What the icons mean
The signal icon will change color to indicate different states, You can hover over this icon to see what it means:
Grey indicates that the Object is not currently communicating with the server. 
Orange indicates that the device is communicating with the server but the GPS is not currently operational, or the device has not moved since the last communication
Green indicates that it is currently communicating and tracking.
Notice Your device will conserve power and data when it can therefore If the object detects that it is at rest for a period of time it may reduce its activity. In this case, it will communicate with the server less frequently and even shut down its GPS receiver. The unit will reactivate If it detects motion via its vibration/ motion sensor.