U.S. patent application number 13/571032 was filed with the patent office on 2012-12-13 for system for coupling a power line communication device to a power line network.
This patent application is currently assigned to SIGMA DESIGNS ISRAEL S.D.I LTD.. Invention is credited to Uri Weiss.
Application Number | 20120313764 13/571032 |
Document ID | / |
Family ID | 45974474 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120313764 |
Kind Code |
A1 |
Weiss; Uri |
December 13, 2012 |
SYSTEM FOR COUPLING A POWER LINE COMMUNICATION DEVICE TO A POWER
LINE NETWORK
Abstract
Coupling circuit for coupling a power line communication device
to a power line network, including a first network port, a second
network port, a third network port, a first modem port, a second
modem port, a third modem port, a fourth modem port, a first
transformer, a second transformer, a third transformer and at least
two capacitors, the first transformer including a first network
side winding including two terminals, a first modem side
transmitter winding including two terminals, a first modem side
receiver winding including two terminals and a center tap,
extending from a midpoint between the two terminals of the first
network side winding, the second transformer including a second
network side winding including two terminals and a second modem
side receiver winding including two terminals, the third
transformer including a third network side winding including two
terminals and a second modem side transmitter winding including two
terminals.
Inventors: |
Weiss; Uri; (Herzliya,
IL) |
Assignee: |
SIGMA DESIGNS ISRAEL S.D.I
LTD.
Tel-Aviv
IL
|
Family ID: |
45974474 |
Appl. No.: |
13/571032 |
Filed: |
August 9, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/IL2012/000078 |
Feb 15, 2012 |
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13571032 |
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61443078 |
Feb 15, 2011 |
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Current U.S.
Class: |
340/12.32 |
Current CPC
Class: |
H04L 25/0274 20130101;
H04L 25/0266 20130101; H04B 3/56 20130101; H04B 2203/5483 20130101;
H01F 38/14 20130101 |
Class at
Publication: |
340/12.32 |
International
Class: |
G08C 19/16 20060101
G08C019/16 |
Claims
1. Coupling circuit for coupling a power line communication device
to a power line network, comprising: a first network port, coupled
with a first network line; a second network port, coupled with a
second network line; a third network port, coupled with a third
network line; a first differential modem port; a second
differential modem port; a third differential modem port; a fourth
differential modem port; a first transformer, comprising: a first
network side winding, said first network side winding comprising
two terminals; a first modem side transmitter (TX) winding, said
first modem side TX winding comprising two terminals; a first modem
side receiver (RX) winding, said first modem side RX winding
comprising two terminals; and a center tap, extending from a
midpoint between said two terminals of said first network side
winding, said first modem side TX winding coupled with said first
differential modem port, said first modem side RX winding coupled
with said second differential modem port, a first one of said two
terminals of said first network side winding coupled with said
first network line and a second one of said two terminals of said
first network side winding coupled with said second network line; a
second transformer, comprising: a second network side winding, said
second network side winding comprising two terminals; and a second
modem side RX winding, said second modem side RX winding comprising
two terminals, said second modem side RX winding coupled with said
fourth differential modem port, a first one of said two terminals
of said second network side winding coupled with said center tap
and a second one of said two terminals of said second network side
winding coupled with said third network line; a third transformer,
comprising: a third network side winding, said third network side
winding comprising two terminals; and a second modem side TX
winding, said second modem side TX winding comprising two
terminals, said second modem side TX winding coupled with said
third differential modem port, a first one of said two terminals of
said third network side winding coupled with said second network
line and a second one of said two terminals of said third network
side winding coupled with said third network line, and at least two
capacitors.
2. The coupling circuit according to claim 1, wherein said first
network line, said second network line and said third network line
are coupled with said power line network and are selected from the
list consisting of: said first network line being a phase line,
said second network line being a neutral line and said third
network line being a ground line; said first network line being a
phase line, said second network line being a ground line and said
third network line being a neutral line; said first network line
being a neutral line, said second network line being a phase line
and said third network line being a ground line; said first network
line being a neutral line, said second network line being a ground
line and said third network line being a phase line; said first
network line being a ground line, said second network line being a
neutral line and said third network line being a phase line; and
said first network line being a ground line, said second network
line being a phase line and said third network line being a neutral
line.
3. The coupling circuit according to claim 1, wherein said first
network line and said second network line form a network phase
neutral (PN) interface, wherein said second network line and said
third network line form a network neutral ground (NG) interface,
wherein said network PN interface is balanced and wherein said
network NG interface is balanced.
4. The coupling circuit according to claim 1, wherein said first
network line and said second network line form a network neutral
phase (NP) interface, wherein said second network line and said
third network line form a network phase ground (PG) interface,
wherein said network NP interface is balanced and wherein said
network PG interface is balanced.
5. The coupling circuit according to claim 1, wherein a first one
of said at least two capacitors is coupled between said first
network port and a first one of said two terminals of said first
network side winding and wherein a second one of said at least two
capacitors is coupled between said second network port and said
coupling of said third transformer with said second network
line.
6. The coupling circuit according to claim 1, wherein a first one
of said at least two capacitors is coupled between said second
network port and said coupling of said third transformer with said
second network line and wherein a second one of said at least two
capacitors is coupled between said third network port and said
coupling of said third transformer with said third network
line.
7. The coupling circuit according to claim 1, wherein a first one
of said at least two capacitors is coupled between said first
network port and a first one of said two terminals of said first
network side winding, wherein a second one of said at least two
capacitors is coupled between said first one of said two terminals
of said third network side winding and said second network line and
wherein a third one of said at least two capacitors is coupled
between said first one of said two terminals of said second network
side winding and said center tap.
8. The coupling circuit according to claim 1, wherein a first one
of said at least two capacitors is coupled between said second
network port and said coupling of said third transformer with said
second network line, wherein a second one of said at least two
capacitors is coupled between said first one of said two terminals
of said third network side winding and said second network line and
wherein a third one of said at least two capacitors is coupled
between said first one of said two terminals of said second network
side winding and said center tap.
9. The coupling circuit according to claim 1, wherein a first one
of said at least two capacitors is coupled between said first
network port and a first one of said two terminals of said first
network side winding, wherein a second one of said at least two
capacitors is coupled between said second network port and said
coupling of said third transformer with said second network line
and wherein a third one of said at least two capacitors is coupled
between said first one of said two terminals of said second network
side winding and said center tap.
10. Power line communication device comprising a coupling circuit
according to claim 1.
11. Coupling circuit for coupling a power line communication device
to a power line network, comprising: a first network port, coupled
with a first network line; a second network port, coupled with a
second network line; a third network port, coupled with a third
network line; a first differential modem port; a second
differential modem port; a third differential modem port; a fourth
differential modem port; a first transformer, comprising: a first
network side winding, said first network side winding comprising
two terminals; a first modem side winding, said first modem side
winding comprising two terminals; and a center tap, extending from
a midpoint between said two terminals of said first network side
winding, said first modem side winding coupled with said first
differential modem port and with said second differential modem
port, a first one of said two terminals of said first network side
winding coupled with said first network line and a second one of
said two terminals of said first network side winding coupled with
said second network line, wherein one of said first and second
differential modem ports is for transmitting at least one signal
over said power line network and wherein the other one of said
first and second differential modem ports is for receiving said at
least one signal over said power line network; a second
transformer, comprising: a second network side winding, said second
network side winding comprising two terminals; and a second modem
side receiver (RX) winding, said second modem side RX winding
comprising two terminals, said second modem side RX winding coupled
with said fourth differential modem port, a first one of said two
terminals of said second network side winding coupled with said
center tap and a second one of said two terminals of said second
network side winding coupled with said third network line; a third
transformer, comprising: a third network side winding, said third
network side winding comprising two terminals; and a second modem
side transmitter (TX) winding, said second modem side TX winding
comprising two terminals, said second modem side TX winding coupled
with said third differential modem port, a first one of said two
terminals of said third network side winding coupled with said
second network line and a second one of said two terminals of said
third network side winding coupled with said third network line,
and at least two capacitors.
12. The coupling circuit according to claim 11, wherein said first
network line, said second network line and said third network line
are coupled with said power line network and are selected from the
list consisting of: said first network line being a phase line,
said second network line being a neutral line and said third
network line being a ground line; said first network line being a
phase line, said second network line being a ground line and said
third network line being a neutral line; said first network line
being a neutral line, said second network line being a phase line
and said third network line being a ground line; said first network
line being a neutral line, said second network line being a ground
line and said third network line being a phase line; said first
network line being a ground line, said second network line being a
neutral line and said third network line being a phase line; and
said first network line being a ground line, said second network
line being a phase line and said third network line being a neutral
line.
