TELECOMMUNICATION SYSTEM AND A MAIN STATION AND A SUBSTATION FOR USE IN SUCH A SYSTEM

摘要

"A telecommunication system and a main station and a substation for use in such a system" Telecommunication systems such as PON-FITL-Systems are known with a TDMA frame structure comprising a main station (2) and a number of substations (4 to 7). From the International Application WO 91/08623 a system (1) is known system comprising means for coarse ranging and means for fine ranging the substations (4 to 7). For achieving accurate fine ranging an A/D-converter (29) for acquiring samples from a ranging pulse transmitted from the substation (4 to 7) is operated at a frequency which is high with respect to the master or bit clock, i.e. real time oversampling occurs. Such high speed A/D-converters are expensive, consume much power and have limited resolution. Furthermore for systems with even higher bit rates the knownoversampling becomes cumbersome. A quasi-oversampled coarse and/or fine ranging (28) is proposed operating at relatively low sampling rates. To this end the substations (4 to 7) send a repetitive ranging-bit-pattern (RBP) which is sampled in the main station (2) and thereafter reconstructed with processing means (32) to a quasi-oversampled ranging-bit-pattern. For finding a ranging error to be sent to the relevant substation (4 to 7), the quasi-oversampled ranging-bit-pattern is matched against a reference pattern, the ranging error to be found from the best match. Fig. 2