Leica Geosystems GPS Basics - Manual (Page 49)

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GPS Basics -1.0.0en Glossary
C/A code
The Coarse/Acquisition GPS code
modulated on the GPS L1 signal. This
code is a sequence of 1023 pseudoran-
dom binary biphase modulations on the
GPS carrier at a chipping rate of 1.023
MHz, thus having a code repetition
period of one millisecond.
Cartesian Coordinates
The coordinates of a point in space
given in three mutually perpendicular
dimensions (x, y, z) from the origin.
Carrier
A radio wave having at least one charac-
teristic (e.g., frequency, amplitude,
phase) which may be varied from a
known reference value by modulation.
Carrier beat phase
The phase of the signal which remains
when the incoming Doppler-shifted
satellite carrier signal is beat (the
difference frequency signal is generated)
with the nominally constant reference
frequency generated in the receiver.
Carrier frequency
The frequency of the unmodulated
fundamental output of a radio transmit-
ter. The GPS L1 carrier frequency is
1575.42 MHz, the GPS L2 carrier fre-
quency is 1227.60 MHz.
Chip
The time interval of either a zero or a one
in a binary pulse code
Chip rate
Number of chips per second (e.g., C/A
code : 1.023*10 6 cps)
Clock offset
Constant difference in the time reading
of two clocks.
Code
A system used for communication in
which arbitrarily chosen strings of zeros
and ones are assigned definite mean-
ings.
Compacted data
Raw data compacted over a specified
time interval (compaction time) into one
single observable (measurement) for
recording.
Conformal Projection
A map projection that preserves angles
on the ellipsoid after they have been
mapped onto the plane.
Control segment
Ground-based GPS System equipment
operated by the U.S. Government that
tracks the satellite signals, determines
the orbits of the satellites, and transmits
orbit definitions to the memories of the
satellites.