Abstract: An example first device includes: processor circuitry configured to establish a cable communication; analog to digital converter circuitry configured to sample cable voltages over time; echo estimator circuitry configured to determine a plurality of echo coefficients corresponding to the plurality of voltages; and physical length estimator circuitry configured to: identify a first echo coefficient in the echo coefficients that satisfies a static threshold, the first echo coefficient corresponding to a near end echo; identify a second echo coefficient in the echo coefficients that satisfies a dynamic threshold, the second echo coefficient corresponding to a far end echo; and estimate the length of a cable for the cable communication based on the first echo coefficient and the second echo coefficient.