초록 ▼

A communications system which enables enhanced services to be provided over cable TV systems. The design of the system is such that amplification is not required. Therefore, two-way transmission is possible on the low band of “two-way capable”cable systems and intermediate power failures do not affe

A communications system which enables enhanced services to be provided over cable TV systems. The design of the system is such that amplification is not required. Therefore, two-way transmission is possible on the low band of “two-way capable”cable systems and intermediate power failures do not affect transmission. Transmission of data takes place in the low band frequency range of five to thirty megahertz. The system design is such that it can withstand over a hundred dB loss between the remote terminal and the head-end. Carrier frequencies, when received, are interleaved for purposes of decoding and microprocessor based controls are used for automatic gain control and error correction. In a preferred embodiment of the invention, two thousand five hundred carriers, each transmitting eight digital data channels of information can be simultaneously transmitted from remote terminals without any effect whatsoever on the TV signals being transmitted at the high band frequencies. The resulting system is a very economical and dependable method to achieve passive transmission of data over cable TV systems.

대표청구항 ▼

A passive data transmission system for a two-way coaxial cable system having repeaters, the repeaters having diplexers to split the transmission spectrum into a high frequency band and a low frequency band, the data transmission to take place in either direction on the low frequency band without amp

A passive data transmission system for a two-way coaxial cable system having repeaters, the repeaters having diplexers to split the transmission spectrum into a high frequency band and a low frequency band, the data transmission to take place in either direction on the low frequency band without amplification, comprising: a plurality of subscriber terminals comprising means for concurrently and continuously transmitting digitally encoded data from all the subscriber terminals at different radio frequencies on the low frequency band and wherein each subscriber terminal is allocated a plurality of digital data channels, each subscriber terminal comprising: means for generating different data signals for each allocated digital data channel to be transmitted; means for encoding the data for transmission; means for generating a different low band carrier frequency for each subscriber terminal; means for connecting each subscriber terminal to the coaxial cable system so that the encoded data from each subscriber is transmitted at the different low band carrier frequencies, each subscriber terminal continuously transmitting on a different one of the carrier frequencies; means for receiving the encoded data transmitted on the cable system comprising; means for connecting the receiving means to the coaxial cable system so that the encoded data from each subscriber is continuously and concurrently received at the plurality of low band carrier frequencies; a plurality of modems, each receiving data from a plurality of subscribers; scanning means for scanning the plurality of modems; means for decoding the transmitted encoded data from each subscriber terminal; and means for directly connecting the transmitting means and the receiving means through the diplexers so that the encoded data is transmitted and received at the plurality of low band carrier frequencies without intervening amplification by the coaxial cable system repeaters.