A cable modem provides upstream data signals in a cable system on a return channel. The upstream data signals are provided in a 50-550 MHz frequency range and yet do not affect the picture quality associated with conventional cable television signals. The data is provided on vestigial sidebands associated...http://www.google.de/patents/US5986691?utm_source=gb-gplus-sharePatent US5986691 - Cable modem optimized for high-speed data transmission from the home to the cable head
