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