A Simple and Efficient Bus System to Connect Single Units within a Satellite Laser Ranging System
Complex systems - like SLR (Satellite Laser Ranging) systems - often need a large amount of cables to connect all remotely controllable add-on units, like flip mirrors, servo-motors, switches etc. on different groups (like mount / telescopes, laser, control PC, observer control station etc.). At the Graz kHz SLR station, more than fifty separate cables connecting these groups have been replaced now with a few single BNC cables, using a simple serial bus system. Each single BNC cable completely connects 2 units (e.g. the PC and the mount); there is no need for synchronization or handshake signals. Data transmission speed ranges from very low - down to a single transmit only on request, or on any change of bits - up to 10 MBits/s. This serial bus is flexible, easy to extent for future upgrades, and fast.
D. Kucharski, S. Schillak, H. C. Lim and T. Otsubo
Borowiec 10 Hz Satellite Laser Ranging (SLR) station is capable to measure spin of the Japanese Experimental Geodetic Satellite (EGP). Spectral analysis of 391 passes measured from March 10, 1994 to November 27, 2009 gives frequency signal representing the 3rd and the 6th harmonics of the satellite spin rate. Analysis of this signal, corrected for the apparent effects, indicates en exponential slowing down of the satellite: the spin rate decreases according to the equation f = 671.115907 ・ exp(-4.08324 x 10-5 ・ D) [mHz], where D is a day after launch. More than 15 years of the SLR measurements allowed investigating the initial spin rate of the satellite fini = 671.116, RMS = 0.203 [mHz] (initial spin period Tini = 1.49006, RMS = 0.0007 [s]).