a second multiplier coupled to said second signal and a second local reference signal and having as an output a fourth signal, said {HEAD ~ second local reference signal phase} offset from said first local reference signal by {TAIL ~ 90 degrees}, 
a second multiplier coupled to said second signal and a second local reference signal and having as an output a fourth signal , said { HEAD ~ second local reference signal phase } offset from said first local reference signal by { TAIL ~ 90 degrees } ,
OTH 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 HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH