Noise immunity Benefits The possibility of using anyone. Methods for increasing noise immunity and noise immunity of data transmission and reception. Secrecy of work of the RSA Farmes
The same link can be used to transmit signals between many sources and receivers, i.e. The communication line can serve several channels.
The synthesis of information transmission systems have to solve two main problems associated with transferring messages:
1) Ensuring messaging messages
2) Ensuring the high transmission efficiency of messages
Under noise immunity It is understood as the ability of information to resist the harmful effects of interference. Under these conditions, i.e. With a given interference, noise immunity determines the loyalty of the transfer of information. Under loyalty It is understood to measure the conformity of the received message (signal) to the transmitted message (signal).
Under efficiency Information transmission systems are understood as the ability of the system to ensure the transfer of a given amount of information in the most economical way. Efficiency characterizes the ability of the system to ensure the transmission of this number of information with the lowest cost of signal power, time and frequency band.
Theory of information establishes the criteria for evaluating the noise immunity and the effectiveness of information systems, and also indicates the general ways to increase noise immunity and efficiency.
Increased noise immunity is almost always accompanied by a deterioration in efficiency and vice versa
In the basics of all methods of increasing the noise immunity of information systems, the use of certain differences between the useful signal and an interference. Therefore, a priori information about interference and signal properties is necessary to combat interference.
Currently, a large number of ways to increase the noise immunity of systems are known. These ways are convenient to break into two groups.
I Group - based on choosing a message transfer method.
Group II - is associated with the construction of noise-resistant receivers.
Simple and applied method of increasing noise immunity is increase signal / interference ratio By increasing the power of the transmitter. But this method may be economically unable, as it is associated with a significant increase in the complexity and cost of equipment. In addition, an increase in the transmission capacity is accompanied by the enhancement of the interfering effect of this channel to others.
An important way to increase the noise immunity of transmission of continuous signals is rational choice of modulation type signals. Applying modulation types that provide a significant extension of the signal frequency band, one can achieve a significant increase in the noise immunity of the transmission.
Radical way to increase the noise immunity of transmission of discrete signals is to use special noise-resistant codes . At the same time there are two ways to increase the noise immunity of the codes:
1. The choice of transmission methods that provide a smaller probability of code distortion;
2. Increase the corrective properties of code combinations. This path is associated with the use of codes that allow you to detect and eliminate distortions in code combinations. This encoding method is associated with the introduction of additional, redundant symbols into the code, which is accompanied by an increase in the transmission time or frequency of transmission of code characters.
An increase in the noise immunity of transmission can also be achieved by re-transmitting the same message. On the receiving side, the received messages are compared and those that have the greatest number of coincidences are taken as true. To eliminate uncertainty when processing adopted information and ensure the selection by the criterion of the majority, the message should be repeated at least three times. This method of increasing noise immunity is associated with increasing transmission time.
Systems with repetition of discrete information are divided into systems with group summation, in which the comparison is made according to code combinations, and on the system with seductive summation, in which the comparison is carried out by code combinations in symbols. Suitable check is more efficient than groupage.
A variety of systems that have an increase in noise immunity due to an increase in transmission time are feedback systems. If there are distortion in the transmitted messages, the information coming over the reverse channel provides a repetition of the transmission. The presence of a reverse channel leads to a complication of the system. However, in contrast to the transmission repetition systems in feedback systems, the transmission repetition will take place only in case of distortion in the transmitted signal, i.e. Redundancy generally turns out to be less.
Noise-resistant reception is to use redundancy, as well as a priori information about signals and interference to solve the optimal method of receiving task: signal detection, signal differences or recovery of messages. Currently, the apparatus of the theory of statistical solutions is widely used for the synthesis of optimal receivers.
The receiver errors decrease with an increase in the signal / interference ratio at the receiver input. In this regard, it often produces preliminary processing of the received signal in order to increase the relationship of the useful component to interference. Such methods of pre-processing signals include the show method (combination of broadband amplifier, limiter and narrowband amplifier), the selection of signal signals, the measurement method, the filtering method, the correlation method, the accumulation method, etc.
