-\ Jitter Jitter refers to the variation in the packet arrival time It is the uneven delay in in Software

Creator Code 39 Full ASCII in Software -\ Jitter Jitter refers to the variation in the packet arrival time It is the uneven delay in

the delivery of audio or video packets For example, let us assume that video packets are sent every 3D ms If some of the packets arrive with 3D-ms delay and others with 4D-ms delay, an uneven quality in the video is the result

A data communications system has five components (see Figure 11)

Rule 1: Rule 2: Rule n: Rule 1: Rule 2:

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forms of information include text, numbers, pictures, audio, and video Sender The sender is the device that sends the data message It can be a computer, workstation, telephone handset, video camera, and so on

3 Receiver The receiver is the device that receives the message It can be a computer, workstation, telephone handset, television, and so on -1 Transmission medium The transmission medium is the physical path by which a message travels from sender to receiver Some examples of transmission media include twisted-pair wire, coaxial cable, fiber-optic cable, and radio waves

5 Protocol A protocol is a set of rules that govern data communications It represents an agreement between the communicating devices Without a protocol, two devices may be connected but not communicating, just as a person speaking French cannot be understood by a person who speaks only Japanese

In data communications, text is represented as a bit pattern, a sequence of bits (Os or Is) Different sets of bit patterns have been designed to represent text symbols Each set is called a code, and the process of representing symbols is called coding Today, the prevalent coding system is called Unicode, which uses 32 bits to represent a symbol or character used in any language in the world The American Standard Code for Information Interchange (ASCII), developed some decades ago in the United States, now constitutes the first 127 characters in Unicode and is also referred to as Basic Latin Appendix A includes part of the Unicode

Numbers are also represented by bit patterns However, a code such as ASCII is not used to represent numbers; the number is directly converted to a binary number to simplify mathematical operations Appendix B discusses several different numbering systems

Images are also represented by bit patterns In its simplest form, an image is composed of a matrix of pixels (picture elements), where each pixel is a small dot The size of the pixel depends on the resolution For example, an image can be divided into 1000 pixels or 10,000 pixels In the second case, there is a better representation of the image (better resolution), but more memory is needed to store the image After an image is divided into pixels, each pixel is assigned a bit pattern The size and the value of the pattern depend on the image For an image made of only blackand-white dots (eg, a chessboard), a I-bit pattern is enough to represent a pixel If an image is not made of pure white and pure black pixels, you can increase the size of the bit pattern to include gray scale For example, to show four levels of gray scale, you can use 2-bit patterns A black pixel can be represented by 00, a dark gray pixel by 01, a light gray pixel by 10, and a white pixel by 11 There are several methods to represent color images One method is called RGB, so called because each color is made of a combination of three primary colors: red, green, and blue The intensity of each color is measured, and a bit pattern is assigned to it Another method is called YCM, in which a color is made of a combination of three other primary colors: yellow, cyan, and magenta