Noise immunity advantages the ability to use anyone. Methods for improving noise immunity and noise immunity of data transmission and reception. The secrecy of the work of the SAR land survey
The same communication link can be used to transmit signals between many sources and receivers, i.e. a communication line can serve several channels.
When synthesizing information transmission systems, two main problems associated with the transmission of messages have to be solved:
1) ensuring the noise immunity of message transmission
2) Ensuring high efficiency of message transmission
Under noise immunity refers to the ability of information to withstand the harmful effects of interference. Under these conditions, i.e. for a given interference, noise immunity determines the correctness of information transmission. Under fidelity the measure of correspondence between the received message (signal) and the transmitted message (signal) is understood.
Under efficiency information transmission system is understood as the ability of the system to provide the transmission of a given amount of information in the most economical way. Efficiency characterizes the ability of the system to ensure the transfer of a given amount of information with least cost signal strength, time and bandwidth.
Information theory establishes criteria for assessing the noise immunity and efficiency of information systems, and also indicates common paths improve noise immunity and efficiency.
An increase in noise immunity is almost always accompanied by a decrease in efficiency and vice versa
The basis of all methods for improving the noise immunity of information systems is the use of certain differences between a useful signal and interference. Therefore, to combat interference, a priori knowledge of the properties of the interference and signal is required.
Currently, there are a large number of ways to improve the noise immunity of systems. These methods can be conveniently divided into two groups.
Group I - based on the choice of message transmission method.
Group II - associated with the construction of noise-immune receivers.
A simple and applicable way to improve noise immunity is increase in the signal-to-noise ratio by increasing the transmitter power. But this method may not be economically viable, as it is associated with a significant increase in the complexity and cost of equipment. In addition, an increase in transmission power is accompanied by an increase in the interfering effect of this channel on others.
An important way to increase the noise immunity of the transmission of continuous signals is rational choice of modulation type signals. By applying modulation types that provide a significant expansion of the signal bandwidth, it is possible to achieve a significant increase in the noise immunity of the transmission.
A radical way to increase the noise immunity of discrete signal transmission is to use special error-correcting codes . In this case, there are two ways to improve the noise immunity of codes:
1. The choice of such transmission methods that provide a lower probability of code distortion;
2. Increasing the corrective properties of code combinations. This path is associated with the use of codes that allow detecting and eliminating distortions in code combinations. This coding 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 symbols.
Improving the noise immunity of the transmission can also be achieved by retransmitting the same message. On the receiving side, the received messages are compared and those that have the largest number of matches are accepted as true ones. To eliminate uncertainty in the processing of received information and ensure selection by the majority criterion, the message must be repeated at least three times. This method of improving noise immunity is associated with an increase in transmission time.
Systems with repetition of transmission of discrete information are divided into systems with group summation, in which comparison is made by code combinations, and into systems with character-by-symbol summation, in which comparison is carried out by symbols of code combinations. A character-by-character check is more efficient than a group check.
A variety of systems in which an increase in noise immunity is achieved by increasing the transmission time are systems with feedback. If there are distortions in the transmitted messages, the information coming through the reverse channel ensures the repetition of the transmission. The presence of the reverse channel leads to the complication of the system. However, in contrast to systems with repetition of transmission, in systems with feedback, repetition of transmission will take place only if distortions are detected in the transmitted signal, i.e. redundancy is generally less.
Noise-immune reception consists in using redundancy, as well as a priori knowledge of signals and interference, to solve the receiving problem in an optimal way: signal detection, signal difference, or message recovery. Currently, for the synthesis of optimal receivers, the apparatus of the theory of statistical decisions is widely used.
Receiver errors decrease as the signal-to-noise ratio at the receiver input increases. In this regard, the received signal is often pre-processed in order to increase the ratio of the useful component to the interference. Such signal preprocessing methods include the SHOW method (combination of a broadband amplifier, limiter and narrowband amplifier), signal selection by duration, interference compensation method, filtering method, correlation method, accumulation method, etc.
Let's look at simple practical ways to build codes that can detect and correct errors. We confine ourselves to considering binary channels and uniform codes.
Parity check method. This is an easy way to discover some of possible errors. We will use half of the possible code combinations as allowed, namely those that have an even number of ones (or zeros). A single error during transmission through the channel will inevitably lead to a parity violation, which will be detected at the output of the channel. Obviously, 3-fold, 5-fold, and in general errors of odd multiplicity lead to parity violation and are detected by this method, while 2-fold, 4-fold, and generally errors of even multiplicity do not.
The practical parity coding technique is as follows. From the sequence of symbols to be transmitted through the channel, the next block is selected from k-1 characters called informational, and added to it k-th symbol called control. The value of the check symbol is chosen so as to ensure the parity of the received codeword, i.e. to make it allowed.
The parity method is of considerable value and is widely used in those cases in which the probability of occurrence of more than one error is negligible (in many cases, if you know for sure that the codeword was received in error, it is possible to request a retransmission). At the same time, code redundancy increases minimally and insignificantly at large k(in k/(k-1) once).
