The first sub path extracts {HEAD ~ the second order intermodulation component} from {TAIL ~ the path} tuning signal of the main path 
The first sub path extracts { HEAD ~ the second order intermodulation component } from { TAIL ~ the path } tuning signal of the main path
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH