Android GPS 的准确度如何？
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How accurate is Android GPS?
提问by Anthony Forloney
I thought I have read somewhere that the accuracy of Android's GPS is about 10 cm?
我以为我在某处读到 Android 的 GPS 精度约为 10 厘米？
Can anyone verify or correct this? Reason being is that my application I am trying to develop keeps track of locations an user has visited and it would help me out tremendously to know the margin of error I can expect.
任何人都可以验证或更正吗？原因是我正在尝试开发的应用程序会跟踪用户访问过的位置，这将极大地帮助我了解我可以预期的误差幅度。
回答by MusiGenesis
10 centimeters? No chance. In any event, Android is just a device OS; the actual accuracy of a GPS device is dependent on the device's chipset. Android may be theoreticallycapable of accomodating devices with that level of accuracy, but that's it.
10厘米？没有机会。无论如何，Android 只是一个设备操作系统；GPS 设备的实际精度取决于设备的芯片组。从理论上讲，Android 可能能够容纳具有该精度级别的设备，但仅此而已。
The accuracy of GPS devices is normally not presented as a simple distance, anyway. Usually, a device's accuracy is given as a distance along with the percentage of measurements that are within that distance from the true location. A typical accuracy for a hand-held GPS device would be something like 30% of your measurements within 50 meters of the true position (yes, the devices are typically thatinaccurate).
无论如何，GPS 设备的精度通常不是简单的距离。通常，设备的精度以距离以及距离真实位置在该距离内的测量值百分比的形式给出。对于手持GPS设备，典型精度会是这样的50米范围内的真实位置的您的测量的30％（是的，这些设备通常是不准确的）。
回答by progrmr
Depends on the actual GPS hardware but it is reasonable to expect about 10m horizontal accuracy now that SAis turned off (it was 100m when SA was on). Vertical accuracy is usually about 3 times worse than horizontal.
取决于实际的 GPS 硬件，但现在SA关闭时预计大约 10m 的水平精度是合理的（SA开启时为 100m）。垂直精度通常比水平精度差 3 倍左右。
If the GPS hardware can receive WAAS correction it can do better, about 7.6m worst case, 1-2m best case. Most phones don't have WAAS though (do any?).
如果 GPS 硬件可以接收 WAAS 校正，它可以做得更好，最坏情况约为 7.6m，最好情况为 1-2m。大多数手机虽然没有 WAAS（有吗？）。
There is a table of expected accuracy for various kinds of devices in the WAAS entry of Wikipedia.
回答by anchorite
Drop the "c" and you've got it about right. Professional grade receivers such as Trimble's Nomad series can do 2-5m accuracy before post-processing, and 1-3m afterward, which requires downloading the points to a PC and correcting them based on satellite information received at nearby base stations, and that's with good satellite lock (perhaps 6 or more) and staying away from large vertical obstructions like trees and utility poles that deflect or block signals. Licensed surveyors can get accuracy at the centimeter level only by using very expensive antennae (USD$10k range) and occupying the same point for hours, taking an average of thousands of readings. And then as some posters here have said, vertical accuracy is still only about a third as good as horizontal. I think 10m with a phone is not impossible given that it is probably indoors or in a car, or while moving, and considering satellite lock comes and goes. The chip's primary duty is to supplement or correct info given to E911 dispatchers, and so it probably doesn't get much better than differentiating one single family home from another.
去掉“c”，你就对了。Trimble 的 Nomad 系列等专业级接收机在后处理之前可以做到 2-5m 的精度，之后可以做到 1-3m，这需要将点下载到 PC 并根据附近基站接收到的卫星信息进行校正，这很好卫星锁（可能有 6 个或更多）并远离大的垂直障碍物，如偏转或阻挡信号的树木和电线杆。获得许可的测量员只能通过使用非常昂贵的天线（10,000 美元的范围）并在同一点占据数小时，平均读取数千个读数，才能获得厘米级的精度。然后正如这里的一些海报所说，垂直精度仍然只有水平精度的三分之一左右。我认为使用手机 10m 并非不可能，因为它可能是在室内或汽车中，或者在移动时，并且考虑到卫星锁定来来去去。该芯片的主要职责是补充或更正提供给 E911 调度员的信息，因此它可能没有比区分一个单户住宅更好的方法了。
回答by Fraggle
You can routinely get 2 meters accuracy with some Android phones, like the original Motorola Droid.
使用某些 Android 手机（例如最初的摩托罗拉 Droid），您通常可以达到 2 米的精度。
I have verified this in many ways over the past 1.5 years.
在过去的 1.5 年中，我已经通过多种方式验证了这一点。
EDIT: And I sell a gps app with over 300k users.
编辑：我销售一个拥有超过 30 万用户的 GPS 应用程序。
回答by phoebus
10CM accuracy is pretty unlikely. Military MGRS systems using the military GPS system, for example, which tend to be a bit better than civilian equivalents, have a 1m resolution. Assisted GPSmay provide tighter resolution if available, but right now it takes a device significantly larger than a cell phone to achieve a 10cm resolution. The GPS resolution depends more on the hardware than the software.
10CM 的精度是不太可能的。例如，使用军用 GPS 系统的军用 MGRS 系统往往比民用同类产品好一点，分辨率为 1m。 如果可用，辅助 GPS可能会提供更严格的分辨率，但现在需要比手机大得多的设备才能实现 10 厘米的分辨率。GPS 分辨率更多地取决于硬件而不是软件。
