hi everyone, while doing a project on ultrasonic distance measurement, i came across the phenomenon of ghost echoes. The ultrasonic waves are emitted and made to reflect on a surface( of which the distance to the source is to be found). This reflected waves are detected, and time for b/w the the instant of emission, reception is measured. A major problem arising is the phenomenon of ghost echoes. The refelcted wave detected, may not be that of the object, but it may be of another object which is placed further off. i.e.. say at t=0, we emit. at t=1, we detect reflected wave from the object of interest. delay measured = 1s at t=2, we again emit at t=2.4, we receive reflected wave delay measured = .4s But the second reflected ray which we measure is due to another object(farther off) which has reflected the ray emitted at t=0. Now my question is, why doesnt the same phenomenon happen in radios? i.e. how is the music reception continuous in a radio. The radio receiver is ( ,say fm 93Mhz) is tuned to 93 Mhz. Now the receiver filters all the signal waves( including the delayed ones) and plays it. Shouldnt the output be scrambled, since the all the signals( including the delayed ones) are filtered, and played.