The International Symposium on Global Navigation Satellite Systems, Space-Based Navigation and Ground-Based Augmentation Systems and Applications was held last week in Berlin. Bringing together representatives from around the world, the event served to provide as a forum for learning about ongoing activity relating to GNSS. Also included were activities and information relating to additional positioning augmentation systems and applications involving radio networks, communications, geodesy, cartography and surveying.
{sidebar id=260 align=right} A pre-event day program included an excursion around the City of Berlin to view the German National SAPOS /EUPOS reference stations in addition to observing one of the few GNSS antenna calibration robots in the world. A ship tour was involved and attendee’s were shown how GPS is being used along the waterways of the city. The central control office of the Berlin city transportation (BVG) facilities was visited where the GPS equipped public transport operations were explained.
The second day of activities saw the beginning of the presentations and discussion forum at the recently opened Berlin Energie Forum (Figure 1 and 2), a new facility along the Spree River that includes unique architecture setting glass against the historical brickwork. The building serves as a hub for Berlin’s expanding renewable energy industry with many smaller company’s housed around the open forum domed setting.
Opening
Senator Ingeborg Junge-Reyer (Figure 3) of the local Berlin city government opened the event. She described the book Die Vermessung der Welt (Measuring the World) by author Daniel Kehlmann whose book is a best seller in Germany. The book speaks about measuring the world from home – something Junge-Reyer suggests is well near possible with GNSS, a satellite based technology capable of measuring with a very high level of accuracy and precision, involving the internet as well. “The technology is applicable to everyday life, depending on science and research,” she said.
Hans J. Haubold (Figure 3) then explained the relationship of the United Nations / ICG to the event, explaining how the UN {sidebar id=261 align=left} increasingly relies upon satellite based technologies for measuring, monitoring and navigating the world in pursuing its activities. He mentioned the value to civilian use and the need for interoperability between systems to enable their use. It is through ICG that GNSS spectrum is protected and orbital degree are maintained.
Janusz Sledzinski on behalf of EUPOS (European Positioning Determination System) explained how the system covers 60% of the European territory, an area covering 10 million square kilometers. EUPOS was initiated by the Berlin Senate in 2002 as a series of multi-functional reference stations for central and eastern Europe and also includes provision for the soon to arrive GALILEO GPS system. “Within EUPOS several levels of accuracy are obtainable with different levels of progress between countries,” Sledzinski said. Czech Republic currently has 27 EUPOS stations, meanwhile Poland has 100. Technical standards for these and other country stations have been developed and EUPOS is a member of GNSS/ICG. Gerd Rosenthal (EUPOS/Berlin) then welcomed guests.
GNSS Providers
David A. Turner, deputy director, U.S. Department of State then initiated the presentations explaining the U.S. Government activities surrounding GPS and GNSS. At the present time 13 Block IIA, 12 Block IIR and 6 Block IIR-M GPS satellites are {sidebar id=262 align=right} operating. The later including new second civil signal. His message was clear, the U.S. GPS system has been improving performance since 1993 (Figure 4).
Werner Enderle of the GNSS Supervision Agency in Belgium then explained the European GNSS program status. The current state of GALILEO (Figure 5) was outlined, including the change from a privately funded to a publicly funded GPS system last year. Several levels of service are anticipated including, Open Service, Commercial Service, Safety of Life Service, Public Regulated Service and a Research and Rescue Service. Some of these services will be freely available while others will be chargeable. Different levels of accuracy and products will be available for them as well. In addition, the EGNOS (European Geostationary Navigation Overlay Service) status was explained and it is proposed that EGNOS will be expanded to include 2 constellation areas, the first covering northern Africa, while the second would cover the western sections of the Middle East.
Koji Terada of JAXA (Japan Aerospace Exploration Agency) described the Japanese GNSS system named ‘QZSS’ – a system that would see a constellation of 3 satellites hovering over Japan with at least one at all times near its zenith over the country. With a large figure-8 orbit, the satellites would augment the U.S. GPS satellites. This augmentation would enable greater penetration into the center of large cities where many tall buildings exist (Figure 6).
