Electronic Operations Of The Rt552 - Reftek REF TEK 130-GPS User Manual

Rev H REF TEK 130-GPS Users Guide 5/20/2021
96259-00-UG

Electronic Operations of the RT552

The 130-GPS is run off +12 VDC. The 130-GPS input voltage should be between +10 and +15
Volts.
The Garmin™ receiver board (GPS-15H) is a twelve-channel GPS, Standard Positioning Service
(SPS) receiver module that uses the C/A code on the L1 frequency carrier. The Garmin™ provides
position accuracy of 5 meters LEP. The United States Department of Defense reserves the right
to implement selective availability (SA) to reduce position accuracy to 100 meters LEP.
The antenna module receives GPS signals (using an internal fixed-pattern antenna), amplifies
them, and forwards them to the receiver board over a coaxial antenna cable. The receiver board
computes position and velocity. The receiver board provides standard NMEA0183 messages to
the 130 host over an RS-232 communications port.
The receiver board tracks as many as twelve satellites. The GPS-15H board automatically selects
at least the best four and up to the best twelve for computations. As the satellites move, the
receiver board automatically tracks new satellites, continuing to select the best signals.
The GPS-15H has very fast time to first fix (TTFF). The typical time-to-acquisition for the GPS in
Hot-Start (GPS off for less than 2 hours) is 2-6 seconds. The typical Cold-Start time-to-acquisition
for the GPS is still only 45 seconds.
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