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RF Spectrum

What Hams Do

Leading edge

Wonderful broadband

Hams & interference

Licensed users

Who else?

What's BPL

Why is it hot

Interference

Efficiency

BPL's expensive

Alternatives to BPL

Trials

When are the trials

What's it look like?

 

Sound Files

1st Trial:

Kirksway Place:

2nd Trial:

Mt Nelson:

Tolmans Hill:

Spectran Files

BPL Virtual Tours

Emission Measurements

Noise Floor Measurements

RF Susceptibility

Experiencing Interference?

Mailing Lists

Other Material

 

 

 

 

Radio and Electronics Association of Southern Tasmanian Inc.
VK7 (Tasmanian) BPL Watch

Radio Frequency Spectrum

The radio frequency spectrum is an international natural resource. It is recognized internationally and regulated by the International Telecommunication Union (ITU) established by the United Nations. The International Amateur Radio Union (IARU) is charged with being the co-ordinating body for all Amateur (or Ham) Radio interests and spectrum. The Australian member of the IARU is the Wireless Institute of Australia (WIA) who acts as the voice for the amateur interests.

There are approximately 3 million radio amateurs worldwide, 14,500 in Australia and 600 in Tasmania.Goto Top of Page

What do radio amateurs “hams” do?

Ham radio is an experimental radio communications service:-

  • It’s an international hobby as we communicate throughout the world using radio, internet and satellite technology;

  • Providing skilled communication personnel in times of emergency like 911, Hurricane Katrina, the Asia Pacific Tsunami and in Tasmania amateurs provided personnel for the Broadmarsh Fires (2003), Kellevie Fires (2006) and the 1967 bushfires where it was amateurs who provided the first communications systems in some '67 bushfires areas;

  • It’s non-commercial – we don’t gain any financial benefit from it however, there are many other benefits like technical challenges, constructing, communicating, supporting community event like Jamboree on the Air, Targa and Subaru Safari;

  • Ham Radio is experimental in that it is forever branching out into new technology. Many commercial and scientifically sound systems have grown out of amateur projects eg. packet/IP radio and satellite communication techniques;

  • We design, build, operate and modify all the equipment we use to communicate on the frequencies allowed by our licence conditions;

  • The amateur service and amateur satellite services are recognised internationally in the International Telecommunications Unions regulations (section 25).

Radio amateurs use leading edge technology

Ham’s lead the way with the use voice over IP (VoIP) technology over the internet to link repeaters all over the world. Our modes and techniques in relation to satellite communication, meteor-scatter, tropo-scatter, earth-moon-earth (Moon Bounce - EME), spread-spectrum, fast-scan & slow-scan television, high speed packet radio and regularly talking (not emailing or phoning) people all over the world on a regular basis. Australian amateurs are credited with the development of some of the first successful communications satellites ever launched. There is even a ham station on the International Space Station.  This is hardly out dated technology!Goto Top of Page

Radio amateurs encourage the use of broadband

Radio amateurs encourage the use and roll-out of broadband. Hams through the technology they utilise are heavy users of broadband. What Hams are against is the interference causing potential of BPL technology.

Radio amateurs do not cause interference

Radio amateurs have to operate their equipment within strict limits imposed by the Radiocommunications Licence Condition (Amateur Licence) Determination No. 1 of 1997 and the Radiocommunications Licence Conditions (Apparatus Licence) Determination 2003.

We also need to conform to compulsory electromagnetic radiation (EMR) exposure limits and we can be audited at any time by the Australian Communications and Media Authority (ACMA) as to compliance with these standards.

Radio amateurs carefully match their transmitter to the antenna being used therefore minimising the potential for interference caused by impedance mismatching. If interference does result then radio amateurs take very seriously the resolution of interference complaints with the assistance of the ACMA where necessary.

