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RT4000 v2 Family

The OXTS RT4000 family products are advanced, precision Inertial and GPS Navigation systems for measuring motion, position and orientation, with 250Hz output..

They use Inertial Navigation System (INS) technology and combine this with the highest quality Survey Grade GPS receivers. The best attributes of Inertial Navigation Systems and GPS are blended together to give an optimum solution.

The systems improve the performance over GPS-only ones by providing accurate velocity in urban or tree-covered environments. The drift common to conventional Vertical Reference Units (VRU) or Stabilized Platforms is corrected automatically so that the RT4000 family products can be used indefinitely without drifting or needing to be reset.


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    The RT4000 Inertial and GPS Navigation System includes three angular rate sensors (gyros), three servo-grade accelerometers, the GPS receiver and all the required processing in one very compact box. The RT4000 works as a standalone, autonomous unit and requires no user input before it starts operating.

    The outputs from the RT4000 Inertial and GPS Navigation System are derived from the measurements of the accelerometers and gyros. Using the inertial sensors for the main outputs gives the RT4000 system a fast update rate (250Hz) and a wide bandwidth. All the outputs are computed in realtime with a very low latency. The RT4000 Inertial and GPS Navigation System outputs its real-time measurements over CANbus, RS232 and Ethernet. Optional outputs can be made over Analogue or RS422.

    The internal processing includes the strapdown algorithms (using a WGS-84 earth model), Kalman filtering and in-flight alignment algorithms. The internal Pentium-class processor runs QNX real-time operating system to ensure that the outputs are always delivered on time. The Kalman filter monitors the performance of the system and updates the measurements using GPS. By using the measurements from GPS, the RT4000 system is able to maintain highly accurate measurements and correct its inertial sensor errors.

    205_RTinVehicleStrutThe optional second GPS receiver in the dual antenna RT4000 product models measures the difference in position compared to the primary GPS receiver using the carrier-phase observations from both. The heading from the inertial navigation system is used in a tightly coupled manner to solve the ambiguities. The use of two GPS receivers enables the dual antenna RT4000 systems to deliver very accurate measurements of heading even when the vehicle’s dynamics are low.

    The main difference between members of the RT4000 family is the accuracy of measurements. With our most accurate system, the RT4002, measurements accurate to 0.01 m can be achieved. The RT4002 requires differential corrections from a suitable base-station such as the RT-Base. All members use the same processing platform, enclosure, cable connections, etc. The specifications for operating temperature, supply voltage and dimensions are all the same, or very similar across the range.