Automatic frequency control system, operation control method thereof and mobile communication device using the same
First Claim
1. An automatic frequency control system comprising:
- controlled oscillation means;
frequency converting means for generating a local oscillation frequency on the basis of a oscillation frequency of said controlled oscillation means and converting a reception signal including a reception reference frequency information into a base band signal on the basis of said local oscillation frequency;
automatic frequency control means for generating a frequency error information of said controlled oscillation means on the basis of said reception reference frequency information contained in said base band signal and controlling said controlled oscillation means by generating a control signal depending upon said frequency error information; and
control means for performing control of an automatic frequency control operation by said automatic frequency control means using said control signal upon preceding automatic frequency control locked state responsive to interruption of communication.
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0 Petitions
Accused Products
Abstract
In a mobile communication device, communication can be resumed upon next communication without causing problem even when an AFC control signal becomes abnormal upon interruption of communication. Locked state and unlocked state of an AFC portion is monitored by an AFC monitoring portion 5. Upon interruption of communication, if in unlocked state, a TCXO 1 is controlled by the AFC portion using a TCXO control signal upon preceding locked state. By this, when communication failure is caused by influence of building, tunnel or the like or when communication is terminated, a reference frequency of the mobile communication device does not significantly offset from the reference frequency of a base station to facilitate communication upon next communication.
12 Citations
9 Claims
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1. An automatic frequency control system comprising:
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controlled oscillation means;
frequency converting means for generating a local oscillation frequency on the basis of a oscillation frequency of said controlled oscillation means and converting a reception signal including a reception reference frequency information into a base band signal on the basis of said local oscillation frequency;
automatic frequency control means for generating a frequency error information of said controlled oscillation means on the basis of said reception reference frequency information contained in said base band signal and controlling said controlled oscillation means by generating a control signal depending upon said frequency error information; and
control means for performing control of an automatic frequency control operation by said automatic frequency control means using said control signal upon preceding automatic frequency control locked state responsive to interruption of communication. - View Dependent Claims (2, 3, 4, 5)
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6. An operation control method for an automatic frequency control system including:
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controlled oscillation means;
frequency converting means for generating a local oscillation frequency on the basis of a oscillation frequency of said controlled oscillation means and converting a reception signal including a reception reference frequency information into a base band signal on the basis of said local oscillation frequency;
automatic frequency control means for generating a frequency error information of said controlled oscillation means on the basis of said reception reference frequency information contained in said base band signal and controlling said controlled oscillation means by generating a control signal depending upon said frequency error information, the operation control method comprising the step of;
control step activated in response to interruption of communication, of performing control of an automatic frequency control operation by said automatic frequency control means using said control signal upon preceding automatic frequency control locked state. - View Dependent Claims (7, 9)
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8. A storage medium storing a program for making a computer to execute an operation control for an automatic frequency control system including:
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controlled oscillation means;
frequency converting means for generating a local oscillation frequency on the basis of a oscillation frequency of said controlled oscillation means and converting a reception signal including a reception reference frequency information into a base band signal on the basis of said local oscillation frequency;
automatic frequency control means for generating a frequency error information of said controlled oscillation means on the basis of said reception reference frequency information contained in said base band signal and controlling said controlled oscillation means by generating a control signal depending upon said frequency error information, said program comprising the step of;
control step activated in response to interruption of communication, of performing control of an automatic frequency control operation by said automatic frequency control means using said control signal upon preceding automatic frequency control locked state.
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Specification