Frequently Asked Questions
What is PLT?
PLT (PowerLine Telecommunications) is an umbrella term for devices which transport computer data over the mains electrical system.
Is PLT the same as BPL?
They are the same technology; BPL refers to a system which transports data over the local electricity network (Regional Electricity Company), rather than on the mains circuits of a single dwelling (PLA = Power Line Adapter).
What data rates are there?
The original HomePlug 1.0 was 14Mbps, later, other versions became available with 50, 85, and 200Mbps. A new version currently being pushed is a Gigabit version. The 'headline rates' are significantly higher than the net throughput. Independent tests with the Belkin and Solwise gigabit adapters saw net throughput often as low as 30Mbps. Wi-Fi technology adhering to the 802.11n standard offers throughput speeds of 300Mbps. A Cat 5E/6 cabled solution will offer speeds up to 1Gbps; as well as providing a back-bone system within the home for a variety of "over-Cat5" devices, such as those offering audio and video routing over Cat5 wiring.
What frequencies do they operate on?
Broadly speaking the non-gigabit versions are 2MHz to 32MHz. The gigabit versions operate right up to 300MHz and close-in interference has been observed to 1000MHz (1GHz).
How do I know if I am suffering interference from an installation?
Those who do not already recognise the sound of PLT may not realise they suffer. For those who are curious, UKQRM has a small 'sound database' with audio samples of the most common. If you have observed changes in your favourite radio station's clarity, PLT may be to blame.
If they are not legal, why hasn't the government taken enforcement action and had them recalled?
There is no clear answer to this. Compliance testing to EN55022 has proven that these devices are simply unable to meet the emissions levels laid down to meet European and UK law. It is commonly believed that pressure from political corners to meet the "Digital Britain" targets and powerful corporate lobby have a part to play. A member of UKQRM has personally witnessed an EC representative from DG Enterprise & Industry threaten treaty if we (UK) try to stop PLT.
Why haven't you, UKQRM, RSGB or anyone else taken legal action?
Fighting a regulator is no simple matter. The RSGB has consulted its lawyers and pressing for a Judicial Review looks the most likely to succeed. An initial price tag of £200,000 has been set. Justice is not cheap!
Is there a way I can contribute to the fight against this invisible menace?
Yes, two ways:
a) If you have PLT interference, report it to Ofcom who will come and investigate.
b) Spread this website around to friends and family to make them aware of the PLT menace.
How far does PLT cause interference?
Piece of string question. The interference has been observed to over 1.1km from a single dwelling; however there is a complication: Shortwave signals can bounce off the upper atmosphere (Ionosphere) and come back down to earth. This behaviour peaks every 11 years and a peak has not happened with PLT in widespread use. From 2010 on, there is an increasing chance a single PLT installation could interfere half-way around the world.
I have a set of Powerline adapters, should I stop using them?
That is a matter for your conscience. However should a Stakeholder (radio user) become aware that they are suffering interference from PLT and request Ofcom's help to resolve the issue, there is every chance that Ofcom may come knocking at your door. To date, most instances of PLT interference have only been resolved to the complainant's satisfaction by removal of the devices.
Will I be fined?
Unlikely in 2011. Until a court actually rules PLT as illegal or Ofcom changes its position, this will not happen. However since Ofcom have taken a very 'grey' position, should a PLT user refuse to cooperate with Ofcom to resolve the interference, the complainant may force this into a court and there is no telling where that could lead. What is certain is that radio is protected by international treaty so you are not likely to come out of this particularly well.
What laws are relevant to PLT?
The answer to this may have changed recently. On 27 September 2010 the United Nations' ITU adopted a recommendation for the maximum permitted level of interference to radio services below 80MHz. Prior to this anyone refusing to cooperate with Ofcom or any complainant was fairly safe. With this new Recommendation (more authoritative than an ITU report), Ofcom's obligations under the International Radio Regulations may now force them to take action in cases which they failed to, previously.
Why has this taken so long to become public?
There is a cocktail of reasons. We 'Brits' are not very good at complaining. Ofcom only started to record PLT interference as a documented source the same time as the UKQRM website went live in 2008. The RSGB has been complaining for over a decade but since the principal victims were amateurs and shortwave listeners, no one cared. With the new gigabit PLT affecting VHF stereo FM and DAB there has been a fundamental shift in the demographic of victims and this may have an effect on the perceived significance of the threat. The PA Consulting report has made a significant contribution to this.
