Roy, WtEL wrote:
"There are a lot of TDR and oscilloscope users out there to contradict
that." (Step functions lost interest with the demise of telegraph, but
ones and zeros are back bigger than ever.)

Lord Kelvin, William Thomson suggested in the 19th century that life may
have arrived here from outer space. He died in 1907. Do you suppose he
was using TDR with an oscilloscope to determine subsea cable faults?

Best regards, Richard Harrison, KB5WZI