Signal seeking system for radio receivers with tuning indicating circuitry for controlling the signal seeking

Claim 2

A signal seeking tuning system for a superheterodyne receiver of the type including tuning circuits adjustable to tune said receiver for any signal in a frequency band, comprising: control circuitry actuable to cause said tuning circuits to tune over said frequency band in one of a first and a second direction and responsive to a control signal to stop the tuning of said tuning circuits when a signal is received; discriminator circuit means for detecting the superheterodyne receiver intermediate frequency, said discriminator circuit means including a first and a second output terminal providing a control voltage at each of said terminals having an amplitude which varies with frequency over a predetermined limited range of frequencies, and having a relatively constant amplitude outside said range of frequencies, the control voltage amplitude at the approximate center of said range of frequencies indicating the desired intermediate frequency; means including a device coupled to said control circuitry, said device having a control electrode coupled by circuit means to said discriminator circuit means first and second output terminals; the conductivity of said device changing to generate said control signal when said tuning circuits are caused to tune over said frequency band in said first direction such that the amplitude of said control voltage has varied by a predetermined amount; and the conductivity of said device changing to generate said control signal when said tuning circuits are caused to tune over said frequency band in said second direction such that the amplitude of said control voltage is varied by a predetermined amount.

Claim 3

A signal seeking system as defined in claim 1 wherein said circuit means includes a first and a second DC steering diode such that said device will be biased to change conductivity when said tuning circuits are adjusted to cause the superheterodyne receiver intermediate frequency to be within said range of frequeNcies.

Claim 4

A signal seeking system as defined in claim 2 wherein said device is a transistor.

Claim 5

A signal seeking system as defined in claim 3 including a Zener diode coupled in series with the collector-emitter current path of said transistor.

Claim 6

A signal seeking tuning system for a television receiver, comprising: tuning means for scanning the frequency spectrum and selecting any one of a plurality of television channels, said tuning means including a variable capacitive element for fine tuning adjustments; automatic fine tuning control circuitry providing a control output voltage coupled to said variable capacitive element to vary the capacitance exhibited by said variable capacitive element such that said tuning means is adjustable to have a pull-in capability over a predetermined range of frequencies to insure proper adjustment of said tuning means; mechanical driving means coupled to drive the tuning means to scan through the frequency spectrum; a control circuit means coupled to deenergize the driving means to stop said tuning means when said control circuit means are actuated by a control signal; and means responsive to (1) the presence of synchronizing pulses, (2) the presence of a predetermined level of automatic gain control voltage, and, (3) the presence of said control output voltage from the automatic fine tuning control circuitry indicating that the receiver is tuned to a frequency within the pull-in capability of the automatic fine tuning control circuitry to insure that said tuning means is adjusted so that proper tuning can be achieved by varying the capacitance of said variable capacitance element, for applying a control signal to said circuit means, said control circuit means actuated by said control signal to deenergize the driving means to stop said tuning means before said tuning means is accurately tuned to a selected television channel, and the inertia of said mechanical driving means causing a further change in said tuning means in the direction for accurate tuning for the selected channel.

Claim 7

A signal seeking tuning system for a television receiver, comprising: tuning means for scanning the frequency spectrum and selecting any one of a plurality of television channels, said tuning means including a variable capacitive element for fine tuning adjustments; automatic fine tuning control circuitry providing a control output voltage coupled to said variable capacitive element to vary the capacitance exhibited by said variable capacitive element such that said tuning means is adjustable to have a pull-in capability over a predetermined range of frequencies to insure proper adjustment of said tuning means; mechanical driving means coupled to drive the tuning means to scan through the frequency spectrum; a control circuit means coupled to deenergize the driving means to stop said tuning means when said control circuit means are actuated by a control signal; and means responsive to (1) the presence of synchronizing pulses, (2) the presence of a predetermined level of automatic gain control voltage, and, (3) the presence of said control output voltage from the automatic fine tuning control circuitry indicating that the receiver is tuned to a frequency within the pull-in capability of the automatic fine tuning control circuitry to insure that said tuning means is adjusted so that proper tuning can be achieved by varying the capacitance of said variable capacitance element, for applying a control signal to said circuit means, said control circuit means actuated by said control signal to deenergize the driving means to stop said tuning means before said tuning means is accurately tuned to a selected television channel, and the inertia of said mechanical driving means causing a further change in said tuning means in the direction for accurate tuning for the selected channel.

