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Automatic frequency control circuit

An automatic frequency control, circuit technology, applied in the direction of automatic frequency control components, electrical characteristic frequency control, radio/induction link selection and arrangement, etc., can solve problems such as difficulty in reducing system size and reducing price

Inactive Publication Date: 2003-01-22
NEC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But this leads to another problem that it is difficult to reduce the size and price of the whole system

Method used

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  • Automatic frequency control circuit
  • Automatic frequency control circuit
  • Automatic frequency control circuit

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Embodiment Construction

[0020] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0021] figure 1 is a block diagram schematically showing the structure of the radio receiving system in the embodiment of the AFC circuit according to the present invention. In the description of the following embodiments, it is assumed that the radio receiving system is a mobile station system in mobile communication.

[0022] Such as figure 1 As shown, the mobile station system of this embodiment includes: an antenna 1 for receiving signals from a base station; a radio unit 2; a demodulator 3; a detection circuit 4; a frequency error determination circuit 5; a frequency error / control voltage conversion circuit 6, In order to generate the control voltage of the reference oscillator (TCXO) according to the frequency error; the detection frequency calculation circuit 8 is used to detect the control data for the phase-locked loop (PLL) circuit 10 by calc...

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Abstract

To increase the pull-in frequency error range, the frequency error range is changed based on the frequency error value of a reference oscillator in the own system as estimated from the base station frequency.

Description

[0001] This application claims priority from Japanese Patent Application No. 2001-184242 filed on June 19, 2001, the contents of which are incorporated herein by reference. technical field [0002] The present invention relates to AFC (Automatic Frequency Control) circuits. Background technique [0003] AFC circuits for frequency pulling in digital demodulators of radio receiving systems are well known in the art so far. [0004] In the prior art AFC circuit, when it is detected that the synchronous data with a fixed sampling frequency has a phase error of about 180°, it cannot be determined whether the frequency is lagging or leading, and this point is the limit point of traction. [0005] As a method of coping with this situation, a high-precision reference oscillator can be provided. But this leads to another problem that it is difficult to reduce the size and price of the entire system. Contents of the invention [0006] In view of the above background, an object of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03J7/02H03J7/04H04B1/16H04L27/00H04L27/22
CPCH04L2027/0057H04L2027/0095H03J7/04
Inventor 小田敏之
Owner NEC CORP