【热点科普】马航失踪地点是如何确定的？

来源: 26484915 于 2014-04-08 15:36:51 [档案] [旧帖] [给我悄悄话] 本文已被阅读：次 (6434 bytes)

【科普】马航失踪地点是如何确定的？2014-03-27 10:25:23

（1）根据MH370航班最后一次 ping 海事卫星接收天线角度和飞机载油量，确定飞机可能在南北两条走廊上。注意这个结论是基于距离，有对称性，所以有南北两种可能。

（2）根据同步海事卫星接收的多次ping 的微波信号的多普勒效应分析，对称性被打破，只有往南一种可能。

几点说明：

a) 在卫星通信中考虑多普勒效应，是成熟技术，不是新技术。卫星通信是微波通信，与手机通信一样是无线电通信的一种。

b) 用微波信号传输的多普勒效应对失事飞机定位，是多普勒效应的新应用。

c) 这个新的应用，用已知飞机的航程做过对比分析，得到了验证。目前卫星发现的大面积残骸，初步证明结果的正确。飞机在南印度洋找到，只是时间问题。

British satellite company Inmarsat’s Chris McLaughlin explains how scientists were able to work out the final flight path of the missing plane, flight MH370. Using models of the last signals sent from the Boeing 777 and comparing that with previous Malaysia Airlines data, they were able to narrow the final flight path down to the southern Indian Ocean.

(CNN) — Japan and Thailand both said Thursday they’ve sent new satellite images to Malaysia showing separate debris fields that could be related to missing Malaysia Airlines Flight 370.

The announcements come just a day after Malaysian officials announced a French satellite had found 122 pieces of something floating nearby, and days after similar findings in the same general area — all part of the search for Flight 370. The plane vanished March 8 with 239 people aboard.

d) 海事卫星是同步卫星，多普勒效应贡献来自飞机的飞行速率与方向（速度矢量）。

(3) 什么是多普勒效应？

一列迎面开来的火车，鸣笛的声音会比停着的火车声音尖锐（高频），而离开的火车鸣笛会更低沉（低频）。迎面开来的汽车鸣笛，在会车的过程中，你听到的声音会从尖锐到低沉。这是声波的多普勒效应。

An animation illustrating how the Doppler effect causes a car engine or siren to sound higher in pitch when it is approaching than when it is receding. The pink circles are sound waves. When the car is moving to the left, each successive wave is emitted from a position further to the left than the previous wave. So for an observer in front (left) of the car, each wave takes slightly less time to reach him than the previous wave. The waves “bunch together”, so the time between arrival of successive wave fronts is reduced, giving them a higher frequency. The waves “stretch apart”, so the time between the arrival of successive wave-fronts is increased slightly, giving them a lower frequency.