Method and apparatus for demodulating a GMSK signal
First Claim
1. A method for demodulating a GMSK signal comprising:
- a frequency converting step of shifting a received GMSK signal into a baseband and separating the shifted signal into I and Q component signals;
an A-D converting step of quantizing the I and Q component signals of the baseband separated in the frequency converting step and encoding the quantized I and Q component signals received to generate I and Q component data;
an offset error detecting step of checking the correlation between the I and Q component data generated in said A-D converting step and the standard waveform data to detect a slot interval and an offset error;
a phase locking step of selecting the I and Q component slot data by the slot interval information and the offset error amount detected in said offset error detecting step and compensating the offset error of the selected I and Q component slot data; and
software decision step of integrating a predetermined number of data among the I and Q component slot data compensated in the phase locking step and determining the I and Q component demodulation data according to the result of the integration.
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Abstract
A method for demodulating a GMSK signal and the apparatus thereof is disclosed. The apparatus is applied to a digital communication system and demodulates a GMSK signal which is received from the transmitting source. The apparatus for demodulating the GMSK signal comprises a frequency converter for converting the received GMSK signal into a baseband and separating the converted signals into the received I and Q component signals, an A-D converter for quantizing the received I and Q component signals of the baseband separated in the frequency converter and encoding the quantized I and Q component signals to generate the I and Q component receiving data, a memory where the standard waveform data with respect to the standard waveform is stored, an offset error detector for checking the correlation between the I and Q component receiving data and the standard waveform data and detecting the slot interval and the offset error, a phase locking portion for selecting the I and Q component slot data by the slot interval information and the offset error detected in the offset error detector and compensating the offset error of the selected I and Q component slot data, and a software determiner for integrating the predetermined number of data among the I and Q component slot data compensated in the phase locking portion and determining the I and Q component demodulation data according to the integrated result.
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Citations
5 Claims
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1. A method for demodulating a GMSK signal comprising:
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a frequency converting step of shifting a received GMSK signal into a baseband and separating the shifted signal into I and Q component signals; an A-D converting step of quantizing the I and Q component signals of the baseband separated in the frequency converting step and encoding the quantized I and Q component signals received to generate I and Q component data; an offset error detecting step of checking the correlation between the I and Q component data generated in said A-D converting step and the standard waveform data to detect a slot interval and an offset error; a phase locking step of selecting the I and Q component slot data by the slot interval information and the offset error amount detected in said offset error detecting step and compensating the offset error of the selected I and Q component slot data; and software decision step of integrating a predetermined number of data among the I and Q component slot data compensated in the phase locking step and determining the I and Q component demodulation data according to the result of the integration. - View Dependent Claims (2, 3)
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4. An apparatus for demodulating a GMSK signal comprising:
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frequency converting means for shifting a received GMSK signal into a baseband and separating the shifted signal into I and Q component signals; A-D converting means for quantizing the I and Q component signals of the baseband separated in the frequency converting means into a predetermined period and encoding the quantized I and Q component signals to generate I and Q component data; a memory where the standard waveform data with respect to the standard waveform is stored; offset error detecting means for checking the correlation between the I and Q component data generated in said A-D converting means and the standard waveform data stored in the memory; phase locking means for selecting I and Q component slot data by the slot interval information and the offset error detected in said offset error detecting means and compensating the offset error of the selected I and Q component slot data; and a software decision means for integrating the predetermined number of data among the I and Q component slot data compensated in the phase locking means and determining the I and Q component demodulation data according to the integrated result. - View Dependent Claims (5)
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Specification