US 4,908,803 AGranted

Semi-sequential transmission method and system using simultaneously several radio transmission frequencies for connecting a seismic reception assembly to a central control and recording laboratory

AssigneeInstitut Francais du Petrole

InventorJoseph Rialan

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Abstract

A semi-sequential transmission method and system are provided making it possible for successive groups of seismic acquisition apparatus to communicate simultaneously, using several transmission frequencies, with a central seismic laboratory. Each of said apparatus comprises a frequency synthesizer capable, by means of switches, of setting itself to any one of different frequencies, and means for automatic distribution of the frequencies between the apparatus of the same group. Each of the apparatus, being given an order number dependent on its position along a seismic profile to be studied, determines the difference between its own order number and an order number which it receives by radio and which is that assigned to the first acquisition apparatus of its group. Depending on the difference measured and respecting certain limitations, each acquisition apparatus attributes to itself its own transmission frequency.

Claims9

Dependent claims

A method for the semi-sequential transmission of signals, by short wave link, between an assembly of N data acquisition apparatus of a seismic reception device and a central control and recording laboratory, by means of a restricted number n of different transmission frequencies less than the number N of acquisition apparatus of said assembly, each data acquisition apparatus being adapted to collect signals received by at least one seismic receiver disposed along a seismic profile to be studied, to digitize and record said signals and, controlled by the central laboratory, to transmit thereto by radio the digitized signals, further comprising:

assigning to each acquisition apparatus of an order number as a function of the position thereof along the seismic profile,
subdividing the assembly of acquisition apparatus into groups each containing at most n acquisition apparatus,
transmitting from the laboratory of a transmission control signal designating the order number of first acquisition apparatus of each of the groups successively,
comparing in each of the N acquisition apparatus of the assembly, the order number designated by the control signal with its own order number and, if a difference between said designated order number and its own order number is compatible with the number n of frequencies available,
switching of the transmission means to a transmission frequency assigned to said difference, the acquisition apparatus of the same group thus sharing out among themselves all the available transmission frequencies, and
transmitting signals from the acquisition apparatus of the same group to the central laboratory, each one using the particular frequency imposed by said comparison.

3 more elements

A system for the semi-sequential transmission of signals, by short wave link, between an assembly of data acquisition apparatus of a seismic reception device and a central control and recording laboratory, by means of a restricted number n of different transmission frequencies less than the number N of acquisition apparatus of said assembly, wherein all the acquisition apparatus of said assembly and the central laboratory are each provided with radio transmission and reception means which may be switched indifferently to any one of the transmission frequencies, each of the acquisition apparatus further comprising means for storing an order number depending on its position along the seismic profile, means for determining a difference between the order number which is assigned to it and a number designated by control signals emanating from the central laboratory and switching means for selecting among all the available frequencies and a transmission frequency, assigned to said difference.

Dependencies are inferred from the claim text.