US 4,334,323 A · Self tracking tuner

Abstract

A tuner includes a channel or target frequency selection means, a tunable oscillator, a tunable circuit means having at least one tunable circuit, and tuning means, responding to the target frequency select means, for automatically and individually tuning the tunable circuit. Typically the tuner includes several tunable circuits, which are tuned successively. The illustrated embodiments have three individually controlled varactor tuned circuits and a varactor tuned oscillator. To move to a new target frequency, the tuner locks the oscillator to the target frequency via a phase locked loop. This target frequency is inputted to the first varactor tuned circuit, and a microprocessor cooperating with a DC detector for sensing the output of the set of tuned circuits steps a voltage step generator which controls the first varactor tuned circuit while the tuning of the other varactor tuned circuits is held fixed. The microprocessor adjusts the voltage step generator to maximize the DC output and signals corresponding to this voltage are stored in a memory. Next, the second varactor tuned circuit having a corresponding voltage step generator is adjusted in the same way, and corresponding signals are stored in memory. This continues until all varactor tuned circuits are locked to the target frequency, after which the varactor tuned oscillator is returned to its standard frequency of 43.5 MHz greater than the target frequency. In a second embodiment, one oscillator remains at 43.5 MHz higher than the target frequency and cooperates with a mixer and a 43.5 MHz oscillator to provide a target frequency signal for use in the self-alignment procedure.

Claims24

Dependent claims

In a tuner circuit of the type having a tunable oscillator and tunable circuit means including a tunable circuit receiving at an input thereof a signal from an antenna or other signal input apparatus, the tunable circuits cooperating with the tunable oscillator to provide an intermediate frequency signal at an output of the tuner circuit, the tuner circuit having means associated therewith for a user to select a target frequency at which the tuner is to be tuned, the improvement comprising:

tuning means cooperatively coupled to the tunable circuit means and responsive to the target frequency selection means for individually, automatically, and successively tuning each tunable circuit to the selected target frequency.

In a tuner circuit of the type having a tunable oscillator and a set of tunable circuits receiving at an input thereof a signal from an antenna or other signal input apparatus, the tunable circuits cooperating with the tunable oscillator to provide an intermediate frequency signal at an output of the tuner circuit, the tuner circuit having means associated therewith for a user to select a target frequency at which the tuner is to be tuned, the improvement comprising:

a set of frequency controllers each controllingly coupled to a respective one of the tunable circuits;
and
means for applying a signal at the target frequency to the input of the set of tunable circuits and for controlling each of said frequency controllers to maximize the output of the corresponding tuned circuits when said target frequency signal is inputted to the tuned circuit set, whereby the tuner circuit accurately responds to selection of a target frequency by the user.

Dependencies are inferred from the claim text.

Self tracking tuner

Life of this patent

Self tracking tuner

Life of this patent

Abstract

Claims24