BPL and BPL operators are not currently subject to EMR/EMC exposure limit or operational compliance.Goto Top of Page

Hams are licensed users of the spectrum

Radio amateurs – “hams” are licensed users of certain parts of the radio spectrum. We have to pass up to three examinations that are regulated by the ACMA and delivered by the WIA to prove we are competent to operate radio equipment in the allocated radio frequency spectrum and within the strict electromagnetic radiation standards.

Part of the spectrum that we are licensed to operate in is the high frequency (HF 3-30MHz) spectrum that affords long-distance communications, across the world. It is this spectrum that current BPL technology uses indiscriminately.

As a group, amateurs only use portions of the spectrum, and as individuals we use just sections of those portions, at any one time. Whereas, one BPL location uses all of the HF spectrum and leaves no room for any other user.

Amateur Radio Allocation within High Frequency Spectrum

 

Broadband over PowerLine usage of High Frequency Spectrum

3.5-3.8MHz

 

2 - 7MHz
7.85 - 12.85MHz
13.5 - 23.5MHz
24 - 30MHz
3.0 - 13MHz
14 - 34MHz
4 - 34MHz
(dependent on BPL band plan used)

7.0-7.3MHz

10.10-10.15MHz

14.0-14.35MHz

18.068-18.168MHz

21.0-21.45MHz

24.89-24.99MHz

28.0-29.7MHz

BPL systems are an array of radio transceivers using the powerlines as the transmission medium. These powerlines act in some instances as large antennas with dynamically varying characteristics due to power factor correction and changing power network configuration.

BPL operators are not a licensed user of the HF spectrum and yet the technology they are deploying has the potential to cause interference across the whole HF part of the radio frequency spectrum.

Who else uses the HF Spectrum:

  • Defence

  • Aeronautical

  • Broadcasting (TV, Radio Australia, etc)

  • Radio Astronomers

  • Maritime services

  • Marine emergency

  • Fixed and land mobile users

  • Recreational users also utilise this spectrum.

What is BPLGoto Top of Page

BPL (Broadband over Power Lines) or PLT (Power Line Telecommunications) is a technology to enable the delivery of high speed data service over the power distribution system.

This technology injects high power, high frequency (typically between 2 and 80MHz) signals over the power distribution network to deliver high speed data services to homes and businesses. This type of BPL is termed "Access BPL". There is also "in-house BPL" which uses building wiring to distribute data service throughout a building. These systems are currently incompatible.

What is the Issue?

The issue is that there is a high potential for interference to the high frequency spectrum through the use of this technique. It has been described as "spectrum pollution". This is mainly due to the power distribution network not being an efficient and effective medium for the transmission of high frequency data services.

It creates interference to such a level that a HF spectrum user within the trial area cannot hear or transmit a signal. Due to the nature of the high frequency spectrum and its ability to propagate long distances, this interference can propagate around the world.

This causes great concern about this technology not only now but into the future when the sun-spot cycle improves propagation. The technology is also prone to interference from other transmitters in the area.Goto Top of Page

Even the ACMA in their Access BPL Guidelines admit:

“Use of the electricity supply network to convey BPL signals will result in the leakage of radiofrequency emissions. This leakage has potential to cause interference to radiocommunications services.”

Each time a radio amateur operates, he or she listens first to ensure that their transmission will not interfere with an existing communication path. With the presence of BPL, the amateur is prevented from hearing as to whether another communication already exists or not. Thus he or she is prevented from transmitting anything at all, as well as hearing any reply that may have been possible

Interference

Access BPL systems cause interference to radiocommunications services, this is a demonstrable fact:

EXAMPLES of interference:Goto Top of Page

  • Trial in Europe, the UK, Japanese and USA trials and deployments that Access BPL systems generate significant RF interference to existing spectrum users by raising the local spectrum noise floor many tens of decibels (references 1-8);

  • Australian trials of Access BPL systems have demonstrated the same capacity to generate significant RF interference (ACMA & Owen Duffy);

  • Access BPL systems generate RF interference over large geographic areas (refs 2(c), 3, 8).

