A discussion of BPL:
It's
benefits, faults, and what they don't want you to know
(Revision 1 - 02/07/2005)
BPL (Broadband over Power Lines) is
a controversial new technology used to deliver high-speed internet access to
homes via the existing electrical wiring. BPL has several benefits for
both power companies and consumers, however there are also several downsides
to this new technology. I will mainly discuss BPL in Cincinnati which
is provided by Current Communications under contract from Cinergy, the local
power company.
BPL allows you to achieve high
speed internet connectivity through any outlet in your home by simply
plugging in a BPL modem and connecting an Ethernet cable between the modem
and your computer.
BPL works by transmitting radio
data signals over existing power lines. These signals are in the area
of 1-30 MHz.
The BPL data originates on fiber optic
cable which is run from the Cinergy network hub to each neighborhood.
It is only within the neighborhood that the data is inserted onto the power lines.
A fiber optic interface inserts the data onto the 7,500 volt high voltage
line which feeds all of the step-down transformers in the neighborhood.
At each step-down transformer there is an interface to bypass the
transformer. This interface converts the data to fiber optic as
isolation and then
inserts it back onto the low voltage lines which directly feed the houses.
The technology used on the
low-voltage side of the Cinergy system utilizes HomePlug networking, a
technology often used for networking within a home. Other BPL test
systems around the country utilize wireless networking (802.11b/802.11g) or
other wired formats including direct wired Ethernet.
You may ask "Why are Cinergy and
other power companies getting into the broadband internet business which is
already very competitive?". The answer is fringe benefits. These
benefits include but are not limited to:
-
Remote meter reading (Power and
Gas)
-
Remote power/gas shut off/turn on
-
Remote demand metering
-
Remote load control (Turning on/off
your air conditioning/heat at peak times)
-
Remote power outage monitoring
-
Remote real-time load analysis
-
Remote water meter reading (Possible if
Water Works signs a contract)
-
And many others...
It is easy to see now why the power
companies are enthusiastic about implementing this technology as quickly as
possible despite the enormous cost of the infrastructure necessary to deliver
it. Broadband service will actually be a secondary function for the
system. The majority of the cost of implementation will be made up by the
elimination of the need for meter readers and their salaries as well as the
increased efficiency of line repair crews due to pinpoint location of outages
and avoided outages through use of peak demand limiting. Additional income
may also come from other utilities such as the water works if BPL is utilized to
read their meters as well.
Now that I have covered all of the
positive aspects of BPL more or less I will discuss the faults of this new
technology.
Speed:
Current Communications claims BPL is
capable of 6 megabits per second download, however often this is not the case.
In tests, the BPL in Cincinnati is capable of only 2-4 megabits per second
sustained transfer and sometimes worse. Aluminum house wiring can often
slow the connection below 2 megabits. In extreme cases Current
Communications has had to install BPL repeaters boost
the BPL signal. According to Current's Tech Support installation of an
outside repeater located on the pole outside your house limits the bandwidth to
a maximum of 2.5 Megabits. Installation of an inside repeater located by
your circuit breaker box limits your maximum bandwidth to 1 Megabit. In
extreme cases Current says they will install a dedicated circuit for the BPL
modem or install a wireless access point at your breaker box. This limits
you to connecting to 1 special outlet in your house. This is funny since
one of Current's primary examples of the benefits of BPL is the ability to
connect a modem to any outlet in your home. This means that some customers are left with mediocre
connections of only 1-2 megabits, far slower than both DSL (3-7 megabits) and
cable (2.5 Megabits). The label on the side of Current's BPL
modem says it all -
"IMPORTANT: Plug this modem
directly into a standard 110 Volt outlet. DO NOT use a power strip,
surge protector or extension cord as this will degrade service."
 
How is this a step forward?
Radio Frequency Interference (RFI):
As mentioned toward the beginning of
this discussion, BPL uses radio frequencies between 1 and 30 MHz. This would
be perfectly fine assuming that these signals remain on the line and are not
broadcast into the surrounding area. Unfortunately unshielded power lines
function as amazingly effective antennas. BPL, therefore can cause harmful
interference to any service, licensed or otherwise, utilizing frequencies
between 1 and 30 MHz and its harmonics (2-60 MHz, 3-90 MHz, 4-120 MHz ......and
so on). It is possible that BPL, when fully implemented may interrupt or
interfere with many radio licensees including public service (fire, police) and
Amateur radio (1-30 MHz encompasses the entire amateur HF band).
BPL equipment, being unlicensed must
comply with part 15 of the FCC rules which basically states that any unlicensed
device which interferes with a licensed service must immediately be disabled.
