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Short Wave Radio

Page history last edited by rince@iwc.edu 9 years, 3 months ago

Overview

 

 

   

     Short-wave radio is used for amplitude-modulated (AM) broadcasting over long distances and for communication to ships and aircraft using the ionosphere [1]. According to the Websters dictionary, the ionosphere is one of the four layers of the Earth's upper atmosphere in which  ionization of atmospheric gases affects and create free electrons that can reflect radio signals, enabling their transmission around the world. Shortwave broadcasts can be easily transmitted over a distance of several thousands of kilometers, which equals the distance between America and Europe. The short wave radio is one of the cheapest most effective way to communicate information through out the world. the affect that the Ionsphere have on the frequency waves of the short wave radio allows for information to be transmitted anywhere by just the flick of a switch 

 

 

 

     Radio waves are broadcasted in several wave bands, bands are groups of frequencies grouped together by wavelengths in meters, often called long wave, medium wave, short wave bands. Each band contains a range of frequencies or wavelengths and each station or channel has its own particular frequency or wavelength within a band.  Long wave bands can range anywhere from 30 to 300 kilohertz, while medium wave bands can range from 300 to 3000 kilohertz. Short wave radios on the other hand only range from 3 to 30 megahertz.

 

 

History

 

     The first successful short-wave radio transmission was conducted in 1920 by Guglielmo Marconi and his researchers. Marconi led the way for short-wave radio. His successful transmission from his observation station in Cornwall, England to his yacht in the Cape Verde Islands made the demand for short wave communication robust. By the late 1920s majority of the long distance communications moved from the idea of transoceanic cables and long-wave wireless services to shortwave communication capabilities [2]. The use of short-wave radios led to the decline in investments of new transoceanic telegraph cables and massive long-wave wireless stations.  With the lost of these million dollar investments, more money was able to be used to sustain short wave communication methods throughout the world.

 

Applications

 

     There are three main uses for short wave radios. The most familiar of them all were International broadcasting. These international broadcasts were made by the government and intended to entertain, inform, or coerce foreign viewers.  Another important way that short wave radios were utilized is with the idea of domestic broadcasting.  Domestic broadcasting refers to transmission of local news, music, and media to the population [3]. The final way that short wave radios are incorporated in to the everyday life of humans, are the application it holds to emergency radio transmission.  Emergency radio transmission is a term used by the government to describe all communication with government agencies and organizations that is conducted over radio frequencies [4].  A few examples of how of short wave emergency radio transmissions would be ships that are away at sea, airplanes, weather stations. Short wave radios have been known to even be used in emergency vehicles such as police cars and fire trucks.

 

Shortwave Band Chart [6]
BAND MEGAHERTZ (MHz) KILOHERTZ (KHz)
120 m 2.300-2.500 MHz 2300-2500 KHz
90 m 3.20-3.40 MHz 3200-3400 KHz
75 m 3.90-4.00 MHz 3900-4000 KHz
60 m 4.750-5.060 MHz 4750-5060 KHz
49 m 5.950-6.20 MHz 5950-6200 KHz
41 m 7.10-7.60 MHz 7100-7600 KHz
31 m 9.20-9.90 MHz 9500-9900 KHz
25 m 11.600-12.200 MHz 11600-12100 KHz
22 m 13.570-13.870 MHz 13570-13870 KHz
19 m 15.10-15.80 MHz 15100-15800 KHz
16 m 17.480-17.90 MHz 17480-17900 KHz
13 m 21.450-21.850 MHz 21450-21850 KHz
11 m 25.60-26.10 MHz 25600-26100 KHz

 

     The ability for the ionosphere to free up electrons, that are vital to the ability to transmit short wave radio signals, is due to the sun. With this being said, some short wave frequencies may receive better signals than others due to the time of day. according to researchers of the short wave radio, the best time for listening to short wave broadcast is right around sunset and sunrise [6]. The Chart above shows stations at both their day time and night time frequency. The difference between day time and night time listening, is based on the simple idea of the frequency of the specific band. During the day wave bands with frequencies above 13 MHZ or 13000 KHZ can travel further making reception clearer and stations easily accessible. this is the exact opposite for night time listeners. wave bands below 13 MHZ or 13000 KHZ can travel further at night making night time listening simple.

 

Advantages

 

     In regards to all of the applications that are dependent of short wave radios, there are a lot of advantages that comes with owning and using short wave radios. The advantage that might seem more prevalent is the idea that Short wave radios are very inexpensive. With this being said short wave radios were easily obtainable by all classes of society. Another key advantage is , that due to the fact that short wave frequencies transmission are easily acquired and functional, makes censoring by government officials complicated. With this being said short wave transmission are hard to detect and makes monitoring the information a serious and not easily done task. These kinds of frequencies are favorable by emergency organizations because short wave radios transmissions can be accessed in areas that internet and satellite communications are undetectable [5].

 

Disadvantages

 

     The disadvantages of short wave radios aren’t as prominent as the advantages but are just as important. There are three main disadvantages that short wave radios pose. The first is, due to the easily pirated stations short wave frequencies can become extremely crowded which lowers the quality of the sound and interferes with the transmission of information. Similar to the problem of pirated stations, the availability of the television and internet leaves short wave radios as a technological system that is on the verge of extinction [5]. The television and internet allows people to receive the same information that can be perceived through the radio at more accessible times and forms of technology. The most nonchalant disadvantage is the fact that, most people who use short wave radios are those who are interested in them and knows the correct way to maneuver through the technology.  With this being said those users who are not interested in the technology might find it difficult to use and operate short wave radios.

 

Implications To Media Ecology

     

     The connection of the short wave radio to media ecology is a simple and sometimes overlooked connection. The impact of the radio alone was vital to the everday life of early citizens, the radio offered people a form of entertainment that the whole family could enjoy. The short wave radio on the other hand, although mostly used as an entertainment device, one of the main impact was that it allowed the way for people to connect to and listen to broadcast from all over the world. This allowed people in the united states to listen to broadcast from Europe, in order to get an idea of the life over there by listening to the local news of the area. The biggest impact that short wave radio had on the people as well as societies around the world is the ability it had to advance emergency communications. In times of disasters and places where a phone is hard to come by, communication was made possible due to the transmission of short wave radio signals. These messages can be transmitted all around the world naturally by using the ionosphere, leaving no area without some form of communication.

 

References

[1] Gibilisco, Stan, and Neil Sclater. Encyclopedia of Electronics. 2nd ed. Blue Ridge Summit: TAB Books, 1990. 764-65. Print

[2] Macaulay, David. New Way Things Work. New York: Houghton Mifflin Company, 1998. 240-41. Print.

[3]radio wave. (2009). In Britannica Concise Encyclopedia. Retrieved from http://www.credoreference.com/entry/ebconcise/radio_wave

[4]radio." The Macmillan Encyclopedia. Basingstoke: Macmillan Publishers Ltd, 2003. Credo Reference.

[5]Batchelor, Bob. "Radio." Dictionary of American History. Ed. Stanley I. Kutler. 3rd ed. Vol. 7. New York: Charles Scribner's Sons, 2003. 18-21. Gale Virtual Reference Library.http://go.galegroup.com/ps/i.do?&id=GALE%7CCX3401803496&v=2.1&u=mt85337&it=r&p=GVRL&sw=w

[6] http://www.etoncorp.com/shortwavetutorial

Comments (1)

Jeff Martinek said

at 10:44 am on Apr 25, 2011

Ronnie:

This is a start, but you've only written a few paragraphs. Please review the assignment and the model article on General Semantics for an idea on what is expected in order to receive full credit for the assignment. -- JM

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