By Richards. Prodan, Majid Chelehmal,Thomas H. William, Craig M. Chamberlain, Cable Television Laboratories, Inc.
CableLabs has performed an evaluation ofcable channel characteristics to statisticallyquantify the cable environment for high speed,band-limited transmission of digital informationin a study conducted in cooperation withseveral of our member cable system operators.
Approximately three hundred subscriber homesites in twenty cable systems were measured andanalyzed over a wide range of channel frequencies.
The range of channel characteristics, degreeof impairment, and relative frequency ofoccurrence in a statistical distribution of boththe cable plant and the subscriber home wiringis presented. These results provide the purveyorsof digital cable modem equipment with valuabledesign information which can be used todetermine the receiver interference mitigationtechniques required, the complexity and performancecharacteristics of a demodulator design,and the relative percentage of cable subscriberswho can satisfactorily receive a digital transmissionutilizing a specific demodulator implementation.
Various measurements of relevant channelcharacteristics provide useful informationneeded for both cost and performance optimizationof the digital demodulator, as well as thecable system transmission equipment.