Channels of Communication | 通信信道：物理原理与CIE考点解析

📚 Channels of Communication | 通信信道：物理原理与CIE考点解析

Communication systems transfer information from a transmitter to a receiver through a physical channel. The channel may be a pair of wires, a coaxial cable, an optical fibre, or free space carrying radio waves or microwaves. In CIE A-Level Physics, “Channels of communication” focuses on how these channels behave, how signals are attenuated and distorted, and how modulation and digital techniques improve reliability.

通信系统通过物理信道将信息从发射端传输到接收端。信道可以是一对导线、同轴电缆、光纤，也可以是传播无线电波或微波的自由空间。在 CIE A-Level 物理中，”通信信道”这一主题重点考察这些信道的特性、信号的衰减与失真，以及调制和数字技术如何提高通信可靠性。

1. The Communication System Block Diagram | 通信系统框图

Every communication system can be modelled as a chain: information source → encoder/transmitter → channel → receiver/decoder → destination. The channel is the medium that carries the signal; it may introduce attenuation, noise and distortion. A carrier wave is often used because the original information signal has a low frequency and cannot travel efficiently through many channels.

每个通信系统都可以简化为链路：信息源 → 编码/发射器 → 信道 → 接收器/解码 → 接收端。信道是承载信号的介质，它可能引入衰减、噪声和失真。通常需要使用载波，因为原始信息信号频率较低，无法高效通过许多信道传输。

The transmitter modulates the information onto a high-frequency carrier. The receiver demodulates the signal to recover the original information. In this topic, we mainly study the channel itself and the physical limitations it imposes.

发射器将信息调制到高频载波上，接收器再解调信号以恢复原始信息。在本主题中，我们主要研究信道本身及其产生的物理限制。

2. Types of Communication Channels | 通信信道的类型

Common channels include wire pairs, coaxial cables, optic fibres, and electromagnetic waves in free space, such as radio waves and microwaves. Each channel has different bandwidth, attenuation, noise immunity, cost and installation constraints. The choice of channel depends on distance, data rate, mobility and environment.

Published by TutorHao | A-Level Physics Revision Series | aleveler.com

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