C-Nav 2050, User Manual

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2050 User Guide
PDOP mask the highest PDOP value at which a receiver computes positions.
phase center the point in an antenna where the GPS signal from the satellites is received. The
height above ground of the phase center must be measured accurately to ensure accurate GPS
readings. The phase center height can be calculated by adding the height to an easily measured
point, such as the base of the antenna mount, to the known distance between this point and the
phase center .
Position the latitude, longitude, and altitude of a point. An estimate of error is often associated with
a position .
Position Dilution of Precision (PDOP) a measure of the magnitude of Dilution of Position ( DOP )
errors in the x, y, and z coordinates.
Post-processing a method of differential data correction, which compares data logged from a
known reference point to data logged by a roving receiver over the same period of time. Variations in
the position reported by the reference station can be used to correct the positions logged by the
roving receiver . Post-processing is performed after you have collected the data and returned to the
office, rather than in real time as you log the data, so it can use complex, calculations to achieve
greater accuracy.
Precise code see P-code .
PRN (Uppercase) typically indicates a GPS satellite number sequence from 1 – 32.
prn (Lower Case) see Pseudorandom Noise.
Protected code see P-code .
Proprietary commands those messages sent to and received from GPS equipment produced by
NavCom Technology, Inc. own copyrighted binary language.
pseudo-random noise ( prn ) a sequence of data that appears to be randomly distributed but can be
exactly reproduced. Each GPS satellite transmits a unique PRN in its signals. GPS receivers use
PRN s to identify and lock onto satellites and to compute their pseudoranges.
Pseudorange the apparent distance from the reference station ’s antenna to a satellite, calculated by
multiplying the time the signal takes to reach the antenna by the speed of light (radio waves travel at
the speed of light). The actual distance, or
range , is not exactly the same because various factors
cause errors in the measurement.
PVT GPS information depicting Position, Velocity, Time in the NCT proprietary message format.
Radio Technical Commission for Maritime Services - see RTCM .
range the distance between a satellite and a GPS receiver’s antenna. The range is approximately
equal to the pseudorange . However, errors can be introduced by atmospheric conditions which slow
down the radio waves, clock errors, irregularities in the satellite’s orbit, and other factors. A GPS
receiver’s location can be determined if you know the ranges from the receiver to at least four GPS
satellites. Geometrically, there can only be one point in space, which is the correct distance from
each of four known points.
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