Other sources of radio interference (QRM)
Power Line Technology and its lack of EMC compliance is just the tip of the iceberg. Members of UKQRM, drawn from Radio Amateurs, Shortwave radio listeners, Citizens' Band radio users, and people with an interest in seeing justice done, have spent the last few years discussing other sources of radio interference (known as QRM) and how to mitigate them.
Examples of QRM generators are:
- Switched Mode Power Supplies (SMPS) - used to switch the domestic mains to voltages suitable for lower-powered electronic devices are a very efficient way of converting power when designed and manufactured correctly. Unfortunately, there are unscrupulous manufacturers who like to omit filtering components to save a few dollars on manufacture. These filter-less SMPS devices can generate a considerable amount of RFI when in operation.
- Variable heat-control Combi (Gas) boilers - have been designed with a Pulse-Width-Modulated (PWM) valve which radiates interference.
- Thermostats - ageing electrical contacts act as a spark gap transmitter causing a great deal of interference.
- Ageing Plasma televisions - create large amounts of interference when they increase their screen-driver power to maintain brightness.
- Photovoltaic power inverters (solar panels) - cheap and nasty models have been detected creating large amounts of interference when the sun shines.
What can you do?
Check it is not within your property. If you have a radio which can run on batteries, power down your entire house at the fuse board and check the interference is not coming from something you own. If the interference is still present, it is most likely external in origin. If the interference has gone away, power up individual items until the interference comes back. Once detected, isolate that piece of equipment to double-check.
If you are suffering from PLT related interference, throwing the switch at the fuse board may not stop it from entering your property (contrary to the claims of the PLT manufacturers!). The 'Conducted Emissions' injected onto the mains wiring by PLT devices travels into the homes of everyone who are also connected to the same local 11kV-415V transformer; as each home (and lamp post) shares a common neutral with the transformer. The Protective Multiple Earthing system employed in the UK sees the earth wires running around your house all connect back to the same common neutral; which provides a nice aerial to radiate the PLT interference! We do not recommend disconnecting the PME for your house as this will stop the safety devices in your fuse board from operating correctly.
Once you are certain the interference is external, report it to Ofcom and be prepared for the run-around!
Ofcom
Use this link: https://stakeholders.ofcom.org.uk/tell-us/abuse-amateur-radio-system to report the interference; or telephone: 0300 123 3333
Ignore the part about being a Radio Amateur and enter "n/a" in the licence number and callsign area. Ofcom are trying exceptionally hard to hide and obscure the ability to report interference.
Ofcom now triage calls on a 24/7 basis, so you may receive a phone call shortly after filing the complaint (unless you telephone them). Be prepared to be fobbed off on the BBC (for shortwave listening complaints) and given the brush-off. Stick to your guns and insist on a Field Engineer visit.
Ensure you receive a Case number for your complaint. Ask for one if they do not automatically offer it. Without the case number you have no ability to track the complaint! If you are filing complaints for multiple interference sources, ensure each source is given a case number, else Ofcom will continue to lie about the total number of complaints and their sources.
The Radio Society of Great Britain would also like to hear from you. Please complete their EMC survey to help them compile real figures on the extent of interference.
Case closed
Ofcom do not like to do their job, unless it makes loads of cash! It makes their stats look bad, so they prefer to close cases without resolving the issues. They will close the case without investigating...
If you are a Citizens' Band radio user, Ofcom will cite section 1.6 of the Wireless Telegraphy Act to justify their in-action!
Wireless Telegraphy (WT) Act licence exemption and regulatory issues
1.6 Please note: users must understand that CB radio equipment shall be operated on a 'non-interference, non-protected' basis; that is, it shall not cause harmful interference to, and shall not claim protection from, other radio services.
If you are a Shortwave radio listener, Ofcom will forcefully insist you contact the BBC's new Radio and Television Investigation Service. If the problem is EMC non-compliance related (as with PLT), the BBC will send you straight back to Ofcom!
The only hope you have of an investigation is if you hold a licence, such as a Radio Amateur Foundation/Intermediate/Full licence, or a licence for services such as Taxi radio, or shopping centre security. Even then, there is no guarantee that your investigation will yield results. If the device found to be causing interference is CE marked, Ofcom will state their hands are tied and they cannot remove it from service.
The buck stops at BIS
The UK Department for Business, Innovation and Skills are responsible for Ofcom and you should address your complaint(s), via your MP, to Mark Prisk MP, the Minister (currently) in charge of BIS.
We recommend you use the WriteToThem website to write to BIS via your MP. List your details, your case number(s), times, dates, etc., and provide the Minister with a first-hand account of Ofcom's failings. Maybe then, BIS will do the decent thing and get rid of Ofcom?!
Page updated: 17th May 2011
What does PLT sound like?
UPA PLT sounds.
HPA PLT sounds.
Sounds courtesy of UKQRM.