| 摘要 |
An asymmetrical modem system wherein a modem at a first location transmits information to a modem at a second location on a downstream signal and the modem at the second location transmits information to the modem at the first location on an upstream signal. The system includes a first location transmitter section, having an N-point inverse frequency transform, for converting information into the downstream signal having up to (N/2)-1 carriers. A second location transmitter section having, an [(NL)/(2K)-point inverse frequency transform, converts information into the upstream analog signal having up to [(NL)/(2K)]-1 carriers, where K is the ratio of downstream signal bandwidth to upstream signal bandwidth and L is greater one. A receiver section at the first location, having an [NM/K]-point frequency transform, separates the upstream signal into up to [(NM)/(2K)]-1 upstream carriers, where M is greater than one. A receiver section at the second location, having an N-point frequency transform, separates the downstream analog signal into up to (N/2)-1 downstream carriers.
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