A Uniquely Simplified TV Tuning System Incorporating an Equally Unique Digital Automatic and Manual Fine Tuning Scheme

This paper presents a phase-locked loop tuning scheme for television that uniquely simplifies the phase-locked loop design by manipulation of the dividers to take advantage of the 6 MHz channel spacing. The system also incorporates a unique digital AFT scheme that utilizes the phase-locked-loop components and provides a means for manually offsetting the IF from its precise tuning of 45.75 MHz. The accuracy of tuning (worst case) occurs on channel 83 with an error of less than ±30 kHz, while the AFT has an error of less than ±1.5 kHz independent of channel. The following list summarizes the system capabilities.