EUREF
EUREF (European Reference Frame Sub Commission for Europe) information was presented by Johannes Ihde who explained that EUREF began with the 1987 IUGG conference in Vancouver. The mission of the organisation is to develop and realise geodetic reference systems and infrastructure. The current 3D version being EVRS2007. “Since EUREF is not a legal entity, we are looking into ways that we can achieve this status. At the moment this involves work with EUROGEOGRAPHICS (who are a {sidebar id=263 align=left} legal entity)”, he said (Figure 7). “We are also interested to help AFREF (African Reference Frame) to realise more activities.” Currently ETRS89 is moving 2-3 cm. yearly in a northwest direction.
Ihde explained that it made sense for EUREF to connect with a wider GNSS network. There are currently 212 GNSS permanent stations across Europe along with 7 processing centers. Current wrk includes EVRF2007 based on 13 datum points and involves a reduction to zero tidal influences with an epoch of 2000. Other related projects that EUREF is involved with include CHAMP, GRACE and GOCE projects. A combined European Geodetic Network (ECGN) involving “all forms of measurement” (presumably involving augmentation systems) is being pursued and would involve 21 countries and 74 stations.
An agreement was signed at the symposium between EUPOS and Poland that would effectively formalise the relationship between the two. Heinrich Tilly representing Brandenburg and Jolanta Orlinska who represented Poland were on hand to sign the agreement (Figure 8).
EUPOS
Gerd Rosenthal of the Office of the International EUPOS Steering Committee, Senate Berlin then presented the activities of that organisation. The EUPOS Member list was presented and included a wide number of countries from central and eastern Europe. Unified international standards were presented for EUPOS, which would in effect enable and support business and other activities based on the program. GALILEO would also be supported through EUPOS and basic standards would enable a wide variety of communications protocols including GPRS, UMTS, HSDPA, WLAN etc.
EUPOS DGNSS Service would provide a 2m accuracy and include provision for 0.5m level of accuracy for dynamic applications. EUPOS Network RTK Service would offer less than 2 cm horizontal service, meanwhile EUPOS Geodetic Service for post processing by code and phase in either static or dynamic mode would with decimetre up to sub-centimetre would exist on {sidebar id=264 align=right} GNSS data in RINEX 3.0 for the third GPS frequency L5 and GALILEO signals, although recommended in RINEX 2.11 and 3.0. Terms of Reference have been updated, as have Technical Standards during 2008. In addition EUPOS works in cooperation with the UN, is a member of ICG, works with GALILEO, sub-Saharan African nations and participates in EUREF.
Quality, DGNSS and RTK
Martin Schmidt of Geo++ company presented on the topic of calibrating GPS antennas. This is accomplished through the use of robotic calibration devices. The face contour and offset for each antenna can be calculated through tilting and rotating the antenna. Multi-path can be adjusted for through this technique. Three such antennas exist in the country including one in Hannover, one in Berlin and one held by the company Geo++.
The magnitude of 3D errors can be determined and accuracy to the level of 1mm is achievable. In total there are 154 antenna types on the market “and even new antenna need calibration because they have outliers in the order of 0.5mm. Both far and near multi-path can be calibrated for and rainfall can also impact antenna calibration and accuracy.
Geo++ has even had the opportunity to calibrate a GPS Block III/IIA satellite antenna. Additionally, the company has used methods involving garden sprinklers to simulate rainfall. Several published examples of Geo++ work were available on site and it can be noted that they are involved in a significant number of calibration projects worldwide.
{sidebar id=265 align=left} Georg Weber of the Federal Agency for Cartography and Geodesy, Germany presented on the topic \Towards a EUREF Service Providing Real Time GNSS Clock and Orbit Corrections. A special project called ‘EUREF-IP’ was originally developed in 2002 with the idea to create a DGNSS infrastructure through the internet. As that developed, NTRIP Caster technology was released, based on RTCM.
