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 for automatic classification, according to various selection criteria, of seismic or microseismic events picked up by seismic receivers coupled with an underground formation under development, according to whether the events are purely of microseismic nature or depend, on any account, on artifacts related to the outer environment or to formation development or monitoring activities, and for selection of the significant parts of traces for the purpose of analysis. The method has an application for monitoring of production or storage reservoirs under development.

Abstract: Method intended for automatic classification, according to various selection criteria, of seismic or microseismic events picked up by seismic receivers coupled with an underground formation under development, according to whether the events are purely of microseismic nature or depend, on any account, on artifacts related to the outer environment or to formation development or monitoring activities, and for selection of the significant parts of traces for the purpose of analysis.

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: The invention relates to a two-phase method of transmitting, to a central station (CS), seismic signals received by seismic receivers (R) and picked up by collecting units (A) disposed in the field. In the first phase, a compression is applied to each seismic trace, the ratio of which is adapted to the duration of a transmission window placed in the time intervals between successive seismic transmission-reception cycles, as well as to the rate of the transmission route used. The compressed trace as a whole is thus transmitted, allowing an operator at central station (CS) to check qualitatively that recording took place correctly in each collecting unit (A) even though he does not have the exact trace available.

Abstract: Seismic data acquisition devices (BA) distributed in an exploration zone are divided into n groups (GA1 to GAn) and, therein, into sub-groups having each a specific frequency for communicating with a concentration unit (Ck) which is connected to a central station (1) through Hertzian channels or cables or optical fibers. Acquisition devices in the various subgroups communicate simultaneously with the corresponding concentration unit (Ck) during predetermined emission windows. The concentration unit collects the signals received from the acquisition devices to transmit them in series to station (1). The acquisition devices are adapted for delaying their own emission window according to the rank which has been previously assigned thereto within the respective subgroups thereof.

Abstract: The arrangement in the field of seismic emission-reception system changes as it progrsses along the profile explored, which modifies the respective distances between the source of seismic signals (S) and each of the siesmic receivers (Ri). In order to take account thereof, each of the acquisition boxes (Bi) used in the field for amplifying, digitizing and storing the siesmic signals received during each emission-reception cycle (or possibly a central station) is provided with a processor for determining automatically the gain to be assigned to the various amplifiers from all of the signals acquired and with selection rules taking into account the level of the signals and their evolution observed over several successive emission-reception cycles. The invention has an application in decentralized automatic control of acquisition devices.

Abstract: The system includes a plurality of acquisition devices (A.sub.i) for collecting signals received by receivers (Rk) and a central control, recording and processing station. This station manages the performance of the devices (A.sub.i), of successive signal acquisition cycles and thereafter the centralization thereof. In order to relieve the central station of part of the tasks thereof in case of a high volume of data to be collected and processed, acquisition devices are used which have management processors (2, M.sub.1, M.sub.2) and with complementary computing processors (7, M.sub.3) programmed for carrying out processings of the data before the transmission thereof. Various combinations of seismic signals, data compression, and quality controls are performed in real time during the phase of setting of the seismic equipment (seismic receivers and acquisition device electronics (CA1 to CAn) in the devices A.sub.i in the field), etc, immediately accessible to operators in the field.

Abstract: A method and an apparatus are applied to the seismic data received by receivers (Ri) distributed in the field and collected by acquisition boxes (Bi), in order to be transmitted to a central control and recording station (P), for example through hertzian channels. Digital words by adding to each N1-bit digitized signal sample, in each acquisition box, a n-bit coding suffix sufficient for detecting and correcting any transmission-related error. In order to eliminate the effect of long interferences, the method also comprises arranging the words in blocks, interleaving the words of each block at the time of the transmission, and forming digital symbols. A complementary sequence for reverse interlacing, deblocking and correcting possible errors brings the digital samples back to the original state thereof.

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.