I need to set up a system capable of detecting the distance between an object moving further away and an anchor point. This object would be traveling through a slightly curved tunnel (of 1m diameter), making line of sight laser range-finding impossible. The object travels a maximum of ~35m and the object's position should have less than 15cm of error over that distance. From my research, 30m is too long of a distance for typical ultrasonic sensors in which the sensor emits a pulse and then waits for its echo. So instead, if I had a transmitter at my anchor point and a receiver attached to the back of the moving object, could I expect to get accurate distance data based on the time it takes to receive each pulse? Would this data be useable despite the fact that the pulses would likely reflect significantly on the walls of the tunnel? Would this work over such a large distance as well? Thank you.