A system for transmitting data in an upstream direction on broadband cable plant equipped only with downstream transmission is described.
A multiple-frequency repeater technique allowing transmission of low frequency signals over long cascades in an upstream direction is used. This technique overcomes the need to undertake any significant modifications to existing plant and eliminates the problems of crosstalk and attenuation occurring in a single-frequency approach.
The resulting modem designs facilitate simple and economic addition of remote monitoring capability to any cable system using existing software and power supply interfaces.