I agree with Al (airborne rather than system borne.) In addition to the sources of RFI he mentions, I'd like to add two more: (1.) the power cables on ANY digital equipment, and (2.)the RFI created by static discharge such as people walking across rugs/carpets, clothes tumbling in the dryer, etc.
It is important that power cables used with ANY equipment containing digital processing circuits (even if it's just a digital display) are well shielded. And that the associated outlets (wall or power conditioner) have filters that drain 'digital hash' to ground.
It is important that power cables used with ANY equipment containing digital processing circuits (even if it's just a digital display) are well shielded. And that the associated outlets (wall or power conditioner) have filters that drain 'digital hash' to ground.