Tracking carrier timing
First Claim
1. Circuitry for receiving a transmitted signal, the transmitted signal comprising a modulated signal (TXMODSIGA) generated under the control of a transmit timing signal (TXC) of a first predetermined frequency and up-converted by a carrier frequency at a multiple n of the first predetermined frequency, the circuitry comprising:
- a signal source (42) for generating a receiver timing signal (RXC) of a second predetermined frequency;
a frequency multiplier (44) having a multiply ratio of n and connected to receive as an input the receiver timing signal (RXC) and for generating a carrier reference signal (REFCARRIER) having a reference frequency of a multiple n of the second predetermined frequency;
a down-converter (48) connected to receive as a first input the transmitted signal and as a second input the carrier reference signal (REFCARRIER), and for generating at an output an offset modulated signal (OFFRXMODSIGD) corresponding to the modulated signal (TXMODSIGA) offset by a frequency equal to the difference between the carrier frequency and the reference frequency, a frequency compensator (52) connected to receive as an input the offset modulated signal (OFFRXMODSIGD) and for generating at an output a difference signal having a frequency corresponding to the difference between the carrier frequency and the reference frequency;
a frequency divider (54), having a divide ratio of n, connected to receive the difference signal and to generate at an output thereof an error signal having a frequency equal to the difference between the first and second predetermined frequencies;
timing control means (56), connected to receive the error signal and for generating at least one timing control signal in dependence on the error signal;
timing adjustment means (60) coupled to the output of the down-converter (48), and for adjusting the time phase of the output of the down-converter (48) responsive to said at least one timing control signal.
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Accused Products
Abstract
The timing of a carrier signal is tracked in a receiver. The receiver receives a signal produced by a transmitter having a single frequency source which is used to generate a reference clock frequency and a carrier signal frequency, there being a fixed, predetermined relationship between the reference and carrier frequencies. In the receiver there is a single frequency source which is used to generate a reference clock frequency and a carrier reference signal frequency, there being a fixed, predetermined relationship between the reference and carrier reference frequencies. The fixed, predetermined relationship in the transmitter and the receiver is the same.
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Citations
8 Claims
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1. Circuitry for receiving a transmitted signal, the transmitted signal comprising a modulated signal (TXMODSIGA) generated under the control of a transmit timing signal (TXC) of a first predetermined frequency and up-converted by a carrier frequency at a multiple n of the first predetermined frequency, the circuitry comprising:
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a signal source (42) for generating a receiver timing signal (RXC) of a second predetermined frequency;
a frequency multiplier (44) having a multiply ratio of n and connected to receive as an input the receiver timing signal (RXC) and for generating a carrier reference signal (REFCARRIER) having a reference frequency of a multiple n of the second predetermined frequency;
a down-converter (48) connected to receive as a first input the transmitted signal and as a second input the carrier reference signal (REFCARRIER), and for generating at an output an offset modulated signal (OFFRXMODSIGD) corresponding to the modulated signal (TXMODSIGA) offset by a frequency equal to the difference between the carrier frequency and the reference frequency, a frequency compensator (52) connected to receive as an input the offset modulated signal (OFFRXMODSIGD) and for generating at an output a difference signal having a frequency corresponding to the difference between the carrier frequency and the reference frequency;
a frequency divider (54), having a divide ratio of n, connected to receive the difference signal and to generate at an output thereof an error signal having a frequency equal to the difference between the first and second predetermined frequencies;
timing control means (56), connected to receive the error signal and for generating at least one timing control signal in dependence on the error signal;
timing adjustment means (60) coupled to the output of the down-converter (48), and for adjusting the time phase of the output of the down-converter (48) responsive to said at least one timing control signal. - View Dependent Claims (2, 3, 4)
an analogue-to-digital converter coupled to the output of the down-converter and responsive to the receiver timing signal, wherein the output of the down-converter is a digital signal.
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5. A method of tracking carrier timing of a transmitted signal in a receiver, the transmitted signal comprising a modulated signal (TXMODSIGA) generated under the control of a transmit timing signal (TXC) of a first predetermined frequency and up-converted by a carrier frequency at a multiple n of the first predetermined frequency, the method comprising:
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receiving the transmitted signal;
generating a receiver timing signal (RXC) of a second predetermined frequency;
generating a carrier reference signal (REFCARRIER) having a reference frequency of a multiple n of the second predetermined frequency;
down-converting the transmitted signal by mixing it with the carrier reference signal (REFCARRIER), thereby generating an offset modulated signal (OFFRXMODSIGD) corresponding to the modulated signal offset by a frequency equal to the difference between the carrier frequency and the reference frequency;
generating a difference signal having a frequency corresponding to the difference between the carrier frequency and the reference frequency;
dividing the difference signal by n, thereby generating an error signal having a frequency equal to the difference between the first and second predetermined frequencies;
generating at least one timing control signal in dependence on the error signal; and
adjusting the time phase of the down-converted signal responsive to said at least one timing signal. - View Dependent Claims (6, 7)
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8. A communication system, including a transmitter comprising:
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a signal source (12) for generating a transmitter timing signal (TXC) of a first predetermined frequency;
a frequency multiplier (14) having a multiply ratio of n and connected to receive as an input the transmitter timing signal (TXC) and for generating a carrier signal (TXCARRIER) having a frequency of a multiple n of the first predetermined frequency; and
an up-converter (48) connected to receive as a first input a modulated signal to be transmitted and as a second input the carrier signal (TXCARRIER), and for generating at an output a transmit signal (TXSIGNAL);
the communication system further including a receiver comprising;
a signal source (42) for generating a receiver timing signal (RXC) of a second predetermined frequency;
a frequency multiplier (44) having a multiply ratio of n and connected to receive as an input the receiver timing signal (RXC) and for generating a carrier reference signal (REFCARRIER) having a reference frequency of a multiple n of the second predetermined frequency;
a down-converter (48) connected to receive as a first input the transmitted signal and as a second input the carrier reference signal (REFCARRIER), and for generating at an output an offset modulated signal (OFFRXMODSIGD) corresponding to the modulated signal (TXMODSIGA) offset by a frequency equal to the difference between the carrier frequency and the reference frequency, a frequency compensator (52) connected to receive as an input the offset modulated signal (OFFRXMODSIGD) and for generating at an output a difference signal having a frequency corresponding to the difference between the carrier frequency and the reference frequency;
a frequency divider (54), having a divide ratio of n, connected to receive the difference signal and to generate at an output thereof an error signal having a frequency equal to the difference between the first and second predetermined frequencies;
timing control means (56), connected to receive the error signal and for generating at least one timing control signal in dependence on the error signal;
timing adjustment means (60) coupled to the output the down-converter (48), and for adjusting the time phase of the output of the down-converter (48) responsive to said at least one timing control signal.
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Specification