13. Coupling circuit for coupling a power line communication device
to a power line network, comprising: a first network port, coupled
with a first network line; a second network port, coupled with a
second network line; a third network port, coupled with a third
network line; a first differential modem port; a second
differential modem port; a third differential modem port; a fourth
differential modem port; a first transformer, comprising: a first
network side winding, said first network side winding comprising
two terminals; a first modem side transmitter (TX) winding, said
first modem side TX winding comprising two terminals; a first modem
side receiver (RX) winding, said first modem side RX winding
comprising two terminals; and a center tap, extending from a
midpoint of said first network side winding, said first modem side
TX winding coupled with said first differential modem port, said
first modem side RX winding coupled with said second differential
modem port, a first one of said two terminals of said first network
side winding coupled with said first network line and a second one
of said two terminals of said first network side winding coupled
with said second network line; a second transformer, comprising: a
second network side winding, said second network side winding
comprising two terminals; a second modem side TX winding, said
second modem side TX winding comprising two terminals; and a second
modem side RX winding, said second modem side RX winding comprising
two terminals, said second modem side TX winding coupled with said
third differential modem port, said second modem side RX winding
coupled with said fourth differential modem port, a first one of
said two terminals of said second network side winding coupled with
said center tap and a second one of said two terminals of said
second network side winding coupled with said third network line,
and at least two capacitors, coupled between at least any two of:
said midpoint of said first network side winding and said first one
of said two terminals of said second network side winding; a first
one of said two terminals of said first network side winding and
said first network port; and a second one of said two terminals of
said first network side winding and said second network port.
14. The coupling circuit according to claim 13, wherein said first
network line, said second network line and said third network line
are coupled with said power line network and are selected from the
list consisting of: said first network line being a phase line,
said second network line being a neutral line and said third
network line being a ground line; said first network line being a
phase line, said second network line being a ground line and said
third network line being a neutral line; said first network line
being a neutral line, said second network line being a phase line
and said third network line being a ground line; said first network
line being a neutral line, said second network line being a ground
line and said third network line being a phase line; said first
network line being a ground line, said second network line being a
neutral line and said third network line being a phase line; and
said first network line being a ground line, said second network
line being a phase line and said third network line being a neutral
line.
15. The coupling circuit according to claim 13, wherein said first
network line and said second network line form a network phase
neutral (PN) interface and wherein said network PN interface is
balanced.
16. Power line communication device comprising a coupling circuit
according to claim 13.
17. Coupling circuit for coupling a power line communication device
to a power line network, comprising: a first network port, coupled
with a first network line; a second network port, coupled with a
second network line; a third network port, coupled with a third
network line; a first differential modem port; a second
differential modem port; a third differential modem port; a fourth
differential modem port; a first transformer, comprising: a first
network side winding, said first network side winding comprising
two terminals; a first modem side winding, said first modem side
winding comprising two terminals; and a center tap, extending from
a midpoint of said first network side winding, said first modem
side winding coupled with said first differential modem port and
with said second differential modem port, a first one of said two
terminals of said first network side winding coupled with said
first network line and a second one of said two terminals of said
first network side winding coupled with said second network line,
wherein one of said first and second differential modem ports is
for transmitting at least one signal over said power line network
and wherein the other one of said first and second differential
modem ports is for receiving said at least one signal over said
power line network; a second transformer, comprising: a second
network side winding, said second network side winding comprising
two terminals; and a second modem side winding, said second modem
side winding comprising two terminals; said second modem side
winding coupled with said third differential modem port and with
said fourth differential modem port, a first one of said two
terminals of said second network side winding coupled with said
center tap and a second one of said two terminals of said second
network side winding coupled with said third network line, wherein
one of said third and fourth differential modem ports is for
transmitting at least one signal over said power line network and
wherein the other one of said third and fourth differential modem
ports is for receiving said at least one signal over said power
line network; and at least two capacitors, coupled between at least
any two of: said midpoint of said first network side winding and
said first one of said two terminals of said second network side
winding; a first one of said two terminals of said first network
side winding and said first network port; and a second one of said
two terminals of said first network side winding and said second
network port.
18. The coupling circuit according to claim 17, wherein said first
network line, said second network line and said third network line
are coupled with said power line network and are selected from the
list consisting of: said first network line being a phase line,
said second network line being a neutral line and said third
network line being a ground line; said first network line being a
phase line, said second network line being a ground line and said
third network line being a neutral line; said first network line
being a neutral line, said second network line being a phase line
and said third network line being a ground line; said first network
line being a neutral line, said second network line being a ground
line and said third network line being a phase line; said first
network line being a ground line, said second network line being a
neutral line and said third network line being a phase line; and
said first network line being a ground line, said second network
line being a phase line and said third network line being a neutral
line.
19. Coupling circuit for coupling a power line communication device
to a power line network, comprising: a first network port, coupled
with a first network line; a second network port, coupled with a
second network line; a third network port, coupled with a third
network line; a first differential modem port; a second
differential modem port; a third differential modem port; a fourth
differential modem port; a first transformer, comprising: a first
network side winding, said first network side winding comprising
two terminals; a first modem side winding, said first modem side
winding comprising two terminals; and a center tap, extending from
a midpoint of said first network side winding, said first modem
side winding coupled with said first differential modem port and
with said second differential modem port, a first one of said two
terminals of said first network side winding coupled with said
first network line and a second one of said two terminals of said
first network side winding coupled with said second network line,
wherein one of said first and second differential modem ports is
for transmitting at least one signal over said power line network
and wherein the other one of said first and second differential
modem ports is for receiving said at least one signal over said
power line network; a second transformer, comprising: a second
network side winding, said second network side winding comprising
two terminals; a second modem side transmitter (TX) winding, said
second modem side TX winding comprising two terminals; and a second
modem side receiver (RX) winding, said second modem side RX winding
comprising two terminals, said second modem side TX winding coupled
with said third differential modem port, said second modem side RX
winding coupled with said fourth differential modem port, a first
one of said two terminals of said second network side winding
coupled with said center tap and a second one of said two terminals
of said second network side winding coupled with said third network
line, and at least two capacitors, coupled between at least any two
of: said midpoint of said first network side winding and said first
one of said two terminals of said second network side winding; a
first one of said two terminals of said first network side winding
and said first network port; and a second one of said two terminals
of said first network side winding and said second network
port.
20. The coupling circuit according to claim 19, wherein said first
network line, said second network line and said third network line
are coupled with said power line network and are selected from the
list consisting of: said first network line being a phase line,
said second network line being a neutral line and said third
network line being a ground line; said first network line being a
phase line, said second network line being a ground line and said
third network line being a neutral line; said first network line
being a neutral line, said second network line being a phase line
and said third network line being a ground line; said first network
line being a neutral line, said second network line being a ground
line and said third network line being a phase line; said first
network line being a ground line, said second network line being a
neutral line and said third network line being a phase line; and
said first network line being a ground line, said second network
line being a phase line and said third network line being a neutral
line.
21. Coupling circuit for coupling a power line communication device
to a power line network, comprising: a first network port, coupled
with a first network line; a second network port, coupled with a
second network line; a third network port, coupled with a third
network line; a first differential modem port; a second
differential modem port; a third differential modem port; a fourth
differential modem port; a first transformer, comprising: a first
network side winding, said first network side winding comprising
two terminals; a first modem side transmitter (TX) winding, said
first modem side TX winding comprising two terminals; a first modem
side receiver (RX) winding, said first modem side RX winding
comprising two terminals; and a center tap, extending from a
midpoint of said first network side winding, said first modem side
TX winding coupled with said first differential modem port, said
first modem side RX winding coupled with said second differential
modem port, a first one of said two terminals of said first network
side winding coupled with said first network line and a second one
of said two terminals of said first network side winding coupled
with said second network line; a second transformer, comprising: a
second network side winding, said second network side winding
comprising two terminals; and a second modem side winding, said
second modem side winding comprising two terminals; said second
modem side winding coupled with said third differential modem port
and with said fourth differential modem port, a first one of said
two terminals of said second network side winding coupled with said
center tap and a second one of said two terminals of said second
network side winding coupled with said third network line, wherein
one of said third and fourth differential modem ports is for
transmitting at least one signal over said power line network and
wherein the other one of said third and fourth differential modem
ports is for receiving said at least one signal over said power
line network; and at least two capacitors, coupled between at least
any two of: said midpoint of said first network side winding and
said first one of said two terminals of said second network side
winding; a first one of said two terminals of said first network
side winding and said first network port; and a second one of said
two terminals of said first network side winding and said second
network port.
22. The coupling circuit according to claim 21, wherein said first
network line, said second network line and said third network line
are coupled with said power line network and are selected from the
list consisting of: said first network line being a phase line,
said second network line being a neutral line and said third
network line being a ground line; said first network line being a
phase line, said second network line being a ground line and said
third network line being a neutral line; said first network line
being a neutral line, said second network line being a phase line
and said third network line being a ground line; said first network
line being a neutral line, said second network line being a ground
line and said third network line being a phase line; said first
network line being a ground line, said second network line being a
neutral line and said third network line being a phase line; and
said first network line being a ground line, said second network
line being a phase line and said third network line being a neutral
line.
Description
FIELD OF THE DISCLOSED TECHNIQUE
[0001] The disclosed technique relates to power line communication,
in general, and to methods and systems for inductively coupling a
power line communication modem to a power line network so that the
phase-neutral interface as well as the neutral ground interface of
the power line network are balanced, in particular.
BACKGROUND OF THE DISCLOSED TECHNIQUE
[0002] Power line communication (herein abbreviated PLC) refers to
systems for enabling data to be transferred over electrical cables.
PLC is also referred to in the art as a power line digital
subscriber line, a power line carrier, mains communication, power
line telecom and power line networking. Electrical cables can also
be referred to as power cables, power lines, electrical power
lines, electrical wiring, electrical cabling and the like. These
terms are used interchangeably herein and represent the cabling
used to transfer electricity from an electricity provider, such as
an electric company (e.g. Pacific Gas & Electric, Florida Power
& Light, etc. . . . ) or an electricity generator (e.g., a wind
energy converter), to a residence, as well as the wires used in a
residence to transfer electricity to various wall sockets,
electrical outlets, wall plugs and power points in the
residence.
