This is a test smple I build for US Army handhold GPS navigation device.

It can operate without GPS signal.

Environment such as underground cave, tunnel, deep canyon, underwater, lake, rive, ocean, GPS signal is not avaliable.

This device design to work in such environment. 

Not like the GPS in your car dashboard.       



Click here to open GPS nagivation on Google Map 


Contour line  is available in US only. 

High density contour  is only available in California (max zoom level 18) and Hawaii (max zoom level 19).

Low density contour  is available in US 48 states (max zoom level 15) and Alaska  (max zoom level 15



MGRS gzd and 100km is available in the whole world

10km is available in North America and Asia only, Europ is not available.

1km is available in USA only. Max zoom level is 15

Beyond zoom level 15, no more MGRS grid.


How to use 


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Google Maps Javascript Version

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Dense materials (such as concrete, rock, steel, heavy wood), tall buildings, terrain features (like mountains, ridges, and cliffs), and large trees can block or degrade GPS signals and may make it impossible to determine your location. It is well known that the ordinary Global Positioning System (GPS) fails to provide location and time information under waterThe reason is that the electromagnetic signals from the orbiting satellites are heavily damped in water and hence can not be detected by the receiver in most cases of interest.

              Therefor GPS device used in US Airforce Navy Marine Army must work without GPS signal without internet without cell phone signal and any other radio signal.


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