White Papers

Scalable GPS Infrastructure White Papers

• "Federated Filter Approach for GNSS Network Processing" white paper, Trimble 2006



• GNSS Modernization and its Consequences on Reference Station Network Solutions, ENC GNSS 2007



• "New Method for Modeling the Ionosphere" research paper, Trimble 2005

  "...our novel approach leads to improved fixing results even during geomagnetic disturbances and for elevation angles as low as 10°."



• "Trimble Integrated Surveying Techniques" white paper, Trimble 2005

  This paper describes how Trimble products support Integrated Surveying for real-life survey applications. It also discusses techniques that combine, transfer and process data from GPS and conventional instruments. The techniques are applied to real-world survey applications to provide customers with an understanding of how Integrated Surveying can increase survey productivity.



• Will Galileo and GPS L5 Obsolete Network RTK?, GNSS 2004

  Theoretical analyses and simulations show that with the presence of a reference station network, RTK initialization and positioning accuracy are improved considerably.



• Support of Network Formats by Trimble GPSNet Network RTK Solution, Trimble 2005



• Three and Four Carriers for Reliable Ambiguity, GNSS 2004

  The new Factorized Multi-Carrier Ambiguity Resolution (FAMCAR) approach for efficient combination of multi-carrier data was used to analyze OTF ambiguity resolution performance.



• FAMCAR Approach for Efficient Multi-Carrier Am., GNSS 2004

  In the past years, starting with an existing technique a new and very efficient ambiguity resolution algorithm has been developed.



• Factorized Multi-Carrier Ambiguity Resolution, ION 2004

  The proposed addition of a third carrier to the modernized GPS as well as the implementation of three carriers in the planned Galileo system will boost the performance of carrier-phase based positioning within the next decade. In principle, highly-reliable instantaneous (one-epoch) ambiguity resolution becomes feasible for a broad range of applications.



• Galileo Modernized GPS - A New Challenge to Network RTK, ION 2004

  Several preliminary studies have demonstrated that with the third/fourth frequency available from GALILEO and modernized GPS, the reliability and productivity of single base OTF (on the fly) initializations at the rover increase dramatically when comparing with a dual frequency RTK system.



• “GPS Antenna Design and Performance Advancements: The Trimble Zephyr Antenna” white paper, Trimble 2001

  The Trimble Zephyr and Zephyr Geodetic antennas are two new types of survey-grade, dual-frequency, GPS antenna. They are designed to match the performance of the chokering antenna, while being smaller, lighter, and significantly less expensive.



• “NTRIP and Modern Surveying Systems” white paper, Trimble 2004

  Developed by the Federal Agency for Cartography and Geodesy of Germany, NTRIP or "Networked Transport of RTCM via Internet Protocol", enables the streaming of DGPS or RTK correction data via the internet using GPRS or other future technologies. This paper discusses the theoretical and technical basics of NTRIP and illustrates the practical application of the technique using a currently available product, the Trimble Survey Controller software from Trimble Navigation Ltd…



• “New Tools for Networked RTK Integrity Monitoring” research paper, ION GPS/GNSS 2003, Sept. 9-12, 2003, Portland, Oregon

  This paper proposes two indicators of ionospheric linearity:
  

• Ionospheric Residual Integrity Monitoring (IRIM): Omitting one reference station from interpolation and then comparing the interpolation results at that station with the real measurements. Compute a weighted RMS over all satellites. This can also be considered as integrity monitoring for residual interpolation and ambiguity resolution in the network.
• Ionospheric Residual Interpolation Uncertainty (IRIU): With sufficient surrounding reference stations, an interpolation method such as Weighted Linear Interpolation Method (WLIM) produces standard deviation of interpolation. The standard deviation represents the ionospheric linearity over the interpolation region for the field user.


• “Troposphere: Signal or Noise?” research paper, ION GPS/GNSS 2003, Sept. 9-12, 2003, Portland, Oregon

  This paper assesses real time ZTD estimation with postprocessing results. For the AGNES network, the absolute ZTD as well as the differential values between the reference stations were compared. The analyses show that 1 cm accuracy for absolute ZTD and 7 mm for relative ZTD can be achieved in real time...



• “Virtual Reference Stations Versus Broadcast Solutions in Network RTK” research paper, Trimble 2003

  In VRS mode the corrections are applied in the network server whereas in broadcast mode the corrections are applied in the field. Both methods have advantages and limitations. The authors try to quantify and qualify all the arguments by doing some analyses of different scenarios…



• “Network RTK: Concept and Performance” research paper, Trimble 2002

  This paper gives a quantitative assessment of the data characteristics leading to the known rover performance improvements using data from various RTK/VRS networks from Asia, Europe, Australia and the U.S.A.



• “Virtual Reference Station Systems” white paper, Trimble 2002

  The use of a network of reference stations instead of a single reference station allows to model the systematic errors in the region and thus provides the possibility of an error reduction…



• “Broadcast Network RTK – Transmission Standards and Results” research paper, Trimble 2002

  Network RTK involves the use of three or more reference stations to collect GPS data and extract information about the atmospheric and ephemeris errors affecting signalswithin the network.



• “Network RTK Versus Single Base RTK—Understanding the Error Characteristics” research paper, ION GPS 2002, 24-27 September 2002, Portland, Oregon

  Detailed analyses explain the reduction of initialization times, improvement in position accuracy and increase in reliability seen in network RTK systems…



• What is Scalable GPS Infrastructure? white paper, Trimble, 2005

  Similar to the national highway system's importance to the nation as a whole, GPS infrastructure can be said to be essential to the growth and development of the surveying community. Here's why.