A telecommunications transmitting device, including: an encoder configured to generate an initial signal formed by at least one reference sequence including an initial integer number of pulses dispatched over a same integer number of time windows; a transmitter configured to transmit the initial signal to a receiver; a demodulation device configured to determine that no acknowledgement from the receiver in response to the initial signal is received; and a processing unit configured to tune a second integer number of pulses constituting a second reference sequence, the second integer number being larger than the initial integer number, wherein the transmitter is configured to transmit a second signal formed by the second reference sequence including the second integer number of pulses dispatched over a same integer number of time windows.