Apparatus for superimposing an afc voltage on uhf and vhf tuning voltages for channel selection

Claim 2

A channel selecting system, comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator connected to the output of said intermediate frequency amplifier; a first variable resistor having a variable terminal which is connected to the VHF channel selection voltage impression terminal and a fixed terminal which is connected to ground; voltage impression means to impress a constant DC voltage on a third terminal of said first variable resistor; first switching means connected to one output of said frequency discriminator and having a first terminal connected to said voltage impression means; means to connect a second terminal of said first switching means to the UHF channel selection voltage impression terminal; second switching means connected to a second output of said frequency discriminator and having a first terminal connected to ground; a second variable resistor having a variable tap and having first and second terminals connected across a DC voltage source; and means to connect a second terminal of said second switching means to the variable tap of second variable resistor.

Claim 3

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuNer; a frequency discriminator connected to the output of said intermediate frequency amplifier; A first variable resistor having a variable terminal connected to the VHF channel selection voltage impression terminal and a second terminal connected to ground; a second variable resistor having a variable terminal connected to the UHF channel selection voltage impression terminal and a second terminal connected to ground; superimposing means connected to the output of said frequency discriminator to superimpose a constant DC voltage on the output of said frequency discriminator; switching means to selectively switch the output of said superimposing means between third terminals of each of said first and second variable resistors; and gain control means connected between said second variable resistor and said frequency discriminator to control feedback of the output of the variable terminal of said second variable resistor to said frequency discriminator independently of the movement of the variable terminal of said second variable resistor so that a constant output of said frequency discriminator appears at the variable terminal of said second variable resistor.

Claim 4

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuNer; a frequency discriminator connected to the output of said intermediate frequency amplifier; A first variable resistor having a variable terminal connected to the VHF channel selection voltage impression terminal and a second terminal connected to ground; a second variable resistor having a variable terminal connected to the UHF channel selection voltage impression terminal and a second terminal connected to ground; superimposing means connected to the output of said frequency discriminator to superimpose a constant DC voltage on the output of said frequency discriminator; switching means to selectively switch the output of said superimposing means between third terminals of each of said first and second variable resistors; and gain control means connected between said second variable resistor and said frequency discriminator to control feedback of the output of the variable terminal of said second variable resistor to said frequency discriminator independently of the movement of the variable terminal of said second variable resistor so that a constant output of said frequency discriminator appears at the variable terminal of said second variable resistor.

Claim 5

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator connected to the output of said intermediate frequency amplifier; a first variable resistor having a variable terminal which is connected to the VHF channel selection voltage impression terminal and a first fixed terminal which is connected to ground; means connected between a second fixed terminal of said first variable resistor and the output of said frequency discriminator for superimposing a constant DC voltage on the output of said frequency discriminator; a second variable resistor connected between the UHF channel selection voltage impression terminal and ground; means to impress the output of said frequency discriminator on said second variable resistor; switching means for selectively applying the output of said frequency discriminator, having said constant DC voltage superimposed thereon, onto said second fixed terminal of said first variable resistor; and means for substantially impressing the output of said frequency discriminator having said constant DC voltage superimposed thereon onto said UHF channel selection voltage impression terminal when said switching means is switched out of engagement with said second fixed terminal of said first variable resistor, wherein said output of said frequency discriminator having said constant DC voltage superimposed thereon comprises a regulated voltage obtained from the variable terminal of said second variable resistor and the output voltage of said frequency discriminator.

Claim 6

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator connected to the output of said intermediate frequency amplifier; a first variable resistor having a variable terminal which is connected to the VHF channel selection voltage impression terminal and a first fixed terminal which is connected to ground; means connected between a second fixed terminal of said first variable resistor and the output of said frequency discriminator for superimposing a constant DC voltage on the output of said frequency discriminator; a second variable resistor connected between the UHF channel selection voltage impression terminal and ground; means to impress the output of said frequency discriminator on said second variable resistor; switching means for selectively applying the output of said frequency discriminator, having said constant DC voltage superimposed thereon, onto said second fixed terminal of said first variable resistor; and means for substantially impressing the output of said frequency discriminator having said constant DC voltage superimposed thereon onto said UHF channel selection voltage impression terminal when said switching means is switched out of engagement with said second fixed terminal of said first variable resistor, wherein said output of said frequency discriminator having said constant DC voltage superimposed thereon comprises a regulated voltage obtained from the variable terminal of said second variable resistor and the output voltage of said frequency discriminator.

Claim 7

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator connected to the output of said intermediate frequency amplifier; first variable resistance means having a variable terminal which is connected to the VHF channel selection voltage impression terminal; second variable resistance means connected to the UHF channel selection voltage impression terminal; superimposing means connected to said frequency discriminator for superimposing a DC voltage level on the output of said frequency discriminator; VHF selection means for applying the superimposed output of said frequency discriminator to the VHF channel selection Voltage impression terminal through said first variable resistance means; UHF selection means for applying the superimposed output of said frequency discriminator to the UHF channel selection voltage impression terminal through said second variable resistance means; and means for selectively switching the superimposed output of said frequency discriminator between said VHF selection means and said UHF selection means.

Claim 8

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator connected to the output of said intermediate frequency amplifier; first variable resistance means having a variable terminal which is connected to the VHF channel selection voltage impression terminal; second variable resistance means connected to the UHF channel selection voltage impression terminal; superimposing means connected to said frequency discriminator for superimposing a DC voltage level on the output of said frequency discriminator; VHF selection means for applying the superimposed output of said frequency discriminator to the VHF channel selection Voltage impression terminal through said first variable resistance means; UHF selection means for applying the superimposed output of said frequency discriminator to the UHF channel selection voltage impression terminal through said second variable resistance means; and means for selectively switching the superimposed output of said frequency discriminator between said VHF selection means and said UHF selection means.

Claim 9

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator having a first input connected to the output of said intermediate frequency amplifier, and a second input; and UHF-VHF coupling means having an input coupled to the output of said frequency discriminator and first, second and third outputs, said first output being coupled to the second input of said frequency discriminator for applying a gain control signal thereto; said second output being coupled to said UHF channel selection voltage impression terminal for applying to said UHF terminal a voltage corresponding to the output of said frequency discriminator; and said third output being coupled to the VHF channel selection voltage impression terminal for applying to said VHF terminal a voltage corresponding to the output of said frequency discriminator having a DC component superimposed thereon.

Claim 10

A channel selecting system comprising: a VHF tuner having a channel selection voltage impression terminal; a UHF tuner having a channel selection voltage impression terminal and an output terminal which is connected to said VHF tuner; an intermediate frequency amplifier connected to the output of said VHF tuner; a frequency discriminator having a first input connected to the output of said intermediate frequency amplifier, and a second input; and UHF-VHF coupling means having an input coupled to the output of said frequency discriminator and first, second and third outputs, said first output being coupled to the second input of said frequency discriminator for applying a gain control signal thereto; said second output being coupled to said UHF channel selection voltage impression terminal for applying to said UHF terminal a voltage corresponding to the output of said frequency discriminator; and said third output being coupled to the VHF channel selection voltage impression terminal for applying to said VHF terminal a voltage corresponding to the output of said frequency discriminator having a DC component superimposed thereon.