Checksum method. The parity check method considered above can be applied repeatedly for various combinations of bits of transmitted code words - and this will allow not only detecting, but also correcting certain errors.
1. What is meant by a communication line?
2. What device is called a decoder?
3. What device is called decisive?
4. What device is called a decoder?
5. What is called the quantization step?
6. Define level quantization.
7. Define time quantization.
8. What device is called a transmitter?
9. What is called a receiver?
10. What is meant by a message?
11. Define the means of communication transmission?
12. What device is called a data transmission multiplexer?
13. Define the concepts of a concentrator, a repeater.
14. Determine throughput continuous channel without interference.
15. Determine the capacity of a continuous noisy channel.
16. Describe the purpose: source, signal conditioner.
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 is meant by system efficiency?
21. List methods for improving noise immunity.
22. Tell us about the parity check method.
23. What is the checksum method?
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 containing the named folder subfolder created in the previous task.
8. Complete a progress report.
The report should include:
Title page;
3. Estimate the degree of compression of each of the archives - the ratio of the volumes of compressed and uncompressed files (take into account the volume of the file to the nearest bit). Arrange the results of the comparison in the form of a spreadsheet. Analyze the compression ratios obtained for different types of files and when using different formats and different levels of compression.
4. Check the integrity of one of the archives.
5. Create a password-protected self-extracting 7z archive for .txt files with a normal compression level. Explain the difference in file sizes between a self-extracting archive and a corresponding non-self-extracting archive.
6. Create a subfolder in the named folder and extract the contents of the self-extracting archive there, 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 exclusively by shielded wires, distance from sources of interference and testing of transceiver equipment. However, this is not the case, there are many ways to improve the noise immunity of the measuring channel or information transmission channel. Often, designers and developers overlook important points, which we will discuss next. One of the disadvantages of wired lines is low noise immunity and the possibility of a simple unauthorized connection. Consider the main common ways to improve noise immunity.
The choice of transmission medium. twisted pair. Twisting the wires together reduces the wave resistance of the conductors, as a result, and interference. Twisted pair is a fairly noise-resistant cable. The connectors to which the cable is connected, such as RJ45 for Ethernet architecture or RS connectors with built-in filters, also play an important role in protecting against interference. The disadvantages of a twisted pair cable include the possibility of a simple unauthorized connection to the network. Coaxial cable is more immune to interference than twisted pair. Reduces its own radiation, but more expensive and more difficult to install. Cable fiber optic communication channels. Fiber optic cable - requires the conversion of an electrical signal into a light signal, can be combined with a channel encoder. Extremely high level of noise immunity and absence of radiation at data rates of 3Gbps. Main disadvantages fiber optic cable- this is the complexity of its installation, low mechanical strength and sensitivity to WWF, including ionizing radiation.
Another way is, oddly enough, redundancy of communication channels. Very common, for example nuclear power plants in APCS channels. Here I would like to recall 2 more points: masking from a lightning strike of a live power line wire behind a grounded conductor and deterioration or improvement in the quality of reception when moving near a TV or radio antenna. So it is not always the laying of your cable in a common tray or conduit that plays a destructive role, sometimes other lines can mask yours and take on most of the interference energy.
Interface selection. The unified signal 4 - 20 mA has been widely used for several decades to transmit analog signals in the creation of automated control systems. The advantage of this standard is the simplicity of its implementation, the possibility of noise-resistant transmission of an analog signal over relatively long distances. This is a vivid example of the removal of the transmission frequency from the characteristic frequencies of the most probable electromagnetic interference. However, it is quite clear that it is not effective in modern digital ACS. In measuring systems, a unified 4-20 mA signal can only be used to transmit a signal from a sensor to a secondary converter. The noise immunity of such a signal provides a departure from RF interference to direct current and the simplicity of circuitry solutions for filtering interference. The RS-485 interface is relatively weakly noise-immune. USB is better protected as it is a serial interface. However, due to the weak first protocols and the design of the connector, which is unsuccessful in the electrical sense (reminiscent of a microstrip line), it often goes astray with high-frequency interference. The improvement in encoding quality in USB 3.0 and the transition to micro-USB connectors significantly increase its immunity to electromagnetic interference. Ethernet and Internet - from the point of view of measuring systems, the advantages and disadvantages of these interfaces are generally similar to the USB interface. Naturally, when measuring instruments operate in large distributed networks, these interfaces today have practically no alternative. GPIB or IEEE-488 - the principle of operation of the interface on a byte-serial, bit-parallel exchange of information and this explains its high noise immunity compared to packet transmission.
Logic noise immunity. At the physical level, there are many techniques for digitizing a signal to improve noise immunity. For example, using a certain voltage instead of a neutral conductor or "ground" for a logical zero. Even better, if the levels are shifted: + 12V and -5V or + 3V and + 12V. The software implementation of noise immunity here consists in using feedback to re-polling devices when information is distorted and using noise-immune and restoring coding methods.
