The method to reset the altitude value is to press and hold the [ALTI/+] button until 0M is displayed at the bottom of the screen, then start moving, and the altitude value movement will be displayed on the screen. Press the [ALTI/+] button again to return to the actual height value. Relative altimeter: using the relative altimeter is used to clear the height value measured at that moment , and use the position at that time as the 0m height point, and the height value up or down from the 0 height point is the relative height value. Barometer: The current barometric pressure will be displayed on the screen immediately after power-up. Press the [ALTI/+] button to switch between barometer and altimeter. Altimeter: The altitude value displayed on the screen after power-on is the sea level altitude of the current location. In the altitude display state, press [SET] and [ALTITUDE/+] keys simultaneously, you can press [+] or [-] to change the current altitude value. Weather forecast: It can predict the weather conditions in the next 12-24 hours when powered on, and the effective range is 30-50 km. Heritan 1. Long press the [SET] button for 2 seconds, 24 hours flashes, press