Time division multiplex transmission of submultiplex sequences of

Abstract

Time Division Multiplex (TDM) telemetry of submultiplex sequences of signals which may be obtained from successive sections of sensors in a sensor array are transmitted synchronously by locking generators in each section, which determine the time slots in which samples of the sensor signals from each sensor in the array may be transmitted, to successive synchronizing pulses which are generated in the section of the array furthest from the head end of the array where the telemetered signals are received. The synchronizing signals are transmitted once per scan of all of the sensors in the array and phase or time the operation of clock generators and counters which establish the timing so that neither the time slots nor the sensor data signals which are transmitted therein to the collection point at the head end of the array interfere with one another. The sensor array may be a seismic array such as a seismic streamer or spread used in geophysical exploration. Data signals from groups of sensors associated with different data acquisition units of a chain of such units may also be telemetered in synchronous sequences during repetitive scans or frames. Each section or module of the system may be identical and can provide the synchronizing pulses to succeeding section if a preceding unit fails to provide the synchronizing signals.