Self-balancing hybrid circuit

Abstract

A self-balancing telephone-type hybrid having two sets of conjugate ports, wherein conjugacy is maintained between receiving and transmitting ports despite wide variations in impedance conditions at the line and/or balance ports. Included are means of differentiating between bridge unbalance due to impedance unbalance and that due to a signal being injected into the line port.

What is claimed is: 
     
       1. A self balancing hybrid circuit comprising: a hybrid transformer including a plurality of windings; a first conjugate pair of ports comprising a first port connectible to a two-way transmission line and to .Iadd.at least .Iaddend.a first .[.pair.]. .Iadd.one .Iaddend.of said transformer windings and a second port connectible to a balancing network and to .Iadd.at least .Iaddend.a second .[.pair.]. .Iadd.one .Iaddend.of said hybrid transformer windings, a second pair of conjugate ports comprising a first port connectible to a send channel and to a third winding of said hybrid transformer and a second port connectible to a receive channel and to .[.a fourth winding.]. .Iadd.at least one winding of said plurality of windings .Iaddend.of said hybrid transformer; sensing means including a first input circuit connection from said first port of said first conjugate pair, a second input circuit connection from said second port of said .Iadd.first .Iaddend.conjugate pair and a third input circuit connection from said port of said second conjugate pair connected to said send channel; whereby in response to detection of an unbalanced electrical relationship between signals at said first conjugate pair of ports resulting in electrical signals in said send channel port, said sensing means are operated to insert a compensating signal into said second port of said first conjugate pair to correct error signals resulting from electrical unbalance between said first and second ports of said first conjugate pair. 
     
     
       2. A self balancing hybrid circuit as claimed in claim 1 wherein: said sensing means include a transformer comprising a first primary winding connected to said first port of said .Iadd.first .Iaddend.conjugate pair; a second primary winding connected to said second port of said first conjugate pair a third primary winding connected to said send channel port and a secondary winding serially connected with said second primary winding .[.connected.]. to said second port of said first conjugate pair operated in response to signals conducted over said primary windings to couple a compensating signal to said second port of said first conjugate pair. 
     
     
       3. A self balancing hybrid circuit as claimed in claim 2 wherein: said sensing means further include amplifier means included between said secondary winding of said transformer and said second port of said first conjugate pair, operated to amplify said compensating signal.