When the Space Geodesy Facility at Herstmonceux, East Sussex faced reliability problems with their ageing telescope, their engineers turned to Heason Technology for expert assistance. The thirty year old telescope forms part of a global tracking network to monitor the paths of Earth-orbiting satellites to quantify, for example, the amount by which sea level is currently rising. The scientists at Herstmonceux track passing orbital satellites and accurately calculate their distance (to an accuracy of 1mm) by firing a high-powered pulsed laser against a satellite-mounted reflector and measuring the return time delay. With orbiting satellites at passing range of between 400 and 20,000 kilometres, tracking accuracy is extremely important (to within +/- 1 arc seconds). Heason were first commissioned to evaluate the existing telescope set-up. Their conclusion verified the users own thoughts that the actual telescope motion hardware had effortlessly stood the test of time, but the antiquated electronics were considerably more suspect. Furthermore, technical support on the drive package was more or less non-existent from the original manufacturer. Heason successfully tendered for the upgrade programme, which included replacing all of the existing analogue control system with an up-to-date digital package. Heason selected a Delta Tau PMAC motion controller to form the heart of the system. The PMAC ultralite model was specified to be located within the host PC (which generates the predicted satellite path) with Delta Tau’s MACRO network connecting to the drive and feedback interfaces located remotely in a new motion control cabinet. Heason provided new linear power amplifiers, along with new inductosyn and resolver interfaces complete with a revamped I/O and logic control strategy. Working closely with the Herstmonceux technical experts, Heason’s software engineers developed a motion control application code to interface to the host computer taking new motion control demand data from the customers host at 10Hz (with the ability to operate up to 1KHz) and controlling the telescope motion to accurately track passing satellites to with +/- 1 arc-seconds. Azimuth Axis Elevation Axis Max Velocity 15 Degrees/Second 5 Degrees/Second Max Acceleration 5 Degrees/Sec2 2 Degrees/Sec2 Feedback Resolution 23,592,960 Cts/Rev 23,592,960 Cts/Rev Feedback Precision 0.055 Arc-Seconds 0.055 Arc-Seconds Accuracy +/- 1 Arc-Second +/- 1 Arc-Second Specification The upgraded Space Geodesy Facility is now fully operational with the previous operating difficulties resolved largely thanks to Heason Technology thorough understanding of advanced motion applications. For further information email sales@heason.com or call us on +44 (0) 1403 792 300