The initial patent for the concept of a separate "noise receiver"
detecting noise and blanking the IF system was issued to Motorola
for use in their "low band" ... 27 - 54 mHz ... 2-way radios. They
called it a "range extender", and this was the label on the control
heads that turned the feature on and off.
73! Ken Kopp - K0PP
ElecraftCovers at rfwave.net