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| Bandwidth |
A measure of the capacity of a signal to carry information.
It is expressed as the width of the spectrum of that signal
(frequency domain representation) in hertz. |
| Base Station |
Also called a reference station. A receiver that is set up
on a known location specifically to collect data for differentially
correcting rover files. The base station calculates the
error for each satellite and, through differential correction,
improves the accuracy of GPS positions collected at unknown
locations by a roving GPS receiver. |
| Baseline |
The three dimensional vector that represents the distance
and direction from one survey station to another. It is
the result of processing GPS observations that were collected
simultaneously at each station and is expressed as values
of dx, dy, dz in the ECEF coordinate system. |
| Bearing (BRG): |
The precise compass direction (in degrees) from your present
position to the next waypoint. (Readings are selectable
in either degrees magnetic or true north). |
| Beat frequency |
The additional frequencies obtained when signals of two frequencies
are mixed. The beat frequencies are equal to the sum or
difference of the original frequencies. In GPS these are
the wide lane that has an 86 cm wavelength and the narrow
lane that has a 9 cm wavelength. |
| Bias |
See Integer
ambiguity |
| Binary biphase modulation |
Phase changes of either 0 or 180 degrees on a constant frequency
carrier (representing a binary 0 or 1, respectively).
GPS signals are biphase modulated. |
| Binary pulse code modulation |
Pulse modulation using a string of binary numbers (codes).
This coding is usually represented by 1's and 0's with
definite meanings assigned to them. Examples include changes
in phase or direction of a wave. |
| Block I, II,
IIR, IIF satellites |
The various generations of GPS satellites: Block I were prototype
satellites that began being launched in 1978; 24 Block
II satellites made up the fully operational GPS constellation
declared in 1995; Block IIR are replenishment satellites;
and Block IIF refers to the follow-on generation. |
| Bluebook |
A term derived from a blue reference book published by the
NGS in the USA. The book contains information and formats
required by the NGS for survey data that is to be submitted
and considered for use in their national network. |
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