 |
|
|
|
|
After recently purchasing a new home, I decided to set up a home theatre in my daylight basement. I bought the couches, put up the blackout blinds and found a 106" HDTV format screen. However, after all that I didn't have ...
|
New Today: 6 Last 30 Days: 368 Total Published: 9,484 Total Pending: 177 Contributing Authors: 2,806 Article Views: 5,550,758
|
|
|
|
Articles » Communications » How To Dominate Communication Industry
|
|
|
|
|
- Article Views: 692
- Word Count: 738
- Date Contributed: Mar 05, 2007
|
|
- -
|
| How To Dominate Communication Industry |
In the telecommunication environment is dominated by four important sources of information; computer data, music, speech, and pictures. The source of information may be characterised in terms of the signal that carriers the information. The signal is defined as a single valued function of time that plays the role of the independent variable at every instant of time the function has a unique value. The signal can be one dimensional as in the case of speech, music, or computer data. Two dimensional as in the case of pictures, three dimensional as in the case of video data and four dimensional as in the case of volume data over time. In the sequel we elaborate on different sources of information.
In the production an intended message in the speakers mind is represented by a speech signal that consist of sounds generated inside the vocal tract and whose arrangement is governed by the rules of language.
In the propagation the sound waves propagate through the air at a speed of 300 millisecond reaching the listeners ears.
In the perception the incoming sounds are deciphered by the listener into a received message, thereby completing the claim of events that culminate in the transfer of information from the speaker to the listener.
The speech production process may be viewed as a form of filtering in which a sound source excites a vocal tract filter. The vocal tract consists of a tube of non-uniform cross-sectional area beginning at the glottis and ending at the lip. As the sound propagates along the vocal tract the spectrum is shaped by the frequency selectively of the vocal tract this effect is somewhat similar to the resonance phenomenon observed in organ pipes. The important point to note here is that the power spectrum of speech approaches zero for zero frequency and reaches a peak in the neighbourhood of a few hundred hertz. To put matters into proper perspective however we have to keep in mind that the hearing mechanism is very sensitive to frequency. The type of communication system being considered has an important bearing on the band of frequencies considered to be essential for the communication process. A bandwidth of 300 to 3100 Hertz is considered adequate for commercial telephonic communication.
The source of information which is called music, originates from instruments such as the piano, violin, and flute. The note made by a musical instrument may last for a short time interval as in the pressing of a key on a piano or it may be sustained for a long time interval as in the pressing of a key on a piano or it may be sustained for a long time interval. Music has a two structure a melodic structure consisting of a time sequence of sounds and a harmonic structure consisting of a set of simultaneous sounds. A musical signal is a bipolar. However a musical signal differs from a speech signal in that its spectrum occupies a much wider band of frequencies that may extend up to about 15 kilohertz. Accordingly musical signals demand a much wider channel bandwidth than speech signals for their transmission.
The third source of information is a picture relies on the human visual system for its perception. The picture can be dynamic as in television or static as in facsimile. Taking the case of television first the pictures in motion are converted into electrical signals to facilitate their transport from the transmitter to the receiver. To do so each complete picture is sequentially scanned. The scanning process is carried out in a television camera. In a black and white television the camera contains optics designed to focus an image on a photocathode consisting of a large number of photosensitive elements. The charge pattern so generated on the photosensitive surface is scanned by an electron beam thereby producing an output current that varies temporally with the way in which the brightness of the original picture varies spatially from one point to another. The resulting output current is called a video signal. The type of scanning used in television is a form of spatial sampling called raster scanning which converts a two dimensional image intensity into a one dimensional waveform it is somewhat analogous to the manner in which we read a printed paper in that the scanning is performed from left to right on a line by line basis.
Zola Mathe is the researcher and a writer of articles for more information go to http://www.allwiseinformation.com/Electronics_Information_online.html
Article Source: UnArchived Articles
|
|
|
|
|
|
 |
