Conferencing system utilizing oppositely phased hybrids

Claim 2

A conferencing system for interconnecting a plurality of 2wire communication devices, said system comprising: a plurality of hybrids, each hybrid adapted for converting from 2-wire to 4-wire operation, said 4-wire portion of said hybrids including an output bus and an input bus; means for interconnecting said output bus of each hybrid and for interconnecting said input bus of each of said hybrids, said interconnecting means including a summation means for communicating signals from said output bus to said input bus, said hybrids arranged in groups, a first group connected to certain ones of said communication devices and a second group connected to other ones of said communication devices, said first group of hybrids having means for establishing a signal having a first polarity with respect to any reflected transmission signals, said second group of hybrids having means for establishing a signal having a second polarity with respect to any reflected transmission signals; and means for enabling said interconnecting means of selected ones of said first group of hybrids and of selected ones of said second group of hybrids so that a conference connection is possible between said communication devices associated with said interconnected hybrids whereby the polarity differences of the reflected signals of said first group of hybrids and said second group of hybrids act to reduce the overall reflected signal.

Claim 3

The invention set forth in claim 1 wherein each said hybrid includes two amplifiers, each amplifier having two inputs and a single output, said amplifiers arranged so that the output of each is connected to a first one of the inputs of the other amplifier of the same hybrid, and said amplifiers further arranged so that the output of a first one of said amplifiers at each of said hybrids and a second input to the second one of said amplifiers at each of said hybrids are connected to an individuaL one of said communication devices.

Claim 4

The invention set forth in claim 2 wherein said amplifiers each have a noninverting positive input terminal, an inverting negative input terminal, and an output terminal, each said hybrid of said first group of hybrids comprising a connection from said output terminal of a first one of said amplifiers to said 2-wire portion of said hybrid and to said negative input terminal of said second amplifier, a connection from said 2-wire portion of said hybrid to said positive input terminal of said second amplifier, a connection from said output terminal of said second amplifier to said output bus and to said negative input terminal of said first amplifier, and a connection from said positive input terminal of said first amplifier to said input bus; each said hybrid of said second group of hybrids comprising a connection from said output terminal of a first one of said amplifiers to said 2-wire portion of said hybrid and to said positive input terminal of said second amplifier, a connection from said 2-wire portion of said hybrid to said negative input terminal of said second amplifier, a connection from said output terminal of said second amplifier to said output bus and to said negative input terminal of said first amplifier, and a connection from said positive input terminal of said first amplifier to said input bus.

Claim 5

The invention set forth in claim 3 whereby, with respect to said first group of hybrids, the gain from said negative input terminal of each of said second amplifiers to said second amplifier output terminal is a value -n, where n is any positive number, and the gain from said positive input terminal of each said amplifier to said amplifier output terminal is a value of +2n; and, with respect to said second group of hybrids, the gain from said second amplifier output is a value -2n and the gain from said positive input terminal of each said amplifier to said amplifier output terminal is a value of +n.

