| 摘要 |
PURPOSE:To make the training successful, to decrease the loss in information transmission time and to increase the amount of data transmission, by decreasing the training time when the deterioration is less and the line characteristics are excellent and increasing the training time when the line characteristics are worse. CONSTITUTION:When a continuous wave inverted for the phase by 180 deg. is transmitted to a reception side 30 at a segment 1, a demodulator 31 detects it to recognize the start of the MODEM training, and rough adjustment of timing and carrier reproduction is done at first. When the shift in the timing and the phase of carrier is within a predetermined range, a sequencer 33 drives a signal transmitter 32 to generate a transmission request signal for a segment 2 (hereinafter called Seg 2 request signal) and returns it to a transmission side 10. In the Seg 2 request signal is not received during a prescribed period (almost several tens of ms.), the sequencer 14 discriminates it as disable reproduction of timing and carrier, the data in the transmission speed is thrown away and the speed is transferred to a transmission speed lower than the speed. |
