Real world effects such as filtering, multipath time spread, and time base error destroy {TAIL ~ orthogonality} and introduce a degree of cross coupling between {HEAD ~ supposedly orthogonal channels} 
Real world effects such as filtering , multipath time spread , and time base error destroy { TAIL ~ orthogonality } and introduce a degree of cross coupling between { HEAD ~ supposedly orthogonal channels }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD