Balanced transmitting apparatus

• US 20050238107A1
• Filed: 04/14/2005
• Published: 10/27/2005
• Est. Priority Date: 04/16/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamashita, Akihiro, Ichihara, Fumio, Maki, Masahiro, Oishi, Mutsuhiko, Wakisaka, Toshiyuki, Hanada, Tsunehiro
• Granted Patent: US 7,949,056 B2
• Time in Patent Office: Days
• US Class Current: 375/258
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/30 Reducing interference caused by unbalanced currents in a normally balanced line
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals

Abstract

A balanced transmission signal Tx (t) (voltage e, −e) is applied to a transmission line (L1, L2), a suppression signal (e_c) is generated from a common mode suppression signal source (e_c), and the suppression signal (e_c) is superposed on respectives of balanced transmission signals via adders (15a, 15b). By pertinently controlling a level of the suppression signal (e_c), voltage levels and phases of respectives of the transmission signals transmitted to the transmission lines (L1, L2) are controlled.

Claims

1. A balanced transmitting apparatus for transmitting a data by using transmission lines comprising a pair of conductors, said balanced transmitting apparatus comprising:

a suppression signal generator for generating a suppression signal for suppressing an unbalance component produced in the transmission lines based on the detecting signal of an unbalance state of the transmission lines; and

an adder for adding the suppression signal to original balanced signals respectively, which are original balanced transmission signals transmitted to the transmission lines.

2. The balanced transmitting apparatus according to claim 1, wherein the detecting signal is provided to detect at least one of a common mode current, a common mode voltage, an electric field, a magnetic field produced at the transmission lines and a degree of interference caused by radiation from the transmission lines.

3. The balanced transmitting apparatus according to claim 1, wherein the suppression signal generator generates the suppression signal based on at least one of a characteristic of the transmission lines, a characteristic of a transmission signal generator, and a characteristic of an unbalance detector for outputting the detecting signal.

4. The balanced transmitting apparatus according to claim 3, wherein the characteristic includes a frequency characteristic.

5. The balanced transmitting apparatus according to claim 1, wherein the suppression signal generator corrects a difference between a detection level of the detecting signal and a level of interference caused by radiation from the transmission lines for the inputted detecting signal in accordance therewith and generates the suppression signal based on the corrected detecting signal.

6. The balanced transmitting apparatus according to claim 1, wherein the suppression signal is generated in a procedure of elevating a level of the transmission signal.

7. The balanced transmitting apparatus according to claim 6, wherein the level of the transmission signal is elevated in steps.

8. The balanced transmitting apparatus according to claim 1, wherein when the balanced transmitting apparatus is in a nontransmission mode, the suppression signal generator executes a processing for a receiving signal received via the transmission lines to generate an unbalance suppression signal and transmits the unbalance suppression signal to the transmission lines.

9. The balanced transmitting apparatus according to claim 1, wherein the suppression signal generator generates the suppression signal by applying a predetermined signal processing to the detecting signal for detecting the unbalance state of the transmission lines.

10. The balanced transmitting apparatus according to claim 1, wherein the suppression signal generator generates the suppression signal by applying a predetermined signal processing to the original transmission signal transmitted to the transmission lines.

11. The balanced transmitting apparatus according to claim 1, further comprising a transformer for transmitting the transmission signal to the transmission lines,

wherein the suppression signal generator includes a voltage dividing resistor a voltage dividing ratio of which is controlled based on the detecting signal, outputs an induced voltage produced at an auxiliary winding provided at the transformer caused by the transmission signal via the voltage dividing resistor and constitutes the suppression signal by an outputted voltage signal thereof

12. The balanced transmitting apparatus according to claim 11, wherein the voltage dividing resistor is utilized also as a receiving load.

13. The balanced transmitting apparatus according to claim 11, wherein the transformer is inserted with a common mode choke coil.

14. The balanced transmitting apparatus according to claim 1, wherein the adder applies the suppression signal to a common connecting point of two pieces of differential amplifiers provided in correspondence with the pair of conductors of the transmission lines, for amplifying the original balanced signal.

15. The balanced transmitting apparatus according to claim 1, further comprising a transformer for transmitting the transmission signal to the transmission lines,

wherein the adder applies the suppression signal to a tap provided substantially at a center position of a winding constituting the transformer.

16. The balanced transmission apparatus according to claim 1, wherein the adder applies the suppression signal to the transmission lines by magnetic coupling.

17. The balanced transmission apparatus according to claim 1, wherein the adder applies the suppression signal to the transmission lines by electrostatic coupling.

18. The balanced transmission apparatus according to claim 1, wherein the suppression signal generator comprises:

a correction coefficient generator for generating and outputting a correction coefficient in accordance with the detecting signal, and

a multiplier for multiplying the original transmission signal by the correction coefficient outputted from the correction coefficient generator and outputting the suppression signal;

wherein the adder comprises an adder for adding the suppression signal outputted from the multiplier to the original balanced signal.

19. The balanced transmitting apparatus according to claim 3, wherein the suppression signal generator comprises:

a correction coefficient generator for generating and outputting a correction coefficient in accordance with the unbalance state detecting signal,

a characteristic compensator for compensating at least any one characteristic of the characteristic of the transmission lines, the characteristic of the transmission signal generator, and the characteristic of the unbalance detector for outputting the detecting signal for the original transmission signal, and

a multiplier for outputting the suppression signal by multiplying a signal outputted from the characteristic compensator by the correction coefficient outputted from the correction coefficient generator; and

wherein the adder comprises an adder for adding the suppression signal outputted from the multiplier to the original balanced signal.

20. The balanced transmitting apparatus according to claim 19, wherein the characteristic compensator includes at least either of an amplitude equalizer and a phase equalizer for correcting a frequency characteristic of the characteristic.

21. The balanced transmitting apparatus according to claim 20, wherein the amplitude equalizer or the phase equalizer corrects the characteristic by correcting the original transmission signal.

22. The balanced transmitting apparatus according to claim 20, wherein the amplitude equalizer or the phase equalizer corrects the characteristic by correcting the detecting signal.

23. The balanced transmitting apparatus according to claim 8, wherein the suppression signal generator comprises:

a correction coefficient generator for generating and outputting a correction coefficient in accordance with the unbalance state detecting signal, and

a multiplier for multiplying the receiving signal by the correction coefficient to generate the suppression signal when the balanced transmitting apparatus is in a nontransmission mode.

24. The balanced transmitting apparatus according to claim 1, wherein a power line is used as the transmission line.

25. A balanced transmission system comprising:

a transmitting apparatus including the balanced transmitting apparatus comprising;

a suppression signal generator for generating a suppression signal for suppressing an unbalance component produced in the transmission lines based on the detecting signal of an unbalance state of the transmission lines; and

an adder for adding the suppression signal to original balanced signals respectively, which are original balanced transmission signals transmitted to the transmission lines, and

a receiving apparatus communicated with the transmitting apparatus via the transmission lines.