Customs data verification services

Code words were the work of printing factories in the past. Now I have used computer typesetting, which is much more convenient, fast and good. Code Word. A frame contains m data bits (i.e. message) and r redundant bits (check bits).

Know that all the code words can see the information bit after coding. The so-called system code refers to the information sequence contained in the encoded code word. One of the advantages of the system code is that the information bit is obtained directly after the decoding is completed, and the corresponding information needs to be found according to the code word after the system code is decoded.

"Code word" is generally the words used by the creators of online novels to describe their own working status, with a little self-deprecating meaning. The code word is actuallyIt is to write novels, because online novels are generally updated every day, at least one chapter is updated every day, and one chapter is about 3,000 words, so it needs to be written persistently every day.

Modern Communication Principle Chapter 11 - Error Control Coding and Linear Grouping Code

2. The addition of supervision code elements to the information code element sequence is called error control coding, and error control coding belongs to channel coding. There is a relationship between the information code element and the supervision code element. The different relationship, the code types formed are also different. It can be divided into two categories: group code and convolutional code.

3. The types of channel coding mainly include: linear packet code, convolutional code, cascade code, Turbo code and LDPC code. Among them, the group code is divided into: Hamming code, Gray code, loop code (BCH code, RS code, CRC loop redundancy check code.Channel coding, also known as error control coding, is the cornerstone of all modern communication systems.

4. Measures to reduce transmission errors include: channel coding and. And the linear packet code belongs to error control coding.

5. It is a kind of important linear packet code, with simple encoding and decoding methods and strong error detection and error correction capabilities. It is widely used to achieve error control in the field of communication. In fact, in addition to data communication, CRC is also very useful in many other fields.

Mobile device identification code-DeviceID, IMEI, IDFA, UDID

1, IMEI: InteRnational Mobile Equipment Identity, the abbreviation of international mobile device identity code. It is an "electronic serial number" composed of 15 digits. It corresponds to each mobile phone one by one, and each IMEI is unique in the world. UDID: Unique Device Identifier, unique device identification code.

2. Click "Serial Number", and then click "Identifier (UDID)".

3. [First conclusion] UDID is the most reliable device identification code on mobile devices, whether Android or iOS. [ Noun Interpretation] [Let's talk about the process] Is the noun interpretation confused? Don't panic. The following figure introduces the differences between the identification codes of each device and the current situation.

4. IMEI: International Mobile Equipment Identity is the abbreviation of International Mobile Equipment Identity code. It is an "electronic serial number" composed of 15 digits. It corresponds to each mobile phone one by one, and each IMEI is unique in the world. On the motherboard, reinstalling the APP will not change.

5. The full name of UDID is Unique Device Identifier. As the name implies, it is the unique identifier of Apple's IOS device. It consists of 40 letters and numbers. It is often used in many applications that need to limit one device and one account. The UDID of the device can be obtained in iOS5, which was later banned by Apple.

What is internal code

1. Internal code refers to the coding in the computer system; external code refers to the coding that can be directly understood and learned.

2. Internal code refers to the binary character encoding used in the computer Chinese character system. It is the exchange code between communication input, output and the system platform. Through the internal code, the purpose of universal and efficient transmission of text can be achieved. External code External code is a rhetorical exchange relative to the internal code.

3. The internal code is DEB8H. 5E38H is expressed in hexadecimal. Convert it into decimal first and then into binary.

4. In the cashier system, "internal code" usually refers to a unique identification code generated within the system to facilitate commodity management. The inner code isA coding method used to track, manage and distinguish various goods, similar to the internal "ID card" of goods. The internal code is usually automatically generated by the system, and can also be set manually as needed.

5. The internal code in the computer refers to the coding method of converting characters, numbers, symbols and other information into binary numbers. The commonly used encoding methods include ASCII code, Unicode encoding, GB2312, etc. Internal code is widely used in computers to represent and transmit a variety of data types such as text, images and audio.

6. Internal code refers to the character encoding inside the operating system. The internal code of the early operating system is related to the language. Nowadays, Windows uses Unicode internally, and then adapts to various languages with code pages. The concept of internal code is relatively vague.We generally say that the code specified on the default code page is the internal code.

What is the difference between computer internal code and external code

1. Different properties Internal code refers to the coding in the computer system; external code refers to the coding that can be directly understood and learned.

2. Internal code: According to the provisions of the national standard code, each Chinese character has a certain binary code, but this code will conflict with the ASCII code when processed internally by the computer. In order to solve this problem, add 1 to the beginning of each byte of the national standard code.

3. Internal code is the information code used to store, process and transmit Chinese characters inside the computer. It must be compatible with the ascii code but cannot conflict. Therefore, the highest position of the two bytes of the national standard code is 1, to distinguish it from the Western text, which is the inner code.The input code of Chinese characters is called foreign code. The input code refers to the code we use to enter Chinese characters.

If the content of the adjacent 2 bytes in the PC memory is 74 and 51 in hexadecimal form, then they cannot be...

and the highest bit of 751 is 0, so it can't be...

B. The information in the head is mainly to determine the routing C for data transmission in the network. The length of the data part can be changed, up to 56KB (including the head information) D. The IP datagram consists of only two parts, the head and the data area. 2 If the content of the adjacent 2 bytes in memory is hexadecimal 74 51, they cannot be ___.

F0H is a signed 8-bit binary number complement, and its decimal number is represented by -16.

For example: MOV A, the instruction code of #3AH is 74H, 3AH, which is a double-byte instruction. The function of this instruction is to send the immediate number of 3AH to the accumulator A. MOV DPTR, #8200H When we learned the dedicated register of single-chip microcomputer before, we have learned that DPTR is a 16-bit register, which consists of two 8-bit registers, DPH and DPL.