Automatic fall back and restore system for data communication

Patent

Automatic fall back and restore system for data communication

- 23 Jun 1987

20

TL;DR: In this article, 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 is described.

Abstract: 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.

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Citations

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References

Patent

Packetized ensemble modem

Paul Baran

- 11 Jan 1984

TL;DR: In this paper, a high speed digital data modem (10) particularly suited for use in a dial-up telephone line is presented, where the telephone passband is divided into sixty-four sub-bands each with a carrier located approximately in the center of each subband.

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- 18 Mar 1969

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