The disclosure relates to a method for monitoring the performances of a cable for carrying a downhole assembly in a wellbore, the cable comprising at least a conductive core and an insulating outer layer, comprising: measuring a downlink telemetry signal, transmitted from a surface control module to the downhole assembly, and/or an uplink telemetry signal, transmitted from the downhole assembly to the surface control module; representing the downlink and/or uplink telemetry signals as a function of a parameter representative of a depth of the downhole assembly, analyzing a variation of the telemetry signal as a function of the parameter in view of an electrical model of an installation including the cable and the downhole assembly disposed in the wellbore, determining location of anomalies of the cable based on the analysis.