Seismic transmission method and device for a very low error rate

A method of obtaining seismic records of a subterranean zone with a low error rate, utilizing an acquisition apparatus and a central control unit, said method comprising the steps of:

• (a) collecting at the acquisition apparatus a series of seismic signals resulting from passage of a transmitted seismic signal through the subterranean zone;
• (b) storing the received series of seismic signals at the acquisition apparatus, together with synchronizing words, to provide digitized samples having N1 bits each;
• (c) encoding the stored digitalize samples at the acquisition apparatus by adding to the N1 bits of each digitalize sample a group of n check bits to form a set of encoded digital words;
• (d) sequentially storing the encoded digital words at the acquisition apparatus in successive blocks of N2 stored digital words;
• (e) successively reading the stored digital words at the acquisition apparatus by interleaving the blocks of stored digital words to provide (N1+n) digital words of N2 bits each;
• (f) adding to the (N1+n) digital words synchronizing data, including preample data made up of sequences of bits likely to introduce known phase or frequency shifts during transmission;
• (g) encoding the (N1+n) digital words from step (f) into digital symbols at the acquisition apparatus by combining the digital words, with weighting of successive bits of the digital words according to a TFM code;
• (h) transmitting successive digital symbols from the acquisition apparatus to the central control unit by modulating a carrier signal successively in accordance with the preamble data to provide known phase or frequency shifts to the carried signal, and in accordance with the digital symbols;
• (i) receiving the transmitted digital symbols at the central control unit;
• (j) phase or frequency detecting the received digital symbols by reversing the known phase or frequency shifts;
• (k) decoding the detected digital symbols at the central control unit to restore the interleaved blocks of (N1+n) digital words of N2 bits each;
• (l) storing the restored interleaved blocks;
• (m) reconstituting the blocks of N2 digital words of (N1+n) bits each at the central control unit, by reverse interleaving the digital words stored in step (l);
• (n) decoding the n check bits of the digital words in the reconstituted blocks at the central control unit, to correct any errors in the digital words and to suppress the n check bits of each digital word in the reconstituted blocks at the central control unit, thereby providing received digital samples.