Claim 8

A signal seeking system as defined in claim 5 wherein said automatic fine tuning control circuitry is of the type providing a control voltage having an amplitude which varies with frequency over a predetermined limited range of frequencies, and having a relatively constant amplitude outside said range of frequencies, the control voltage amplitude at the approximate center of said range of frequencies indicating a desired signal.

Claim 9

A signal seeking system as defined in claim 6 wherein said means is responsive to a change in the level of said control voltage.

Claim 10

A signal seeking system as defined in claim 7 wherein said means is responsive to a predetermined amount of change in the level of said control voltage.

Claim 11

A signal seeking system as defined in claim 8 wherein said synchronizing pulses are horizontal synchronizing pulses.

Claim 12

A signal seeking tuning system for a superheterodyne receiver of the type including tuning circuits adjustable to tune said receiver for any signal in a frequency band, comprising: control circuitry adjustable to cause said tuning circuits to tune over said frequency band in one of a first and a second direction and responsive to a control signal to stop the tuning of said circuits when said control signal is received; discriminator circuit means for detecting the superheterodyne receiver intermediate frequency and including a first and second output terminal each providing an output voltage having an amplitude which varies with frequency over a predetermined limited range of frequencies, and having a relatively constant amplitude outside said range of frequencies, the voltage amplitude at the approximate center of said range of frequencies indicating the desired intermediate frequency; a three terminal device including a first, a second and a control electrode; a first and a second diode having like electrodes coupleD to the control electrode of said device, the other electrode of said first diode coupled to the first discriminator output terminal and the other electrode of said second diode coupled to the second discriminator output terminal; a first impedance means coupled between the control electrode of said device and a point of reference potential, a second impedance means coupled between the first electrode of said device and said point of reference potential, said first electrode further coupled to said control circuitry to generate said control signal by changes in conductivity of the first-second electrode current path of said device; and means providing a source of operating potential for said device coupled to the second electrode of said device, said operating potential of a magnitude such that in conjunction with said relatively constant amplitude output voltage at said first and said second discriminator output terminals, said device is biased so that said device first-second electrode current path exhibits a first conductivity and in conjunction with said output voltage at said first and said second discriminator output terminals over a part of said range of frequencies, said device is biased so that said device first-second electrode current path exhibits a second conductivity.

Claim 13

A signal seeking tuning system for a superheterodyne receiver of the type including tuning circuits adjustable to tune said receiver for any signal in a frequency band, comprising: control circuitry adjustable to cause said tuning circuits to tune over said frequency band in one of a first and a second direction and responsive to a control signal to stop the tuning of said circuits when said control signal is received; discriminator circuit means for detecting the superheterodyne receiver intermediate frequency and including a first and second output terminal each providing an output voltage having an amplitude which varies with frequency over a predetermined limited range of frequencies, and having a relatively constant amplitude outside said range of frequencies, the voltage amplitude at the approximate center of said range of frequencies indicating the desired intermediate frequency; a three terminal device including a first, a second and a control electrode; a first and a second diode having like electrodes coupleD to the control electrode of said device, the other electrode of said first diode coupled to the first discriminator output terminal and the other electrode of said second diode coupled to the second discriminator output terminal; a first impedance means coupled between the control electrode of said device and a point of reference potential, a second impedance means coupled between the first electrode of said device and said point of reference potential, said first electrode further coupled to said control circuitry to generate said control signal by changes in conductivity of the first-second electrode current path of said device; and means providing a source of operating potential for said device coupled to the second electrode of said device, said operating potential of a magnitude such that in conjunction with said relatively constant amplitude output voltage at said first and said second discriminator output terminals, said device is biased so that said device first-second electrode current path exhibits a first conductivity and in conjunction with said output voltage at said first and said second discriminator output terminals over a part of said range of frequencies, said device is biased so that said device first-second electrode current path exhibits a second conductivity.

Claim 14

A signal seeking system as defined in claim 10 wherein said output voltage at said first and said second discriminator output terminals is a differential output voltage.