公开(公告)号：KR810001085B1

公开(公告)日：1981-09-11

申请号：KR770001186

申请日：1977-05-19

Applicant: RCA CORP

Inventor： WINE C ,  RAST R

IPC: H04N5/50

Abstract: The tuning system for a TV receiver includes a local oscillator(26) which is controlled first by a PLL and then by an AFT discriminator for tuning the receiver to non-standard as well as standard frequency carriers. The PLL includes a programmable divider with a factor corresponding to the presently selected channel. When the local oscillator is being controlled by the AFT discriminator the count accumulated by the programable divider during a reference interval determines how far the local oscillator frenquency has drifted from its nominal value. It a predetermined frequency offset has been exceeded, control is returned to PLL control and the programmable factor is incrementally changed.