A method of testing a shielded cable, comprising: coupling an excitation signal to the shielded cable at an end of a shielded cable; determining one or more resonant frequencies of the shielded cable based on a response of the shielded cable to the excitation signal; and determining that a shielding of the shielded cable has degraded based on a change in the one or more resonant frequencies, wherein said providing an excitation signal comprises providing the excitation signal to the shielded cable at a plurality of different frequencies from a test circuit , the excitation signal having an expected value at each frequency; and wherein said determining one or more resonant frequencies of the shielded cable based on a response of the shielded cable to the excitation signal comprises: measuring the excitation signal at each frequency from the test circuit; and determining that a given frequency constitutes a resonant frequency of the shielded cable if the measured value of the excitation signal at the given frequency differs from the expected value of the excitation signal at the given frequency by more than a predefined difference threshold, and the shielded cable comprises a plurality of conductors that are shielded from one another, including at least one excitation conductor and at least one additional conductor; wherein the excitation signal is coupled to the at least one excitation conductor; and wherein the test circuit is not coupled to the at least one additional conductor, and comprising: determining that the shielding of the shielded cable has degraded based on a change in interference experienced by a sensor that utilizes one or more of the at least one additional conductors. coupling an excitation signal to the shielded cable at an end of a shielded cable; determining one or more resonant frequencies of the shielded cable based on a response of the shielded cable to the excitation signal; and determining that a shielding of the shielded cable has degraded based on a change in the one or more resonant frequencies, wherein said providing an excitation signal comprises providing the excitation signal to the shielded cable at a plurality of different frequencies from a test circuit , the excitation signal having an expected value at each frequency; and wherein said determining one or more resonant frequencies of the shielded cable based on a response of the shielded cable to the excitation signal comprises: measuring the excitation signal at each frequency from the test circuit; and determining that a given frequency constitutes a resonant frequency of the shielded cable if the measured value of the excitation signal at the given frequency differs from the expected value of the excitation signal at the given frequency by more than a predefined difference threshold, and the shielded cable comprises a plurality of conductors that are shielded from one another, including at least one excitation conductor and at least one additional conductor; measuring the excitation signal at each frequency from the test circuit; and determining that a given frequency constitutes a resonant frequency of the shielded cable if the measured value of the excitation signal at the given frequency differs from the expected value of the excitation signal at the given frequency by more than a predefined difference threshold, and the shielded cable comprises a plurality of conductors that are shielded from one another, including at least one excitation conductor and at least one additional conductor; wherein the excitation signal is coupled to the at least one excitation conductor; and wherein the test circuit is not coupled to the at least one additional conductor, and comprising: determining that the shielding of the shielded cable has degraded based on a change in interference experienced by a sensor that utilizes one or more of the at least one additional conductors. <EOS>