HOW THEY WORK:“The Digital Radio”

When we talk of the “Digital Radio”, many people are tempted to think of the radio that has a “Numeric Tuner”. What is a “Numeric Tuner”? If we do not understand this, then we might misunderstand the whole concept of Digital Radio. The Numeric Tuner is that one where the Radio Set owner locates a station by entering the Frequency “numerically”, all the same, this does not amount to that radio being Digital. The digital part is mainly to do with the signal transmission and reception. As earlier discussed, Radio is a way of sending electrical energy between two places without using wires. That’s why it’s often called wireless. The piece of equipment that sends a radio wave is called a transmitter; the radio wave ends its journey at another piece of equipment called a receiver. This is true for both the Digital Radio and its older counterpart, the Analog Radio. However, this does not make the duo the same. Though they may have lots of similarities, they arequite different in form and substance. It is important to draw a clear distinction between the two technologies. In analog radio, the basis of transporting signals from the transmitter to the receiver as in AM and FM transmissions is that, the program signal gets integrated within the wave that carries it, if there is any interruption or disruption in the wave as it travels, part or all of the signal may get lost in the process. And if it gets lost, there is no way of retrieving it back. Imagine you are lost at sea and you try sending a distress signal to be rescued, but along the way, that signal is interrupted by a passing ship and it completely gets lost. In order to find a workaround for this problem we could arrange in advance that we will communicate by a special code. To this end, one could store hundreds of plastic balls on my boat, each one carrying a number. If you get into trouble, you could send an emergency coded message “12345” by releasing just the balls with those numbers. Suppose you are faced with a distress situation. You may release the balls with the numbers 1, 2, 3, 4, and 5, but you could send maybe 20 or 50 of each type of ball so as to increase the chances of the message arriving. This time round, even if two ships pass through the water way, the probability that some of the balls will continue is high; increasing the chances of the balls getting through. Eventually, waves will carry the balls with the numbers 1, 2, 3, 4, and 5 ashore. You collect these balls together and are able to receive the message. When compared, the digital radio breaks the signal into very many fragments, these are coded in numbers or digits (the concept of Digitalisation), these are sent many times or can we say that, they are duplicated several times. When there is an interruption of some of them or even a destruction of them, others will follow and get through to the destination. This is less like the biological process of pollination, where one grain is needed but the bee carrying the pollen may carry up to a thousand grains, this is not waste but a process of eliminating any chances of failure. In order to avoid interference, a digital radio signal travels on a huge, broad band of radio frequencies about 1500 times wider than those used in analog radio. To return to our ship example, if you could send a wave 1500 times wider, it would bypass any ship that got in the way and get to the shore more easily. This wide band allows a single digital signal to carry six stereo music programs or 20 speech programs in one go. Blending signals together in this way is called multiplexing. Part of the signal might be music, while another part could be a stream of text information that tells you what the music is, the name of the DJ, which radio station you’re listening to, and so on. Most of the Digital radio signals are transmitted via the Satellite. This is similar to the DSTV (Digital Satellite TV) but differs from the kind of receivers that they employ to convert the signalback to the recipients’ consumption. A number of Digital Radios require specialised Radio sets and a subscription package. A good example of the above is the popular “World Space Radio”. eddie@afrowebs.com