Low power digital bus

Claim 1

A system for transmitting signals with low crosstalk through multi-conductor cable comprising: a plurality of coaxial lays of insulated conductor lines including at least one inner lay and one outer lay, each lay including a plurality of separate conductor lines, each separate conductor line of each lay being individually insulated from each other conductor line of the respective lay, an electrically conductive coaxial shield surrounding said plurality of lays and providing a common shield and ground for said plurality of lays and conductor lines, all conductor lines within said shield being insulated from said shield and ground, one conductor line in one of said lays providing a signal reference line for said one lay separate from said common ground, first and second like sources of direct voltage connected at respective opposite ends of said conductor lines of said one lay, each said voltage source being connected between ground and respective conductor lines in said one lay and including a voltage divider connected across each said voltage source, each said divider having a tap providing a reference voltage connected to the respective end of said reference line, means for transmitting signals over other conductor lines in said one lay including switching means connected between respective other signal transmitting conductor lines and ground for varying the voltage on said other conductor lines with respect to said reference line voltage, and means for terminating said signal transmitting lines at each end of said cable with the characteristic impedance of the respective line with respect to said shield.

Claim 2

A system for transmitting signals with low crosstalk through multi-conductor cable comprising: a plurality of coaxial lays of insulated conductor lines including at least one inner lay and one outer lay, each lay including a plurality of separate conductor lines, each separate conductor line of each lay being individually insulated from each other conductor line of the respective lay, an electrically conductive coaxial shield surrounding said plurality of lays and providing a common shield and ground for said plurality of lays and conductor lines, all conductor lines within said shield being insulated from said shield and ground, one conductor line in one of said lays providing a signal reference line for said one lay separate from said common ground, first and second like sources of direct voltage connected at respective opposite ends of said conductor lines of said one lay, each said voltage source being connected between ground and respective conductor lines in said one lay and including a voltage divider connected across each said voltage source, each said divider having a tap providing a reference voltage connected to the respective end of said reference line, means for transmitting signals over other conductor lines in said one lay including switching means connected between respective other signal transmitting conductor lines and ground for varying the voltage on said other conductor lines with respect to said reference line voltage, and means for terminating said signal transmitting lines at each end of said cable with the characteristic impedance of the respective line with respect to said shield.