A-GPS Tracker

This is an outdoor Tracker using the A-GPS capabilities of your phone. If activated it may record your track even when the phone goes to stand-by.

It is designed in particular for hikers that want to record a new path or want to follow an existing track and, more importantly, want to avoid losing themselves during their return way.

Features:

- Elevation is given relative to mean sea level ( note that most android programs don't do this)

- Your Latitude and Longitude coordinates are given in degrees and in UTM-WSG84 (published in paper maps)

- A track is stored in a GPX file. It can be recorded, stored or loaded to/from memory and shared with other people. Its Elevation vs Distance profile can be shown on the screen.

- Statistics of a loaded GPX track will include the net walk time, ascent and descent altitude.

- A "follow path" monitor function can be enabled to provide an alarm in case you are leaving a loaded GPX path.

It is important to understand that this App is good to trace your path but if you want to measure a walked distance the accuracy is not so good. A distance is measured as the sum of distances among the points acquired every 3sec or 5meters, but GPS accuracy is about 10/20meters, if the path is casual( not like a car that follows a road) the final result can’t be very accurate. Errors up to 15% in the measurement of distances are normal.

Errors are determined by several factors. The most important are:

- quality of received satellite signals, that is poor is the sky is clouded,

- configuration/relative position of satellites that is continuously changing,

- reflections of the signals on large surfaces like walls,buildings, etc.

These are the reasons why GPS may get poor position coordinates when GPS signals are weakened by meteorological conditions and in particular in urban areas, when satellite signals are received from a multi-path propagation due to reflections on buildings.

NOTE:

GPS is used here as a generic term and refers to the capability to receive position data from signals received from satellites. Modern phones can obtain position data from more than one satellite system, i.e. not only the american GPS but also GLONASS, BeiDou and Galileo. A-GPS Tracker will receive data from all the available satellite navigation systems. In addition A-GPS (Assisted GPS) also uses ground sources like cell tower data and WiFi, that may enhance quality and precision when in poor satellite signal conditions and in particular will help to reduce time to start fixing initial position. GPS will be the source of the more accurate position: Latitude, Longitude and Altitude. Note that for hikers Altitude it is of particular importance and can be given only by GPS.

这是一款使用手机A-GPS功能的户外追踪器。如果激活，即使手机处于待机状态，它也可能会录制您的音轨。

它特别适用于想要记录新路径或想要跟随现有赛道的徒步旅行者，更重要的是，希望避免在返回途中迷失自己。

特征：

- 相对于平均海平面给出高程（请注意，大多数Android程序不这样做）

- 您的纬度和经度坐标以度和UTM-WSG84（在纸质地图中发布）给出

- 轨道存储在GPX文件中。它可以记录，存储或加载到内存中或与其他人共享。它的高程与距离剖面可以显示在屏幕上。

- 加载的GPX轨道的统计数据将包括净步行时间，上升和下降高度。

- 可以启用“跟随路径”监视功能，以便在您离开加载的GPX路径时提供警报。

重要的是要了解此应用程序可以很好地跟踪您的路径，但如果您想测量步行距离，则准确性不是那么好。距离测量为每3秒或5米获得的点之间的距离之和，但GPS精度约为10/20米，如果路径是随意的（不像跟随道路的汽车那样），最终结果不能很准确。距离测量误差高达15％是正常的。

错误由几个因素决定。最重要的是：

- 收到的卫星信号质量差，天空阴云密布，

- 不断变化的卫星的配置/相对位置，

- 墙壁，建筑物等大型表面上的信号反射。

这些是当GPS信号被气象条件削弱时，特别是在城市地区，当由于建筑物的反射而从多径传播接收卫星信号时，GPS可能获得不良位置坐标的原因。

注意：

这里使用GPS作为通用术语，并且指的是从从卫星接收的信号接收位置数据的能力。现代电话可以从多个卫星系统获得位置数据，即不仅是美国GPS，还有GLONASS，BeiDou和Galileo。 A-GPS Tracker将从所有可用的卫星导航系统接收数据。此外，A-GPS（辅助GPS）还使用诸如蜂窝塔数据和WiFi之类的地面信号源，这可以在卫星信号条件差的情况下提高质量和精度，特别是有助于缩短开始固定初始位置的时间。 GPS将成为更准确位置的来源：纬度，经度和海拔高度。请注意，对于徒步旅行者海拔高度来说，它特别重要，只能通过GPS给出。