Frequency translation phase-locked loop for separate or intercarrier type television sound detection

Abstract From the Canadian patent

A frequency translation phase locked loop (PLL) is provided for detecting the audio information from a received television signal. The PLL includes a switching arrangement which, in a first position causes the loop to process the IF picture and sound carriers for detecting the audio information in an intercarrier type of detection method and, in a second position causes the loop to process the IF sound carrier for detecting the audio information without the use of the received picture carrier, in a "separate" (split-sound) type of audio detection method.