Pulse or digital communications – Transceivers – Modems
Patent
1997-10-17
1999-11-23
Chin, Stephen
Pulse or digital communications
Transceivers
Modems
375219, 332103, H04B 138, H04L 516
Patent
active
059913363
ABSTRACT:
The present invention is drawn to a system and method for transmitting a data signal using digital subscriber loops in an expanded frequency band. According to the present invention, an encoder receives a data signal to be transmitted to a second modem. The encoder generates both an in-phase and a quadrature signal based on the data signal. Both the in-phase signal and the quadrature signals are then processed by a signal precoder in preparation for transmission across the channel. Next, the in-phase and quadrature signals are processed by digital filters to produce signals of limited bandwidth which can be transmitted across the channel. The coefficients of the digital filter are chosen such that the resulting filtered in-phase and quadrature signals are transmitted in an expanded bandwidth. The quadrature signal is filtered so as to be orthogonal to the in-phase signal. Thereafter the filtered signals are added and then converted to an analog signal which is transmitted to the second modem. The second modem features signal recovery circuitry which will process the expanded bandwidth resulting in a baseband which features an increased signal to noise ratio making the data transmission less susceptible to interference.
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Performance and Spectral Compatibility of OPTIS HDSL2, Jun. 30, 1997, 7 pages.
Gut Richard
Scholtz William H.
Chin Stephen
Ghayour Mohammad
Globespan Technologies, Inc.
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