This means that if BPL interferes with any licensed service your internet
connection must be disabled immediately. It has already been reported by
many amateur radio operators around the country and around the world that BPL
often interferes severely with the amateur HF bands, sometimes obliterating them
completely.
You ask "What are the amateur HF bands
and why are they important?". Whether you realize it or not, Amateur radio
operators serve a very important purpose in times of emergency.
Many amateur radio operators are
trained for emergency communications. These amateur radio operators are
called upon any time there is a need for communications following any disaster
or public safety communications failure. Any time there is a large flood,
tornado, blizzard, or any other disaster chances are there are amateur radio
operators facilitating emergency communications. Amateurs also pass health
and welfare information on to parties concerned about their loved ones.
Many amateur radio operators are
also trained weather spotters who report weather conditions including severe
storms and tornados to the National Weather Service. Have you ever
wondered where the reported sightings of tornados and reports of hail and
other conditions often broadcast on your local news come from? Many
times it is from these same amateur radio weather spotters.
The HF bands are a unique resource both
for the amateur radio hobbyist and emergency communications. HF has the
unique ability to skip off the earth's atmosphere, allowing for communications
over extremely long distances. When phone lines and satellite links are
down due to a disaster amateurs utilizing the HF bands will still be able to
communicate with areas outside the disaster zone. If BPL is allowed to
interfere with these bands those vital communications may be rendered completely
useless due to local RFI (Radio Frequency Interference) caused by BPL.
During tests in Cincinnati I have not
been able to locate any harmful interference emanating from the power lines in
the amateur HF bands, however many amateurs around the globe have reported
interference from other BPL systems. The question then is what is
different about Cincinnati's system and what other services might it interfere
with if it has been notched for the amateur bands? This may remain a
mystery for some time as Current Communications refuses to divulge the
frequencies they are using for the system.
In my opinion BPL is a misguided
effort. The cost of implementing the system is almost as great as the cost
of running fiber optic cable to every house, an option with almost limitless
potential for speed and reliability. Fiber optic cable cannot create any
interference as the signals are transmitted as light rather than radio waves and
the speed of connections is only limited by the equipment connected at the ends,
not the cable itself.
This is only my opinion based on the
information and observations I have before me. I
welcome any additional information, comments, criticisms, concerns, etc. on this matter.
Dan Woodie
KC8ZUM
4-26-05 -
On April 21,
2005 Ed Hare, W1RFI, Head of the ARRL Labs conducted tests in the Hyde Park
area of Cincinnati. He conducted these tests on the BPL system installed by
Current Technologies for Cinergy. His findings were very promising for the
future of both amateur radio and BPL.
Ed found that the BPL emmisions were at least 20 dB below the FCC limits of
Part 15 devices accross the board. He also found that the amateur
frequencies have been notched and interference from BPL is at least 60 dB
below FCC Part 15 rules in all of the amateur bands with the exception of 60
meters which was very recently added as an amateur band. Ed also noted that
there were many other devices in the test area which interfered far more
severely with the amateur bands than the BPL. Another observation was that
the interference that was present was only present during data activity and
increased as bandwidth demand increased such as for streaming video or large
file downloads.
The BPL equipment installed in Cincinnati appears to be proprietary and was
likely manufactured by Current Technologies with the exception of the
customer premise equipment which is from another vendor and utilizes the
HomePlug transmission standard.
Assuming that this system is overall as clean as it was in the testing area
this system is about as clean as BPL can get and would be the ideal system
for deployment in areas where other systems are interfering, allowing the
power companies to have their BPL and Amateur Radio Operators their bands
without interference.
This information applies only to the
specific testing area and the Current Technologies BPL system installed in
Cincinnati and does not apply to any other system. Many other BPL systems
including at least one other Current Technologies test system interfere with
amateur radio and other communications severely.
Even with
these findings my conclusion is still that BPL is not a good system and is
only marginally viable. Competition from DSL, Cable, and Wireless
systems whose technologies are capable of much higher speeds than BPL
severely threaten the viability of BPL for carrying broadband traffic to
homes, however the financial benefits of remote meter reading etc. (see
above) might still make it financially viable for the BPL system to be
installed for administrative functions alone. BPL, as it currently exists in
the Current Technologies system is NOT viable for broadband delivery to
rural areas due to the very limited distances the signals can travel without
requiring a repeater. I believe that BPL will likely be phased out and
replaced by wireless or direct fiber optic. Fiber optics or long-range
wireless is the best solution for serving rural areas. Many rural
areas are already served by 2.4 GHz or 900 MHz wireless ISPs.
Dan Woodie
KC8ZUM |
