Electromagnetic interference or EMI is any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronic or electrical equipment. It can be induced intentionally, as in some forms of electronic warfare, or unintentionally, as a result of spurious emissions and responses, intermodulation[?] products, and the like. It is also known as radio frequencyinterference.
... their ordinary channels BBC1 and BBC2, using terrestrial signals, and this is seen by some as influential (to a certain limited extent) in promoting the take-up of digital ...