Tuning control apparatus of receiver
First Claim
1. A tuning control apparatus of a receiver for tuning said receiver to a desired broadcasting wave, comprising:
- a tuner including a voltage controlled oscillator as a local oscillator for generating an intermediate frequency output when the receiver is tuned to the desired broadcasting wave,an intermediate frequency circuit for receiving the output of said tuner,a frequency discriminator for receiving the output of said intermediate frequency circuit,a phase locked loop for providing a control voltage to said voltage controlled oscillator on the occasion of a desired broadcasting wave selecting operation by said receiver such that said intermediate output frequency is obtained from said tuner, said phase lock loop including a programable frequency dividing means for dividing the voltage controlled oscillator output by a selectable ratio such that the oscillator has a preset frequency related to the desired broadcasting wave,an automatic frequency control loop responsive to the output of said frequency discriminator for providing a control voltage to said voltage controlled oscillator on the occasion of the reception of the desired broadcasting wave by said tuner,broadcasting wave sensing means responsive to the levels of both the output from said intermediate frequency circuit and an S curve signal obtained from said frequency discriminator for sensing the reception of said broadcasting wave and providing a reception signal relating thereto, andswitching means responsive to said reception signal from said broadcasting wave sensing means for switchably selecting either said phase locked loop or said automatic frequency control loop for supply of said control voltage to said voltage controlled oscillator.
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Accused Products
Abstract
The output of a voltage controlled oscillator serving as a local oscillator is frequency divided by a prescaler and a programmable frequency divider, and the frequency divided output is applied to a phase locked loop including a phase comparator and a charge pump. An S curve signal obtained from a frequency discriminator is applied to an automatic frequency control loop including a window comparator and a charge pump. The outputs of these two charge pumps are applied through an analog switch to a common low-pass filter and the output of the low-pass filter is applied to the voltage controlled oscillator as a control voltage. A state of reception by the tuner is detected based on the output of an intermediate frequency amplifier and the analog switch is responsive to the detected output and a lock detected output of the phase locked loop. Accordingly, a control voltage obtained from the phase locked loop on the occasion of a station selecting operation or a control voltage obtained from the automatic frequency control loop on the occasion of the reception of the electric wave by the tuner, is switchably selected and is applied to the voltage controlled oscillator.
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Citations
9 Claims
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1. A tuning control apparatus of a receiver for tuning said receiver to a desired broadcasting wave, comprising:
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a tuner including a voltage controlled oscillator as a local oscillator for generating an intermediate frequency output when the receiver is tuned to the desired broadcasting wave, an intermediate frequency circuit for receiving the output of said tuner, a frequency discriminator for receiving the output of said intermediate frequency circuit, a phase locked loop for providing a control voltage to said voltage controlled oscillator on the occasion of a desired broadcasting wave selecting operation by said receiver such that said intermediate output frequency is obtained from said tuner, said phase lock loop including a programable frequency dividing means for dividing the voltage controlled oscillator output by a selectable ratio such that the oscillator has a preset frequency related to the desired broadcasting wave, an automatic frequency control loop responsive to the output of said frequency discriminator for providing a control voltage to said voltage controlled oscillator on the occasion of the reception of the desired broadcasting wave by said tuner, broadcasting wave sensing means responsive to the levels of both the output from said intermediate frequency circuit and an S curve signal obtained from said frequency discriminator for sensing the reception of said broadcasting wave and providing a reception signal relating thereto, and switching means responsive to said reception signal from said broadcasting wave sensing means for switchably selecting either said phase locked loop or said automatic frequency control loop for supply of said control voltage to said voltage controlled oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification