A method for characterising a transmission line comprising the following successive steps of: a) Taking a measurement of the temporal impulse response of a reference signal propagated through the line from an injection point, then back-propagated at a measurement point, with the temporal measurement comprising a plurality of amplitude peaks each corresponding to an impedance discontinuity, b) identifying, for each amplitude peak, whether it corresponds to a primary or secondary reflection of the signal on an impedance discontinuity; c) determining, based on the amplitude of the primary peaks, an estimated value of the reflection coefficient associated with the corresponding impedance discontinuities; d) estimating an average attenuation coefficient along the line by means of the following relationship s * Π i (1 - ρ(i) 2) * e -aΣ i d i = A f, with a being the average attenuation coefficient, Af being the amplitude of a peak associated with the end of the transmission line, di being the position of a primary peak i in the impulse response, ρ(i) being the real part of the reflection coefficient associated with the primary peak i, and s being a sign function equal to 1 or -1 depending on the nature of the end of the transmission line, for i varying from 2 to N, with N being the number of interfaces between two sections on which the signal can reflect, excluding an interface with the measurement equipment and the end of the cable, e) correcting the amplitudes of the peaks of the impulse response based on the average attenuation coefficient and returning to step b) or to step c); f) determining a characteristic impedance associated with each primary peak based on each reflection coefficient. a) Taking a measurement of the temporal impulse response of a reference signal propagated through the line from an injection point, then back-propagated at a measurement point, with the temporal measurement comprising a plurality of amplitude peaks each corresponding to an impedance discontinuity, b) identifying, for each amplitude peak, whether it corresponds to a primary or secondary reflection of the signal on an impedance discontinuity; c) determining, based on the amplitude of the primary peaks, an estimated value of the reflection coefficient associated with the corresponding impedance discontinuities; d) estimating an average attenuation coefficient along the line by means of the following relationship s * Π i (1 - ρ(i) 2) * e -aΣ i d i = A f, with a being the average attenuation coefficient, Af being the amplitude of a peak associated with the end of the transmission line, di being the position of a primary peak i in the impulse response, ρ(i) being the real part of the reflection coefficient associated with the primary peak i, and s being a sign function equal to 1 or -1 depending on the nature of the end of the transmission line, for i varying from 2 to N, with N being the number of interfaces between two sections on which the signal can reflect, excluding an interface with the measurement equipment and the end of the cable, e) correcting the amplitudes of the peaks of the impulse response based on the average attenuation coefficient and returning to step b) or to step c); f) determining a characteristic impedance associated with each primary peak based on each reflection coefficient.