In our last episode, we tried to highlight on how the Radio Sets interact with the Radio Stations in order for the broadcasts to be able to reach the intended audience. Many of you will have noticed that, we only cover the basics in order to help the common people understand how the devices under cover operate. We are not there to teach professionals, our goal is to give people the basic theories behind these “magical devices”. Imagine receiving music, news casts, talk shows wherever you go! Lets us agree, before the Internet came along, nothing could beat the power of the radio. A radio is simply an amazing box of electronic components that captures any radio waves from the air and turns them back into audible sound that you and I can hear. The radio technology has also become the basis of such new technologies as wireless Internet, cellular phone, and RFID (radio frequency identification) chips. Radio is a way of sending electrical energy between two places without using wires. That’s why it’s often called wireless. The piece or device that sends a radio wave is called a transmitter; and the one that receives such waves is known as the receiver. There are some cases where one device sends as well as receives the radio waves e.g. a walk talkie, in this case, the device is known as a transceiver. Most radio sets have an antenna, this is a device that serves as the radio’s ear, it is always “listening” out for any matching radio waves that it captures and converts back into sound. In reality, the Microphone is used to convert sound into electrical signal or data. This is acted upon by special purpose magnetizing devices that turn it into Electromagnetic energy that is then relayed to the intended recipients via the transmitter’s antenna. As earlier discussed, the radio operates within a specific frequency. Most radios operate on the lower end of the electromagnetic spectrum. The frequency has several layers (with low frequency at one end and high frequency at the other). The radio waves have a certain speed, length, and frequency. The speed is how fast the wave travels between two places. The wavelength is the distance between one crest (wave peak) and the next, while the frequency is the number of waves that arrive each second. Frequency is measured with a unit called hertz, so if ten waves arrive in a second, we call that ten hertz (10 Hz). If youhave ever observed water waves (ripples) rolling from one point to the other, you may have noticed that, they travel with a speed of maybe one meter per second or so, the wavelength of the water waves tends to be tens of meters, and the frequency is about one wave every few seconds. The radio wave’s wavelength is several hundreds of meters distance between one wave crest and the next. Their frequency can be in millions of hertz hence the term Megahertz, these arrive each second. Radio waves travel unbelievably fast at a speed of light (300,000 km or per second). In Ernest, the Radio is a box that receives radio waves from so many sources, e.g. radio, TV broadcasts, wireless communications, electrical inductions etc. All these and many others may contain all the ingredients of a radio signal but are not all desirable. In order to send and receive organized signals, a system was devised; different radio waves were assigned different frequencies so that the intended audience could employ different devices in receiving the transmissions. AM (Amplitude Modulation) has the lower spectrum, SW (Shortwave ) is next, FM (Frequency modulation) comes next, VHF (Very High Frequency) is next and the UHF (Ultra High Frequency). There is normally a problem of interference in the upper end of the FM frequency by TV broadcasts that operate in the VHF as well as the Walk Talkie radios. The higher the frequency (the higher the energy) means the shorter the wave length, the lesser the coverage. This explains why, an AM transmission may travel hundreds of Kilometres away and yet an FM one fades a few tens of kilometres. We have been looking at the “Analog radio”. At one point in time, we might look at the “digital radio”. We shall then explore one vis avis the other. The radio receiver has a tuner (variable resistor) that helps in filtering the waves from each other and hence allowing the listener to get one clear signal. In addition, there are devices that amplify the signal such that, one gets the desired audibility. eddie@afrowebs.com
