Abstract: A node size estimation tool for calculating a node size for interactive video, voice or data services placed on a system is provided. The estimation tool includes a computer processor, a data storage device, and the data entry device. Inputs are provided for receiving data on bandwidths for downstream and upstream passbands and for receiving data on node splitting information. Inputs are provided for receiving data on any limitations on the upstream and downstream passbands that are unavailable for use by the system. Inputs are provided for receiving data on requirement information for various services, and for receiving data on estimated service penetration rates, estimated simultaneous use rates, and a desired downstream data rate. Also, inputs are provided for processing data received to calculate the node size. A method of calculating node size utilizing the tool is also provided.

Abstract: An HPF for blocking an upstream signal and passing a downstream signal, an LPF for blocking the downstream signal and passing only an upstream data signal, a directional coupler for branching, and a high frequency relay for forming a through line are built in a shielded package integrally as a high frequency module, so as to restrain noise produced by a digital circuit from interfering. This enables the analogue circuit of the high frequency module and the other digital circuits to be built integrally in a network interface module mounted in a cable television set-top box. In addition, a single tuner is used for both analogue and digital signals. In doing so, the switching of an AGC voltage is problematic, which is done by an AGC switching circuit. With a network interface module mounted in a cable television set-top box, the circuit arrangement can be hence simplified, and improvements can be made on cost, size and power consumption.