigation).
These activities logically evolve from the changes GLONASS has experienced over the last decade, establishing the essential groundwork to boost the demand in its services. In 2011, the fully operational constellation of 24 GLONASS-M satellites was deployed. For the first time, civil users got the benefit of navigation signals in two frequency bands (L1 and L2) for positioning.
The GLONASS-K satellite launched the same year transmits a new navigation signal in the L3 frequency band. Its onboard atomic clocks include two Cesium and two Rubidium frequency standards. Implementation of these onboard frequency standards with long-term relative stability less than 5×10-14 provides better accuracy without reliance on ground control. The program of onboard atomic frequency standards development also includes design of a hydrogen maser with relative daily stability of 5×10-15 and its in-orbit validation onboard GLONASS-K satellites in 2017–2018.
Simultanesously, the high reliability of GLONASS-M satellites operating beyond their design lifetime, 1.5 times longer in some cases, led to a change in the constellation replenishment strategy. In 2012, the launch-on-demand approach was adopted for future satellites. Currently, nine GLONASS-M satellites are in ground stock, scheduled for launch in 2015–2017 timeframe.
These factors caused a three-year delay in constellation modernization and launch of new GLONASS-K satellites.
Nevertheless, in 2014 GLONASS-K No. 12 was put into orbit with the single phased antenna array for the L1/L2/L3 signals. GLONASS-M satellites No. 55–61 also have the enhanced functional capabilities due to additional L3 navigation payload. The string structure of navigation message digital information provides for a higher rate of data update in case of necessity.
We contribute to the user navigation equipment interference mitigation capabilities by developing GLONASS signals at the frequency bands different from the common frequencies accepted for GPS, Galileo and BeiDou. It is common knowledge that, in some cases, low-end personal jammers made to jam the L1 band with the center frequency of 1575.42 MHz and installed in vehicles may cause severe problems to critical infrastructure. In similar situations, use of 1600.992 MHz and 1248.02 MHz center frequencies (new GLONASS CDMA signals) allows improving the reliability of navigation.
Efforts on the global network of the radio and laser-ranging stations for precise orbit determination and time synchronization (ODTS) are also of note. Six GLONASS measuring stations have been established abroad so far. Further expansion of the network is scheduled for 2015–2016 to ensure ODTS accuracy of up to 0.1 meter in real time during the next few years.
Global use of GLONASS is impossible without international cooperation, and we pay special attention to the recommendations of the UN International Committee on GNSS. In particular, we are finalizing the GLONASS Open Services Positioning Performance Standard and developing the national GNSS Performance Monitoring and Assessment System to be used to continuously monitor quality of the GLONASS services and its compliance with the standard.
JSC “Russian Space Systems” (RCC), together with ISS Reshetnev, plan to remove imported components in construction of GLONASS satellites, according to an Izvestia article.
Production of the advanced GLONASS satellite “GLONASS-K” is scheduled to begin later this year.
According JSC CEO Andrew Tyulina, the company intends to stop the use of foreign electronic components as soon as possible. The plan is to have 80 percent of the satellites’ electronic components payload be domestically produced by 2019.
The move seems to be spurred by international sanctions in response to Russia’s occupation of Ukraine. Following the occupation, the United States began to prohibit supply of electronic components to Russia, and the British company E2V failed to get permission to import equipment for the Russian space observatory Spektr-UV, Izvestia reports. Russia had difficulty securing components before then, however. In 2013, as relations with the U.S. cooled following Russia’s harboring of Edward Snowden and events in Syria, the U.S. State Department did not authorize a supply of components for the spacecraft Geo-IK-2.
The expected component supplier will be the largest designer and manufacturer of electronic components in Russia, Roselectronika, an entity that unites 112 companies, research institutes and design bureaus. The total investment in Roselectronika will exceed 210 billion rubles to 2020, including provision for modernizing industrial sites that produce electronic payloads for space.
According to its in-house newspaper, Siberian Satellite, the joint-stock company “Information Satellite Systems – Academician M.F. Reshetnev” has signed two loan agreements with the Russian VTB Bank (formerly Vneshtorgbank) worth 2.5 billion rubles ($38 million) to finance the production of GLONASS-K navigation satellites.
Presumably, this refers to the decision to produce more GLONASS-K1 satellites as recently announced.
