摘要 |
In communication system comprising plurality of earth stations tied together by relay (e.g. satellite-borne) in which status of individual subscriber line interface units must be continually reported to central control unit, only status changed since previous interrogation cycle is reported, with unchanged units being skipped over. When control is via satellite-borne relay, control unit sends interrogation commands to different stations at such time intervals that the report from one station arrives just as that from another station ends. For long transit times, this may result in all interrogation signals being transmitted before the first report in the sequence is received.
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