GPS卫星数量和位置过滤
根据可用的 Location 字段，浮点精度似乎是确定 GPS 位置的好坏的主要字段，而不考虑时间戳。我想知道从 NMEA 数据（我认为是 $GPGGA）或通过 LocationManager.getGpsStatus 解析卫星数量是否也有帮助。如何筛选高精度GPS位置？更具体地说，我也有兴趣知道：
- 卫星数量越多，修复效果就越好？我知道卫星的最小数量是 4 颗，但是是否可以说 8 颗卫星的定位比 6 颗卫星的定位要好得多？
- 卫星数量不是已经包含在精度字段中了吗？
- 互联网上的一些页面提到一个重要参数是 DOP（精度稀释）。似乎它出现在 $GPGSA NMEA 句子中。这句话在Android上可用吗？此外，哪些NMEA语句保证在Android中可用？
谢谢。
Based on the available Location fields, the float accuracy seems the main field to determine how good a GPS location is, without taking into account the timestamp. I wonder if it may also be helpful to parse the number of satellites from the NMEA data (I think it was $GPGGA) or via LocationManager.getGpsStatus. How do you filter the high-precision GPS locations? More specifically, I'm also interested in knowing:
- The higher the number of satellites, the better the fix? I know the minimum number of satellites is 4, but can it be said that a fix with 8 sats is considerably better than a 6-sats fix?
- Isn't the number of sats already included in the accuracy field?
- Some pages on the internet mention that an important parameter is the DOP (Dilution of Precision). Seems that it appears in the $GPGSA NMEA sentence. Is this sentence available in Android? Moreover, which NMEA sentences are guaranteed to be available in Android?
Thanks.
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完全取决于 GPS 芯片组及其上运行的代码。一般来说，是的，更多的卫星意味着更好的预测。
是的，NMEA 句子可在 Android 中使用。现在 NMEA 标准非常庞大，因此大多数 GPS 芯片组仅支持 NMEA 的一小部分。我无法保证任何内容，但我发现 GGA、RMC、GSV、GST 和 GSA 是最受欢迎的。我使用过的大多数芯片组都提供 VDOP 和 HDOP。
您似乎想提高 GPS 定位的准确性？为什么不使用加速度计、陀螺仪、方向和其他传感器（甚至气压计/Wifi RSSI） - 或 - 卡尔曼滤波。谷歌地图这样做是为了提高准确性。
这是科学的进步，获得完美的 GPS 位置是一件很困难的事情，因为变量的数量不断变化，并且考虑到我们正在使用 简化民用数据。
Totally depends on the GPS chipset and the code running on it. Typically yes, more satellites means better prediction.
Yeah NMEA sentences are available in Android. Now the NMEA standard is huge, so most of the GPS chipsets only support a small subset of NMEA.I won't guarantee anything, but I found that GGA, RMC, GSV, GST and GSA are the most popular. Most of the chipset that I've worked with gives VDOP and HDOP.
It seems you want to improve the accuracy of your GPS fixes? Why don't you use the Accelerometer, Gyro, Orientation and other sensors (even the Barometer/Wifi RSSI) - or - Kalman filtering. Google Maps does this to improve the accuracy.
This is science in progress, getting a perfect GPS position is difficult thing to do, due to the number of variables that change and considering the fact we are working with dumbed down civilian data.
答案很简单，使用 HDOP 值。
hdop 越小，精度就越好。 （但没有任何保证，就像所有带 GPS 的东西一样）
卫星的数量没有多大帮助，忽略它们。 （卫星星座比较重要，用DOP和HDOP来表示）
使用 hdop < 5、并忽略低于特定速度阈值（例如5公里/小时）的所有修复
此外，您只能使用“3D-fix”类型的修复。您可以在基本 NMEA 消息中找到所有这些内容。 （RMC、GSA、GGA）
不要使用陀螺仪、加速度计，这对你我和大多数其他人来说可能会做很多工作。
The answer is simple, use the HDOP value.
The smaller the hdop, the better should be the accuracy. (But there is no garantee, like for all things with GPS)
The number of satellites does not help much, ignore them. (The satelite constellation is more important, and that is expressed in DOP and HDOP)
Use hdop < 5, and ignore all fixes below a certain speed threshold (e.g 5km/h)
Further you could use only fixes which are of type "3D-fix". You find that all in the basic NMEA messages. (RMC, GSA, GGA)
Don't use gyro, accelormeter, this will be probably to much work for you and me and most other people.
精度因子 (DOP) 值基于卫星几何形状。如果您的 GPS 使用天空中靠近的一组卫星，您将获得比使用分布更广泛的卫星更高的 DOP 值。 DOP 值越低，您的修复就越准确。请参阅https://en.wikipedia.org/wiki/Dilution_of_ precision_(navigation)
The Dilution of Precision (DOP) value is based on the satellite geometry. If your GPS is using a cluster of satellites that are close together in the sky you will get a higher value of DOP than if it is using satellites that are more widely spread out. The lower value of DOP, the more accurate your fix. See https://en.wikipedia.org/wiki/Dilution_of_precision_(navigation)