[0003] PLC enables various electrical devices, such as computers,
printers, televisions and other electrical devices in a residence,
to be coupled with one another as a network without the need for
new wires to be added to the residence. A residence can refer to a
private home, an apartment building, an office building or other
structures where people live that receive electricity. In effect,
the electric cabling forms the backbone of a power line network or
a PLC network. Each electrical device to be coupled in the network
requires a separate communication device for enabling it to
transfer data over the electrical wiring. Such a communication
device is usually referred to as a modem, and commonly referred to
in the art as a power line modem. Such modems usually transfer data
in a high frequency range, such as on the order of megahertz or
higher. PLC systems and methods are known in the art.
[0004] Traditionally, power lines and their associated networks
were designed for providing electricity and not for the purposes of
communication and were thus not designed to provide an optimal
medium for transferring data. Power line networks suffer from high
levels of noise, which distorts and interferes with communication
signals. Noise in PLC networks can be defined as any undesirable
voltage signal which travels along the power line network and which
might be received as a communication signal in one of the power
line modems coupled with the network. Common sources of noise are
various household devices coupled to the power line network.
[0005] Reference is now made to FIG. 1A, which is a schematic
illustrations of a prior art system, generally referenced 10, for
coupling a PLC communication device to a PLC network in a
residence. With reference to FIG. 1A, coupling system 10 includes a
PLC device 12 and a transformer 14. PLC device 12 may be a PLC
modem. Transformer 14 inductively couples PLC device 12 to the PLC
network (not shown). In particular a modem first line 16 and a
modem second line 18 are coupled with a first winding (not
referenced) of transformer 14. Network phase line 20 and network
neutral line 22 are coupled with a second winding (not referenced)
of transformer 14. Network phase line 20 refers to the phase line
(or active line) in the residence, whereas network neutral line 22
refers to the neutral line in the residence. Together, network
phase line 20 and network neutral line 22 define a network phase
neutral (herein abbreviated PN) interface (not referenced). Modem
first line 16 and modem second line 18 define a modem PN interface
(not referenced), which is inductively coupled with the network PN
interface through transformer 14.
[0006] The noise in PLC networks can be classified into two main
categories, common mode (herein abbreviated CM) noise and
differential mode (herein abbreviated DM) noise. CM noise is a
signal which is referenced to the ground wire in a PLC network and
which is injected simultaneously with the same polarity to two
different lines in a PLC network. Hence, CM noise can affect two or
more elements of a PLC network in a similar manner. DM noise is a
signal which is injected simultaneously with opposing polarities to
two different lines in a PLC network. Models are known in the art
for modeling CM noise and DM noise in PLC networks, as shown in
FIGS. 1B and 1C respectively. In FIG. 1B, CM noise is modeled and
filtered out by the transformer. In FIG. 1C, DM noise is modeled
and is not filtered out by the transformer.
[0007] Reference is now made to FIGS. 1B and 1C, which are
schematic illustrations of noise models in PLC networks, generally
referenced 10' and 10'', as is known in the prior art. It is noted
that equivalent elements in FIGS. 1A 1C are referenced using
identical numbering. With reference to FIG. 1B, coupling system 10'
includes all the elements of the coupling system shown in FIG. 1A.
Coupling system 10' further includes an equivalent CM noise voltage
source 24 and a ground terminal 26 for modeling the interaction of
CM noise with a PLC network (not shown) on the network PN
interface. Voltage source 24 is coupled with both network phase
line 20 and with network neutral line 22. Voltage source 24
produces CM noise signals on both network phase line 20 and on
network neutral line 22. In the ideal case, this results in zero CM
noise signals on the modem PN interface, as the noise is filtered
out by transformer 14 on the modem PN interface side (not
referenced).
[0008] A balanced interface is an interface consisting of two
similar ports (or lines), each having substantially similar
impedance relative to ground (i.e., ground impedance). For example,
in FIG. 1B, the network PN interface is, in theory, a balanced
interface as the CM noise signals produced by voltage source 24
cancel out each other at transformer 14 and are not reflected to
PLC device 12. It is noted that CM noise signals are often produced
by household devices coupled with the power line network or are
produced internally by devices of the PLC network, such as the
power supply (not shown) of PLC device 12, which is coupled with
the primary winding (not referenced) of transformer 14.
[0009] With reference to FIG. 1C, coupling system 10'' includes all
the elements of the coupling system shown in FIG. 1A. Coupling
system 10'' also includes a pair of voltage sources 28 and 30 and a
ground terminal 32 for modeling the interaction of DM noise with a
PLC network (not shown). Voltage source 28 is coupled between
ground terminal 32 and network phase line 20. Voltage source 30 is
coupled between ground terminal 32 and network neutral line 22.
Pair of voltage sources 28 and 30 are similar in power but are
opposite in polarity, as is shown in FIG. 1C (i.e., the polarity of
voltage source 28 is opposite that of voltage source 30). Pair of
voltage sources 28 and 30 produce a DM noise signal on the network
PN interface. In particular, voltage source 28 produces a first
portion of the DM noise signal on network phase line 20. Voltage
source 30 produces a second portion of the DM noise signal, which
is opposite in amplitude to the first portion of the DM noise
signal, on network neutral line 22. Transformer 14 induces the DM
noise signal into PLC device 12. Thus, the DM noise signal is not
filtered out by transformer 14. It is noted that the main source
for DM noise signals in a PLC network is the communication signal
itself. Additionally, other noise sources in the electrical system
of the residence may also generate a DM noise component.
[0010] Reference is now made to FIG. 2, which is a schematic
illustration of a coupling system, generally referenced 50, for
inductively coupling a communication device to a power line
network, as is known in the art. Coupling system 50 includes a
communication device 52, a first transformer 60 and a second
transformer 62. Communication device 52 will be referred to herein
as modem 52. The communication section (not referenced) of modem 52
is coupled with first transformer 60 and second transformer 62. It
is noted that even though modem 52 is employed as both a
transmitter and a receiver for the electrical device, the example
set forth with reference to FIG. 2 details the receiver
functionality of modem 52. The communication section of modem 52 is
coupled with a first winding 70 of first transformer 60 (i.e., a
modem side winding) through a first modem line 54 and a second
modem line 56. The communication section of modem 52 is also
coupled with a first winding 72 of second transformer 62 through a
third modem line 57 and a fourth modem line 58.
[0011] A phase line 64 and a neutral line 66 of the PLC network
(not referenced) are coupled with a second winding 74 of first
transformer 60 (i.e., a network side winding). Each of phase line
64 and neutral line 66 includes a respective capacitor 65A and 65B
for safety purposes. Neutral line 66 and a ground line 68 of the
PLC network are coupled with a second winding 76 of second
transformer 62. Phase line 64 and neutral line 66 define a network
PN interface (not referenced). Neutral line 66 and ground line 68
define a network ground neutral (herein abbreviated NG) interface
(not referenced). First modem line 54 and second modem line 56
together define a modem PN interface, which is inductively coupled
with the network PN interface through first transformer 60. Third
modem line 57 and fourth modem line 58 define a modem NG interface,
which is inductively coupled with the network NG interface through
second transformer 62.
[0012] Phase line 64 and neutral line 66 are employed for
delivering power through the power line network. Phase line 64 is
also referred to as an active line or a live line. Ground line 68
is employed for safety purposes. Coupling system 50 inductively
couples modem 52 to the power line network through first and second
transformers 60 and 62 respectively. Modem 52 is a communication
device for transmitting and receiving communication signals to and
from other communication devices in the PLC network, such as other
PLC modems (not shown) coupled with other electrical devices (not
shown) in the residence. For example, a remote PLC modem (not
shown) transmits a modulated signal through the PLC network and
specifically through coupling system 50 to modem 52. In a similar
manner, modem 52 can transmit a modulated signal to the remote PLC
modem through coupling system 50 and through the PLC network.
[0013] As can be seen in FIG. 2, the network PN interface is not
balanced. Put another way, the ground impedance of phase line 64 is
different than that of neutral line 66, since the ground impedance
of phase line 64 includes a summation of the impedances of both
first transformer 60 and second transformer 62 whereas the ground
impedance of neutral line 66 includes only the impedance of second
transformer 62. It is noted that the impedance of each of first
transformer 60 and second transformer 62 is dependent at least on
the impedance of the modem PN interface and the modem NG interface,
respectively. Due to the lack of symmetry between the ground
impedance of phase line 64 and of neutral line 66, CM noise signals
(not shown) on the network PN interface do not fully cancel each
other out on first transformer 60.
SUMMARY OF THE PRESENT DISCLOSED TECHNIQUE
[0014] It is an object of the disclosed technique to provide a
novel system for inductively coupling a PLC modem to a power line
network so that a first receive and transmit interface as well as a
second receive and transmit interface of the PLC network is
balanced. In accordance with the disclosed technique, there is thus
provided a coupling circuit for coupling a power line communication
device to a power line network, including a first network port, a
second network port, a third network port, a first differential
modem port, a second differential modem port, a third differential
modem port, a fourth differential modem port, a first transformer,
a second transformer, a third transformer and at least two
capacitors. The first network port is coupled with a first network
line, the second network port is coupled with a second network line
and the third network port is coupled with a third network line.
