Automatic frequency control device and method of QPSK modulation system
AssigneeLG Electronics Inc.
InventorSeok-Il Chang
Life of this patent
Estimating the term…
Abstract
An AFC (Automatic Frequency Control) device of a QPSK modulation system including a frequency discriminating unit for calculating a real part peak value using frequency discrimination between adjacent I and Q signals of a received sequence and an imaginary part peak value using the frequency discrimination between adjacent I signals and adjacent Q signals, an error detecting unit for detecting an error symbol from the received sequence, and a switching unit for removing the detected error symbol under the control of the error detector. Also included is a frequency difference average calculating unit for calculating a frequency difference of the received sequence without the error symbol.
Claims24
An AFC (Automatic Frequency Control) device of a QPSK (Quadrature Phase Shift Keying) modulation system comprising:
- a frequency discriminating unit for calculating a real part peak value based on a frequency discrimination between adjacent I and Q signals in a received sequence, and for calculating an imaginary part peak value based on a frequency discrimination between adjacent I signals and adjacent Q signals in the received sequence;
- an error detecting unit for detecting an error symbol based on the real part peak value and the imaginary part peak value;
- a switching unit for removing the detected error symbol under the control of the error detecting unit;
- and
- a frequency difference average calculating unit for calculating an average of real part peak values and an average of imaginary part peak values output from the switching unit, the frequency difference average calculating unit further calculating a frequency difference average of the received sequence based on the averages of the real part and imaginary part peak values, wherein automatic frequency control is performed based on the frequency difference average calculated by the frequency difference average calculating unit.
An AFC (Automatic Frequency Control) device of a QPSK (Quadrature Phase Shift Keying) modulation system comprising:
- calculating first and second peak values based on frequency discrimination between adjacent symbols of a received training sequence;
- checking whether a ratio of the first peak value to the second peak value belongs to a region between first and second values;
- passing the first and second peak values if the ratio belongs to the region;
- calculating a frequency difference of the received training sequence using the passed first and second peak values;
- and
- performing automatic frequency control based on the frequency difference.
Dependencies are inferred from the claim text.