A time-domain reflectometer and a distance measurement method for devices sharing a common bus are provided. The time-domain reflectometer determines a time when to transmit a first ranging signal over a cable based at least in part on when a device presents a first impedance on the cable that is lower than a second impedance of the cable. The time-domain reflectometer transmits the first ranging signal over the cable and in response to transmitting the first ranging signal, receives, over the cable, a first response signal having a peak associated with an impedance mismatch present on the cable resulting from the device presenting the first impedance on the cable. The time-domain reflectometer determines, based on the first response signal, a distance between the time-domain reflectometer and the device.