Abstract: A process for optimizing the transmission rates of digitized signals on transmission lines in multifunction cables, such as logging cables linking well tools to surface installations. The process includes digitising of the data to be transmitted and coding thereof through voltages selected from a set of multilevel coding voltages (2 to 32 for example), and widening towards high frequencies of the passband of each transmission line used, by combination with correcting circuits selected so that the transfer function of the corrected line is substantially that of a filter of the Bessel type, at least in a given frequency range on either side of a 3-dB cut-off frequency fc which depends on the number of coding voltages and on the amplification parameters. Using this process makes it possible to exceed very easily a total flow rate higher than one Mbits/s without increasing the transmission error rate.

Abstract: A device is provided for acquiring data coming from sensors distributed in several probes which may be anchored in a well or borehole and transmission thereof to a central control and recording system, including a remote control assembly for checking operating parameters. An acquisition apparatus includes a main multiplexer for seismic channels and an auxiliary multiplexer. The control assembly includes different modules delivering signals indicative of the position of the anchorage arms, of the operating temperature, of the power supply voltage, etc, means for testing the sensors and the seismic channels, and means for detecting any malfunction in the advance of the probes along the borehole. Different lines connected to the auxiliary multiplexer transmit the signals delivered by the control assembly.

Abstract: A system is provided for transmitting signals between a sensor assembly contained in one or more well probes lowered into a well at the end of a cable and a surface control and recording unit. The cable includes a central line surrounded by several other lines and an external metal sheath. The transfer of data from the reception assembly to the surface installation is provided by applying suitably coded signals between the central conductor and the external sheath. A considerable increase in the transmission flow rate of the cable is obtained.

Abstract: A method and apparatus for determining the position of a plurality of seismic echo receivers on a towed cable by interpolating values obtained by measuring, by means of at least one device positioned among said receivers, the angle between the tangent to the cable and a fixed and known direction. The measuring device can also include apparatus for measuring its depth and its distance from a generator of seismic waves. This provides for more effective use of processes which involve the addition of seismic traces in marine seismic prospecting.