Mission channel method and device for two-way transmission by means of two-wire trans

Claim 3

The method set forth in claim 1 in which said polarity states persist for two different time intervals, the shorter of the two intervals is used to encode one binary state and the longer interval is used to encode the other binary state.

Claim 4

The method set forth in claim 1 in which at least two different impedance values are selectable at the second station, the first value encoding one binary state and the second value encoding the other binary state.

Claim 5

The method set forth in claim 3 in which at least one additional impedance value is selectable and encodes control information.

Claim 6

The method set forth in claim 1 in which: said polarity states persist for two different time intervals, the shorter of the two intervals is used to encode one binary state and the longer interval is used to encode the other binary state; at least two different impedance values are selectable at the second station, the first value encoding one binary state and the second value encoding the other binary state; and at least one additional impedance value is selectable and encodes control information.

Claim 7

A communications system for simultaneous bidirectional transmission of coded information between a first and second station over a two-conductor transmission medium interconnecting the first and second station comprising: a voltage source at said first station, means for alternately connecting said voltage source to the transmission medium with one, then the opposite polarity, control means for selectively operating said means for alternately connecting the voltage source to the medium to cause said polarity connections to persist for at least two different time intervals for transmitting coded information to said second station, receiver means at said second station for measuring the time duration of each polarity state and providing a signal indicative of the time duration, means responsive to outputs provided by said receiver means for manifesting the received information from the first station contained in the time duration of the polarity states, means at said second station for selectively changing the impedance between the two conductors of the medium to one of at least two valves for transmitting coded information to the first station, and means at said first station measuring the impedance across the medium during each polarity state to detect the information transmitted from the second station to the first station.

Claim 8

A communications system for simultaneous bidirectional transmission of coded information between a first and second station over a two-conductor transmission medium interconnecting the first and second station comprising: a voltage source at said first station, means for alternately connecting said voltage source to the transmission medium with one, then the opposite polarity, control means for selectively operating said means for alternately connecting the voltage source to the medium to cause said polarity connections to persist for at least two different time intervals for transmitting coded information to said second station, receiver means at said second station for measuring the time duration of each polarity state and providing a signal indicative of the time duration, means responsive to outputs provided by said receiver means for manifesting the received information from the first station contained in the time duration of the polarity states, means at said second station for selectively changing the impedance between the two conductors of the medium to one of at least two valves for transmitting coded information to the first station, and means at said first station measuring the impedance across the medium during each polarity state to detect the information transmitted from the second station to the first station.

Claim 9

A communications system as set forth in claim 6 in which the polarity connections persist for two different time intervals, the shorter of the two intervals is selected to transmit one binary value and the longer selected to transmit the other binary value.

Claim 10

A communications system as set forth in claim 6 in which the means at said second station selects one from two impedance values for transmitting one binary state to the first station and the other value for transmitting the other binary state to the first station.

Claim 11

A communications system as set forth in claim 8 in which the selection means at the second station selects at least one additional impedance value for transmitting control information to the first station.