The delivery system for radio is anything from thirty to ninety years old. Meanwhile, just about everything we do now, from making a phone call or reserving a hotel room to surfing the Internet, involves digital communication processes of some kind. Digital radio will offer fundamental improvements over analogue radio and provide the listener with four key benefits.

CD quality sound

The problem with analogue radio is that it suffers from additional noise and interference to the signal from a variety of sources, such as power lines, car ignitions and even other radio stations. Once this interference creeps into the signal path, there’s really nothing that can be done to remove it. By contrast, digital radio consists of binary digits and because the receiving equipment is only expecting to see a series of ones and zeros, any interfering noise signal tends to be ignored. In fact, in a well designed digital system it’s possible to achieve almost complete immunity from noise and interference.

Interference free reception

There’s a fundamental problem in getting radio signals to work reliably in moving vehicles and since in-car listening is a key segment to any radio station, this is clearly important to overcome.

The culprit is called ‘multipath distortion’, and it affects all FM signals. This is caused by the fact that radio waves do not behave in an orderly fashion, but bounce around reflecting off buildings, mountains and so on. The result is that the receiver will ‘hear’ a signal arriving direct from the transmitter, and reflected signals via a variety of indirect paths. This is the kiss of death to an FM signal – drive round any heavily built up area and you’ll hear the unpleasant hisses and phasing effects of multipath distortion. Digital radio takes advantage of this effect, so the direct and reflected signals actually reinforce each other, rather than trying to destroy each other.

No need to re-tune

Due to digital radio’s immunity to traditional interference effects, a single frequency can be used to cover the entire country. This makes retuning receivers in different parts of the country unnecessary. At a local and regional level, digital radio can use low power single frequency networks (SFN) to provide precise editorial coverage for local stations

Complementary text and data

The opportunity to produce multimedia radio programmes is one of the most exciting aspects of digital radio. This benefit is covered in depth on station 7.