Consider simple practical ways to build codes capable of detecting and correcting errors. We confine ourselves to considering binary channels and uniform codes.
Parity control method. This is an easy way to detect some of the possible errors. We will use as permitted half of possible code combinations, namely, those that have an even number of units (or zeros). A single error during transmission through the channel will inevitably lead to a violation of parity, which will be detected at the channel output. It is obvious that three-time, five times and in general errors of odd multiplicity lead to a violation of parity and are detected by this method, while double, four-time and in general even multiplicity errors - no.
Practical coding technique with parity control is as follows. From the sequence of symbols to be transmitted through the channel, the next block is selected from k-1symbols called informationaland it is added to it k-J.symbol called control. The value of the control symbol is selected so as to ensure the parity of the received code word, i.e. To make it allowed.
The reading method is considerable value and is widely used in cases where the likelihood of more than one error is negligible (in many cases, if you certainly know that the code word is accepted with an error, it is possible to request a re-transmission). At the same time, the redundancy of the code increases the minimum and slightly at large k.(in k / (K-1)time).
The method of checksums. The parity control method considered above can be applied multiple times for various combinations of transmitted code words - and this will allow not only to detect, but also correct certain errors
Control questions:
1. What do you understand under the link line?
2. What device is called a decoder?
3. What device is called decisive?
4. What device are called decoding?
5. What is called quantization step?
6. Give the level of quantization by level.
7. Give the definition of quantization in time.
8. What device is called a transmitter?
9. What is called the receiver?
10. What do you understand under the message?
11. Give the definition of communication tools?
12. What device is called multiplexer data transfer?
13. Determine the concept of a concentrator, repeater.
14. Determine the bandwidth of the continuous channel without interference.
15. Determine the bandwidth of the continuous channel with interference.
16. Describe the destination: source, signal generator.
17. How does the signal affect the communication line?
18. How does the recognition device work?
19. Give the definition of noise immunity.
20. What do you understand under the efficiency of the system?
21. List methods for increasing noise protection.
22. Tell us about the record of parity.
23. What is the method of checksum?
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
7. Create a multi-volume archive with a volume size of 300kb, which contains the sub-folder created in the previous job.
8. Perform a report on the work done.
The report should include:
Title page;
3. Evaluate the compression degrees of each of the archives - the ratio of compressed and uncompressed files (the volume of the file is taken into account with an accuracy of the bit). Tell the results of the comparison in the form of a spreadsheet. Analyze the degree of compression obtained for different types of files and when using different formats and various levels of compression.
4. Check the integrity of one of the archives.
5. Create a palared self-extracting 7z archive for files.txt with a normal level of compression. Explain the difference in the volumes of self-extracting files and the corresponding non-spanking archives.
6. Create a subfolder in the nominal folder and unpack the contents of the self-extracting archive, as well as any of the files contained in the archive with * .bmp files.
Many people think that the protection of electrical signals and transmitted information from electromagnetic interference is provided by exclusively shielded wires, removing from interference sources and testing equipment. However, this is not the case, there are many ways to increase the noise immunity of the measuring channel or the channel transmission channel. Often, designers and developers are missing from the type of important moments, which we will be told about. One of the disadvantages of wired lines is the low noise immunity and the possibility of simple unauthorized connection. Consider the main common ways to increase noise immunity.
Select the transfer medium.Twisted couple. Twisting wires with each other reduce the wave resistance of the conductors, as a result, and the tip. Twisted pair is a fairly noise-resistant cable. A large role in protection against interference is also played by the connectors to which the cable, for example, RJ45 for Ethernet architecture or RS connectors with built-in filters. The disadvantages of the "Twisted Pair" cable can be attributed to a simple unauthorized connection to the network. Coaxial cable - more obstructed than twisted steam. Reduces its own radiation, but more expensive and more difficult in installation. Cable fiber optic communication channels. The fiber optic cable - requires the transformation of the electrical signal into the light, can be combined with the channel encoder. Extremely high level of noise immunity and lack of radiation at 3GBIT / C data transmission speeds. The main disadvantages of the fiber optic cable are the complexity of its installation, small mechanical strength and sensitivity to GWF, including ionizing radiation.
