Characteristics Of Radio 3s34m

CHARACTERISTICS OF RADIO In early times messages were sent over the wires by alternately turning electrical currents on and off, producing a series of "dots" and "dashes" in accordance with a telegraph code. There were many drawbacks of this system like it was one to one message delivery method , and was wire dependent or we can say the media was the wires that had a network between the places where the communication was needed. Another was the data transferred in coded form, special training was needed to code and decode the data. But with the more development in science, a significant advancement in communications was the developed as radio, or wireless communication. It proved to be revolution in communication field. Radio extended the communication range to ships in the sea and to remote areas of the world, providing for the first time instantaneous and worldwide communication. After people learned how to encode and decode the human voice in a form that could be super imposed on electromagnetic waves and transmitted to a receiver, they used this mode as radio communication directly with human speech. So the human voice was transmitted thousands of miles, picked up by receivers and converted back into speech by loudspeakers. It was like revolution in the field of communication. Radio came to be the first complete electronic communication system. Speech now could be transferred from one part of the earth to another or from a point on earth to a point in space. This was not limited to land or land to space but also from land to sea and sea to space. Also the message delivery rate was increased to the speed of light, making international communications possible within fractions of second, and space communications within seconds. Now communicating with the soldiers or people on the far most outskirts was not a big deal. The radiation concept of radio waves can be visualized by dropping a pebble into a pool of still water. As the pebble enters the water, a surface disturbance is created, causing the water to move up and down. From this point, the disturbance is transmitted on the surface of the pool in the form of expanding circles of waves. Here the water is not moving away from the point. The type of wave here produced is called the transverse wave. That is the wave occurring in a direction or directions perpendicular to the direction of wave propagation. Same are the characteristics of the radio waves. Although there is no clear cut demarcation between radio waves and micro waves, electromagnetic waves ranging in frequencies between three kilohertz and one gigahertz are normally called radio waves. However the behavior of waves, rather than the frequencies is a better criterion for classification.

FM Radio Transmission

Radio waves are a type of electromagnetic wave. Since it is a wave, we can make an analogy between radio waves and water waves. The figure at the left shows a scenerio where water waves propogate from a single center point by the a ction of tossing a rock into the water. Radio waves cause electrons in an antenna to surge back and forth the same way that the ripples in a pond case the the water to move up and down. Unlike water waves, radio waves travel at the speed of light (186,000 miles per second). " Just like light waves, radio waves travel in straight lines. Radio waves can reflect off of surfaces, such as layers of ionized gases in the ionosphere. Radio waves reflect off of surfaces the same way that water waves do. The reflection of radio waves is shown in the figure below. Here, radio waves are reflected off of the ionosphere and the Earth. Radio waves, however are not shaped like the circular water waves. Radio waves typically are domed shaped as shown in the picture to the right. These domed-shaped waves radiate from a transmitting antenna in all directions. Waves of different wavelenghts can cross or even travel along the same lines without interfering with the others. This allows several waves to exist at the same time - all at different frequencies. It is the job of the receiver to tune into a specific frequency and ignore all radio signals at other frequencies.

Amplitude modulation was the first radio transmission method. Amplitude modulation works by creating a signal which is has a constant frequency at whatever radio frequency you want to broadcast at (1Mhz for example). The amplitude of the wave is then changed according to the strength of the signal being broadcasted. The sound that humans here is caused by vibrations in air. If a sound is loud, the vibration will be large, if the sound is soft, the vibration will be small. This is shown in the figure above. The changing magnitude and the frequency of the wave shown above is what actually carries sound information to the human ear. The human ear can hear sounds in the range from 20Hz to 20,000Hz, where the unit Hz is used to indicate the frequency of the sound wave. A really deep sound will have a low frequency and a really highpitched sound will have a high frequency. These small frequency waves cannot be transmitted. These audio frequency waves must somehow be changed in order to be transmitted. The two methods of doing this are frequency modulation (FM) and amplitude modulation (AM). Amplitude modulation was the first radio transmission method. Amplitude modulation works by creating a signal which is has a constant frequency at whatever radio frequency you want to broadcast at (1Mhz for example). The amplitude of the wave is then changed according to the strength of the signal being broadcasted. Frequency Modulation is the most popular radio transmission technique used today. FM is so popular because it is able to transmit more of the sound that we want to here. AM has problems in transmitting sounds which are at higher frequencies, such as those created by a flute. Frequency modulation works by first creating a signal at the desired carrier frequency (107.7Mhz for example). Then the varying sound level causes frequency changes - The louder the sound, the frequency of the carrier wave increases. Frequency modulation is shown in the figure below. An important factor in FM is that the carrier signal has a constant amplitude.

