| 摘要 |
PURPOSE:To decide optimum transmission speed by one training by providing a mean square error calculation circuit calculating a mean square error during the reception of a prescribed scramble data to an equalizer so as to measure the degree of line equalization. CONSTITUTION:The number of times of accumulation N is set to '8' and '48' by using the CCITT modem recommendations V27ter segment 5 and V29 segment 4. In case of using a V29 modem at first an error rate versus S/N curve of the V29 modem is plotted to obtain the S/n with respect to the user allowable error rate and it is referred to as a threshold level TH. Thus, in the actual facsimile communication, when the value QL is smaller than the TH, 9600bps as the optimum transmission speed is adopted and when larger, 7200bps is selected as the optimum transmission speed. Thus, one training is enough to determine the optimum transmission speed. |
