초록 ▼

Disclosed is a system for automatically falling back and restoring two transmission speeds in a data transmission system including transmission and reception modems bidirectionally connected through transmission lines. The reception modem includes two automatic equalizers for receiving a reception s

Disclosed is a system for automatically falling back and restoring two transmission speeds in a data transmission system including transmission and reception modems bidirectionally connected through transmission lines. The reception modem includes two automatic equalizers for receiving a reception signal. The first automatic equalizer generates a signal quality detection signal representing degradation of transmission line quality. The second automatic equalizer generates a signal quality detection signal representing restoration of transmission line quality. The first automatic equalizer changes reference values for equalization correction in response to both the signal quality detection signals and generates an equalized signal. One of the two signal quality detection signals is selected by a selector, and the selected signal is sent to the transmission modem. The transmission modem includes an encoder for encoding a modem output while changing its operation mode in response to the two signal quality detection signals sent from the reception modem. This encoder adds a random bit to each fallen back data point from terminal equipment in the fall back mode and sends the same data point data as in the normal operating state.

대표청구항 ▼

An automatic fall back and restore system comprising transmission and reception modems bidirectionally connected to a transmission line, said automatic fall back and restore system being used in a data communication system for reducing a transmission speed due to transmission line degradation and re

An automatic fall back and restore system comprising transmission and reception modems bidirectionally connected to a transmission line, said automatic fall back and restore system being used in a data communication system for reducing a transmission speed due to transmission line degradation and restoring the transmission speed upon restoration of transmission line degradation, wherein said transmission modem comprises encoder means for setting the number of types of data to be transmitted in one time slot or data points within one time slot to be l, reducing the number of data points of one time slot from l to k upon reception of a first signal quality detection signal generated by said reception modem and representing degradation of transmission line quality, adding (l-k) data point bits to transmission data and transmitting resultant data as l data points, increasing the number of data points back to l upon reception of a second signal quality detection signal generated by said reception modem and representing restoration of transmission line quality, and outputting the transmission data; and said reception modem comprises first automatic equalizing means for receiving the output data from said transmission modem, equalizing the output data, outputting the data as reception data and the first signal quality detection signal on the basis of the reception data, and changing the number of data points as a reference of an equalization correction amount in response to the first and second signal quality detection signals, second automatic equalizing means for receiving the output data from said transmission modem and outputting the second signal quality detection signal, and means, connected to the output from said first and second automatic equalizing means, for selecting the first or second signal quality detection signal, and outputting a selected signal quality detection signal to said transmission modem.