Teleinformatics. Over the years, computer development has had great events, one of which is the emergence of Teleinformatics , which has given the possibility of transmitting information over long distances through a set of procedures, techniques and standards. It is directly related to Telematics and Telecommunications , and has given solutions to previously impossible problems.
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- 1 Data Transmission Systems
- 1 Coding
- 1.1 Amount of information or self-information
- 1.2 Probability of symbol occurrence
- 1.3 Entropy
- 2 Compression
- 2.1 Compression algorithm Length Coding. Run Lenght Encoding (RLE)
- 2.2 Microcom Networking Protocol (MNP) compression algorithm
- 2.3 LZ-77 or LZ-1 compression algorithm
- 2.4 LZ-78 or LZ-2, LZ-W compression algorithm
- 3 Modulation
- 3.1 Baseband modulation
- 3.2 Band pass modulation
- 4 Multiplexing
- 1 Coding
- 2 Data networks
- 1 Local Area Networks (LAN)
- 1.1 Definition
- 1.2 Definition according to IEEE
- 2 Features
- 2.1 Characteristics that distinguish LANs from other types of networks
- 3 Classification
- 1 Local Area Networks (LAN)
- 3 References
Data Transmission Systems
For a good data transmission, the general communication process must be taken into account, which is based on the source of information, the Transmitter , the transmission medium , the receiver and the destination. Using Shannon’s communication model , you can get a better idea of the communication process that takes place, which can be as simple as a conversation between two people or as complicated as downloading a File on the web .
Amount of information or self-information
Many times you have asked yourself what is the amount of information that exists in a book, in a newspaper or in a given and if they provide us with a lot, little or no information, because these are considered as sources of discrete information and through a mathematical formula we can know the occurrence of each of its Symbols , but to calculate this occurrence the following requirements must be met:
- That associates in an inversely proportional way the Amount of Information of a symbol with the Probability of its occurrence.
- That results with values from null to positive. There is no reason for the information quantity value to be negative. An Event can give no or some information.
The information in a message should be the sum of the information in each of its symbols . The mathematical formula that meets the requirements and assumes that the amount of information (I (s)) is calculated in the following way is: I (s) = Log 2 1 / P (si) or I (s) = -Log 2 P (yes)
Either of the two formulas can be used, although the first is more feasible for Fractional Values and the second for Decimal Values.
Symbol occurrence probability
The probability of a symbol’s occurrence is given by the number of times it is present over the total number of symbols.
Example given the string : ABCDDDCBBBB the probability of occurrence of the symbols are:
The information Average or also called entropy is denoted H (s) and is calculated:
H (s) = Σ n = 0 P (if) * log 2 1 / P (if) or H (s) = – Σ n = 0 P (if ) * log 2 P (if)
The Understanding of information, as the word indicates, allows us to make the information smaller, how many times we have compressed the images, videos, music or texts with the different existing Extensions.
Compression algorithm Length Coding. Run Lenght Encoding (RLE)
To carry out this compression method, it must be taken into account that it is working with binary information. It consists of referencing 8 consecutive byte of the compressed string, with a ninth in which each of the bits indicates whether the byte it refers to is the indicator of the number of repeated symbols. Example compression of the string AAAACCCCDDD3SRRRRR through RLE would be the following:
The values that are presented below give you better information about the compressed string. Compression Ratio (RC) = Number of Input Bytes / Number of Output Bytes
RC = 18/10 = 1.8
Compression Radius = Number of Output Bytes / Number of Input Bytes
Microcom Networking Protocol (MNP) compression algorithm
The MNP compression algorithm is a version of RLE with the difference that those characters that exceed three are compressed. They are represented as follows:
XXXL: where X is the character and L is the number of characters that exceed three and represent one byte of information.
|Original data||Compressed transmission data|
|XXX||XXX0 or XXX00000000|
|AAAA||AAA1 or AAA00000001|
|KKKKKKKK||KKK5 or KKK00000101|
Compression algorithm LZ-77 or LZ-1
The algorithm [[[LZ77 | LZ-77]] or LZ-1 ] is performed using a buffer search and a buffer in advance. It will be made through Triplets and which is defined:
- (distance, length, symbol)
Compression algorithm LZ-78 or LZ-2, LZ-W
These algorithms are defined as follows:
- the output will be two fields (code, character)
The transmission of a signal is given by two approaches , base band modulation or band pass modulation (broadband transmission).
The modulation baseband (baseband transmission) is based on sending signals digital via a communications channel, preserving the form of the digital signal. This type of transmission is only possible if you have a channel with a bandwidth infinite or very wide, so it requires a lowpass, is the case channel when a dedicated channel occupies the full bandwidth of the medium as a channel only.
Band pass modulation
Band pass modulation (broadband transmission) is the action of modifying some of the characteristics of an analog signal , based on the information in its digital data. In essence, modulation is based on the systematic alteration of the parameters of an analog signal (amplitude, frequency, or phase) called a carrier, in such a way that the resulting signal resembles a digital signal.
The intention to unite in a single Stream the data from numerous sources increases the efficiency of use of the bandwidth available in the transmission medium. To achieve this capacity, it is necessary to use techniques that allow a single link to share several channels. There are three basic techniques :
- Frequency Division Multiplexing (FDM).
- Time Division Multiplexing (TDM).
- Wavelength Division Multiplexing (WDM).
Nowadays, the advances in Computer Science have allowed communication between people no matter how far one is from another, the need for communication has given rise to users and even companies wanting to interconnect their PC in order to enjoy these privileges.
Local Area Networks (LAN)
The Networks Local Area is a way to improve communication between users, and we can share information, resources, applications, among many other things that can be done via a network.
Communication systems that link a series of configurations of macro computers, mini computers , micro computers, terminals, and all kinds of independent peripherals located in the same administrative or manufacturing center, with the aim of sharing resources and exchanging information.
Definition according to IEEE
Computer network Optimized for moderate extensions Used and operated by a single organization (Non-public). Employ shared streaming media . (corrected) Does not provide inherent privacy. Stations communicate directly without intermediate switching nodes. They need a media access sublayer.
- They cover sparsely dispersed geographical areas
- They interconnect devices that can work autonomously .
- They allow very high transmission speeds.
- They facilitate communication between all devices connected to the network.
- They transfer information in digital form.
Characteristics that distinguish LANs from other types of networks
- Its size.
- Your Transmission Technology .
- Your Topology . 
Networks are classified as:
- LAN : Local Area Networks.
- MAN : Metropolitan Area Networks.
- WAN : Global Area Networks.