This is a load of old horse shit from a bunch of wrinkly old radio hams.
We can only hope that you and your family do not one day require safety-of-life services and their radios. It would be a little brutal of us to say "I told you so!" when you lose a loved one because the radio spectrum in your area was jammed and the Ambulance did not receive their radio message. In reality amateurs could walk away from the fight since the radio amateur bands are protected and notched; if nothing is done amateurs will have the only tenable spectrum left in ten years. Amateurs are involved because the PLT industry is riding roughshod over everyone and this is not acceptable. Shortwave radio listeners and Citizens' Band radio users are involved as they have a legal right to use their allotted radio frequencies. PLT does not!
I want to continue using my PLT equipment because the Wi-Fi channels are all full in my area. Is there something I can do to stop it interfering?
Turn it off and run an Ethernet cable or purchase new Wi-Fi networking technology using 802.11a or 802.11n which uses the 5GHz U-NII band. This band offers less interference (than 2.4GHz) and 802.11n technology is offering up to 300Mbps throughput - idea for High Definition IPTV.
Is there a chance you could be wrong about this?
None. Please see the videos page and see the effects for yourself. The BBC, NATO, EMCIA, Radiocommunications Agency (forerunner to Ofcom) all concluded that PLT was inappropriate.
I read somewhere that 'Adaptive Notching' will stop the interference. Will it?
No. Unless the PLT device has a radio and aerial system similar to the local radio users AND the PLT device knows which station EACH and every user is listening to at ANY moment, it is not possible. Jonathan Stott, the revered ex-BBC engineer stated at the 3 August 2010 meeting, the 'adaptive notching' adapters were supposed to have a synchronised silent period to "listen" for broadcasting signals to notch but this has mysteriously disappeared from the specification. The adapters will be listening to the emissions of other adapters and thus the technique cannot work.
The PA Consulting report states that dynamic power control will fix this, will it?
Just prior to the Stakeholder meeting on 3rd August 2010, the specification for power control was scrutinised. It was discovered that in stark contrast to the claim it was a power reduction (thus mitigation) scheme, it was in fact a power INCREASE scheme, permitting the PLA's to output 15dB higher emissions than the current Comtrend adapters used by BT.
Someone told me to stick a load of clip-on ferrite suppressors on the mains cables of household appliances, will this work?
It is very unlikely since the adapters plug straight into the mains sockets and connect into the ring-main of your house. The embedded electrical wiring itself acts as an antenna.
I've just bought a set of adapters, can I get my money back?
Since the adapters cause interference when they are operating at specification, they are not faulty (they break the law intentionally!). Ofcom have made it clear that from a legal standpoint once the devices have been manufactured and imported, it becomes a matter for Trading Standards to enforce compliance legislation (strictly speaking this is correct). Your best bet is to try and return them as 'bought in error' if they are unopened or "Not fit-for-purpose due to radio interference".
I want to pursue non-compliance through Trading Standards, how should I do this?
EMC law is complex and to succeed you need to be back by sympathetic experts. We suggest speaking with the RSGB or the EMCIA who may be able to offer some tips and/or some measure of support. Also UKQRM is an action group of people who have been affected by PLT or are ethically opposed to the technology, support can be found there.
I have heard that some PLT interferes with VHF, is this true?
Yes. The new Gigabit PLT has been directly observed to interfere to above 350 MHz, blocking VHF FM radio broadcast, the new DAB radio system and even the Civil Air band! Recent tests which demonstrate PLAs are really radio transceivers, operating wirelessly, spectral analysis have shown emissions to 1000 MHz.
How is this going to end?
Unknown. There are ~70,000 Amateur transmitting licences in the UK. The number of Shortwave Listeners and Citizens' Band users is unknown. Other Stakeholders of Shortwave include Emergency Communications, Aeronautical and maritime communications, military and diplomatic communications, Time signals and radio astronomy. As the ionospheric propagation increases with the 11 year sunspot cycle the distances PLT interference can travel will only increase. In the end it is a numbers game. Some people will carry on using the devices for years to come immaterial of any legal developments so the sum of the interference will be determined by the number of PLT devices left in service. The ITU issued a Recommendation on 27th September 2010 stating the maximum permissible level of interference from PLT at 0.5dB above the noise floor. It is unlikely most installations will meet this and so the question of Regulation and enforcement will continue to be hotly debated.
Page updated: 10th September 2012
What is PLT?
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What can I do?
Shame on you!
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