The first transformer including a first network side winding
including two terminals, a first modem side transmitter (TX)
winding including two terminals, a first modem side receiver (RX)
winding including two terminals and a center tap, extending from a
midpoint between the two terminals of the first network side
winding. The first modem side TX winding being coupled with the
first differential modem port, the first modem side RX winding
being coupled with the second differential modem port, a first one
of the two terminals of the first network side winding being
coupled with the first network line and a second one of the two
terminals of the first network side winding being coupled with the
second network line. The second transformer includes a second
network side winding including two terminals, and a second modem
side RX winding including two terminals. The second modem side RX
winding is coupled with the fourth differential modem port, a first
one of the two terminals of the second network side winding is
coupled with the center tap and a second one of the two terminals
of the second network side winding is coupled with the third
network line. The third transformer includes a third network side
winding including two terminals and a second modem side TX winding
including two terminals. The second modem side TX winding is
coupled with the third differential modem port, a first one of the
two terminals of the third network side winding is coupled with the
second network line and a second one of the two terminals of the
third network side winding is coupled with the third network line.
In accordance with another embodiment of the disclosed technique,
there is thus provided a power line communication device including
a coupling circuit as described above.
[0015] In accordance with a further embodiment of the disclosed
technique, there is thus provided a coupling circuit for coupling a
power line communication device to a power line network, including
a first network port, a second network port, a third network port,
a first differential modem port, a second differential modem port,
a third differential modem port, a fourth differential modem port,
a first transformer, a second transformer, a third transformer and
at least two capacitors. The first network port is coupled with a
first network line, the second network port is coupled with a
second network line and the third network port is coupled with a
third network line. The first transformer includes a first network
side winding including two terminals, a first modem side winding
including two terminals and a center tap, extending from a midpoint
between the two terminals of the first network side winding. The
first modem side winding is coupled with the first differential
modem port and with the second differential modem port, a first one
of the two terminals of the first network side winding is coupled
with the first network line and a second one of the two terminals
of the first network side winding is coupled with the second
network line, wherein one of the first and second differential
modem ports is for transmitting at least one signal over the power
line network and wherein the other one of the first and second
differential modem ports is for receiving the signal over the power
line network. The second transformer includes a second network side
winding including two terminals and a second modem side receiver
(RX) winding including two terminals. The second modem side RX
winding is coupled with the fourth differential modem port, a first
one of the two terminals of the second network side winding is
coupled with the center tap and a second one of the two terminals
of the second network side winding is coupled with the third
network line. The third transformer includes a third network side
winding including two terminals and a second modem side transmitter
(TX) winding including two terminals. The second modem side TX
winding is coupled with the third differential modem port, a first
one of the two terminals of the third network side winding is
coupled with the second network line and a second one of the two
terminals of the third network side winding is coupled with the
third network line.
[0016] In accordance with another embodiment of the disclosed
technique, there is thus provided a coupling circuit for coupling a
power line communication device to a power line network including a
first network port, a second network port, a third network port, a
first differential modem port, a second differential modem port, a
third differential modem port, a fourth differential modem port, a
first transformer, a second transformer and at least two
capacitors. The first network port is coupled with a first network
line, the second network port is coupled with a second network line
and the third network port is coupled with a third network line.
The first transformer includes a first network side winding
including two terminals, a first modem side transmitter (TX)
winding including two terminals, a first modem side receiver (RX)
winding including two terminals and a center tap, extending from a
midpoint of the first network side winding. The first modem side TX
winding is coupled with the first differential modem port, the
first modem side RX winding is coupled with the second differential
modem port, a first one of the two terminals of the first network
side winding is coupled with the first network line and a second
one of the two terminals of the first network side winding is
coupled with the second network line. The second transformer
includes a second network side winding including two terminals, a
second modem side TX winding including two terminals and a second
modem side RX winding including two terminals. The second modem
side TX winding is coupled with the third differential modem port,
the second modem side RX winding is coupled with the fourth
differential modem port, a first one of the two terminals of the
second network side winding is coupled with the center tap and a
second one of the two terminals of the second network side winding
is coupled with the third network line. The capacitors are coupled
between at least any two of the midpoint of the first network side
winding and the first one of the two terminals of the second
network side winding, a first one of the two terminals of the first
network side winding and the first network port, and a second one
of the two terminals of the first network side winding and the
second network port. In accordance with a further embodiment of the
disclosed technique, there is thus provided a power line
communication device including a coupling circuit as described
above.
[0017] In accordance with another embodiment of the disclosed
technique, there is thus provided a coupling circuit for coupling a
power line communication device to a power line network including a
first network port, a second network port, a third network port, a
first differential modem port, a second differential modem port, a
third differential modem port, a fourth differential modem port, a
first transformer, a second transformer and at least two
capacitors. The first network port is coupled with a first network
line, the second network port is coupled with a second network line
and the third network port is coupled with a third network line.
The first transformer includes a first network side winding
including two terminals, a first modem side winding including two
terminals and a center tap, extending from a midpoint of the first
network side winding. The first modem side winding is coupled with
the first differential modem port and with the second differential
modem port, a first one of the two terminals of the first network
side winding is coupled with the first network line and a second
one of the two terminals of the first network side winding is
coupled with the second network line, wherein one of the first and
second differential modem ports is for transmitting at least one
signal over the power line network and wherein the other one of the
first and second differential modem ports is for receiving the
signal over the power line network. The second transformer includes
a second network side winding including two terminals and a second
modem side winding including two terminals. The second modem side
winding is coupled with the third differential modem port and with
the fourth differential modem port, a first one of the two
terminals of the second network side winding is coupled with the
center tap and a second one of the two terminals of the second
network side winding is coupled with the third network line,
wherein one of the third and fourth differential modem ports is for
transmitting at least one signal over the power line network and
wherein the other one of the third and fourth differential modem
ports is for receiving the signal over the power line network. The
capacitors are coupled between at least any two of the midpoint of
the first network side winding and the first one of the two
terminals of the second network side winding, a first one of the
two terminals of the first network side winding and the first
network port, and a second one of the two terminals of the first
network side winding and the second network port.
[0018] In accordance with a further embodiment of the disclosed
technique, there is thus provided a coupling circuit for coupling a
power line communication device to a power line network including a
first network port, a second network port, a third network port, a
first differential modem port, a second differential modem port, a
third differential modem port, a fourth differential modem port, a
first transformer, a second transformer and at least two
capacitors. The first network port is coupled with a first network
line, the second network port is coupled with a second network line
and the third network port is coupled with a third network line.
The first transformer includes a first network side winding
including two terminals, a first modem side winding including two
terminals and a center tap, extending from a midpoint of the first
network side winding. The first modem side winding is coupled with
the first differential modem port and with the second differential
modem port, a first one of the two terminals of the first network
side winding is coupled with the first network line and a second
one of the two terminals of the first network side winding is
coupled with the second network line, wherein one of the first and
second differential modem ports is for transmitting at least one
signal over the power line network and wherein the other one of the
first and second differential modem ports is for receiving the
signal over the power line network. The second transformer includes
a second network side winding including two terminals, a second
modem side transmitter (TX) winding including two terminals and a
second modem side receiver (RX) winding including two terminals.
The second modem side TX winding is coupled with the third
differential modem port, the second modem side RX winding is
coupled with the fourth differential modem port, a first one of the
two terminals of the second network side winding is coupled with
the center tap and a second one of the two terminals of the second
network side winding is coupled with the third network line. The
capacitors are coupled between at least any two of the midpoint of
the first network side winding and the first one of the two
terminals of the second network side winding, a first one of the
two terminals of the first network side winding and the first
network port and a second one of the two terminals of the first
network side winding and the second network port.
[0019] In accordance with another embodiment of the disclosed
technique, there is thus provided a coupling circuit for coupling a
power line communication device to a power line network including a
first network port, a second network port, a third network port, a
first differential modem port, a second differential modem port, a
third differential modem port, a fourth differential modem port, a
first transformer, a second transformer and at least two
capacitors. The first network port is coupled with a first network
line, the second network port is coupled with a second network line
and the third network port is coupled with a third network line.
The first transformer includes a first network side winding
including two terminals, a first modem side transmitter (TX)
winding including two terminals, a first modem side receiver (RX)
winding including two terminals and a center tap, extending from a
midpoint of the first network side winding. The first modem side TX
winding is coupled with the first differential modem port, the
first modem side RX winding is coupled with the second differential
modem port, a first one of the two terminals of the first network
side winding is coupled with the first network line and a second
one of the two terminals of the first network side winding is
coupled with the second network line. The second transformer
includes a second network side winding including two terminals and
a second modem side winding including two terminals. The second
modem side winding is coupled with the third differential modem
port and with the fourth differential modem port, a first one of
the two terminals of the second network side winding is coupled
with the center tap and a second one of the two terminals of the
second network side winding is coupled with the third network line,
wherein one of the third and fourth differential modem ports is for
transmitting at least one signal over the power line network and
wherein the other one of the third and fourth differential modem
ports is for receiving the signal over the power line network. The
capacitors are coupled between at least any two of the midpoint of
the first network side winding and the first one of the two
terminals of the second network side winding, a first one of the
two terminals of the first network side winding and the first
network port, and a second one of the two terminals of the first
network side winding and the second network port.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The disclosed technique will be understood and appreciated
more fully from the following detailed description taken in
conjunction with the drawings in which:
[0021] FIG. 1A is a schematic illustration of a prior art system
for coupling a PLC communication device to a PLC network in a
residence;
[0022] FIGS. 1B and 1C are schematic illustrations of noise models
in PLC networks, as is known in the prior art;
[0023] FIG. 2 is a schematic illustration of a coupling system for
inductively coupling a communication device to a power line
network, as is known in the art;
[0024] FIG. 3A is a schematic illustration of a balanced coupling
circuit for inductively coupling a PLC modem to a power line
network, constructed and operative in accordance with an embodiment
of the disclosed technique;
[0025] FIG. 3B is a schematic illustration of another balanced
coupling circuit for inductively coupling a PLC modem to a power
line network, constructed and operative in accordance with another
embodiment of the disclosed technique;
[0026] FIG. 3C is a schematic illustration of a further balanced
coupling circuit for inductively coupling a PLC modem to a power
line network, constructed and operative in accordance with a
further embodiment of the disclosed technique;
[0027] FIG. 3D is a schematic illustration of an additional
balanced coupling circuit for inductively coupling a PLC modem to a
power line network, constructed and operative in accordance with
another embodiment of the disclosed technique;
[0028] FIG. 4A is a schematic illustration of a balanced coupling
circuit for inductively coupling a PLC modem to a power line
network including a transmitter section and a receiver section,
constructed and operative in accordance with a further embodiment
of the disclosed technique; and
[0029] FIG. 4B is a schematic illustration of another balanced
coupling circuit for inductively coupling a PLC modem to a power
line network including a transmitter section and a receiver
section, constructed and operative in accordance with another
embodiment of the disclosed technique.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0030] The disclosed technique overcomes the disadvantages of the
prior art by providing a circuit for inductively coupling a PLC
modem to a power line network such that the network PN interface of
the PLC network is balanced. The balanced coupling circuit includes
two differential modem ports, three network ports, two transformers
and a center tap. Each of the differential modem ports is coupled
with a respective transformer. Each of the network ports is coupled
with a selected network line (i.e., a network phase line, a network
neutral line and a network ground line). A first line of a first
differential modem port and a second line of the first differential
modem port are coupled with the terminals of the modem side winding
of the first transformer. A first line of a second differential
modem port and a second line of the second differential modem port
are coupled with the terminals of the modem side winding of the
second transformer. The first network port and the second network
port are coupled with the terminals of the network side winding of
the first transformer. The third network port is coupled with a
first terminal of the network side winding of the second
transformer. The center tap extends from the midpoint of the
network side winding of the first transformer to a second terminal
of the network side winding of the second transformer. Thus, the
ground impedances of the first network port and the second network
port are substantially similar. In this manner, an interface
defined by the first network port and the second network port is
balanced.
[0031] The disclosed technique also overcomes the disadvantages of
the prior art by providing a circuit for inductively coupling a PLC
modem to a power line network such that the network PN interface as
well as the network NG interface of the PLC network are balanced.
The balanced coupling circuit includes four differential modem
ports, three network ports, three transformers, at least two
capacitors and a center tap. Two of the differential modem ports
are coupled with the first transformer, with one differential modem
port acting as a transmitter over the PN interface and the other
differential modem port acting as a receiver over the PN interface.
The third differential modem port is coupled with the second
transformer and acts as a receiver over the NG interface. The
fourth differential modem port is coupled with the third
transformer and acts as a transmitter over the NG interface. The
first transformer includes a network side winding for receiving and
transmitting signals. A first terminal of the network side winding
is coupled with the first network port, while a second terminal of
the network side winding is coupled with the second network port.
The second transformer also includes a network side winding for
receiving signals. A first terminal of the network side winding is
coupled with the third network port, while a second terminal of the
network side winding is coupled with a center tap of the first
transformer. The center tap is located at a midpoint between the
network side winding of the first transformer. The third
transformer includes a network side winding for transmitting
signals. A first terminal of the network side winding is coupled
with the second network port, while a second terminal of the
network side winding is coupled with the third network port.
[0032] Reference is now made to FIG. 3A, which is a schematic
illustration of a balanced coupling circuit, generally referenced
100, for inductively coupling a PLC modem to a power line network,
constructed and operative in accordance with an embodiment of the
disclosed technique. The balanced coupling circuit enables a
network PN interface to be balanced. Balanced coupling circuit 100
includes a first differential modem port 101A, a second
differential modem port 101B, a first network port 108, a second
network port 110, a third network port 112, a first transformer
line 114, a second transformer line 116, a third transformer line
117, a fourth transformer line 118, a first network line 120, a
second network line 122, a third network line 124, a first
transformer 126, a second transformer 128, a center tap 138, a
center tap capacitor 140A and a first network line capacitor 140B.
First differential modem port 101A includes a first terminal 102
and a second terminal 104. Second differential modem port 101B
includes a third terminal 105 and a fourth terminal 106. It is
noted that first differential modem port 101A and second
differential modem port 101B are not coupled with one another.
First transformer line 114 and second transformer line 116 extend
from first terminal 102 and second terminal 104 respectively to the
terminals (not referenced) of a modem side winding 130 of first
transformer 126. Third transformer line 117 and fourth transformer
line 118 extend from third terminal 105 and fourth terminal 106
respectively to the terminals (not referenced) of a modem side
winding 134 of second transformer 128. First network line 120 and
second network line 122 extend from first network port 108 and
second network port 110 respectively to the terminals (not
referenced) of a network side winding 132 of first transformer 126.
Third network line 124 extends from third network port 112 to a
first terminal 142 of a network side winding 136 of second
transformer 128. Center tap 138 extends from the midpoint (not
referenced) of network side winding 132 of first transformer 126 to
a second terminal 144 of network side winding 136 of second
transformer 128. Center tap capacitor 140A is coupled in between
center tap 138 of network side winding 132 and second terminal 144
of network side winding 136. First network line capacitor 140B is
coupled in between a first terminal (not referenced) of network
side winding 132 of first transformer 126 and first network port
108. Center tap capacitor 140A and first network line capacitor
140B are installed for meeting safety regulations.
[0033] First terminal 102 and second terminal 104 form a pair of
terminals in first differential modem port 101A. First transformer
line 114 and first terminal 102 can represent, for example, a modem
side phase line, if first network line 120 is a phase line. Second
transformer line 116 and second terminal 104 can represent, for
example, a modem side neutral line, if second network line 122 is a
neutral line. Third terminal 105 and fourth terminal 106 form a
pair of terminals in second differential modem port 101B. Fourth
transformer line 118 and fourth terminal 106 can represent, for
example, a modem side ground line, if third network line 124 is a
ground line. Third transformer line 117 and third terminal 105 can
represent, for example, a modem side phase-neutral line, if first
network line 120 and second network line 122 are respectively a
phase line and a neutral line. First network port 108 is coupled
with a PLC network line, such as a PLC network phase line (not
shown). Second network port 110 is coupled with a PLC network line,
such as a PLC network neutral line (not shown). Third network port
112 is coupled with a PLC network line, such as a PLC network
ground line (not shown). First terminal 102 and second terminal 104
together define a first modem communication interface (not
referenced), such as a modem PN interface. Third terminal 105 and
fourth terminal 106 together define a second modem communication
interface (not referenced), such as a modem PNG interface. First
network port 108 and second network port 110 together define a
first network communication interface (not referenced), such as a
network PN interface. Second network port 110 and third network
port 112 together define a second network communication interface
(not referenced), such as a network NG interface.
[0034] According to the disclosed technique, the first network
communication interface is balanced as it consists of similar
conducting lines, i.e. first network line 120 and second network
line 122, having similar impedances along their length and having
similar ground impedances. Thus any CM noise signals traveling
through first network line 120 and second network line 122, i.e. CM
noise signals traveling through the network PN interface,
substantially cancel each other on network side winding 132 of
first transformer 126. Network side winding 132 of first
transformer 126 defines a first phase-neutral-ground (herein
abbreviated PNG) communication channel. In particular, network side
winding 132 is coupled with, either directly or indirectly, each of
first network line 120 (e.g. a phase line), third network line 124
(e.g. a ground line) and second network line 122 (e.g. a neutral
line). Network side winding 136 of second transformer 128 defines a
second PNG communication channel. In particular, network side
winding 136 is coupled with, either directly or indirectly, each of
first network line 120, third network line 124 and second network
line 122.
[0035] Hence, modem side winding 130 of first transformer 126
couples first differential modem port 101A of a PLC modem (not
shown) to the first PN communication channel. Modem side winding
134 of second transformer 128 couples second differential modem
port 101 B of the modem to the second PNG communication channel. A
signal received on first and second terminals 102 and 104 is a
combination of the signals on the first and second network lines,
e.g. the PN lines. In addition, a signal received on third and
fourth terminals 105 and 106 is a combination of the signals on
first, second and third network lines, e.g. the PNG lines. As a
consequence, balanced coupling circuit 100 couples two different
combinations of the PN and NG signals to the PLC modem instead of
independently coupling the PN signal alone to one port on the PLC
modem and the NG signal alone to another port of the PLC modem as
is done in the prior art.
