2. The procedure.
2.1. Reseaching of data transmission systems with dual symmetric connection channel without using of corrected code.
For carrying out of research is necessary to compose connection channel model,carrying out the following operations:
• Using command commlibv1, to call structural scheme of connection on the screen and to activate information coding block system Error control coding;
• In appearance window Demo Error - Control Coding/Decoding Library to choose a window of Hamming codes;
• On new window to choose a system with sequence transmission of dual elements of coding combination of Hamming Binary sequence Hamming encode;
•To activate a green window, which allows to receive etalon model for nk - code (7,4) Sequence Codec demo;
• On the line of main menu of new window to activate the word File and appearance menu to click New, further in menu on the right to click Model, is appeared free word;
• Using a method of dragging to gather by sample
Figure 1. Model for test of the gaussian channel
Before setting off a model for selection of statistic data it is necessary to install parameters for every modeling systems. For carrying out of given procedure is necessary to click twice with the left button of mouse in the field of interested block. Panel with parameters is appeared
Figure 2. A view of panel for installing block parameter.
It is possible to call to the screen one or more panels. Left panel on the Figure 2. refers to the block of Read workspace. The first line installs a view of combination for primary filling of sensor recurring sequence , which is used in the form of testing sequence. A figure after comma means a number of sensor.
The second line installs duration of impulse in units modeling time (in that case this time is equal to 5 unit)
On the third line presence 1 testifies about duration of reading cycle.
On the forth installs a number of active exit.
From the right is presented panel of parameter for the block of Error meter, that is destined for the accumulation of statistic data.
On the first line is installed a number of bite, came to the transmitted symbol(is recommended to enter to this 1 line)
On the second line a researcher concludes a number of lines, which appear on the screen in the cause of carrying out of experiment. If a number of lines installs 30 then in the cause of carrying out of experiment noticed dynamic of appearance are 11 errors in the sequence of accepted symbols. For the speeding of the modeling process isn’t recommended to output on the screen of a panel statistic data accumulation not to waist time and volume of operative memory PECM on the graph. On the third line is displayed delay by time between the first and second input of block. Really on the first input a signal enters from the output of sensor of information without delay, and to the second input can pass several blocks for coding and decoding of information and time difference between the two ways of signal it is necessary to take into account that testing sequences were synchronized between themselves.
A modeling time is installed on the forth graph. It is recommended to install 1.
A sample of the screen with statistical data are presented on the figure
Figure 3.
A left column Sender shows a sequence of dual symbols on the output information sensor. The right column Receiver demonstrates a result of information reception. In this column incorrectly received symbols are registered with red color. On the low part of panel are separated data about number of transmitted combination (the upper three lines) and the data of a number of transmitted symbols (4,…,6 lines).
Symbol Transferred – means a common number of transmitted combination.
Error Number – a number of combination with mistakes.
Error Rate – a frequency of mistakes which on certain conditions can be received as incorrect receiption of.
Bit Transferred – a number of transmitted bites.
Error Number – a number of mistaking bites.
Error Rate – a fчequency of mistake on bite
In the cause of carrying out of the researcher’s experiment researcher is often interested in oscillograph of signals on the input of system and on its output. For this purpose possibilities of connection are considered in unlimited number of oscillograph.On the Figure 3 a scheme with two devices Scope 1 и Scope 2 is shown. For receiving of corresponded “ pictures”is necessary to produce double click of mouse in the field of corresponded instrument.
Figure 4.
From the figures it becomes clearly that the screen by x - direction is rated on 10 unit of modeling time and duration of impulse composes 5 unit of time. Which corresponds to the left panel of the second line. (Figure 8)
Study of statistics mistakes occurred on transmission of information by channel with interference was conducted in supposing historically that interfering factors carry independent feature. Such supposition on the first stages was justified and it is comfortable for researching of mathematic modeling of channels. Hence was detected that in majority channels of connection errors are grouped, i.e supposing of their independence isn’t justified from the point of view of ad equation of of modeling by passed process. Nevertheless in modern literature by coding theory of modeling with independent errors are used for initial evaluation of coding system as far as analytical modeling of such systems are simple and reflected the main probable features of exchange system by data. .
The channels with independent errors were received the names of discrete channels without memory.:
P(bv/au) = Puv, where is u = 1, 2, 3, … , U; v = 1, 2, 3, … , V.
The simplest channel modelling without memory is dual, symmetric channel presented in the Figure 5.
Figure 5. Binary symmetric channel a graph of transitional state
For such channel are carried out the following probable correspondence
P11 = P00 = q, P10 = P01= P= 1 – q.
As far as in DSC are indicated only the probability of errors then to evaluate system behavior is succeeded only on degree of symbols assigning of value R. To set value R you can activating a channel block of modeling by double click of the mouse and setting in the first line of parameters corresponded size R ,as it is shown in the Figure 6.
Figure 6.
Let’s stop on main thing: modeling time. For installation of this parameter it is necessary to find a command Simulation on the main menu of modeling. After its activation appears a context menu in which it is necessary to press It brings to the appearance of panel. (look Figure 6) On a panel a researcher installs modeling time in corresponding windows (Start time, Stop time).
For achieving of required accuracy of modeling it is necessary to treat about 106 signals. For the purpose of time economy a transmission of 103 - 104 symbols are assumed in the given work. Рекомендуется настраивать модель на параметрах малой величины.
In case of error existence in installation of parameters of modeling on the screen in automatic regime is produced a panel of errors, a common view which is presented in the Figure 7. on the low right corner. In this case a block in which isn”t installed a parameter in modeling is brightened with red color with yellow border. In the given example parameters in the third and forth line of information source isn’t indicated
Figure 7.