  • WIA observations of Australian trials have shown that the capacity of these BPL systems to cause interference extends to 2 km or more from the activated power lines.

  • Widely-deployed Access BPL systems have the capacity to cause RF interference over enormous geographic areas (refs 3, 4, 8). This would be exacerbated by over-the-horizon propagation via the ionosphere, particularly from Sporadic E layers which afford specular (ie. lossless) reflection and ray-focusing, resulting in RF field strengths above that arising from free-space path loss values (refs 3, 14).

  • It has also been demonstrated that Access BPL systems generate RF interference extending more than a decade beyond the top system frequency (ie. >300 MHz). This effect has been ascribed to non-linearities in the power lines (refs 8(b), 12 (c)).

Access BPL systems are intended to be “always on”. Thus:

  • the RF interference they generate will be ever-present;

  • only the level and system bandwidth will vary with system parameters and varying user demand.

(WIA Submission to the ACMA on the Management of BPL Interference p.11)

BPL is not an efficient technologyGoto Top of Page

Inductive and capacitive injection of radio frequency on to powerlines originally designed to carry power is a very inefficient process and this means that the signal needs to be injected with high power and boosted every 3-4 power poles and this makes the technology more expensive than other competing technologies.

This also means there is a radio frequency transmitter every 3-4 poles that boosts the signal. This also means it is not a cost effective technology in rural areas and relies on densely populated areas (the suburbs) to get any appreciable return on investment.

BPL is an expensive technology to deploy

The following table provides an indication of the relativities between different broadband technology costs: 

Product

$/House Hold passed

Customer Premises Equipment Cost

Speed (Mbps)

ADSL2+

US$5

US$50

6-10

Unlicenced – WiFi, etc (2.4 & 5.8GHz) wireless

US$7-15

US$50

1

Unlicenced – Motorola Canopy wireless

US$7

US$120-180

1

WiMax (licenced spectrum)

US$12

US$50

1

Licenced spectrum wireless

US$12-20

US$200-$300

1

BPL

US$30-$125

US$30-50

1-2

Source: Earthlink’s Submission report to FCC 12/2004

The State of New Jersey white paper includes additional information from the Shpigler Group report on the deployment cost of competing access technologies:

Deployment Cost Per Subscriber:

Access Method

Cost Per Subscriber (US$)

Wireless

$800

DSL

$828

Cable Modem

$900

BPL

$1,007

Satellite

$1,408

FTTH

$1,825

Source: The Shpigler Group, United Telcom Council Research, Opportunities in Broadband over Power Line, Final Report at 189, (2004)

BPL is often touted as the solution for internet service provision in rural areas. However Anthony Good in his FAQ on BPL convincing proves this wrong

Alternatives to BPLGoto Top of Page

  • DSL (Digital Subscriber Lines) – ADSL, ADSL2, etc

  • Cable Television,

  • WiFi and WiMax,

  • Mesh Networks – wireless mesh,

  • Wireless Internet Service Providers (WISPs)

  • Fibre Optic cable,

  • Satellite (currently being utilised in rural and regional areas),

  • Technology Improvements – CableLabs improvement in bandwidth over cable – Motorola Canopy WiFi/Homeplug solutions.

In America & Europe - take a look at: BPL Deployment

In Australia - take a look at: ACMA Australia TrialsGoto Top of Page

Summary of overseas trial outcomes: Caslon Analytics

Concluded Deployments: Wikipedia

Other Australian Trials

Owen Duffy – VK1OD conclusions – comments sourced from the VK1OD website:

Queanbeyan BPL trial - VK1OD conclusion:

An amateur station located in the trial precinct would not be safely able to transmit at all on the 7MHz band because of the high risk of interference to possibly active stations that would not be heard through the BPL interference, effectively curtailing all activity on the band by such a station.

