Merge pull request #47 from waterlinked/UGPS-update

Add important info

Author: wl-estensd

docs/underwater-gps/gui/position.md

@@ -2,7 +2,10 @@
 
 The Underwater GPS GUI is web based. Using your favorite web browser, go the IP address as defined [here](../network-settings.md). We currently support and recommend Chrome, Firefox, Safari and Edge.
 
-!!! attention 
+!!! Note
+    You will need **internet access** on your computer that are showing the GUI if you also want to see the map and not only relative position to the locator. This is because the map is fetched from the internet. 
+
+!!! Attention 
     Internet Explorer is not supported as of now.
 
 ![gui_global_position](../../img/gui_global_position_r100.png)

docs/underwater-gps/introduction.md

@@ -43,6 +43,8 @@ Please read the following carefully before the UGPS G2 system is installed and u
 | **Temperature** | Make sure the system does not overheat. Avoid placing it in direct sunlight over extended periods of time. |
 | **Salt water** | The contents of the topside housing will corrode and/or short if in contact with salt water. Keep the housing lid closed when in the field to avoid salt water getting inside. |
 | **Force** | Avoid using excessive force on connectors, screws and other parts of the system, as this can lead to mechanical failure. |
+| **Locator U1** | It will discharge when not in use, so always remember to charge it before operation. See [U1 charging procedure.](locators/locator-u1.md#charging)|
+| **External position and U1** | You can use external poition data to give a better position estimate, however, if using the U1 the topside will still need GPS lock for time synchronization purposes. |
 
 
 ## Discussion

docs/underwater-gps/locators/locator-u1.md

@@ -10,9 +10,12 @@ Before deployment, the Locator-U1 must obtain a GPS lock. The integrated status
 
 A rotary switch is located inside the cap, allowing you to select the channel on which the Locator transmits. The same channel must be set in the Water Linked Underwater GPS GUI. Each side of the Locator has three M3 mounting holes, and a standard bracket is included.
 
+!!! Note
+    You will need GPS lock on the topside as well when using the U1. This is for timing purposes, it will not help to use only external GPS position as this can not be used for time synchronization. It is not enough to only have GPS lock on the U1.
+
 ## Charging
 
-The Locator-U1 has an internal rechargeable battery. Use the included USB-C cable and a 5 V / 2 A (or higher) wall adapter to charge it.
+The Locator-U1 has an internal rechargeable battery. Use the included USB-C cable and a 5 V / 2 A (or higher) wall adapter to charge it. The U1 will require to be fully charged before each operation as it will discharge over time when left with the cap off. Depending on the age of the U1 and the temperature in the environment the discharging effect will be worse. 
 
 1) **Insert the USB-C cable**  
    Plug one end of the cable into the Locator-U1’s charging port.

docs/underwater-gps/quickstart.md

@@ -13,9 +13,9 @@ A quick guide on how to start using the Underwater GPS system:
 
 ## Power the topside unit
 
-Start by connecting power to the UGPS G2 topside box. The GPS receiver in the topside box will begin receiving signals and achieve a lock whilst we setup the rest of the system.
+Start by connecting power to the UGPS G2 topside box. Make sure to place the box where there s good GPS signals. The GPS receiver in the topside box will begin receiving signals and achieve a lock whilst we setup the rest of the system.
 
-If you are using the Locator-U1, power it on now as well; it too will acquire a GPS lock whilst we setup the rest of the system.
+If you are using the Locator-U1, power it on now as well. It too will acquire a GPS lock whilst we setup the rest of the system.
 
 If you are inside, use of a GPS repeater or similar will be necessary.