A tone signal is mixed with a reference signal which alternates, at {HEAD ~ a multiplex frequency}, between sine and cosine signals, each being at a predetermined reference frequency which is less than {TAIL ~ the multiplex frequency} 
A tone signal is mixed with a reference signal which alternates , at { HEAD ~ a multiplex frequency } , between sine and cosine signals , each being at a predetermined reference frequency which is less than { TAIL ~ the multiplex frequency }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL