PURPOSE: To recognize the occurrence of an error due to fading and to accurately predict the deterioration of equipment by separating an error second at the time of fading from that at a stationary state when the error second is counted.

CONSTITUTION: A reception input level detected by a reception input level detecting means 1 and a band area spectrum distortion quantity detected by a band area spectrum distortion quantity detecting means 2 are compared with a prescribed threshold value by a second error second counter means 4, respectively. Next, the means 4 separates and counts the error second counted by a first error second counter means 3 at the time of fading from that at the stationary state based on the above comparison, and each counted result is displayed on a display part. In such a way, it is possible to recognize the occurrence of the error due to the fading, and also, to accurately predict the deterioration of the equipment.