Abstract: The invention proposes a data transmission process, from a first unit (1) situated at a predetermined depth of an oil well to a second unit (2) situated at the surface of this well, the process comprising a digital-analog conversion stage (8) of the data to obtain an analog signal forming support of the data, and an amplification stage (9) of this signal prior to its emission in a cable (11) connecting the two units, characterized in that at least two distinct scramblings (20, 21) of the data are completed, such that there is a first and a second set of scrambled data. After passage in a single complex inverse Fourier transform, that intended for emission is selected (26), whereof the dynamic in amplitude is the lowest. If the probability of saturating with a single set is 10?q, then due to this process the probability will be 10?2q.

Abstract: The invention proposes a data transmission process, from a first unit (1) situated at a predetermined depth of an oil well to a second unit (2) situated at the surface of this well, the process comprising a digital-analog conversion stage (8) of the data to obtain an analog signal forming support of the data, and an amplification stage (9) of this signal prior to its emission in a cable (11) connecting the two units, characterised in that at least two distinct scramblings (20, 21) of the data are completed, such that there is a first and a second set of scrambled data. After passage in a single complex inverse Fourier transform, that intended for emission is selected (26), whereof the dynamic in amplitude is the lowest. If the probability of saturating with a single set is 10?q, then due to this process the probability will be 10?2q.

Abstract: The invention relates to a method of estimating the frequency offset of a packet of phase modulated symbols received with phase error, the method comprising: applying a phase correction to the symbols of the received packet for all possible pairs of frequency offset and phase offset; and selecting from said offset pairs, the pair which provides the most likely packet of corrected symbols, thereby determining the frequency offset of the received packet. Compared with known solutions, the invention makes it possible to reduce errors concerning estimated frequency. Advantageously, the method comprises a step of quantizing the possible phase corrections, thereby making it possible to reduce the complexity of the calculations to be performed, without degrading performance.

Abstract: The analysis of an image of the field of observation from a heat camera by bands of n lines prompts the appearance of streaks or "striping" in certain zones of the image, all these zones constituting a "striping space". The device for the implementation of the method includes means to determine a base of orthonormal functions H and V, generating a vector space of functions for which the values taken, at each point of the image, represent the luminance values of all the types of striping, means to modelize the striping exhibited by the image in determining the coefficients of distribution of this striping on the basic functions, means to synthesize the striping, in determining the luminance values of the striping from the coefficients of correlation and from the values of he basic functions, and, finally, means to substract the luminance values of the synthesized striping from the luminance values of the initial image.

Abstract: According to the method, after a step for the digital processing of the video signal of the image analyzed by rows, there is determined, for each row, on the basis of the distribution of the mean light energy values below and above each position of the row, a step modelling function, the jump position of which gives the position of the horizon in this row. The device used to implement this method includes a sampler of the video signal coupled with a flip flop memory through an accumulator which adds up the luminance values row by row, and a processor which, on the basis of the distribution of the mean light energy levels, computes the signal to be subtracted from the digital video signal by means of a subtractor. The disclosed method and device can be applied to the detection of the horizon from an image analyzed by columns or by lines.