Claim 6

In a communication system where a number of common interest stations are connectable to each other over line circuits and where any such station is connectable to other stations connected to the system over trunk circuits, an arrangement for establishing conference connections between selected ones of said stations served by said line circuits and up to two of said stations served by said trunk circuits, said arrangement comprising: a plurality of hybrids, each hybrid adapted for converting from 2-wire to 4-wire operation, said 4-wire portion of each said hybrid including an output bus and an input bus and each said hybrid having the 2-wire input thereof connected to an individual one of said line circuits or to an individual one of said trunk circuits; means for forming a station output bus by connecting together all said output buses of said hybrids connected to line circuits; means for forming a station input bus by connecting together all said input buses of said hybrids connected to line circuits; means for forming a trunk output bus by connecting together all said output buses of hybrids connected to trunk circuits; means for forming a trunk input bus by connecting together all said input buses of hybrids connected to trunk circuits; means, including a first summing amplifier, a second summing amplifier and a first transmission pad circuit, for connecting said station output bus to said station input bus so that transmission from any selected station served by a line circuit can be communicated to and from any other selected station served by a line circuit, said transmission between line-served stations having a transmission loss established by said first transmission pad circuit; means, including a third summing amplifier and a fourth summing amplifier for connecting said trunk output bus to said trunk input bus so that transmission from any selected station served by a trunk circuit can be communicated to any selected station served by a trunk circuit, said transmission between trunk-served stations having no artificially introduced transmission loss; means, including said second and said third summing amplifiers, for connecting said trunk output bus to said station input bus so that transmission from any selected station served by a trunk circuit can be communicated to any selected station served by a line circuit, said transmission having no artificially introduced transmission loss; means, including said first summing amplifier and said fourth summing amplifier, for connecting said station output bus to said trunk input bus so that transmission from any selected station served by a line circuit can be communicated to any selected station served by a trunk circuit, said transmission having no artificially introduced transmission loss; and means for reducing the total reflected transmission signal of the system, said means including means in said hybrids connected to said line circuits for establishing a signal having a first polarity with respect to any reflected transmission signals originating therewithin, and means in said hybrids connected to said trunk circuits for establishing a signal having a second polarity with respect to any reflected transmission signals originating therewithin.

Claim 7

In a communication system where a number of common interest stations are connectable to each other over line circuits and where any such station is connectable to other stations connected to the system over trunk circuits, an arrangement for establishing conference connections between selected ones of said stations served by said line circuits and up to two of said stations served by said trunk circuits, said arrangement comprising: a plurality of hybrids, each hybrid adapted for converting from 2-wire to 4-wire operation, said 4-wire portion of each said hybrid including an output bus and an input bus and each said hybrid having the 2-wire input thereof connected to an individual one of said line circuits or to an individual one of said trunk circuits; means for forming a station output bus by connecting together all said output buses of said hybrids connected to line circuits; means for forming a station input bus by connecting together all said input buses of said hybrids connected to line circuits; means for forming a trunk output bus by connecting together all said output buses of hybrids connected to trunk circuits; means for forming a trunk input bus by connecting together all said input buses of hybrids connected to trunk circuits; means, including a first summing amplifier, a second summing amplifier and a first transmission pad circuit, for connecting said station output bus to said station input bus so that transmission from any selected station served by a line circuit can be communicated to and from any other selected station served by a line circuit, said transmission between line-served stations having a transmission loss established by said first transmission pad circuit; means, including a third summing amplifier and a fourth summing amplifier for connecting said trunk output bus to said trunk input bus so that transmission from any selected station served by a trunk circuit can be communicated to any selected station served by a trunk circuit, said transmission between trunk-served stations having no artificially introduced transmission loss; means, including said second and said third summing amplifiers, for connecting said trunk output bus to said station input bus so that transmission from any selected station served by a trunk circuit can be communicated to any selected station served by a line circuit, said transmission having no artificially introduced transmission loss; means, including said first summing amplifier and said fourth summing amplifier, for connecting said station output bus to said trunk input bus so that transmission from any selected station served by a line circuit can be communicated to any selected station served by a trunk circuit, said transmission having no artificially introduced transmission loss; and means for reducing the total reflected transmission signal of the system, said means including means in said hybrids connected to said line circuits for establishing a signal having a first polarity with respect to any reflected transmission signals originating therewithin, and means in said hybrids connected to said trunk circuits for establishing a signal having a second polarity with respect to any reflected transmission signals originating therewithin.

Claim 8

The invention set forth in claim 5 wherein each said hybrid includes two amplifiers, each amplifier having two inputs and a single output, said amplifiers arranged so that the output of each is connected to a first one of the inputs of the other amplifier of the same hybrid, said amplifiers further connected so that the output of a first one of said amplifiers at each of said hybrids and a second input to the second one of said amplifiers at each of said hybrids are connected to an individual one of said communicating devices.

Claim 9

The invention set forth in claim 6 wherein each of said hybrids connected to said line circuits further includes a second transmission pad circuit connected between said output of said second amplifier and said input of said first amplifier, said transmission pad circuit operable for introducing a transmission loss equal to said transmission loss introduced by said first transmission pad circuit.