At the current time, there are 96 EPN stations out of 212 total with real-time capability in Europe. Of this number, 52 have GPS + GLONASS capability – in other words they are GNSS functional. The special project has now evolved and is moving toward EPN operations, which began at the end of 2007. GNSS development is accelerating and now users can acquire hourly files. They also have access to near real-time products. It is foreseen that real-time corrections are the way forward for all these stations and a movement from relative positioning to precise point positioning is underway. Essentially, GNSS streams are becoming available through NTRIP now and version 1.6 is now under development – capable of offline mode, RTCM v3 clock decoding and RTCM v3 stream checking.
GNSS Networking
Richard Gedon from the Bavarian Surveying Authority in Germany talked about ‘Sparse GNSS – Renewal of Reference Networks’. His presentation pointed to the fact that the change from single GPS networks, based solely on a single GPS constellation, to those based on GNSS configurations would take time. “You can’t introduce combined systems overnight,” he said. In fact, even in Bavaria, 70% the network stations are GPS only networks (37), with 30% (13) having GNSS operating equipment.
He mentioned the costs of moving to GNSS networks and the fact that they not only involve field equipment but the network stations, training and updates as well. “It’s simply not practical to completely switch to GNSS.” Rather, a phased approach that changed with budget cycles was seen as a reasonable alternative. Indeed, even in those countries where GNSS is more fully {sidebar id=266 align=right} operational, EU funding has played a significant role. “We currently achieve 76% coverage in Bavaria based on a GPS only signal, but with GPS+GLONASS we are expecting a 90% coverage” he indicated.
The sun was mentioned as having primary impacts on GPS accuracy. Currently a minimum of sun activity is contributing toward higher accuracy. However, it is anticipated that as GALILEO reaches its operational phase, an increase of sun induced activity is projected to be realised.
Jan-Hendrik Ottman from the Waterway and Shipping Directorate, North West Germany gave an interesting presentation that discussed issues relating to waterways. Most people do not think of the need for accuracy of GPS on inland waterways, but it is a critical factor for managing and operating inland waters. Ottman discussed the wider issue of international monitoring of ships traveling in German waters and the high seas. A need exists to standardise these vessels, thereby improving their location performance for security, rescue, navigation and other factors. Working with the UN, his job is to help move toward this level of standardisation, however, it is proving to be more difficult than first expected. Many owners do not want to equip their vessels with the technology, citing competition among other factors.
Ottman mentioned the term – “E-navigation as the harmonised collection, integration, exchange, presentation and analysis of maritime information onboard and offshore by electronic means to enhance berth to berth navigation and related services for safety and security at sea and protection of the marine environment.”
The use and application of GNSS for agricultural applications was explored and presented by Tamas Horvath of the University of Novi Sad, Faculty of Technical Sciences, Serbia. His presentation showed the benefits of higher accuracy precision farming. The {sidebar id=267 align=left} pictures of crops perfectly distributed on the landscape with no row overlaps were interesting. However, considerable discussion surrounded issues relating to the transfer of GNSS data and signal to moving field equipment in real-time. Possibilities included VHF, satellite and mobile phone tele-links. FM radio signal was also mentioned. Anette Blaser of the Berlin Senate, Department for Urban Development summarised ongoing EUPOS activity on the topic ‘EUPOS InterRegional Cooperation with EUPOS-IRC’ that discussed the inter-regional cooperation between agencies. She mentioned the importance of urban development during the last round of funding.
This symposium included a comprehensive variety of GNSS technology and application examples that enabled those attending to gain a full understanding as to the current status and operations pertaining to GNSS within Europe and other international locations. The inclusion of augmentation systems such as EUPOS provided useful information for realising the potential of GNSS.
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Additional blog coverage of this event.
International Symposium on GNSS Opens in Berlin
Berlin Int’l GNSS Conference: GNSS Trends, Trials and Perspectives
Further Reading
