Abstract: An method of synchronizing a signal coming from at least one sensor positioned on an engine with a periodic event of the engine such as the crankshaft rotation is disclosed having application for engine control. A crankshaft rotation signal indicative of a reference time (TR), with which the engine signal(s) is to be synchronized, is acquired. The effective time difference (D) between the reference time and the time that is the closest to each temporally acquired engine signal is measured. Then the coefficients of a fractional digital compensation filter (FSDF) for compensating for the fractional part (d) of the measured effective time difference are determined. Finally, this digital compensation filter is applied to each temporally sampled engine signal, allowing obtaining of a series of digitized samples resealed from reference time (TR) for each engine signal.

Abstract: An method of synchronizing a signal coming from at least one sensor positioned on an engine with a periodic event of the engine such as the crankshaft rotation is disclosed having application for engine control. A crankshaft rotation signal indicative of a reference time (TR), with which the engine signal(s) is to be synchronized, is acquired. The effective time difference (D) between the reference time and the time that is the closest to each temporally acquired engine signal is measured. Then the coefficients of a fractional digital compensation filter (FSDF) for compensating for the fractional part (d) of the measured effective time difference are determined. Finally, this digital compensation filter is applied to each temporally sampled engine signal, allowing obtaining of a series of digitized samples resealed from reference time (TR) for each engine signal.

Abstract: A method and system for transferring synchronization data between a central control and seismic recording station and dependent stations in all the cases where the time of transmission through the connection channels between the elements may be liable to too great fluctuations is disclosed. The invention provides a central station (CCU) and intermediate local control and concentration stations (RRS), each connected to local acquisition units (RTU), with a common time reference or clock (H) (that can for example be provided by a satellite positioning network of a well-known type such as the GPS system, or based on the carrier frequency of a radio transmitter) which is picked up by specialized receivers associated with the elements of the seismic device, and in using this common reference to calculate the real transmission time and to local readjust seismic acquisition units (RTU).

Abstract: Method and system for transferring synchronization data between a central control and seismic recording station and dependent stations in all the cases where the time of transmission through the connection channels between the elements may be liable to too great fluctuations.

Abstract: Method and device intended for synchronized acquisition of seismic signals by one or more acquisition units suited for seismic signal digitizing, allowing to obtain, for each signal, a series y[n] of samples of these signals readjusted from a reference time on, from a first series x[n] of digitized samples of this seismic signal produced from any initial time prior to the reference time. The method essentially comprises detecting a synchronization signal indicative of this reference time (TR), measuring the effective time difference (D) between the reference time and the initial time, determining coefficients of a digital filter (F) suited to compensate for the fractional part (d) of the measured effective time difference, and applying this compensation digital filter to the first series of samples, which allows to obtain a series of digitized samples readjusted from the reference time.

Abstract: The invention pertains to transmission to a remote station, by means of transmission channels (generally radio transmission channels), of seismic data acquired by a data collection equipment comprising a plurality of acquisition units, each being suited to acquire, to store and preferably to compress the data to be transmitted.

Abstract: A method for the automatic association, with seismic signals received by receivers (R1 . . . Rn) distributed on a site to be explored, of topographic data relative to the location of these receivers. The seismic signals are collected and stored by seismic acquisition devices (B1-Bn) which, after each seismic "shooting", transmit the signals successively to a central station 1. When the receivers are positioned in the field, each receiver is located by means of radiopositioning of the GPS type for example, and the position indications are introduced into an auxiliary memory of the corresponding acquisition device. After each repatriation of the data of a shooting, the indications are read in this memory and remain associated with those data at the time of the general grouping on the tape recorder of the central station.

Abstract: A digitalization assembly of the over-sampling type includes an analog to digital converter (2) producing at a frequency F=kf small-format p samples and a digital filter (3) which, through the summation of a certain number n of over-samples, produces validated larger P-format samples at the frequency f, at instants fixed by a clock. In order to readjust the sampling instants in relation to an outside event which can occur at any time, a temporary memory store (5) is inserted between the converter (2) and the filter (3) and, according to the instant of arrival of this event, the appropriate samples to be sent towards the filter for their summation are selected.

Abstract: In a data acquisition for seismic exploration, where the terrain is rugged or includes natural features which prohibit satisfactory radio communication between a central control and recording system and a plurality of seismic data signal acquisition devices, a relay element and a transmission cable are provided so that those acquisition devices which are not capable of satisfactory radio communication with the central control and recording system communicate instead with the relay element either by transmission cable or radio transmission and the relay element in turn communicates with the central control and recording system either by radio transmission or transmission cable, respectively.

Abstract: A method and device are provided for initializing acquisition apparatus including the use of coded infrared rays for transmitting data and a control case, the initialization being provided by modulating a light beam in amplitude by means of a carrier signal, this latter being modulated both in frequency and in phase and the modulation depending on the initialization signals. A programmable processing unit delivers the digital data to an infrared ray transmitter, the light signals received in return from the acquisition cases provided with similar transmission means being received by an infrared receiver, decoded and reshaped before being applied to the processing unit.

Abstract: A system is provided for radio transmission between a central control and recording laboratory and spaced apart acquisition boxes in which relay transmission units are used for communicating with boxes which are directly inaccessible. It includes a centralization unit adapted for managing the exchanges of orders or data from the central laboratory with directly accessible boxes by means of a radio link in a first frequency band (f2), on the one hand and with the relay units by means of a radio link in another frequency band (f1). These latter manage the radio links with the inaccessible boxes by means of radio links at a frequency (f3) distinct from (f2). The relay units and the centralization unit are programmed for automatically managing the links between the central laboratory and any one of the boxes, whether they are direct or indirect, and, on the other hand, for reserving a part of the interrogation time of each box for the transmission of service data indicative of their correct operation.

Abstract: In a system for seismic exploration, a narrow passband channel of relatively-slow transmission speed is used to transmit commands from a control station to one or more remote signal acquisition devices to initiate acquisition and processing of echo signals generated by triggering of a seismic signal generator at a selected reference time. To permit use of the slow speed transmission channel for transmitting commands without delay in the recording of the echo signals, a first command to initiate processing and recording of received signals is transmitted to the acquisition devices prior to the selected reference time by an amount of time at least equal to the transmission time of the narrow passband channel. This first command also initiates in each acquisition device the counting of signal samples which are being recorded at a predetermined rate.

Abstract: Device for the sequential transmission of signals by radio or by cable between a central control and recording station and local data acquisition apparatuses, comprising cables connecting said data acquisition apparatuses to the central station and radio transmission and reception means associated with each acquisition apparatus and with the central station, and switching means for establishing the cable connection and interrupting the radio connection between the central station and any particular apparatus for which said radio connection becomes defective as a result of obstacles on the path between the location of said apparatus and that of the central station.