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US 4,736,388 AGranted
Automatic fall back and restore system for data communication
AssigneeNEC Corporation
InventorMikiro Eguchi
Life of this patent
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AssigneeNEC Corporation
InventorMikiro Eguchi
Estimating the term…
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.
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
An automatic fall back and restore system in a data modem system comprising automatic equalizers each having a shift register for shifting reception data every time slot, a correction register for storing an equalization correction amount, operating means for multiplying the equalization correction amount with an output of each time slot from said shift register and for adding products to output equalized data, a first discriminator for calculating a difference between an ideal value and the equalized data output from said operating means, and a corrector for changing the equalization correction amount on the basis of the difference,
Dependencies are inferred from the claim text.