Another way is, oddly enough, reservation of communication channels. Very common, for example, at nuclear power plants in the channels of ACS TP. Here I want to even remember 2 points: disguise from the lightning strike of the wires of the LAP voltage behind the grounded conductor and deterioration or improve the quality of the reception when moving near TV or radioantenna. So not always the gasket of your cable in a common tray or conduit plays a destructive role, sometimes other lines can disguise your and take most of the energy interference on yourself.
Select interface. A unified signal 4 - 20 mA has been widely used for several decades to transmit analog signals when creating automated control systems. The advantage of this standard is the simplicity of its implementation, the possibility of noiseless transmission of analog signal to relatively long distances. This is a vivid example of removing the frequency of transmission from the characteristic frequencies of the most likely electromagnetic interference. However, it is absolutely clear that in modern digital sau it is not effective. In the measuring systems, the unified signal 4-20 mA can only be used to transmit a signal from the sensor to the secondary converter. The noise immunity provides for the departure of the RF interference to the DC and the simplicity of circuitry solutions when filtering interference. The RS-485 interface is relatively poorly observed. USB is better protected, as it is a serial interface. However, due to the weak first protocols and unsuccessful in the electrical sense of the connector's design (reminds the microstrip line), it is often riveted with high-frequency interference. Improving the quality of coding in USB 3.0 and the transition to the micro-USB connectors significantly increase its resistance to electromagnetic effects. Ethernet and Intenet - from the point of measurement systems of dignity and disadvantages of these interfaces are generally similar to the USB interface. Naturally, during the operation of measuring instruments in large distributed networks, these interfaces are practically no alternatives today. GPIB or IEEE-488 - the principle of operation of the interface on the byte-serial, bit-parallel information and this is explained by its high noise immunity compared to batch transmission.
Logic noise immunity. At the physical level there are many receptions of the digitization of the signal to increase noise immunity. For example, using a specific voltage instead of a zero conductor or "land" for logical zero. Even better if the levels are shifted: + 12V and -5B or + 3V and + 12V. The programming of noise immunity here is to use feedback to re-survey devices when the information and the use of observance and restoring encoding methods.
Some more techniques for increasing noise immunity:
use of differential signal and reception methods;
the use of individual reverse conductors inside the cable;
grounding of unused or backup conductors;
elimination of different potentials at various points of grounding or general conductors;
increasing power and amplitudes of signals;
the broadcast of one interface is different, excluding the minuses of both;
an increase in the potential difference between logical levels;
removing the transmitted frequencies from the characteristic interference spectrum;
the choice of methods of triggering triggers (on fronts, amplitude, increment, frequency, phase, a certain sequence, etc.);
synchronization;
the use of logical and signal lands and their shielding;
The list of techniques is not exhausted, perhaps, anything, except for resources, knowledge and smelting of a particular person or organization.
Combine with Emcestlab
Noise-protecting characterizes the ability of a communication system to resist the effects of interference. Noise immunity includes such concepts as secrecy and noise immunity. It is known that the noise resistance of the reception of signals against the background of broadband interference (Δfn\u003e Δfc) of the White Gaussian noise is determined only by the ratio of the EU signal energy to the spectral density of noise N
q0 \u003d 2e / n \u003d 2pct / n, (2.3)
and does not depend on the type of signal. Therefore, at a well-known spectral density of interference, the noise immunity of the optimal admission of the SPS to broadband interference is equal to noise immunity of optimal reception of narrowband signals under these conditions.
If the width of the interference spectrum does not exceed the width of the signal spectrum, the use of the SPS provides an increase in the signal / interference ratio relative to narrowband signals
Thus, the signal-to-hover ratio in the ShsS is improved in proportion to the signal base.