A few more techniques to improve noise immunity:
application of differential signal and reception methods;
the use of separate return conductors inside the cable;
grounding of unused or reserve conductors;
elimination of different potentials at various points of grounding or common conductors;
increase in signal power and amplitudes;
translation of one interface to another, excluding the disadvantages of both;
increase in potential difference between logic levels;
removal of transmitted frequencies from the characteristic interference spectrum;
selection of triggering methods (by fronts, amplitude, increment, frequency, phase, certain sequence, etc.);
synchronization;
use of logic and signal grounds and their shielding;
The list of techniques is not limited, perhaps, to nothing but the resources, knowledge and ingenuity of a particular person or organization.
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Interference immunity characterizes the ability of a communication system to withstand the effects of interference. Noise immunity includes such concepts as secrecy and noise immunity. It is known that the noise immunity of signal reception against the background of broadband interference (Δfn > Δfc) of the white Gaussian noise type is determined only by the ratio of the signal energy Ec to the noise spectral density N
q0 = 2E/N = 2PcT/N, (2.3)
and does not depend on the type of signal. Therefore, with a known spectral density of interference, the noise immunity of the optimal NLS reception to broadband interference is equal to the noise immunity of the optimal reception of narrow-band signals under these conditions.
If the width of the interference spectrum does not exceed the width of the signal spectrum, then the use of NLS provides an increase in the signal-to-noise ratio relative to narrow-band signals
Thus, the signal-to-noise ratio in the SSN improves in proportion to the signal base.
The noise immunity of the NSS is determined by the relationship that relates the signal-to-noise ratio at the output of the receiver q2 with the signal-to-noise ratio at its input p2
where is the ratio of the NPS power to the interference power; q2 = 2E/Np is the ratio of the NPS energy E to the interference power spectral density Np in the NPS band, i.e. E = РсТ, Np = Рp /Δfc.
It follows from this ratio that the reception of NLS is accompanied by a signal amplification by 2V times.
The secrecy of a communication system determines its ability to resist detection and measurement of signal parameters. If it is known that a communication system can operate in a given frequency range, but its parameters are unknown, then in this case we can talk about the energy secrecy of the communication system, since its detection is possible only with the help of spectrum analysis. The secrecy of the NSS 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. V times less than that of a narrowband signal with equal power and information transfer rate. The ratio of the power spectral density of the signal Nc to the power spectral density of the input noise N of the receiver detecting the signal is
(2.7)
those. V times less than that of narrowband signals. Therefore, at the receiving point with an unknown NSS structure, the probability of its detection against the background of noise is extremely low. Thus, the wider the NLS spectrum and the larger its base, the higher the energy and parametric secrecy of the communication system.
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Noise immunity– the ability of a device (system) to receive information without interference with a given degree of reliability, i.e. perform their functions in the presence of interference.
Noise immunity is evaluated by the intensity of interference at which the violation of the device's functions does not yet exceed the permissible limits. The stronger the interference at which the device remains operational, the higher its noise immunity.
Noise immunity– the ability of the device (system) to prevent interference.
According to noise immunity and noise immunity, codes are divided into:
Error Detection Codes
Correction codes
Non-jamming
Noise-immune
Noise-immune - codes in which you can correctly highlight the message (noise immunity + secrecy of transmission).
7.Characteristics of codes: number systems, power, relative speed, weight.
base of the calculus:
Binary k=2;
Ternary k=3;
Quaternary k=4;
Modulation - physical structure
Coding - mathematical structure
Ternary - in transmission systems, octal - for computers
Word length n (number of bits)
n=k+m, k- Information system characters, m - check characters
.Code Power– number of working combinations, determined by the word length, working code Mp; Mp =, Mmax=, k-base of the calculus.
Relative code rate.,
Code weight ω is the number of ones in a binary codeword
10011 -> w=3, 0001 -> w=1.
8. The concept of code redundancy, code distance, code distance characteristics. Properties of codes depending on the value of the code distance.
Code redundancy- shows which part of the working combinations is used as a working
= (for binary codes) = 
Code distance d(Hamming distance) - the number of digits in which one combination differs from another. 1≤d≤n
code jump. The shape of the code transition relates the code distance to the correction capability. d = r+s+1 is the code transition formula, r is the number of detected errors, s is the number of correctable errors, r≥s Code transition is the number of bits in which one combination differs from another: 
Code properties determined by the minimum code distance.
Properties of codes according to codesdistance
If d=1, then (r=0;s=0) is an equally accessible code
If d=2, then (r=1;s=0)
If d=3, then (r=1;s=1) (r=2;s=0)
If d=4, then (r=3;s=0) (r=2;s=1)
9.Probabilistic characteristics of the code.
To assess the probability of information passing through the CS, probabilistic characteristics are used: Posh or Ppr - these quantities make up a complete group. Therefore, Posh + Ppr = 1 (probability of correct passage + probability of error = 1)
Interference distribution law
Signal parameters
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