Satellite navigation systems are based on the Global Positioning System (GPS) and other national and multinational satellite initiatives (for example, Glonass and Galileo) with applications in consumer and commercial markets. Satellite navigation systems are embedded in vehicles, available as portable units (personal navigation devices [PNDs]) or offered as applications in mobile phones, with an internal or external GPS antenna, and can be complemented with cellular tower or Wi-Fi-enabled triangulation (assisted GPS).