Technical Papers

TECHNICAL PUBLICATION constantly being modernized with new generations of satellites. These new signals, while improving the performance of user equipment, pose a challenge for receiver manufacturers to support the structure of new signal transmissions. Trimble receivers equipped with Maxwell 7 and ProPoint Technology are ready to reap benefits from all current GNSS signals transmitted on all frequencies. These include: ► GPS: L1 C/A, L1C, L2E, L2C, L5 ► GLONASS: L1 C/A, L1P, L2P, L2 C/A, L3 CDMA ► Galileo: E1, E5A, E5B, E5AltBOC, E6 ► BeiDou: B1C, B1i, B2i, B2A, B2B, B3i ► QZSS: L1 C/A, L1S, L2C, L5, LEX ► IRNSS: S1 C/A, L5 ► SBAS: L1 C/A, L5 ► MSS: Trimble RTX, OmniSTAR Trimble ProPoint GNSS technology is capable of using all available signal inputs, provided an RTK base receiver is transmitting corrections for the same signals. This has resulted in a system which is more flexible and also provides a more accurate solution in challenging GNSS environments. The new Trimble ProPoint GNSS technology also allows for flexible signal management, which helps mitigate the effects of signal degradation and provides a GNSS constellation-agnostic operation. For example, when individual frequencies and constellations are spoofed or jammed, the receiver continues to provide positioning using available measurements. Tight coupling of IMU data with RTK and RTX The Trimble ProPoint Engine is designed from the ground up with Inertial Navigation and Sensor Fusion in mind. The raw GNSS measurements together with the gyroscope and accelerometer data are combined in a single position and orientation solution. The IMU in most products is an in-house design built on the same circuit board as the GNSS receiver. This tight integration provides a robust solution that maximizes the benefits of GNSS and INS. Large filter and accurate modelling of all error sources Owing to advances in the GNSS signal spectrum and low power mobile computing technology, Trimble ProPoint was designed with an improved approach to data signal filtering. By combining all of the measurements together into a single filter and estimating the carrier integer ambiguities simultaneously with an extended set of filter states, an optimal solution is achieved. While more computationally intensive, this approach delivers the most flexible use of all available GNSS signals. Multi-filter techniques using combiners, such as Trimble's FAMCAR (Factorized Multi-Carrier Ambiguity Resolution) had benefits in reducing processing load with earlier generation CPUs, but ultimately can result in some suboptimal behavior in demanding high multipath environments. The result of this new approach to signal filtering is that it permits any and all available signals to be used in the RTK position solution, as a variety of traditional methods based on signal combinations have become redundant. Although dual-frequency data is required to account for atmospheric effects on GNSS signals in RTK positioning, the improved filtering technology means that the processor can use any or all of the signals, including individually in harsh tracking environments, to generate that optimal solution. TRANSFORMING THE WAY THE WORLD WORKS

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