FIELD: physics; communication.
SUBSTANCE: disclosed is apparatus for effective evaluation of communication quality in a communication system. The communication device generates a four-digit character with a frequency-shift keying (FSK) form by adding a redundant bit to the most significant part of the encoded sound information. The character which contains the redundant bit is placed such that the value of the character is equal to the maximum value of the minimum value from four values which can be obtained. A receiving device R receives a FSK wave, restores the character, counts the number of redundant bits in the restored character and having false values, decides whether to carry out the process of masking the bad frame or which type of the masking process to carry out, and carries out the process based on the decision taken. That way, it is possible to accurately or quickly evaluate communication quality using a simple configuration.
EFFECT: prevention of errors in evaluating communication quality.
10 cl, 8 dwg
