Frequency offset correction based on the presence or absence of a received signal
First Claim
1. A method comprising:
- determining a change of an internal reference oscillator frequency relative to a frequency of a received signal, which signal would be received from a transmitting station upon use of a receiver with the telecommunications system,determining a frequency control value for controlling the internal reference oscillator frequency,storing plural values indicating the change of the internal reference oscillator frequency so as to monitor the changes of the internal reference oscillator frequency over time to serve as a prediction of future change of the internal reference oscillator frequency, where the plural values indicate that the change of the internal reference oscillator frequency is a time dependent history of the change of the internal reference oscillator frequency for reestablishing a communication link in the telecommunications system, and the slope of the change of the internal reference oscillator frequency is calculated and stored for determining the frequency control value in case that the received signal has been missed, andcontrolling the internal reference oscillator frequency by the frequency control value in accordance with the oscillator frequency relative to the received signal frequency in the presence of the received signal, and in accordance with the stored change-of-frequency value in the absence of the received signal.
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Accused Products
Abstract
The present invention relates to a method for controlling a frequency in a receiver, in particular in a receiver used in a telecommunications system. To keep precise clock frequency even when the synchronization signal from base-station is missing the method comprises the steps of: determining a change of an internal reference oscillator frequency relative to the frequency of the received signal from a transmitting station, determining a frequency control value for controlling the internal reference oscillator frequency, storing at least one value indicating the change of the internal reference oscillator frequency, and controlling the internal reference oscillator frequency in accordance with the frequency control value, that has been determined either in accordance with the change of the internal reference oscillator frequency relative to the frequency of the received signal in case that the signal from the transmitting station has been received (S20), or in accordance with the stored value(s) indicating the change of the internal reference oscillator frequency in case that the received signal has been missed (S30).
14 Citations
12 Claims
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1. A method comprising:
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determining a change of an internal reference oscillator frequency relative to a frequency of a received signal, which signal would be received from a transmitting station upon use of a receiver with the telecommunications system, determining a frequency control value for controlling the internal reference oscillator frequency, storing plural values indicating the change of the internal reference oscillator frequency so as to monitor the changes of the internal reference oscillator frequency over time to serve as a prediction of future change of the internal reference oscillator frequency, where the plural values indicate that the change of the internal reference oscillator frequency is a time dependent history of the change of the internal reference oscillator frequency for reestablishing a communication link in the telecommunications system, and the slope of the change of the internal reference oscillator frequency is calculated and stored for determining the frequency control value in case that the received signal has been missed, and controlling the internal reference oscillator frequency by the frequency control value in accordance with the oscillator frequency relative to the received signal frequency in the presence of the received signal, and in accordance with the stored change-of-frequency value in the absence of the received signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus comprising:
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circuitry for determining a change of an internal reference oscillator frequency relative to a frequency of a received signal, which signal would be received from a transmitting station upon use of the apparatus in a telecommunications system, a controller for determining a frequency control value for controlling the internal reference oscillator frequency, a memory for storing plural values indicating the change of the internal reference oscillator frequency so as to monitor the changes of the internal reference oscillator frequency over time to serve as a prediction of future change of the internal reference oscillator frequency, where the plural values indicate that the change of the internal reference oscillator frequency is a time dependent history of the change of the internal reference oscillator frequency for reestablishing a communication link in the telecommunications system, and the slope of the change of the internal reference oscillator frequency is calculated and stored for determining the frequency control value in case that the received signal has been missed, and circuitry for controlling the internal reference oscillator frequency by the frequency control value in accordance with the oscillator frequency relative to the received signal frequency in the presence of the received signal, and in accordance with the stored change-of-frequency value in the absence of the received signal. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification