| 摘要 |
PURPOSE:To estimate the quality of a transmission line fast with high precision in the case of interference by detecting samples consisting of code sequences indicating a specific difference and counting the samples only when there is a frame error detection signal. CONSTITUTION:A sample detection circuit 11 inputs an ADPCM 4-bit received signal and the frame error detection signal and detects the ADPCM 4-bit received signal only when the frame error detection signal indicates an error. Only when the detected signal indicates the specific difference, '1' is outputted as its detection output and a detection counter 12 increases its counter value by one only when the output of the circuit 11 becomes '1'. Once sample output equivalent to one frame ends, the quality of the line is estimated according to the counter value, and after the estimation signal is inputted to a line quality improvement circuit 15, the counter 12 is reset. This operation is repeated thereafter to estimate the line quality in a radio section, frame by frame. |
