STELLA - Results of two years' operation for megabit/sec data transmission

A progress report on STELLA, an experimental digital-transmission system using the OTS satellite to link physics laboratories in Switzerland, the UK, and Italy, is presented for the years 1980-1982. The program was designed to demonstrate the feasibility of 500-kbit/sec transmission with error rates of the order of 10 to the -9th and to gain practical experience and user evaluation of the protoype system, which includes the three earth stations, a 2-Mbit/sec modem, a codec with half-rate convolutional encoding and Viterbi decoding, a communications interface module, a link-driving minicomputer, and a transmission-control protocol. Maximum data-block length was increased from 4 to 8 kbytes in 1981. The installation of the equipment and the operational history are depicted, and the lack of reliability due to extended earth-station down time is found to be the most serious problem. A list of STELLA reports is appended.