ashtech DG14, Справочное руководство

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349
Glossary
studies.
Point positioning
A geographic position produced from
one receiver in a stand-alone mode. At
best, position accuracy obtained from a
stand-alone receiver is 5 meters to less
than 1 meter, depending on the
geometry of the satellites.
POS
Position
Post-processing
The reduction and processing of GPS
data after the data was collected in the
field. Post-processing is usually
accomplished on a computer in an
office environment where appropriate
software is employed to achieve
optimum position solutions.
Precise Positioning System (PPS)
The more accurate GPS capability that
is restricted to authorized, typically
military, users.
Pseudo-kinematic surveying
A variation of the kinematic method
where roughly five-minute site
occupations are repeated at a minimum
of once each hour.
Pseudorandom noise (PRN)
The P(Y) and C/A codes are pseudo-
random noise sequences which
modulate the navigation signals. The
modulation appears to be random noise
but is, in fact, predictable hence the
term "pseudo" random. Use of this
technique allows the use of a single
frequency by all GPS satellites and also
permits the satellites to broadcast a low
power signal.
Pseudo-range
The measured distance between the
GPS receiver antenna and the GPS
satellite. The pseudo-range is
approximately the geometric range
biased by the offset of the receiver clock
from the satellite clock. The receiver
actually measures a time difference
which is related to distance (range) by
the speed of propagation.
RAM
Random-Access Memory. A memory
device whose data can be accessed at
random, as approved to sequential
access. RAM data is lost when power is
removed.
Range rate
The rate of change of range between the
satellite and receiver. The range to a
satellite changes due to satellite and
observer motions. Range rate is
determined by measuring the doppler
shift of the satellite beacon carrier.
RDOP
Relative Dilution of Precision. See
Dilution of Precision.
Reconstructed carrier phase
The difference between the phase of the
incoming Doppler-shifted GPS carrier
and the phase of a nominally constant
reference frequency generated in the
receiver. For static positioning, the
reconstructed carrier phase is sampled
at epochs determined by a clock in the
receiver. The reconstructed carrier
phase changes according to the
continuously integrated Doppler shift of
the incoming signal biased by the integral