Woomera Online BPL Trial Moruya NSW – VK1OD conclusion:

An amateur radio station located in a residential environment where a similar BPL system was deployed would not be safely able to transmit at all on the 3.6MHz and 21MHz bands because of the high risk of interference to possibly active stations that would not be heard through the BPL interference, effectively curtailing all activity on the band by such a station.

Who is trailing it in Tasmania?

The first BPL trial in April/May 2004 was conducted by Aurora Energy in partnership with Japan’s Mitsubishi Electric and Tasmanian Internet company KeyPoint. The second BPL trial started in late August 2005 and is being conducted by Aurora Energy again in partnership with Japan’s Mitsubishi Electric and Aurora's telco company Tastel.

First Trial

The first trial occurred in April/May 2004. It  provided broadband internet to 4 houses (23-29 Kirksway Place and the 1st and 2nd floors of the Aurora office building in 21 Kirksway Place, 7 users all up. Mitsubishi engineers from Japan installed the equipment.

kirkswayplace.JPG (105139 bytes)The four houses and Aurora Building behind

More comprehensive report on the trial can be found HERE.Goto Top of Page

Second Trial

The second trial commenced on August 29, 2005. The trial will cover 500 homes in Mt Nelson/Tolmans Hill, Burnie and Hobart areas. The trial will run for 9-12 months and the success of the trial will apparently depend on the number of subscribers to the Tastel BPL service. 

Aurora Energy abandoned its second trial on 27 November 2007 citing it was not commercially viable in the current telecommunications climate.

What does BPL infrastructure look like?

Pole installations around Hobart: 

SthHobart_A.jpg (131021 bytes)Goto Top of PageMtNelsonWirelessAntenna&Coupler200601B.jpg (34338 bytes)15a.jpg (65261 bytes)

SthHobart_B.jpg (138307 bytes)Goto Top of PageBPL_kit_Sth_Hobart.jpg (40385 bytes)BPL_kit_Sth_Hobart_Davey.jpg (64692 bytes)MNWirelessD.jpg (54136 bytes)

Customer Premises Equipment:

Mitsubishi_CPE_Installation.jpg (114053 bytes)Mitsubishi_CPE_Modem_A.jpg (121300 bytes)Mitsubishi_CPE_Modem_B.jpg (192457 bytes)

What does it sound like on the air?

  • First Aurora Trial (DS2 45Mbps OFDM) 14Mhz AM in Kirksway Place. Courtesy of VK7TAS. (wav file)

  • Second Aurora Trial (DS2 200Mbps OFDM) Mt Nelson (80m band, LSB) . Courtesy of VK7HCK. (MP3 file)

  • Second Aurora Trial (DS2 200Mbps OFDM) Mt Nelson Normal Background Noise on 28.200MHz (USB, Rx B/W 2153Hz). Courtesy of VK7TW. (MP3 file)

  • Second Aurora Trial (DS2 200Mbps OFDM) Mt Nelson 28.200MHz (USB, Rx B/W 2153Hz) in Trial area. Courtesy of VK7TW. (MP3 file)

  • Second Aurora Trial (DS2 200Mbps OFDM) Mt Nelson Tuning across the 15m band (USB, Rx B/W 2153Hz). Courtesy of VK7TW. (MP3 file)

  • Second Aurora Trial (DS2 200Mbps OFDM) Mt Nelson Tuning across the 20m band (USB, Rx B/W 2153Hz). Courtesy of VK7TW. (MP3 file)Goto Top of Page

  • Second Aurora Trial (DS2 200Mbps OFDM) Tolmans Hill 21.100MHz (USB, Rx B/W 2153Hz). Courtesy of VK7TW. (MP3 file)

Spectran Files

Application Used: SPECTRAN

BPL Virtual Tours

Emission Measurements

Are you experiencing interference?Goto Top of Page

If you believe you are being affected by BPL interference we suggest you contact the WIA BPL Interference Advisory Service.

Mailing Lists

 
 


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Last modified: February 02 2009 21:33:47.
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