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Automatic frequency control circuit and method

A technology of automatic frequency control and voltage control, applied in automatic frequency control parts, frequency control of electrical characteristics, radio/inductive link selection arrangement, etc., can solve problems such as difficult system size reduction and price reduction

Inactive Publication Date: 2005-05-11
NEC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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 and method
  • Automatic frequency control circuit and method
  • Automatic frequency control circuit and method

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Embodiment Construction

[0023] The preferred embodiments of the present invention will be described below with reference to the drawings.

[0024] figure 1 It 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.

[0025] 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, It is used 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 calculating...

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Abstract

In order to increase the pulling frequency error range, the frequency error range is changed according to the frequency error value of the reference oscillator in the own system estimated from the base station frequency.

Description

Technical field [0001] The present invention relates to AFC (Automatic Frequency Control) circuits and methods. Background technique [0002] So far, in the field, an AFC circuit for frequency pulling in a digital demodulator of a radio receiving system has been widely known. [0003] In the prior art AFC circuit, when it is detected that the synchronization data with a fixed sampling frequency has a phase error of about 180°, it is impossible to determine whether the frequency is lagging or leading, and this point is the limit point of traction. [0004] As a method to deal with this situation, a high-precision reference oscillator can be provided. But this leads to another problem, that is, it is difficult to reduce the size and price of the entire system. Summary of the invention [0005] Considering the above background, the purpose of the present invention is to provide an AFC circuit which can increase the pulling frequency range and does not require a high-precision refer...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03J7/02H03J7/04H04B1/16H04L27/00H04L27/22
CPCH03J7/04H04L2027/0057H04L2027/0095
Inventor 小田敏之
Owner NEC CORP