User`s guide

Appendix
Motorola GPS Products - M12+ User's Guide Revision 6.X 09FEB05
210
SEP
Spherical Error Probable, a statistical measure of precision defined as the 50th percentile
value of the three-dimensional position error statistics. Thus, half of the results are within
the 3D SEP value.
Sidereal Day
Time between two successive upper transits of the vernal equinox. One sidereal day is
just under four minutes shorter than one solar day.
Simultaneous Measurements
Measurements referenced to time-frame epochs that are either exactly equal or so
closely spaced in time that the time misalignment can be accommodated by correction
terms in the observation equation rather than by parameter estimation.
Slope Distance
The three-dimensional vector distance from station one to station two. The shortest
distance (a chord) between two points.
Slow Switching Channel
A switching channel with a sequencing period that is too long to allow recovery of the
integer part of the carrier beat phase.
Solar Day
Time between two successive upper transits of the sun.
Speed of Light (SOL)
For GPS pseudorange calculations the speed of light is defined as 3x10
8
m/S per GPS
ICD-200.
Spheroid
See Ellipsoid.
Spread Spectrum
The received GPS signal is a wide bandwidth low-power signal (-160 dBw). This property
results from modulating the L-band signal with a PRN code in order to spread the signal
energy over a bandwidth that is much greater than the signal information bandwidth. This
is done to provide the ability to receive all satellites unambiguously and to provide some
resistance to noise and multipath.
Spread Spectrum System
A system in which the transmitted signal is spread over a frequency band much wider
than the minimum bandwidth needed to transmit the information being sent.