Method and apparatus for radio communication with improved automatic frequency control
First Claim
1. In a communications system for providing communications between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile station including a receiver for receiving the radio-frequency signal, the receiver including a reference oscillator generating a reference signal having a frequency responsive to a frequency of the frequency calibration signal, the receiver further including a local oscillator and a radio-frequency mixer for mixing the radio-frequency signal with a signal from the local oscillator thereby converting the radio-frequency signal into an intermediate-frequency signal, a method comprising the steps of:
- synchronizing the local oscillator signal with the reference signal;
dividing a frequency of the intermediate-frequency signal and thereby deriving a frequency-divided signal; and
controlling a frequency of the reference signal in response to the frequency-divided signal.
1 Assignment
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Accused Products
Abstract
A base station transmits a radio-frequency signal to a mobile station. The radio-frequency signal includes a frequency calibration signal. The mobile station includes a receiver receiving the radio-frequency signal. The receiver includes a referance oscillator generating a reference signal whose frequency is controlled in accordance with the frequency calibration signal. The receiver includes mixers and local oscillators. The mixers mix the radio-frequency signal with local oscillator signals from the local oscillator signals and convert the radio-frequency signal into a corresponding intermediate-frequency signal. The local oscillator signals are synchronized with the reference signal. The frequency of the intermediate-frequency signal is divided to derive a frequency-divided signal. The frequency of the reference signal is controlled in accordance with the frequency-divided signal.
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Citations
10 Claims
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1. In a communications system for providing communications between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile station including a receiver for receiving the radio-frequency signal, the receiver including a reference oscillator generating a reference signal having a frequency responsive to a frequency of the frequency calibration signal, the receiver further including a local oscillator and a radio-frequency mixer for mixing the radio-frequency signal with a signal from the local oscillator thereby converting the radio-frequency signal into an intermediate-frequency signal, a method comprising the steps of:
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synchronizing the local oscillator signal with the reference signal; dividing a frequency of the intermediate-frequency signal and thereby deriving a frequency-divided signal; and controlling a frequency of the reference signal in response to the frequency-divided signal. - View Dependent Claims (2)
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3. In a communications system for providing communications between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile station including a receiver for receiving the radio-frequency signal, the receiver including a reference oscillator supplying a reference signal having a frequency responsive to a frequency of said frequency calibration signal, the receiver including a local oscillator and a radio-frequency mixer for mixing the radio-frequency signal with a local oscillator signal supplied by the local oscillator and, in response, converting the radio-frequency signal into an intermediate-frequency signal, a method comprising the steps of:
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synchronizing a frequency of the local oscillator signal with a frequency of the reference signal; dividing a frequency of the intermediate-frequency signal and thereby deriving a frequency-divided gate signal; counting pulses of the reference signal during an interval determined by the gate signal; detecting a frequency error of the reference signal from an optimal frequency in response to a number of the counted pulses, the optimal frequency responsive to a frequency of the frequency calibration signal; and controlling the frequency of the reference signal in response to the detected frequency error. - View Dependent Claims (4)
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5. In a communications system for supplying communication between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile station including a receiver for receiving the radio-frequency signal, the receiver including a local oscillator and a mixer for mixing the radio-frequency signal with a local oscillator signal supplied by the local oscillator thereby converting the radio-frequency signal into an intermediate-frequency signal, a method comprising the steps of:
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generating a reference signal; controlling a frequency of the local oscillator signal in response to a frequency of the reference signal; dividing a frequency of said intermediate frequency-signal thereby deriving a gate signal; detecting a frequency error of the reference signal responsive to a frequency of the frequency calibration signal and said gate signal; and controlling the frequency of the reference signal in accordance with the detected frequency error.
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6. In a communications system for providing communications between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile station including a receiver for receiving the radio-frequency signal, the receiver including a reference oscillator supplying a reference signal having a frequency controlled in response to a frequency of the frequency calibration signal, the receiver including a local oscillator and a mixer for mixing the radio-frequency signal with a local oscillator signal supplied by the local oscillator and converting the radio-frequency signal into an intermediate-frequency signal, an apparatus comprising:
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means for synchronizing the a frequency of the local oscillator signal with the frequency of the reference signal; means for dividing a frequency of the intermediate-frequency signal and thereby deriving a frequency-divided signal; and means for controlling the frequency of the reference signal in in response to a frequency of the frequency-divided signal. - View Dependent Claims (7)
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8. In a communications system for providing communications between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile station including a receiver for receiving the radio-frequency signal, the receiver including a reference oscillator generating a reference signal a frequency of which is responsive to a frequency of the frequency calibration signal, the receiver including a local oscillator and a radio-frequency mixer for mixing the radio-frequency signal with a local oscillator signal supplied by the local oscillator and converting the radio-frequency signal into a intermediate-frequency signal, an apparatus comprising:
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means for synchronizing the local oscillator signal with the reference signal; means for dividing a frequency of the intermediate-frequency signal and thereby derive a frequency-divided gate signal; means for counting pulses of the reference signal during an interval a responsive to the gate signal; means for detecting a frequency error of the reference signal from a nominal frequency in response to a number of the counted pulses, the nominal frequency responsive to a frequency of the frequency calibration signal; and means for controlling the frequency of the reference signal in response to the detected frequency error. - View Dependent Claims (9)
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10. In a communications system for providing communications between a base station and a mobile station, the base station transmitting a radio-frequency signal to the mobile station, the radio-frequency signal including a frequency calibration signal, the mobile statio including a receiver for receiving the radio-frequency signal, the receiver including a local oscillator and a radio-frequency mixer for mixing the radio-frequency signal with a local oscillator signal supplied by the local oscillator and converting the radio-frequency signal into an intermediate-frequency signal, as apparatus comprising:
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means for generating a reference signal; means for controlling a frequency of the local oscillator signal in response to a frequency of the reference signal; means for dividing a frequency of said intermediate-frequency signal thereby deriving a gate signal; means responsive to said reference signal and said gate signal for detecting a frequency error of the reference signal responsive to the frequency of the calibration signal; and means for controlling the frequency of the reference signal in response to the detected frequency error.
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Specification