Patent ID: 7260152

Claim:
A device for injecting a noise signal into a first wire and a second wire of a communication link comprising: a first input port; a second input port for, in combination with the first input port, receiving a differential mode noise signal for being injected into the communication link; a first transformer having a primary coil and a secondary coil, the primary coil and the secondary coil, each having a first end tap and a second end tap, the first end tap and the second end tap of the primary coil coupled to the first input port and the second input port, respectively; a first output port in electrical communication with the first end tap of the secondary coil, the first output port for being connected to the first wire, for injecting a first portion of the differential mode noise signal into the communication link; a second output port in electrical communication with the second end tap of the secondary coil, the second output port for being connected to the second wire, for injecting at least a second portion of the differential mode noise signal into the communication link; a first resistor interposed between the first input port and the first end tap of the primary coil; and, a second resistor interposed between the second input port and the second end tap of the primary coil, wherein the device when measured from the first and second output ports has a high impedance for not disturbing an impedance of the communication link and, wherein the first resistor and the second resistor have an impedance substantially lower than the high impedance.