Monaural signal judgement circuit

A method for judging inputted signals by a monaural signal judgement circuit to determine whether the inputted signals are monaural, comprising the steps of:

• generating a wave-form shape for a left-side signal and a right-side signal inputted to the monaural signal judgement circuit;
• computing a signal level difference between the generated left-side wave form shape and right-side wave form shape;
• setting a control signal based on the computed signal level difference;
• adjusting the signal level of one of the generated left-side or right-side wave form shapes based on the control signal;
• controlling the signal level difference to be within a predetermined range;
• and
• detecting a monaural signal based on the signal level difference being within the predetermined range.

A monaural signal judgement circuit, comprising:

• a wave-form shaping circuit having a left and right portion for rectifying left-side and right-side signals respectively;
• an operation circuit having a first and second input for receiving the rectified left-side and right-side signals and for judging whether a signal level and phase of the rectified left-side signal and right-side signal are the same;
• control signal setting circuit for eliminating a signal level difference between the rectified left-side signal and right-side signal;
• input control circuit for controlling a signal level of an input to the operation circuit to be within a predetermined (dB) range of a signal level of the other input to the operation circuit;
• and
• signal detection circuit for detecting a signal level of the output of the operation circuit and upon detection of a zero signal level outputting a detection signal indicating monaural signals.