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手机中的高度测量有多准确

[英]how accurate is the altitude measurement in mobile phones

原文 2011-04-28 22:36:27 2 4 iphone/ android/ windows-phone-7/ gps/ mobile-phones

How accurate is the altitude measurement from a mobile phone's GPS?手机 GPS 的高度测量有多准确？ I've gathered that the lat/long can vary by hundreds of meters but is that same level of uncertainty present in the altitude values?我已经收集到纬度/经度可以变化数百米，但是海拔值中是否存在相同程度的不确定性？

In particular I'm working with Windows Phone 7 but I'm sure that this question applies to other mobile devices.特别是我正在使用 Windows Phone 7，但我确信这个问题适用于其他移动设备。 I expect that there are only a few GPS chip manufacturers and the same chip would be used by different phones.我预计只有少数 GPS 芯片制造商，并且不同的手机会使用相同的芯片。

This question deals with how it is calculated but it doesn't mention anything about accuracy or reliability.这个问题涉及它是如何计算的，但它没有提到任何关于准确性或可靠性的内容。

4 个解决方案

I don't know specifically about the iPhone, but elevation is often much less accurate than X,Y information from a GPS.我不具体了解 iPhone，但海拔通常远不如 GPS 的 X、Y 信息准确。 Here are some sources of information about this.这里有一些关于这方面的信息来源。

It requires fairly complicated math to understand fully, but no the altitude on a ANY gps is not as accurate the lat/long position.它需要相当复杂的数学才能完全理解，但是任何 gps 的高度都没有纬度/经度 position 准确。

http://weather.gladstonefamily.net/gps_elevation.html http://weather.gladstonefamily.net/gps_elevation.html

http://gpsinformation.net/main/altitude.htm http://gpsinformation.net/main/altitude.htm

http://www.sawmillcreek.org/showthread.php?83752-Do-civilian-GPS-unts-do-accurate-altitude http://www.sawmillcreek.org/showthread.php?83752-Do-civilian-GPS-unts-do-accurate-altitude

quote from the third link - "The altitude error is much greater because it is a satellite based system. If you think about it, the best satellite positions for a perfect read are going to be evenly distributed in an imaginary sphere surrounding you. Unfortunately, since you are standing on the earth, that rules out half the sphere because you need line-of-sight to the satellite. As a practical matter, it even rules out a constellation with satellites close to the horizon. So, generally speaking, your fixes will be overhead--which means that the cumulative error is mainly in the vertical plane. So, I think the offhand estimate is vertical error = 1.5x horizontal error."引用第三个链接-“高度误差要大得多，因为它是基于卫星的系统。如果您考虑一下，完美读取的最佳卫星位置将均匀分布在您周围的假想球体中。不幸的是，因为你站在地球上，所以排除了一半的球体，因为你需要对卫星的视线。实际上，它甚至排除了卫星靠近地平线的星座。所以，一般来说，你的修复将是开销——这意味着累积误差主要在垂直平面上。所以，我认为临时估计是垂直误差 = 1.5x 水平误差。

Vertical error is specified as 1.5 * horizontal error.垂直误差指定为 1.5 * 水平误差。 You must also allow for local deviation between the geodetic model and the planetary surface because the geodetic oblate spheroid model is an approximation only even when local correction tables are in use.您还必须考虑大地 model 和行星表面之间的局部偏差，因为即使在使用局部校正表时，大地扁球体 model 也是近似值。

Since the triangulation hands back a point in space, the same inaccuracies would apply to the Z axis like they do to X and Y.由于三角测量返回空间中的一个点，因此与 X 和 Y 相同的不准确性将适用于 Z 轴。

In other words, it's no more and no less accurate than the accuracy of the LAT/LONG.换句话说，它的准确度不亚于 LAT/LONG 的准确度。