NavCom RT-3020 Rev.D User Manual
Page 60

RT-3020 User Guide - Rev. E
RTCM
(Radio Technical Commission for Maritime Services)
a standard format for
Differential GPS
corrections used
to transmit corrections from a
base station
to
rovers
.
RTCM allows both
real-time kinematic
(
RTK
) data
collection and post-processed differential data
collection. RTCM SC-104 (RTCM Special Committee
104) is the most commonly used version of RTCM
message.
RTK see
Real-time kinematic
.
RTG Real Time GIPSY, a processing technique
developed by NASA’s Jet Propulsion Laboratory to
provide a single set of real time global corrections for
the
GPS
satellites.
S/A see
Selective availability
.
SBAS (Satellite Based Augmentation System) this is
a more general term, which encompasses
WAAS
,
StarFire
™ and
EGNOS
type corrections.
Selective Availability (S/A) deliberate degradation of
the
GPS
signal by encrypting the
P-code
. When the US
Department of Defense uses
S/A
, the signal contains
errors, which can cause positions to be inaccurate by as
much as 100 meters.
Signal-to-Noise Ratio (
SNR
) a measure of a satellite’s
signal strength.
single-frequency a type of receiver that only uses the
L1
GPS
signal. There is no compensation for ionospheric
effects.
SNR see
signal-to-noise
Ratio.
Glossary-58