[0036] Reference is now made to FIG. 3B, which is a schematic
illustration of another balanced coupling circuit, generally
referenced 100', for inductively coupling a PLC modem to a power
line network, constructed and operative in accordance with another
embodiment of the disclosed technique. Balanced coupling circuit
100' is substantially similar to balanced coupling circuit 100
(FIG. 3A). Equivalent elements in FIGS. 3A and 3B are referenced
using identical numbers. Balanced coupling circuit 100' differs
from balanced coupling circuit 100 in that a first network line
capacitor 140B (FIG. 3A) has been removed from balanced coupling
circuit 100'. In addition, balanced coupling circuit 100' includes
a second network line capacitor 140C, coupled in between a second
terminal (not referenced) of network side winding 132 of first
transformer 126 and second network port 110. As in FIG. 3A, second
network line capacitor 140C along with a center tap capacitor 140A
are installed for meeting safety regulations.
[0037] Reference is now made to FIG. 3C, which is a schematic
illustration of a further balanced coupling circuit, generally
referenced 100'', for inductively coupling a PLC modem to a power
line network, constructed and operative in accordance with a
further embodiment of the disclosed technique. Balanced coupling
circuit 100'' is substantially similar to balanced coupling circuit
100' (FIG. 3B). Equivalent elements in FIGS. 3B and 3C are
referenced using identical numbers. Balanced coupling circuit 100''
differs from balanced coupling circuit 100' in that both first
network line 120 and second network line 122 include respective
first network line and second network line capacitors 140B and 140C
and that a center tap capacitor 140A has been removed. Therefore in
FIG. 3C, a center tap 138 directly couples a network side winding
132 of a first transformer 126 with a second terminal 144 of a
network side winding 136 of a second transformer 128. First network
line capacitor 140B is coupled between a first network port 108 and
a first terminal (not referenced) of network side winding 132 of
first transformer 126. Second network line capacitor 140C is
coupled between a second network port 110 and a second terminal
(not referenced) of network side winding 132 of first transformer
126. As mentioned above, first network line and second network line
capacitors 140B and 140C are installed for meeting safety
regulations.
[0038] Reference is now made to FIG. 3D, which is a schematic
illustration of an additional balanced coupling circuit, generally
referenced 100''', for inductively coupling a PLC modem to a power
line network, constructed and operative in accordance with another
embodiment of the disclosed technique. Balanced coupling circuit
100''' is substantially similar to balanced coupling circuits 100
(FIG. 3A), 100' (FIG. 3B) and 100'' (FIG. 3C). Equivalent elements
in FIGS. 3A, 3B and 3C are referenced using identical numbers.
Balanced coupling circuit 100''' includes a center tap capacitor
140A, a first network line capacitor 140B and a second network line
capacitor 140C, each positioned in balanced coupling circuit 100'''
in a manner similar to their respective positions in FIGS. 3A-3C.
As mentioned above, center tap capacitor 140A, first network line
capacitor 140B and second network line capacitor 140C are installed
for meeting safety regulations.
[0039] It is noted that each of the embodiments of the balanced
coupling circuit of the disclosed technique, as shown above in
FIGS. 3A, 3B, 3C and 3D, may be enclosed within a PLC modem (not
shown). Therefore, balanced coupling circuits 100, 100', 100'' and
100''' may each be embodied as part of a PLC modem. Such a PLC
modem would have one side which would couple it to the power line
network via first network port 108, second network port 110 and
third network port 112. Such a PLC modem could also optionally have
another side which would couple it to an electrical device, such as
a computer (not shown) or a printer (not shown), via first
differential modem port 101A and second differential modem port
101B.
[0040] Reference is now made FIG. 4A, which is a schematic
illustration of a balanced coupling circuit for inductively
coupling a PLC modem to a power line network including a
transmitter section and a receiver section, generally referenced
200, constructed and operative in accordance with a further
embodiment of the disclosed technique. Unlike the examples of
balanced coupling circuits 100, 100', 100'' and 100'''
(respectively FIGS. 3A-3D), where a first differential modem port
101A (FIGS. 3A-3D) and a second differential modem port 101B (FIGS.
3A-3D) are shown for receiving signals over a power line network,
balanced coupling circuit 200 shows four differential modem ports
for receiving and transmitting signals over a power line network.
The interface setup (i.e., the setup of coupling circuit 200) shown
in FIG. 4A is substantially similar to the interface, or coupling
circuit setups of FIGS. 3A-3D except that FIG. 4A shows an
interface which includes both a receiver and a transmitter for
receiving and transmitting over a PLC network. Balanced coupling
circuit 200 includes a first transformer 202 and a second
transformer 204. First transformer 202 and second transformer 204
inductively couple a PLC device (not shown) with a power line
network (not labeled).
[0041] As shown, first transformer 202 includes a modem side (not
labeled) and a network side (not labeled). The modem side includes
a first modem side transmitter (herein abbreviated TX) winding 206A
and a first modem side receiver (herein abbreviated RX) winding
206B, for coupling first transformer 202 with the PLC device. The
network side includes a first network side winding 208, for
coupling first transformer 202 with the power line network. First
modem side TX winding 206A is coupled with a transmitter analog
front end (herein abbreviated TX AFE) 214A for transmitting signals
over the power line network. First modem side RX winding 206B is
coupled with a receiver analog front end (herein abbreviated RX
AFE) 216A for receiving signals over the power line network. TX AFE
214A may also be coupled with a line driver (not shown), an
amplifier (not shown) and the like. RX AFE 216A may also be coupled
with at least one filter (not shown), such as an analog filter, and
the like. TX AFE 214A is coupled with a first differential modem
port 228.sub.1. RX AFE 216A is coupled with a second differential
modem port 228.sub.2. Both of first modem side TX winding 206A and
first modem side RX winding 206B are symmetrically coupled with
first network side winding 208. It is noted that in another
embodiment of the disclosed technique, the modem side of first
transformer 202 includes only one winding (not shown). In such an
embodiment, TX AFE 214A and RX AFE 216A are both coupled with the
one winding for both transmitting and receiving signals over a PLC
network. First differential modem port 228.sub.1 and second
differential modem port 228.sub.2 are coupled with the PLC device.
First differential modem port 228.sub.1 enables signals to be
transmitted from the PLC device over a PN interface (as explained
below) of the power line network. Second differential modem port
228.sub.2 enables signals to be received by the PLC device from the
power line network over the PN interface of the power line
network.
[0042] First network side winding 208 includes a first terminal
220.sub.1 and a second terminal 220.sub.2. First terminal 220.sub.1
couples first network side winding 208 with a phase line of the
power line network, shown as a phase terminal 230.sub.1. Second
terminal 220.sub.2 couples first network side winding 208 with a
neutral line of the power line network, shown as a neutral terminal
230.sub.2. In this respect, first network side winding 208 couples
first transformer 202 to phase terminal 230.sub.1 and neutral
terminal 230.sub.2 thus forming a phase-neutral (herein abbreviated
PN) interface over which signals can be transmitted and
received.
[0043] Second transformer 204 includes a modem side (not labeled)
and a network side (not labeled). The modem side includes a second
modem side TX winding 210A and a second modem side RX winding 210B,
for coupling second transformer 204 with the PLC device. The
network side includes a second network side winding 212, for
coupling second transformer 204 with the power line network. Second
modem side TX winding 210A is coupled with a TX AFE 214B for
transmitting signals over the power line network. Second modem side
RX winding 210B is coupled with an RX AFE 216B for receiving
signals over the power line network. TX AFE 214B may also be
coupled with a line driver (not shown), an amplifier (not shown)
and the like. RX AFE 216B may also be coupled with at least one
filter (not shown), such as an analog filter, and the like. TX AFE
214B is coupled with a third differential modem port 228.sub.3. RX
AFE 216B is coupled with a fourth differential modem port
228.sub.4. Both of second modem side TX winding 210A and second
modem side RX winding 210B are symmetrically coupled with second
network side winding 212. It is noted that in another embodiment of
the disclosed technique, the modem side of second transformer 204
includes only one winding (not shown). In such an embodiment, TX
AFE 214B and RX AFE 216B are both coupled with the one winding for
both transmitting and receiving signals over a PLC network. Third
differential modem port 228.sub.3 and fourth differential modem
port 228.sub.4 are coupled with the PLC device. Third differential
modem port 228.sub.3 enables signals to be transmitted from the PLC
device over a PNG interface (as explained below) of the power line
network. Fourth differential modem port 228.sub.4 enables signals
to be received by the PLC device from the power line network over
the PNG interface of the power line network.
[0044] Second network side winding 212 includes a first terminal
218.sub.1 and a second terminal 218.sub.2. First terminal 218.sub.1
couples second network side winding 212 with a midpoint 222 of
first network side winding 208, as explained above in FIGS. 3A-3D.
First terminal 218.sub.1 couples second transformer 204 with first
transformer 202 such that first terminal 218.sub.1 is substantially
coupled with a center tap (not labeled) of first transformer 202.
Second terminal 218.sub.2 couples second network side winding 212
with a ground line of the power line network, shown as a ground
terminal 230.sub.3. In this respect, second network side winding
212 couples second transformer 204 to ground terminal 230.sub.3 and
a midpoint between first terminal 220.sub.1 and second terminal
220.sub.2 of first transformer 202, thus forming a
phase-neutral-ground (herein abbreviated PNG) interface over which
signals can be transmitted and received. It is noted that coupling
circuit 200 includes at least two capacitors (not shown) on the
network side of first transformer 202 and second transformer 204.
