The Prime Power Unit (PPU) is an air- and highway-transportable, trailer-mounted 1.3MW (megawatt) Generator Set, a key component of the Terminal High Altitude Air Defense (THAAD) system.

主动力单元（PPU）是一种可搭载空中和公路运输，拖车式1.3MW （兆瓦）发电机组，这也是终端高空防御系统（THAAD）的关键组成部分。

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The Global Positioning System enables properly equipped users to determine precise time and velocity and worldwide latitude, longitude and altitude to within a few meters.

GPS允许持有对应设备的用户来确定精确的时间、速度、经纬度以及海拔，而误差只有几米。

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With this radar system and a specially trained Air Force crew the aircraft can operate at a low altitude and in night or adverse weather conditions.

有了这种雷达和经过特别训练的空军机组，飞机可以在很低的高度、夜间或不利的天气条件下飞行。

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Alongside the HTC-made handset are an altitude and orbit control system, two propulsion setups and a Linux-based computer with a "high-speed" processor.

ENGADGET

And what - we can't leave out the terminal phase of missile defense, which is things like PAC-3, the Patriot Missile System, and the Terminal High Altitude Area Defense or THAAD, which would shoot down on a threat missile in the final phase of its flight.

NPR: Missile Defense, the U.S. and Europe

To combat this threat, aircraft have a warning system which alerts the crew if the cabin altitude is approaching dangerous levels.

BBC: NEWS | Europe | Dangers of aircraft decompression