Data Defined Clearly | Generated by AI
Question: In the basic concepts of data communications, what term refers to physical symbols and their combinations that record the nature, state, and interrelationships of objective things?
Answer:
Correct Answer: C — Data (数据)
Why the Answer is “Data” (C), Not “Signal” (B)
This is a concept-definition question that requires precise understanding of four key terms in data communications. Your selected answer (B: Signal) is incorrect because “signal” refers to the physical/electrical carrier of data — not the symbolic record itself.
Definitions of All Four Options
A. Message (消息)
The purpose of communication is to transmit messages. Examples include speech, text, images, and video — all of which are forms of messages. A message is the object being transmitted in a communication system, serving as the carrier of information.
B. Signal (信号)
A signal is the electrical or electromagnetic representation of data. In other words, a signal is the physical medium (e.g., voltage, light waves, electromagnetic waves) used to carry data through a transmission channel. It is not a symbolic record of facts.
C. Data (数据) ✅ — Correct Answer
Data is the entity used to convey information — it consists of identifiable, abstract symbols used to record and express information, such as numbers, text, letters and their combinations, graphics, images, video, and audio.
More precisely, according to RFC 4949, data is information represented in a specific way, usually a meaningful sequence of symbols. This representation can be processed or produced by computers, other machines, or humans.
This matches the question’s definition exactly: physical symbols and their combinations that record the nature, state, and interrelationships of objective things.
D. Information (信息)
Information emphasizes the aspects of “processing” and “use.” A piece of material belongs to the data category before it is used; only after it is applied does it transform into information. Information is the meaning or value extracted from data — it is the content, not the symbolic form itself.
Key Relationship Summary
| Term | Chinese | Role in Communication |
|---|---|---|
| Information (信息) | 信息 | The meaning/content (abstract, semantic) |
| Message (消息) | 消息 | The carrier of information (text, voice, image) |
| Data (数据) | 数据 | Symbolic records of objective facts |
| Signal (信号) | 信号 | Physical/electrical transmission of data |
Information is the essence; message is the carrier of information; signal is the transmission method. Without information, the communication system loses its purpose; without messages, information cannot be conveyed; without signals, information cannot be transmitted.
Why Students Confuse Data and Signal
The confusion arises because both “data” and “signal” are physical in nature. However:
- Data = symbolic/logical representation (numbers, letters, symbols)
- Signal = physical/electrical form used for transmission (voltage, electromagnetic waves)
Data is the entity through which a computer system conveys meaning; a signal is the method of transmitting data. When data is sent from one end of a network to another, the data is converted into signals regardless of whether physical or wireless links are used.
Conclusion: The question asks about “physical symbols and their combinations recording objective things” — this is the textbook definition of Data (数据). The correct answer is C.
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