| <html devsite><head> |
| <title>音频环回适配器</title> |
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| </head> |
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| <p>以下示意图和照片展示的是<a href="http://en.wikipedia.org/wiki/Phone_connector_(audio)">耳机连接器</a>的音频环回<a href="http://en.wikipedia.org/wiki/Dongle">适配器</a>，我们称之为“Dr. Rick O'Rang 音频环回适配器”。Android 音频团队根据拉尔森效应（反馈环）用其衡量<a href="measure.html#measuringRoundTrip">往返音频延迟</a>。 |
| </p> |
| |
| <h2 id="loopbackCircuit">电路</h2> |
| |
| <img src="/devices/audio/images/loopback_circuit.png" alt="电路" id="figure1"/> |
| <p class="img-caption"> |
| <strong>图 1.</strong> 电路图</p> |
| |
| <p>为了确保输出信号不会超出麦克风输入负荷，我们使其音量降低了约 20 分贝。麦克风极性开关可从电阻器负载得知，音频环回适配器是一种美标/CTIA 4 段式 TRRS 插头。 |
| </p> |
| |
| <h2 id="loopbackAssembled">组装完成图</h2> |
| |
| <img src="/devices/audio/images/loopback_assembled.jpg" alt="完全组装" id="figure2"/> |
| <p class="img-caption"> |
| <strong>图 2. </strong> 组装完成图 |
| </p> |
| |
| </body></html> |
