article_snippet: Take GPS for example.
article_snippet: How about communicating with satellites?
article_snippet: Five very high frequency and high frequency radios that could transmit and receive voice and data transmissions.
article_snippet: Two transponders that could send identification and altitude data to air traffic control radar screens.
article_snippet: One satellite transceiver that could transmit and receive text messages and phone calls.
article_snippet: To understand why, you first have to know a little about the technology and the gaps in the system.
article_snippet: The  technology is called Automatic Dependent Surveillance Broadcast, or ADS-B.
article_snippet: The  technology is the keystone component of NextGen.
article_snippet: The system can be increased to real time monitoring should an abnormal situation arise.