The noise resistance of the ShSS is determined by the relationship that connects the signal-to-interference ratio at the Q2 receiver output with the signal / interference ratio at its input P2
where - the ratio of power supply to the power of interference; Q2 \u003d 2E / NP - the ratio of the energy of the SPS E to the spectral density of the interference power of the NP in the STS band, i.e. E \u003d PCT, NP \u003d RP / ΔFC.
From this ratio, it follows that the admission of the SSP is accompanied by a signal amplification of 2rd times.
The connection system secrecy determines its ability to resist the detection and measurement of signal parameters. If it is known that a communication system may operate in this frequency range, but its parameters are unknown, then in this case we can talk about the energy secretion of the communication system, since its detection is possible only by analyzing the spectrum. ShsS secrecy is associated with a decrease in the spectral density of the signal as a result of an increase in its base, i.e.
(2.6)
those. in times less than a narrowband signal with equal capacities and speed of information transmission. The ratio of the spectral density of the NC signal power to the spectral density of the power of the input noise N receiver, which detects the signal, is
(2.7)
those. in times less than narrowband signals. Therefore, at the point of reception, with an unknown structure of the SPS, the likelihood of its detection against the background of noise is extremely low. Thus, the wider the SPS spectrum and the larger base, the higher the energy and parametric power system of the communication system.
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Noise immunity - the ability of the device (system) to receive information without interference with a given degree of reliability, i.e. Perform your functions in the presence of interference.
Noise immunity estimate the intensity of the interference in which the violation of the function of the device does not exceed the permissible limits. The stronger the interference at which the device remains operational, the higher its noise immunity.
Noiselessness - The ability of the device (system) to impede the effects of interference.
By noise immunity and noise immunity, codes are divided into:
Error detection codes
Corrective codes
Non-worker
Noise resistant
Noise-protective - codes in which you can select the message (noise immunity + transfer secrecy).
7. Characteristics of codes: number systems, power, relative speed, weight.
the basis of the calculus system:
Binary k \u003d 2;
Tropic k \u003d 3;
Quantine k \u003d 4;
Modulation - Physical Structure
Coding - Mathematical Structure
Tropic- in transmission systems, octal - for computer
Length of the word N (number of discharges)
n \u003d k + m, k - symbol information system, M - check characters
.Code power - the number of working combinations is determined by the word length, the MP operating code; MP \u003d, Mmax \u003d, K-base degree of calculus.
Relative code transfer rate.,
Code weight Ω. - Number of units in a binary code combination
10011 -\u003e w \u003d 3, 0001 -\u003e w \u003d 1.
8. Connect the redundancy of the code, the code distance, the characteristic of the code distance. Properties of codes depending on the code distance value.
Code redundancy Shows which part of the working combinations is used as a working
\u003d (for binary codes) \u003d 
Code Distance D. (Hamming distance) - the number of discharges in which one combination differs from the other. 1≤ D ≤ n
Code transition. The shape of the code junction links the code distance with the adjustment ability. d \u003d R + S + 1 - code transition formula, R - number of errors detectable, S - the number of errors corrected, R≥S code transition - the number of discharges in which one combination differs from the other: 
Properties codes defined at the minimum code distance.
Properties of codes in accordance with the codesafter distance
If D \u003d 1, then (r \u003d 0; s \u003d 0) - the equation code
If D \u003d 2, then (r \u003d 1; s \u003d 0)
If D \u003d 3, then (r \u003d 1; s \u003d 1) (r \u003d 2; s \u003d 0)
If D \u003d 4, then (r \u003d 3; s \u003d 0) (r \u003d 2; s \u003d 1)
9.Toble characteristics of code.
To estimate the probability of passing information on the COP, probabilistic characteristics are used: Posh or RPR - these values \u200b\u200bconstitute a complete group. Therefore, POS + RPR \u003d 1 (the likelihood of proper passage + the probability of error \u003d 1)
The law of interference distribution
Signal parameters
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