The possible positions of these at least two capacitors in FIG. 4A
are substantially equivalent to the various capacitor positions
shown above in FIGS. 3A-3D. It is noted that other electrically
equivalent positions of the at least two capacitors, besides those
shown in FIGS. 3A-3D are possible and are within the knowledge of
the worker skilled in the art. It is also noted that phase terminal
230.sub.1, neutral terminal 230.sub.2 and ground terminal 230.sub.3
can be respectively referred to as a phase network port, a neutral
network port and a ground network port.
[0045] The coupling circuit of the disclosed technique shown in
FIG. 4A is used for the simultaneous transmission of signals
through two transmit ports (first differential modem port 228.sub.1
and third differential modem port 228.sub.3) and for the
simultaneous reception of signals through two receive ports (second
differential modem port 228.sub.2 and fourth differential modem
port 228.sub.4). Each transmit and receive port forms a transmit
and receive interface. These two transmit and receive interfaces
use three network ports. A first receive and transmit interface
(first differential modem port 228.sub.1 and second differential
modem port 228.sub.2) uses two network ports, for example the phase
port (shown as phase terminal 230.sub.1) and the neutral port
(shown as neutral terminal 230.sub.2). In coupling circuit 200, the
second transmit and receive interface (third differential modem
port 228.sub.3 and fourth differential modem port 228.sub.4)
requires the use of a third network port, such as the ground port
(shown as ground terminal 230.sub.3), since signals can not be
transmitted and received simultaneously over two transmit ports
having just two network ports for transmission. Thus a third
network port is required. This second receive and transmit
interface is coupled with coupling circuit 200 such that the
symmetry between the two network ports of the first receive and
transmit interface with respect to the third network port is
maintained. Current being received over the ground wire (not
labeled) is split, by the center tap coupling second transformer
204 with first transformer 202, to currents over phase terminal
230.sub.1 and neutral terminal 230.sub.2 which are substantially
equal in magnitude and in polarity, such that no current is induced
on first modem side RX winding 206B. The polarity is substantially
equal in that current on the phase line (not labeled) and neutral
line (not labeled) is either flowing away from first transformer
202 or flowing into first transformer 202. Such a current flow over
the phase and neutral terminals results is substantially no current
being induced on first modem side RX winding 206B. When signals are
received by RX AFE 216B over the PNG interface, current from second
network side winding 212 may travel in the direction of an arrow
224B over neutral terminal 230.sub.2 and in the direction of an
arrow 224D over ground terminal 230.sub.3. The topology of coupling
circuit 200 is such that signals received over the PNG interface
travel from neutral terminal 230.sub.2 to RX AFE 216B via the
center tap (not labeled) of first transformer 202 which is coupled
with midpoint 222 to second network side winding 212. This topology
enables the PNG interface to prevent current from being induced on
first modem side RX winding 206B.
[0046] The coupling circuit shown in FIG. 4A is balanced with
regards to the PN interface but not with regards to the PNG
interface. Thus signals transmitted over the PLC network in the
interface setup of FIG. 4A may suffer from excess levels of
radiation. Signals transmitted over the PN interface via first
network side winding 208 exhibit minimal levels of excess radiation
and thus this interface is balanced. Excess radiation is any
radiation emitted from the phase, neutral or ground lines above a
predefined limit which may radiate off, or leak out of those power
lines and interfere with signals and devices in the vicinity of
those power lines. However, signals transmitted over the PNG
interface via second network side winding 212 may exhibit higher
levels of excess radiation which may cause interference and noise
on signals and devices in the vicinity of coupling circuit 200.
This is because signals transmitted by TX AFE 214B travel in the
direction of an arrow 224C towards neutral terminal 230.sub.2, with
the current of the transmitted signal being split by the center tap
such that a portion travels via neutral terminal 230.sub.2 and
another portion travels via phase terminal 230.sub.1. Signals
transmitted by TX AFE 214B via the PNG interface are not balanced
since the magnitude of the current over neutral terminal 230.sub.2
and ground terminal 230.sub.3 is not substantially equivalent and
the magnitude of the current over phase terminal 230.sub.1 is not
substantially zero. When transmitting signals via the PNG interface
of FIG. 4A, current leaks out of phase terminal 230.sub.1 and may
radiate in the air surrounding first transformer 202, thus
potentially corrupting devices in the vicinity. This is due to the
topology of coupling circuit 200. In general, excess radiation over
pairs of wires can be minimized by balancing the magnitude of the
current on each wire in a pair and minimizing the magnitude of the
current on the third wire which is not part of the wire pair. In
the interface setup of FIG. 4A, the topology of TX AFE 214A is such
that the current provided to first network side winding 208 is
substantially balanced between phase terminal 230.sub.1 and neutral
terminal 230.sub.2. Therefore signal transmissions over the PN
interface are balanced and do not exhibit excess radiation over the
phase and neutral lines. However, the topology of TX AFE 214B is
such that the current provided to second network side winding 212
is unbalanced between neutral terminal 230.sub.2 and ground
terminal 230.sub.3. The current induced in neutral terminal
230.sub.2 is not at the same magnitude as the current induced in
ground terminal 230.sub.3 and the magnitude of the current induced
in phase terminal 230.sub.1 is not substantially zero. Therefore
signal transmissions over the PNG interface are not balanced and
thereby exhibit excess radiation over the phase, neutral and ground
lines. According to the disclosed technique, the unbalanced current
between the phase, neutral and ground lines can be balanced such
that the symmetric characteristics of the receiving circuits of
coupling circuit 200 are maintained. A coupling circuit, or
interface setup, having both a balanced PN interface and a balanced
NG interface is shown below in FIG. 4B which maintains the
symmetric characteristics of the receiving circuits of FIG. 4A.
[0047] It is noted that FIG. 4A shows three network side terminals,
a phase terminal 230.sub.1, a neutral terminal 230.sub.2 and a
ground terminal 230.sub.3. According to the disclosed technique,
the three network side terminals shown in FIG. 4A are not limiting
and are brought merely as an example. According to the disclosed
technique, each of the terminals labeled 230.sub.1, 230.sub.2 and
230.sub.3 may be coupled to respectively one of a phase line, a
neutral line and a ground line. For example, terminal 230.sub.1 may
be a neutral terminal (not shown), terminal 230.sub.2 may be a
phase terminal (not shown) and terminal 230.sub.3 may be a ground
terminal (as shown). Terminal 230.sub.1 may be a phase terminal (as
shown), terminal 230.sub.2 may be a ground terminal (not shown) and
terminal 230.sub.3 may be a neutral terminal (not shown). Terminal
230.sub.1 may be a ground terminal (not shown), terminal 230.sub.2
may be a neutral terminal (as shown) and terminal 230.sub.3 may be
a phase terminal (not shown). Terminal 230.sub.1 may be a ground
terminal (not shown), terminal 230.sub.2 may be a phase terminal
(not shown) and terminal 230.sub.3 may be a neutral terminal (not
shown). Terminal 230.sub.1 may be a neutral terminal (not shown),
terminal 230.sub.2 may be a ground terminal (not shown) and
terminal 230.sub.3 may be a phase terminal (not shown).
[0048] Reference is now made to FIG. 4B, which is a schematic
illustration of another balanced coupling circuit for inductively
coupling a PLC modem to a power line network including a
transmitter section and a receiver section, generally referenced
250, constructed and operative in accordance with another
embodiment of the disclosed technique. Like FIG. 4A, FIG. 4B shows
a balanced coupling circuit with four differential modem ports for
receiving and transmitting signals over a power line network.
Balanced coupling circuit 250 includes a first transformer 252, a
second transformer 254 and a third transformer 256. First
transformer 252, second transformer 254 and third transformer 256
inductively couple a PLC device (not shown) with a power line
network (not labeled).
[0049] As shown, first transformer 252 includes a modem side (not
labeled) and a network side (not labeled). The modem side includes
a first modem side TX winding 258A and a first modem side RX
winding 258B, for coupling first transformer 252 with the PLC
device. The network side includes a first network side winding 260,
for coupling first transformer 252 with the power line network.
First modem side TX winding 258A is coupled with a TX AFE 265A for
transmitting signals over the power line network. First modem side
RX winding 258B is coupled with an RX AFE 267A for receiving
signals over the power line network. TX AFE 265A may also be
coupled with a line driver (not shown), an amplifier (not shown)
and the like. RX AFE 267A may also be coupled with at least one
filter (not shown), such as an analog filter, and the like. TX AFE
265A is coupled with a first differential modem port 278.sub.1. RX
AFE 267A is coupled with a second differential modem port
278.sub.2. Both of first modem side TX winding 258A and first modem
side RX winding 258B are symmetrically coupled with first network
side winding 260. It is noted that in another embodiment of the
disclosed technique, the modem side of first transformer 252
includes only one winding (not shown). In such an embodiment, TX
AFE 265A and RX AFE 267A are both coupled with the one winding for
both transmitting and receiving signals over a PLC network. First
differential modem port 278.sub.1 and second differential modem
port 278.sub.2 are coupled with the PLC device. First differential
modem port 278.sub.1 enables signals to be transmitted from the PLC
device over a PN interface of the power line network, i.e. over a
wire pair channel including a phase wire and a neutral wire. Second
differential modem port 278.sub.2 enables signals to be received by
the PLC device from the power line network over the PN interface of
the power line network.
[0050] First network side winding 260 includes a first terminal
272.sub.1 and a second terminal 272.sub.2. First terminal 272.sub.1
couples first network side winding 260 with a phase line of the
power line network, shown as a phase terminal 280.sub.1. Second
terminal 272.sub.2 couples first network side winding 260 with a
neutral line of the power line network, shown as a neutral terminal
280.sub.2. In this respect, first network side winding 260 couples
first transformer 252 to phase terminal 280.sub.1 and neutral
terminal 280.sub.2 thus forming a PN interface over which signals
can be transmitted and received.
