| 摘要 |
PURPOSE:To prevent the divergence of a MODEM by adding a function warranting timing recovery or the like and a function restoring the warrant function to the normal state when hung-up of the MODEM is discriminated through comparison of an evaluation scale with a predetermined threshold level at every symbol rate. CONSTITUTION:The abnormality of an equalizer 3 is detected by comparing an evaluation scale with a predetermined threshold level at every symbol rate. When it is discriminated that a MODEM hungs up due to the malfunction of functions such as timing recovery, equalizer coefficient updating calculation and carrier recovery caused by the abnormality, the operation of the functions is stopped. A coefficient relating to the calculation by preceding prescribed symbol rate number is loaded from a buffer 7 and used without modification and demodulation processing to succeeding data is implemented. Then the evaluation scale calculated at every symbol rate and when the sample number in which the evaluation scale exceeds a prescribed threshold level reaches a predetermined number, a control section 6 controls the updating processing of various coefficients so as to restore the operation of the estimated rotation quantity. |
