Trimble Outdoors AcutimeTM2000 Synchronization Kit, Part Number 45005-00-ENG manual Sep

	Glossary
satellite masks	As satellites approach the horizon, their signals can become
	weak and distorted, preventing the receiver from gathering
	accurate data. Satellite masks enable you to establish criteria
	for using satellite data in a position solution. There are three
	types of satellite masks: Elevation, SNR, and PDOP.
SA	Selective Availability. This is the name of the policy and the
	implementation scheme by which unauthorized users of
	GPS will have their accuracy limited to 100 meters 2D RMS
	horizontal and 156 meters 2D RMS vertical.
SEP	Spherical Error Probability. The radius of a sphere such that
	50% of the position estimates will fall within the surface of
	the sphere.
serial	A system of sending bits of data on a single channel one
communication	after the other, rather than simultaneously.
serial port	A port in which each bit of information is brought in/out on
	a single channel. Serial ports are designed for devices that
	receive data one bit at a time.
signal-to-noise	GPS signals with SNRs that do not meet the mask criteria
level	are considered unusable.
signal-to-noise	A measure of the relative power levels of a communication
ratio	signal and noise on a data line. SNR is expressed in decibels
	(dB).
SNR	Signal-to-Noise Ratio.
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 which 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 multi-path.

Acutime 2000 Synchronization Kit User Guide Glossary-11