什么原因导致在特定时间间隔内GPS估计不稳定？ [英] What causes erratic GPS estimates during certain time intervals?
问题描述
我一直在开发位置跟踪应用程序，并且主要在运行Android 1.6的HTC G1上测试它们。我发现有一定的时间间隔 - 大约1-2小时 - 当记录的GPS位置变得非常不稳定时：我最终看到的是随机分布在我的实际位置周围的点，而不是紧密聚集在一起通常情况下，我们在10-50米范围内（我使用最低准确度记录这些位置），它们以1-5公里的半径展开 - 即使这些位置中的每一个都带有报告准确度低于50米。
就好像实际的位置精确度在这些时间段内一样，但报告的精确度保持不变。这是相对罕见的，当它发生时只持续几个小时，之后一切都恢复正常。因为它非常少见，而且我通常也在修改应用程序，所以我很难排除这是由我的代码中的错误引起的可能性。
是否有其他人遇到过这种情况？是否有已知的硬件或固件问题可能导致它？如果是这样，有没有人有一个很好的方式来发现问题，并纠正报告的准确度值？我假设一个选项是依赖NMEA语句，但我希望能够在Android API级别4上运行该应用程序，并且我发现GpsStatus.NmeaListener需要5或更高版本。
我会非常感谢任何建议。
如果发生这种情况，它看起来像一个替代的位置服务是活跃的，如细胞塔位置和wifi位置。
如果你想一个精确的位置，你应该过滤所有非GPS的。
GPS位置可以检测到他们有一个速度和方向（方位）分配时，设备移动。
（我不知道是否检查高度是否有帮助）
线条图案来自新的GPS卫星进入视图时的情况，其他（s）将进入视野。这种新的星座也可以称为所谓的多径效应（GPS信号在对面建筑物的反射）。
我希望你不要在室内进行测量，（GPS不能可靠工作）
I have been developing location tracking apps and testing them mostly on my HTC G1 running Android 1.6. I find that there are certain time intervals -- of approximately 1-2 hours -- when the recorded GPS locations become very erratic: I end up with what looks like a random distribution of points around my actual location, but instead of being clustered tightly within a 10-50 meter circle as they normally are (I use a minimum accuracy for recording these locations), they are spread out with a radius of something like 1-5 km -- even though each of these locations comes in with a reported accuracy of under 50 meters.
It's as if the actual location accuracy balloons during these periods but the reported accuracy remains the same. This is relatively infrequent and when it occurs it lasts only for a few hours, after which everything appears normal again. Because it is so infrequent, and because I am usually also in the process of tinkering with the app, I am having a hard time ruling out the possibility that this is caused by a bug in my code.
Has anyone else experienced this? Are there known hardware or firmware issues that could be causing it? If so, does anyone have a good way of detecting the problem when it is occurring and correcting the reported accuracy values? I assume one option would be to rely on the NMEA sentences, but I would like to be able to run the app on Android API level 4 and I see that GpsStatus.NmeaListener requires 5 or above.
I would really appreciate any suggestions.
1-5km deviance should never happen in GPS receivers.
If that happens then it looks like an alternate location service is active, like cell tower location, and wifi location.
If you want a precise position you should filter out all non GPS ones.
GPS positions can be detected that they have a speed and heading (bearing) assigned when the device moves.
(I am not sure if the check for an altitude helps)
The line patterns comes from the situation when a new GPS sattelite comes into the view, and other(s) are going ou of view. The new situation can be worse from the geometric sattelite constellation.
This new constellation can also called so called Multi-Path Effects (Reflections of the GPS Signal at the opposite building)
And I hope that you don't do you measurements indoors, (where GPS does not work reliably)
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