@@ -149,21 +149,21 @@ tags: ["王道408", "计算机网络","物理层"]
149149
150150### 编码与调制的过程
151151
152- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-encode.jpg )
152+ ![ ] ( https://s2.loli.net/2025/09/25/SUurVmac5TbvGLM.png )
153153
154154** 数字数据编码为数字信号**
155155
156156编码方式有下面六种
157157
158- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-encode-type.jpg )
158+ ![ ] ( https://s2.loli.net/2025/09/25/gNusT9XFV4PyGiO.png )
159159
1601604B/5B编码,编码效率80%
161161
162162** 数字数据调制为模拟信号**
163163
164164数字数据调制技术在发送端将数字信号转为模拟信号,而在接收端将模拟信号还原为数字信号,分别对应于调制解调器和解调过程
165165
166- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-da.jpg )
166+ ![ ] ( https://s2.loli.net/2025/09/25/29oT7q6hC1uImKD.png )
167167
168168** 模拟信号编码为数字信号**
169169
@@ -199,21 +199,21 @@ tags: ["王道408", "计算机网络","物理层"]
199199
200200### 电路交换
201201
202- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-cs-1.jpg )
202+ ![ ] ( https://s2.loli.net/2025/09/25/36gR5Dq97hQoAwS.png )
203203
204- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-cs-2.jpg )
204+ ![ ] ( https://s2.loli.net/2025/09/25/UPX4psi31CTY2r5.png )
205205
206206### 报文交换
207207
208- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-me-1.jpg )
208+ ![ ] ( https://s2.loli.net/2025/09/25/fys8HhVi9drQWEO.png )
209209
210- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-me-2.jpg )
210+ ![ ] ( https://s2.loli.net/2025/09/25/LJVaesOR41zblTi.png )
211211
212212### 分组交换
213213
214- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-ps-1.jpg )
214+ ![ ] ( https://s2.loli.net/2025/09/25/FGmVSYxNcyuIptC.png )
215215
216- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-ps-2.jpg )
216+ ![ ] ( https://s2.loli.net/2025/09/25/6pQz8DRCcVETWIA.png )
217217
218218### 数据交换的选择
219219
@@ -225,7 +225,7 @@ tags: ["王道408", "计算机网络","物理层"]
225225
226226### 分组交换-数据报方式
227227
228- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-ps-m.jpg )
228+ ![ ] ( https://s2.loli.net/2025/09/25/Azn9vcljwOMY4Ks.png )
229229
230230数据报方式为网络层提供无连接服务。发送方可以随时发送分组,网络中的节点可随时接收分组
231231
@@ -242,7 +242,7 @@ tags: ["王道408", "计算机网络","物理层"]
242242
243243### 分组交换-虚电路方式
244244
245- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-ps-v.jpg )
245+ ![ ] ( https://s2.loli.net/2025/09/25/Yfl3E2BXFV61QuN.png )
246246
247247虚电路方式为网络层提供连接服务。源节点和目的节点之间建立一个逻辑连接而非物理连接
248248
@@ -258,7 +258,7 @@ tags: ["王道408", "计算机网络","物理层"]
258258
259259### 虚电路和数据报的区别
260260
261- ![ ] ( https://jihulab.com/xnzone/earth-bear/-/raw/master/network-physical-ps-mv-diff.jpg )
261+ ![ ] ( https://s2.loli.net/2025/09/25/TBWrLAOjUbCvEhd.png )
262262
263263## 物理传输介质
264264
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