# 物理层

## **计算机网络 - 物理层**

## 通信方式

根据信息在传输线上的传送方向，分为以下三种通信方式：

* 单工通信：单向传输
* 半双工通信：双向交替传输
* 全双工通信：双向同时传输

## 带通调制

模拟信号是连续的信号，数字信号是离散的信号。带通调制把数字信号转换为模拟信号。

[![img](https://github.com/CyC2018/CS-Notes/raw/master/notes/pics/c34f4503-f62c-4043-9dc6-3e03288657df.jpg)](https://github.com/CyC2018/CS-Notes/blob/master/notes/pics/c34f4503-f62c-4043-9dc6-3e03288657df.jpg)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://im-qianuxn.gitbook.io/pytorch/ji-suan-ji/interview/2-1.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.