Will Be Employable for Surveying, Precise Positioning, and Geodesy
By Peter Steigenberger and André Hauschild, German Aerospace Center (DLR) / German Space Operations Center
The first Full Operational Capability (FOC) Galileo satellite started transmitting L-band navigation signals on November 29, 2014. Based on data collected by a global network of GNSS tracking stations of the Cooperative Network for GNSS Observation (CONGO) and the Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS), we determined that an E1 signal with pseudorandom noise code (PRN) E18 was first tracked at the station LLAG (La Laguna, Tenerife, Canary Islands) at 06:08 UTC. A few moments later, the satellite’s transmissions were also tracked at other MGEX stations including the E5a, E5b, and E5 AltBOC signals. Based on the computed satellite visibility at various tracking stations, the satellite could be positively identified as GSAT0201, also known as Galileo FOC-FM1 or Galileo 5 with COSPAR ID 2014-050A and NORAD ID 40128.
FIGURE 1 shows the carrier-to-noise-density ratio (C/N0) of the E18 signals tracked at the CONGO/MGEX station SIN1 (Singapore, using a Trimble NetR9 receiver with a Leica AR25.3 antenna). We selected the signals from this station for analysis due to an E18 pass occurring close to the zenith and covering almost the full range of elevation angles. The E5a and E5b signals (S5X and S7X RINEX identifiers) show very similar performance, whereas the C/N0 values of the E1 signal are 1–2 dB-Hz higher. The C/N0 values of the E5 AltBOC signal (S8X) reach 60 dB-Hz at high elevation angles, which is about 6 dB-Hz higher than the other signals.
Figure 1. Galileo E18 carrier-to-noise-density ratio for the CONGO/MGEX station SIN1 (Singapore).
The first pair of Galileo FOC spacecraft was launched on August 22 with a Soyuz launcher from the Guiana Space Centre, Kourou, French Guyana. Due to a malfunction of the Fregat upper stage, the satellites were injected into elliptical orbits with an inclination of about 49° instead of near circular orbits with 55° inclination. In November, the perigee of the first FOC satellite was raised by about 3,500 kilometers by a series of 11 maneuvers with a corresponding reduction in orbit eccentricity from 0.23 to 0.16.
E18 has been included in the precise orbit and clock solutions of the MGEX analysis center at Technische Universität München (TUM) in Munich, Germany, since December 5. FIGURE 2 shows the detrended estimates of the active Galileo E18 clock for December 7. The presence of a pronounced quadratic term as well the large drift of 33.9 microseconds per day indicate that the active clock is a rubidium atomic frequency standard rather than a more precise passive hydrogen maser. The FOC satellites carry two of each kind of clock.
Figure 2. Galileo E18 clock estimates for December 7, 2014, with respect to the hydrogen maser at the Ottawa IGS station (NRC1) after removing an offset and drift (blue) or a second order polynomial (red).
The TUM orbit and clock product allows researchers to again compute dual-frequency positioning solutions using only Galileo observations, as the In-Orbit Validation satellite E20 has not transmitted an E5 signal since May, when a power anomaly left the satellite with the capability to only transmit an E1 signal. Furthermore, E20 currently does not transmit a navigation message.
TABLE 1 shows the scatter of single-point positioning using pseudorange (code) observations from the MGEX station MAS1 (Maspalomas, Gran Canaria, Canary Islands) for a Galileo-only, a GPS-only, and a combined Galileo+GPS solution for December 6. At an elevation cut-off angle of 10°, four Galileo satellites were visible from 10:15 until 12:25 UTC (see FIGURE 3). The GPS-only solution covers the same time interval. The start time is not limited by the cut-off angle but an E18 transmission outage from 3:45–10:15 UTC.
TABLE 1. Single point positioning results for the MGEX station MAS1 (Maspalomas) for December 6, 2014.Figure 3. Galileo visibility at the MGEX station MAS1 (Maspalomas) on December 6, 2014. The time period considered in the single-point positioning is indicated by vertical lines.
We used an ionosphere-free linear combination of Galileo E1 and E5 AltBOC code observations and GPS L1 and L2 code observations with a 30-second sampling interval. As the Galileo-only solution suffered from position dilution of precision (PDOP) values of up to 830, a total of 32 epochs with PDOP values greater than 25 were excluded. The geometry of the remaining epochs is still pretty unfavorable. At a mean PDOP value of 7.4, the standalone position solution exhibits a 3D standard deviation (STD) error of 3.4 meters. Use of the Galileo satellites in a combined GPS+ Galileo solution improves the positioning performance. In particular, the height component benefits from the inclusion of the four Galileo satellites with a standard deviation improvement of 25 percent.
Despite the orbit injection error, the new Galileo FOC satellite has now been successfully activated and added to the Galileo constellation. Unfortunately, the current orbit is incompatible with the standard Galileo almanac format, which may cause restrictions for some commercial receiver types.
