Based on the three-antenna method, the three-cable method has been devised to be applied to correcting for variations in cable transfer characteristic due to motion, flexure or aging. The method is to measure the cable in transmission and to infer the characteristic of the cable from a set of three pairwise measurements and get the correction factor to correct the measured data. By measuring in transmission, rather than in reflection, it overcomes the limitation imposed by cable loss on the use of the switched reflectometer.