"Digital whine" (PLT interference)

PLT (Power Line Telecommunications) products have been found to produce interference on LW, MW and shortwave. The interference is a high-pitched pulsating whine which also has the characteristic of regular cyclic variations in sound quality as you tune steadily across the dial. It rarely causes problems when listening to strong stations, but is a nuisance when signals are weaker.

The commonest PLT devices are Powerline Ethernet Adapters used for home computer networking and internet connection, using the mains wiring to transfer data from one room to another. They may be supplied by your Internet Service Provider (ISP) as part of a package.

N.B. True wireless modems and hubs are not PLT devices and do not normally cause problems.


What to do

If the devices are in your own home, you can turn them off when listening on AM, or replace them with a conventional wireless network. Contact your ISP if they supplied the device to you. Tests have found that some makes of PLT device produce a lower level of interference so if your (or a neighbour's) device is a higher level, you may ask your ISP to change your units for a different model.

The UK communications regulator Ofcom are aware of this issue. To find out more about PLT and possible future developments, visit the Ofcom Website and enter PLT in the search box.

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