[0051] Second transformer 254 includes a modem side (not labeled)
and a network side (not labeled). The modem side includes a second
modem side RX winding 262, for coupling second transformer 254 with
the PLC device. Unlike second transformer 204 (FIG. 4A), second
transformer 254 does not include a second mode side TX winding. The
network side includes a second network side winding 264, for
coupling second transformer 254 with the power line network. Second
modem side RX winding 262 is coupled with an RX AFE 267B for
receiving signals over the power line network. As described below,
a TX AFE 265B is coupled with third transformer 256. TX AFE 265B
may also be coupled with a line driver (not shown), an amplifier
(not shown) and the like. RX AFE 267B may also be coupled with at
least one filter (not shown), such as an analog filter, and the
like. TX AFE 265B is coupled with a third differential modem port
278.sub.3. RX AFE 267B is coupled with a fourth differential modem
port 278.sub.4. Third differential modem port 278.sub.3 and fourth
differential modem port 278.sub.4 are coupled with the PLC device.
Third differential modem port 278.sub.3 enables signals to be
transmitted from the PLC device over an NG interface (as explained
below) of the power line network. Fourth differential modem port
278.sub.4 enables signals to be received by the PLC device from the
power line network over the NG interface of the power line
network.
[0052] Second network side winding 264 includes a first terminal
282.sub.1 and a second terminal 282.sub.2. First terminal 282.sub.1
couples second network side winding 264 with a midpoint 270 of
first network side winding 260, as explained above in FIGS. 3A-3D
and FIG. 4A. First terminal 282.sub.1 couples second transformer
254 with first transformer 252 such that first terminal 282.sub.1
is substantially coupled with a center tap (not labeled) of first
transformer 252. Second terminal 282.sub.2 couples second network
side winding 264 with a ground line of the power line network,
shown as a ground terminal 280.sub.3. In this respect, second
network side winding 264 couples second transformer 254 to ground
terminal 280.sub.3 and a midpoint between first terminal 272.sub.1
and second terminal 272.sub.2 of first transformer 252, thus
forming a PNG interface over which signals can be received.
[0053] Third transformer 256 includes a modem side (not labeled)
and a network side (not labeled). The modem side includes a second
modem side TX winding 266, for coupling third transformer 256 with
the PLC device. The network side includes a third network side
winding 268, for coupling third transformer 256 with the power line
network. Second modem side TX winding 266 is coupled with TX AFE
265B. Third network side winding 268 includes a first terminal
284.sub.1 and a second terminal 284.sub.2. First terminal 284.sub.1
couples third network side winding 268 with the neutral wire at a
point 286. Second terminal 284.sub.2 couples third network side
winding 268 with a ground wire at a point 288. Third transformer
256 thus couples TX AFE 265B with neutral terminal 280.sub.2 and
ground terminal 280.sub.3 thus forming an NG interface for
transmitting signals over the power line network.
[0054] As shown, when signals are transmitted over the PN interface
by TX AFE 265A, current is induced over phase terminal 280.sub.1 in
the direction of an arrow 274A and over network terminal 280.sub.2
in the direction of an arrow 274B. Substantially no current is
induced over ground terminal 280.sub.3. Thus the PN interface of
coupling circuit 250 is balanced. When signals are transmitted over
the NG interface by TX AFE 265B, current is induced over network
terminal 280.sub.2 in the direction of arrows 274C and 274E and
over ground terminal 280.sub.3 in the direction of an arrow 274D.
No current is induced over phase terminal 280.sub.1. Thus the NG
interface of coupling circuit 250 is also balanced with regards to
transmitting signals over the PLC network. As shown, the coupling
of the network sides of first transformer 252 and second
transformer 254 are equivalent to the coupling of the network sides
in coupling circuit 200 (FIG. 4A) such that the behavior of RX AFE
267A and RX AFE 267B is equivalent to that of RX AFE 216A (FIG. 4A)
and RX AFE 216B (FIG. 4A). In coupling circuit 250, signals are
transmitted over a PN interface and an NG interface whereas signals
are received over the PN interface and a PNG interface. Thus the
setup of coupling circuit 250 maintains balanced PN and NG
interfaces for transmitting signals as well. In the setup of FIG.
4B, signals which are transmitted via TX AFE 265B bypass second
transformer 254 and the center tap of first transformer 252.
Signals which are transmitted via TX AFE 265B are transmitted
directly over the neutral wire and the ground wire, thus over an NG
interface. As shown, the topology of third transformer 256 enables
any current representing a transmission on neutral terminal
280.sub.2 and ground terminal 280.sub.3 to be balanced. At the same
time, the current of signals transmitted via TX AFE 265A remains
balanced over phase terminal 280.sub.1 and neutral terminal
280.sub.2. In addition, signals received from the power line
network to RX AFE 267A via the PN interface and to RX AFE 267B via
the PNG interface maintain their symmetric characteristics as
explained above in FIG. 4A. The coupling circuit of FIG. 4B thus
enables a PLC device to be coupled with a power line network
wherein the PN and NG interfaces for transmission are balanced in
terms of the magnitude of the current induced over each wire in the
phase-neutral wire pair and the neutral-ground wire pair. The
balanced current thus enables signals to be transmitted over the PN
and NG interfaces with minimal excess of radiation leaking out of
the phase, neutral and ground wires which could potentially
interfere with other devices in the vicinity.
[0055] It is noted that coupling circuit 250 includes at least two
capacitors, similar to the capacitors mentioned above in FIG. 4A
and shown above in FIGS. 3A-3D. The various possibilities of the
positioning of the at least two capacitors in coupling circuit 250
are shown in FIG. 4B via a plurality of arrows 290A-290E, wherein
each arrow demarcates a particular location in coupling circuit 250
where a capacitor can be placed. Arrow 290A represents a position
on the phase line between first terminal 272.sub.1 and phase
terminal 280.sub.1. Arrow 290B represents a position on the neutral
line between second terminal 272.sub.2 and neutral terminal
280.sub.2 after the coupling of third transformer 256 to the
neutral line, i.e. between point 286 where third transformer 256 is
coupled with the neutral line and neutral terminal 280.sub.2. Arrow
290C represents a position on the ground line between ground
terminal 280.sub.3 and after the coupling of third transformer 256
to the ground line, i.e. between point 288 where third transformer
256 is coupled with the ground line and ground terminal 280.sub.3.
Arrow 290D represents a position on a line (not labeled) between
first terminal 284.sub.1 and a coupling of third transformer 256 to
the neutral line. Arrow 290E represents a position on a line (not
labeled) between first terminal 282.sub.1 and the center tap of
first network side winding 260. In a preferred embodiment of the
disclosed technique, two capacitors are positioned, a first where
arrow 290A indicates and a second where arrow 290B indicates. In
another embodiment of the disclosed technique, two capacitors are
positioned, a first where arrow 290B indicates and a second where
arrow 290C indicates. In a further embodiment of the disclosed
technique, three capacitors are positioned, a first where arrow
290A indicates, a second where arrow 290D indicates and a third
where arrow 290E indicates. In another embodiment of the disclosed
technique, three capacitors are positioned, a first where arrow
290B indicates, a second where arrow 290D indicates and a third
where arrow 290E. In a further embodiment of the disclosed
technique, three capacitors are positioned, a first where arrow
290A indicates, a second where arrow 290B indicates and a third
where arrow 290E indicates. It is noted that other electrically
equivalent possibilities exist for the positioning of the at least
two capacitors in coupling circuit 250 and are within the knowledge
of the worker skilled in the art.
[0056] It is noted that FIG. 4B shows three network side terminals,
a phase terminal 280.sub.1, a neutral terminal 280.sub.2 and a
ground terminal 280.sub.3. According to the disclosed technique,
the three network side terminals shown in FIG. 4B are not limiting
and are brought merely as an example. According to the disclosed
technique, each of the terminals labeled 280.sub.1, 280.sub.2 and
280.sub.3 may be coupled to respectively one of a phase line, a
neutral line and a ground line. For example, terminal 280.sub.1 may
be a neutral terminal (not shown), terminal 280.sub.2 may be a
phase terminal (not shown) and terminal 280.sub.3 may be a ground
terminal (as shown). Terminal 280.sub.1 may be a phase terminal (as
shown), terminal 280.sub.2 may be a ground terminal (not shown) and
terminal 280.sub.3 may be a neutral terminal (not shown). Terminal
280.sub.1 may be a ground terminal (not shown), terminal 280.sub.2
may be a neutral terminal (as shown) and terminal 280.sub.3 may be
a phase terminal (not shown). Terminal 280.sub.1 may be a ground
terminal (not shown), terminal 280.sub.2 may be a phase terminal
(not shown) and terminal 280.sub.3 may be a neutral terminal (not
shown). Terminal 280.sub.1 may be a neutral terminal (not shown),
terminal 280.sub.2 may be a ground terminal (not shown) and
terminal 280.sub.3 may be a phase terminal (not shown).
[0057] It will be appreciated by persons skilled in the art that
the disclosed technique is not limited to what has been
particularly shown and described hereinabove. Rather the scope of
the disclosed technique is defined only by the claims, which
follow.
* * * * *