By Brian Bauer, Raychem Corporation
Digital modulation techniques and refined terminal devices are rapidly becoming available, paving the way for a whole new world of communications and entertainment services to the home. An unanswered question is whether existing drop components and systems are capable of effectively transmitting this digital superhighway traffic. This paper reports on the testing of 64 QAM modulated signals over typical and less-than-ideal drop systems. Also, from a joint Raychem/CableLabs sponsored indoor cabling project, important performance criteria, such as shielding effectiveness and return loss, are reported on for a variety of drop components. Sources of these components include electrical contractor distributors, consumer retail outlets, and typical CATV operator vendors. Digital signal transmitted through drops containing these products show significant Symbol Error Rate degradation, requiring the Carrier to Noise levels to be well maintained. Furthermore, many products being installed today can allow considerable levels of noise into the system, reducing any 'safety (fade) margin' in the Carrier to Noise ratio. Recommendations for insuring a reliable Residential Communications Network are offered.