Patent ID: 8145452

Claim:
A disk drive comprising: a disk; an interconnect connectable to a host; a signal measurement circuit to measure voltage amplitudes of signals from the host; and a processor for controlling operations in the disk drive including writing and reading data to and from the disk, the processor being coupled to the signal measurement circuit, the processor under the control of a program in conjunction with the signal measurement circuit to: transmit a first signal to the host over a transmission medium at a first transmission frequency according to a first speed negotiation process; receive a second signal from the host at the first transmission frequency; determine a first voltage amplitude of the second signal; transmit a third signal to the host at a second transmission frequency according to a second speed negotiation process; receive a fourth signal from the host at the second transmission frequency; determine a second voltage amplitude of the fourth signal; and determine an approximate voltage loss in response to the first and second voltage amplitudes.