The exploitation of a mode locked train laser pulse for satellite ranging has been used. The Nd YAG oscillator/amplifier/frequency doubler/laser generates a mode locked train at 0.53um, most of the energy is contained in three pulses, the individual pulse duration is 70psec. During the 1963 Merit Campaign, within 4 months, 10 low satellite passes and 31 Lageos passes have been ranged. When tho mode locked substructure has been resolved for the received signal (50 % of passes), the BMS was 6-8 cm.
To fulfill the requirements on the laser ranging systems, the soft/hardware package of the Helwan station was significantly modified in period 1982-84. The max. ranging reprate was increased up to 5 pps. The mount pointing accuracy was increased implementing the mechanical inaccuracies software model. The automatical comparison of the time base to the Loran C signal was put into operation.