7 inch Screen Bluetooth Portable GPS Car Navigation Systems free world map

Description:

> 7" touch screen car gps navigation

> DDR 128mb, 4GB flash memory

> Bluetooth hand free call

> FM transmitter sending the gps voice to car radio loud speaker

> AV-IN for rear view parking camera, no worried about the rear situation

> Free World Map

> Length: 180mm

> Width: 114mm

> Weight: 300g

Specifications

Global Navigation Satellite System

The FAA Global Navigation Satellite System (GNSS) Program Office provides satellite (GPS) based positioning, navigation, and timing (PNT) services in the United States to enable performance-based (RNP/RNAV) operations for all phases of flight from en route, terminal, approach, and surface navigation. PNT services are an essential enabler required to overcome the deficiencies in today's air traffic infrastructure and support implementation of the Next Generation Air Transportation (NEXTGEN) system for the United States' National Airspace System (NAS). The FAA's plan to provide PNT services requires implementation of two GPS augmentation systems, the Wide Area Augmentation System (WAAS) and the Ground Based Augmentation System (GBAS). Both systems improve the accuracy, availability, and integrity needed to support continuous all-weather use of GPS as a primary means of navigation and automated dependent surveillance (ADS-B) within the NAS.

FAQ:

How Does GPS work?

GPS receivers integrate a radio and a navigation computer and can receive the faint, twenty-watt signals coming from the satellites. The computer uses these signals to calculate the distance between the satellites and the receiver. With this information, the computer can further calculate the position and velocity of the receiver.
The number of satellites visible to a receiver constantly varies between four and eleven according to time and location. Each satellite broadcasts a number of unique spread-spectrum codes, but only one, the Coarse Acquisition (C/A) code, is easily accessible for civilian use. The C/A in orbit 11,000 miles above earth, GPS satellites transmit at twenty watts a number of unique spread-spectrum code. The number of satellites visible to a GPS receiver constantly varies between four and eleven according to time and location. Code is effectively a timing signal synchronized to an international time standard-Universal Coordinated Time (UCT). UCT is kept by a world-wide ensemble of cesium and hydrogen maser frequency standard atomic docks. The highest-quality GPS receivers measure the C/A code to better-than- nanosecond precision.

Where can GPS work?

GPS reception is available around the globe. You will need to have a clear view of the skies so the receiver can triangulate at least three satellites. An office window works well, but you may have problems receiving signals in the inner area of buildings. In general, metal and masonry block GPS signals, while glass, wood, or plastic does not.

Under specific conditions, GPS will not provide the time. For instance, the 1,542 MHz GPS signal does not penetrate buildings, which makes it difficult to receive signals indoors away from windows. Also the signal can be critically weakened by heavy foliage and interfered with by other sources such as poorly maintained television broadcasting equipment.