A system providing a spread spectrum and a narrowband data transmission may comprise a DSSS transmitter and a DSSS receiver. The DSSS transmitter may convert a bit succession (di) into a chip succession (sk) using a chip sequence (cj, cj′) and send a succession of impulses (s(t)) corresponding to the chip succession (sk). The DSSS receiver may receive impulses (s(t)) sent by the transmitter and filter the received impulses (r(t)) using a filter having an impulse response (x(t)) dependent on the chip sequence (cj, cj′). The chip sequence (cj) may be a spread sequence. The narrowband data transmission may use chip sequence (cj′) and a corresponding impulse response (x(t)) of the filter. The chip sequence (cj′) does not comprise a succession having two directly successive arithmetic sign changes and an arithmetic sign change does not occur after the first and before the last chip in the chip sequence (cj′).
