Method and device for injecting a noise signal into a paired wire communication link

• US 7,260,152 B2
• Filed: 09/16/2002
• Issued: 08/21/2007
• Est. Priority Date: 08/07/2002
• Status: Expired due to Fees

• Current Assignee: Spirent Communications PLC (Spirent Communications Incorporated), DEW Engineering and Development Limited (Trelleborg AB)
• Original Assignee: Spirent Communications PLC (Spirent Communications Incorporated)
• Inventors: Golo, Dragan
• Primary Examiner(s): Fan; Chieh M.
• Assistant Examiner(s): Zheng; Eva
• Application Number:
  US10/243,691
• Publication Number:
  US 20040028144A1
• Time in Patent Office: 1,800 Days
• Field of Search: 375/258, 375/346, 375/257, 375/222, 379/402, 379/377, 370/480, 370/200
• US Class Current: 375/257
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04L 1/24 Testing correct operation
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

The present invention relates to a device and method for injecting a noise signal into a wire pair of a communication link. In operation a differential mode noise signal is received at a first and a second input port, which are connected via a first and a second resistor to a first and a second end tap of a primary coil of a transformer, respectively. The transformed differential mode noise signal is then transmitted via a first and a second end tap of a secondary coil of the transformer and a third and a fourth resistor to a first and a second output port for injection at high impedance into a first and a second wire of the communication link. Optionally, the device comprises a third input port connected to a center tap of the secondary coil for receiving a common mode noise signal. The common mode noise signal is then provided at low impedance to the first and the second wire via the first and the second end tap of the secondary coil and via the third and fourth resistor having low impedance, respectively. The device allows injection of a noise signal into the communication link at a desired location without splitting the same. Furthermore, the device allows injection of differential mode noise signals and common mode noise signals using same circuitry without switching and/or rewiring between different electrical circuits.

Claims

1. 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.

2. A device according to claim 1, comprising:

a third resistor disposed between the secondary coil and the first output port; and

,

a fourth resistor, disposed between the secondary coil and the second output port, wherein the third and the fourth resistor have low impedance for injecting a common mode noise signal into the communication link.

3. A device as defined in claim 2, wherein the first and the second output port are for being connected to the first and the second wire without splitting the communication link.

4. A device as defined in claim 1, wherein the communication link is used for providing DSL conformant communication.

5. A device as defined in claim 4, wherein the first and the second resistor have variable impedance for tuning during a calibration step.

6. A device as defined in claim 2, comprising:

a third input port connected to a center tap of the secondary coil for receiving the common mode noise signal, the common mode noise signal for being provided at low impedance to the first and the second wire via the first and the second output ports, respectively.

7. A device according to claim 1, comprising:

a second transformer disposed between the secondary coil of the first transformer and the first output port and between the secondary coil of the first transformer and the second output port.

11. A device as defined in claim 7, wherein the first and the second resistor have variable impedance for tuning during a calibration step.

12. A device as defined in claim 7, wherein the first and the second transformer have a same frequency response.

13. A device as defined in claim 7, comprising:

a third resistor disposed between the secondary coil and the first output port; and

,

a fourth resistor, disposed between the secondary coil and the second output port, wherein the third and the fourth resistor have low impedance for injecting a common mode noise signal into the communication link.

14. A device as defined in claim 13, comprising:

a third input port connected to a center tap of the secondary coil of the second transformer for receiving the common mode noise signal, the common mode noise signal for being provided at low impedance to the first and the second wire via the first and the second end tap of the secondary coil of the second transformer and the third and fourth resistor, respectively.

15. A device as defined in claim 7, comprising a fifth and a sixth resistor interposed between the first and the second end tap of the secondary coil of the first transformer and the first and the second end tap of the primary coil of the second transformer, respectively.

16. A device as defined in claim 15, wherein the fifth and the sixth resistor have variable impedance for tuning during a calibration step.

8. A device for injecting a noise signal into a first wire and a second wire of a communication link comprising:

a first input port for receiving a common mode noise signal for being injected into the communication link;

a first transformer having a primary coil and a secondary coil, the primary coil having a first end tap, a center tap and a second end tap, the secondary coil, having a first end tap and a second end tap, the center tap of the primary coil coupled to the first input port;

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 the common 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 the common mode noise signal into the communication link;

a first resistor disposed between the secondary coil and the first output port; and

,

a second resistor, disposed between the secondary coil and the second output port, wherein the first and the second resistor have low impedance for injecting the common mode noise signal into the communication link.

9. A device as defined in claim 8, comprising:

a second input port;

a third input port;

a third resistor interposed between the second input port and the first end tap of the primary coil; and

,

a fourth resistor interposed between the third input port and the second end tap of the primary coil, the third resistor and the fourth resistor providing a high impedance at the first output port and the second output port for not disturbing an impedance of the communication link.

10. A device as defined in claim 9, wherein the device when measured from the first and second output ports has the high impedance and, wherein the third resistor and the fourth resistor have an impedance substantially lower than the high impedance.

17. A method for injecting a noise signal into a pair of wires of a communication link comprising:

receiving the differential mode noise signal;

transforming the differential mode noise signal in a transformer stage having a first and a second resistor connected to a first and a second end tap of a primary coil of a transformer for provision at high impedance for not disturbing an impedance of the communication link; and

,

providing the transformed differential mode noise signal to a first and a second wire via a third and a fourth resistor interposed between a first and a second end tap of a secondary coil of the transformer and the first and the second wire, respectively, the third and the fourth resistor having low impedance for injecting a common mode noise signal into the communication link;

receiving a common mode noise signal at a center tap of the secondary coil; and

, providing the common mode noise signal at low impedance via the first and the second end

tap of the secondary coil and the third and the fourth resistor to the first and the second wire, respectively.

18. A method according to claim 17, wherein the differential mode noise signal and the common mode noise signal are provided to the first and the second wire without splitting the communication link.

19. A method for injecting a noise signal into a signal propagating within a line coupled with a communication device comprising:

receiving a differential mode noise signal;

transforming the differential mode noise signal in a transformer stage having a first and a second resistor connected to a first and a second end tap of a primary coil of a transformer for provision at 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; and

,

providing the transformed differential mode noise signal to a first and a second wire of the line via a first and a second output port in electrical communication with a first and a second end tap of a secondary coil of the transformer, respectively; and

,

testing the device performance in the presence of the injected noise.