Nevertheless, the satellite can already be tracked by a wide range of geodetic receivers with existing firmware versions and it will, in fact, be possible to use the new satellite for diverse applications in surveying, precise positioning, and geodesy, as well as in general multi-GNSS studies. We now look forward to the activation of the second FOC satellite, which can be expected in early 2015 and will, for the first time, offer multi-frequency signals from a total of five Galileo satellites.
Sanctions Delay GLONASS-K2
According to Nikolai Testoyedov, the CEO of Information Satellite Systems Reshetnev, manufacturer of the GLONASS satellites, the company will now produce nine GLONASS-K1 satellites.
“For a smooth transition to a multi-functional group and due to issues with the very complex GLONASS-K2 satellites, we decided to continue with the GLONASS-K1 intermediate range of satellites, and we are preparing for the launch of nine units of this series,” he said.
He recalled the original plan was to launch two K1 satellites and then move to GLONASS-K2 satellites.
“In the beginning, really, we wanted after the two GLONASS-K1 satellites No. 11 and 12, to go for the launch of more advanced GLONASS-K2 devices. But, unfortunately, the plans had to be adjusted somewhat because of the sanctions restricting the delivery of radiation-resistant electronic components from the West. We have to put a hold on the in-depth development of technical and technological documentation and that delays us in terms of moving ahead by at least a year or two,”he said.
Reported by the Russian magazine Vestnik GLONASS, and relayed by Richard Langley’s CANSPACE listserv.
GNSS Mandates Would Violate Trade Agreements
A U.S. government representative stated at an international satnav forum that mandating use of specific GNSS services for applications such as air-traffic control, freight shipments, emergency calling, and road tolling could violate the terms of World Trade Organization (WTO) agreements that many nations, including all six GNSS providers, have signed.
Regional mandates already exist for GLONASS in Russia and BeiDou in China, and have been suggested and extensively discussed in Europe, as a way of stimulating the market adoption of Galileo receiver chipsets, thus recouping some of the massive public investment in the satnav system.
The presentation occurred during the Ninth Meeting of the International Committee on Global Navigation Satellite Systems (ICG), held Nov. 10–14, 2014, in Prague, Czech Republic.
Jason Kim, a senior policy analyst at the U.S. Department of Commerce, stated that the United States and the European Union already enjoy a productive dialog on GNSS trade issues under the 2004 U.S.-EU Agreement on GPS-Galileo Cooperation. In that agreement, both parties agreed to consult before establishing GNSS standards, certification requirements, regulations, mandates; affirmed their non-discriminatory approach with respect to GNSS trade; and established a working group to consider non-discrimination and other trade related issues.
Finally, the United States and the European Union recognized and reiterated in 2004 their commitments to WTO rules including those governing technical barriers to trade, specifically, that there would be no goods discrimination based on non-tariff measures such as regulations, standards, testing, or certification.
Kim made the remarks in the course of his presentation titled “GNSS Market Access.” He told GPS World that his presentation was directed less at the European Union, which has been conscientious of its WTO commitments, and more towards the rest of the ICG members, including non-provider nations that may be asked by GNSS providers to mandate specific systems.
“To promote adoption of their systems,” Kim stated, “GNSS providers are considering/implementing equipage mandates for various applications: aviation, motor-carrier and HAZMAT vehicle tracking, car accident reporting (eCall/ERA-GLONASS), and emergency phone calls (E112).
“The United States recommends technology-neutral, performance-based standards,” Kim continued, giving as example the U.S. E911 rules that specify a required positioning accuracy and then allow wireless carriers to choose the best technical solutions according to their lights.
The U.S. government presentation at ICG revealed particular concern that regulations under consideration could adversely affect the sales of U.S. GPS-enabled hardware in many industry sectors. All members of the WTO, including the six GNSS providers on the ICG, are bound to a range of trade agreements designed to promote open-market access, all cited in the Prague ICG presentation: the General Agreement on Tariffs and Trade (GATT), the Agreement on Technical Barriers to Trade (TBT), and the General Agreement on Trade in Services (GATS). The United States, Europe, Japan, and 12 others are also parties to the WTO Agreement on Government Procurement (GPA).
European Commission officials have publicly and recently stated that they are considering how to stimulate Galileo use, in particular through regulatory measures requiring that navigation equipment be installed on aircraft, automobiles, and other platforms.
“Requiring specific systems arbitrarily prevents or penalizes imports of goods having perfectly functional GNSS capability,” said Kim. “WTO members must comply with TBT obligations in setting technical regulations.”
He concluded his presentation by requesting that the ICG Providers’ Forum add GNSS market access to its future agenda for discussion, and consider developing a new principle on market access for future adoption.
