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manual:user_guide:tools:altitude [2015/04/01 16:37] – mstupka | manual:user_guide:tools:altitude [2024/02/16 12:11] (current) – mstupka | ||
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- | ====== Altitude Manager ====== | + | {{ : |
---- | ---- | ||
- | < | ||
- | ===== Settings ===== | ||
- | ==== Altitude | + | Altitude |
- | + | * **Settings** | |
- | * **Use altitude offset** - defines offset between real and GPS altitude. More in the **Offset | + | * **Offset** |
- | ==== Pressure sensor | + | * **Pressure** |
- | + | ===== Settings ===== | |
- | * **Use pressure sensor** - measures precise | + | Contains general switches of offset and pressure sensor |
==== Elevation data ==== | ==== Elevation data ==== | ||
- | | + | <wrap info> |
+ | {{ : | ||
+ | * **Don' | ||
+ | | ||
+ | * **Replace GPS values** - uses offline elevation data only for displaying elevation and calculating elevation gain and charts | ||
+ | <WRAP round alert > | ||
+ | **Warning for pilots**: optimizing or replacing GPS altitude by elevation data is not recommended for activities when you are **not moving on the ground** - displayed altitude values are influenced by the ground altitude measuring and calculation | ||
+ | </ | ||
==== Altitude filter ==== | ==== Altitude filter ==== | ||
- | * Filter - applies | + | Applies a filter to altitude |
+ | ===== Altitude offset ===== | ||
+ | {{ : | ||
+ | Altitude calculated by internal or external (Bluetooth) GPS unit is related to a different method of referencing the Earth' | ||
+ | |||
+ | Locus Map can define this offset by three methods: | ||
+ | * **Manual correction** - the basic method used when the exact offset value is known | ||
+ | * **Automatic correction** - a method used in most cases - Locus Map can compute the offset of the whole world from a Geoid model. This method is accurate enough for use in mobile phones and sufficiently precise for all locations (the offset slightly varies based on location). <wrap info> | ||
+ | * **NMEA correction** - mobile device communicates with GPS unit over special messages called NMEA. These messages contain values of Geoid height that Locus Map can read and apply them to correct this offset.< | ||
+ | |||
+ | ===== Pressure sensor ===== | ||
+ | {{ : | ||
+ | Some devices are equipped with a barometric pressure sensor. Barometric sensors measure atmospheric pressure very precisely which can be used for calculating relative altitude changes. I.e. if you know certain pressure at a certain altitude you can calculate altitude changes between the known and current position. | ||
- | ===== Offset | + | The pressure sensor must be calibrated to a known altitude value so that it can be used for real altitude value calculations. Locus Map offers several methods: |
+ | * **Automatic** - Locus Map uses GPS altitude or elevation files and current barometric pressure as basic values and relates all other measurements to these values. It also checks measured values in 2-hour intervals and eventually re-calibrates the pressure sensor.< | ||
+ | * **Pressure** - current pressure value at a particular sea level as the reference can be obtained from the Internet. The resulting altitude calculation is also quite accurate but the base pressure changes in time so it can be a problem. | ||
+ | * **Altitude** - uses some other source of ground altitude - external maps, measuring, tourist guide posts, etc. as the reference. Locus Map then calibrates the pressure sensor according to this value. | ||
+ | < | ||
+ | </ | ||
+ | ===== Altitude measurement workflow | ||
+ | Locus Map applies the above-mentioned computations in the following order: | ||
- | ........... | + | * received altitude from the GNSS unit |
- | Enable Altitude offset in settings tab before setting offset parameters. | + | * using elevation data files (if enabled) |
- | ... | + | * using the pressure sensor |
+ | * final filtering | ||
+ | If step 2 is missing, the pressure sensor calibration uses directly received altitude values. | ||
- | Pressure | + | <WRAP center round tip> |
- | ............. | + | The **recommended setup** is using elevation data (fully replacing GNSS) without a pressure |
- | Enable Pressure | + | </ |
- | Automatic | ||
- | Automatic calibration according to GPS |