Method and apparatus for radio communication with improved automatic frequency control

Claim 2

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.

Claim 3

The method of claim 1 wherein the controlling step comprises supplying a control signal a voltage of which is responsive a frequency of the frequency divided signal, and varying the frequency of the reference signal in response to the control signal.

Claim 4

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: 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.

Claim 5

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: 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.

Claim 6

The method of claim 3 wherein the controlling step comprises supplying a voltage signal having a voltage responsive to the detected frequency error, and varying the frequency of the reference signal in in response to said voltage of the voltage signal.

Claim 7

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: 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.

Claim 8

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: 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.

Claim 9

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: 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.

Claim 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 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: 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.

Claim 11

The apparatus of claim 6 wherein the controlling means comprises means for generating a voltage signal in response to a frequency of the frequency-divided signal, and means for controlling the frequency of the reference signal in in response to a voltage of the voltage signal.

Claim 12

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: 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.

Claim 13

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: 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.

Claim 14

The apparatus of claim 8 wherein the controlling means comprises means for generating a voltage signal in response to the detected frequency error, and means for controlling the frequency of the reference signal in response to a voltage of the voltage signal.

Claim 15

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: 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.

Claim 16

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: 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.