Chapter 4 Flashcards
(34 cards)
GPS
the Global Positioning System, a technology using signals broadcast from satellites for navigation and position determination on Earth
NAVSTAR GPS
the United States Global Positioning System
GNSS
the global navigation satellite system, an overall term for the technologies that use signals from satellites to find locations on Earth’s surface
space segment
one of the three segments of GPS, consisting of the satellites and the signals they broadcast from space
constellation
the full complement of satellites comprising a GNSS
control segment
one of the three segments of GPS, consisting of the control stations that monitor the signals from the GPS satellites
user segment
one of the three segments of GPS, consisting of the GPS receivers on the ground that pick up the signals from the satellites
channels
the number of satellite signals a GPS unit can receive
single frequency
a GPS receiver that can pick up only the L1 frequency
dual frequency
a GPS receiver that can pick up both the L1 and L2 frequency
almanac
data concerning the status of a GPS satellite, which is included in the information being transmitted by the satellite
ephemeris
data referring to the GPS satellite’s position in orbit
C/A code
the digital code broadcast on the L1 frequency, which is accessible by all GPS receivers
P code
the digital code broadcast on the L1 and L2 frequencies, which is accessible by the military
Y code
encrypted version of the P code
Pseudorange
the calculated distance between a GPS satellite and a GPS receiver
trilateration
finding a location in relation to three other points of reference
3D trilateration
finding a location on Earth’s surface in relation to the positions of three satellites
selective availability
the intentional degradation of the timing and position information transmitted by a GPS satellite
PDOP
the position dilution of precision - it describes the amount of error due to the geometric position of the GPS satellites
multipath
an error causes by a delay in the signal due to reflecting from surfaces before reaching the receiver
DGPS
Differential GPS - a method using a ground-based correction in addition to the satellite signals in position determination
NDGPS
National Differential GPS - it consists of ground-based DGPS locations around the United States
CORS
Continuously Operating Reference Stations - a system operated by the National Geodetic Survey to provide a ground-based method of obtaining more accurate GPS positioning
