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