Circuit for detecting a center level of a FSK demodulated signal to correct same

A circuit for detecting a center level of a FSK demodulated signal to correct same comprising:

• control means for holding a sample peak value of a demodulated base band signal of a FSK signal and a second sample value thereof having a polarity opposite to the first sample value in a first or a second sample hold circuit respectively in response to data information of said FSK signal;
• average calculation means for calculating a center level value of the demodulated FSK signal by averaging said first and second sample values;
• shift width calculation means for calculating a shift width value by taking ½ of difference between the first sample value and the second sample value;
• third sample means holding said shift width value in response to said data information;
• adder means for adding said shift width value to said first sample value to calculate a center level value;
• subtraction means for subtracting said shift width value from said second sample value to calculate a center level value;
• selection means for selecting the center level value calculated by said average calculation means, adder means or subtraction means in response to said data information;
• and
• judgement means for judging whether a received information data of said FSK signal is “1” or “0” on a basis of a selected center level value.