TV Television (TV) is a widely used telecommunication medium for transmitting and receiving moving images, either monochromatic ("black and white") or color, usually accompanied by sound. "Television" may also refer specifically to a television set,

television programming or television transmission. The word is derived from mixed Latin and Greek roots, meaning "far sight": Greek tele (τῆλε), far, and Latin visio, sight (from video, vis- to see, or to view in the first person). Commercially available since the late 1930s, the television set has become a common communications receiver in homes, businesses and institutions, particularly as a source of entertainment and news. Since the 1970s the availability of video cassettes, laserdiscs, DVDs and now Blu-ray Discs, have resulted in the television set frequently being used for viewing recorded as well as broadcast material. Although other forms such as closed-circuit television (CCTV) are in use, the most common usage of the medium is for broadcast television, which was modeled on the existing radio broadcasting systems developed in the 1920s, and uses high-powered radio-frequency transmitters to broadcast the television signal to individual TV receivers. Broadcast TV is typically disseminated via radio transmissions on designated channels in the 54–890 megahertz frequency band[1]. Signals are now often transmitted with stereo and/or surround sound in many countries. Until the 2000s broadcast TV programs were generally recorded and transmitted as an analog signal, but in recent years public and commercial broadcasters have been progressively introducing digital television broadcasting technology. A standard television set comprises multiple internal electronic circuits, including those for receiving and decoding broadcast signals. A visual display device which lacks a tuner is properly called a monitor, rather than a television. A television system may use different technical standards such as digital television (DTV) and high-definition television (HDTV). Television systems are also used for surveillance, industrial process control, and guiding of weapons, in places where direct observation is difficult or dangerous. Amateur television (ham TV or ATV) is also used for experimentation, pleasure and public service events by amateur radio operators. Ham TV stations were on the air in many cities before commercial TV stations came on the air.[2]

Radio documentary A radio documentary or feature is a radio documentary programme devoted to covering a particular topic in some depth, usually with a mixture of commentary and sound pictures. Some radio features, especially those including specially composed music or other pieces of audio art, resemble radio drama in many ways, though non-fictional in subject matter, while others consist principally of more straightforward, journalistic-type reporting – but at much greater length than found in an ordinary news report.

Phone-in In broadcasting, a phone-in or call-in is a programme format in which viewers or listeners are invited to air their live comments by telephone, usually in respect of a specific topic selected for discussion on the day of the broadcast. On radio (especially talk radio), it is common for an entire programme to be dedicated to a phone-in session. On television, phone ins are often part of a wider discussion programme: a current example in the UK is The Wright Stuff. BBC Radio Nottingham is credited with having aired the first British phone-in on 4 February 1968, in a programme called What Are They Up To Now? Speech based Talk Radio UK was launched in 1995, with much of its programming featuring phone-ins. It also introduced the notion of the shock jock to the UK, with presenters like Caesar the Geezer and Tommy Boyd constructing heated discussions. Ian Hutchby has researched power relations in phone ins, looking at arguments and confrontations. Using conversation analysis, he describes how the host retains power through devices such as "The Second Position" — the concept of going second in a discussion, giving the host time to formulate a response. Similarly, the last word is always the broadcast word. The public can choose to end the conversation, but they are doing so by withdrawing from the interactional arena (Hutchby, 1996: 94-5; Talbot et al.). In 2007, the BBC suspended all phone-in competitions (but not voting) due to an internal inquiry into corruption in the production of these games in shows such as charity telethons after a nationwide inquiry into the whole process leading to the cancellation of ITV Play. Technology The caller is connected via a telephone hybrid, which connects the telephone line to the audio console through impedance matching, or more modernly through digital signal processing, which can improve the perceived audio quality of the call. Telephone calls are often organised through a system which also provides broadcast automation, with an istrative assistant answering calls and entering caller information on a personal computer, which also displays on the radio presenter's screen. A profanity delay is often used to keep profanity and other inappropriate material off the air. For contests, the conversation can be recorded and edited "on the fly", before playback on the air just a few minutes later.