Fast Acquisition Enhanced Sensitivity 20 Channels "All-In-View" Tracking GPS Sensor Module.
The AG-101 receiver continuously tracks all satellites in view and provides accurate satellite positioning data. The AG-101 is optimized for applications requiring good performance, low cost, and maximum flexibility; suitable for a wide range of OEM configurations including handhelds, sensors, asset tracking, PDA-centric personal navigation system, and vehicle navigation products.
The AG-101's 20 parallel channels and 4000 search bins provide fast satellite signal acquisition and short startup time. Tracking sensitivity of -159 dBm offers good navigation performance even in urban canyons having limited sky view.
Satellite-based augmentation systems, such as WAAS and EGNOS, are supported to yield improved accuracy.
Receiver Operation:
Upon power up, after initial self-test has completed, the AG-101 will begin satellite acquisition and tracking process. Under normal open-sky condition, position-fix can be achieved within approximately 35 seconds (within 10 seconds if valid ephemeris data is already collected from recent use). After receiver position has been calculated, valid position, velocity and time information are transmitted through the on board serial interface.
The receiver uses the latest stored position, satellite data, and current RTC time to achieve rapid GPS signal acquisition and fast TTFF. If the receiver is transported over a large distance across the globe, cold-start automatic-locate sequence is invoked. The first position fix may take up to 50 sec searching the sky for the GPS signal. The acquisition performance can be improved significantly if the host initializes the receiver with a rough estimate of time and user position.
As soon as GPS signal is acquired and tracked, the AG-101 will transmit valid navigation information through its serial interface. The navigation data contains following information:
Receiver position in latitude, longitude, and altitude
Receiver velocity
Time
DOP error-magnification factor
GPS signal tracking status
The AG-101 will perform 3D navigation when four or more satellites are tracked. When three or fewer satellites are tracked, altitude-hold is enabled using the last computed altitude and 2D navigation mode is entered.
With signal blockage or rising and setting of the satellites, where a change in satellite constellation used for position fix occurred, large position error may result. The AG-101 incorporates a proprietary algorithm to compensate the effect of satellite constellation change, and maintains an accurate smooth estimate of the receiver position, velocity, and heading.
