Hemisphere GPS S321 - Terms and Definitions

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Terms and Definitions
The following table lists the terms and definitions used in this document.
Term Definition
1PPS 1 pulse-per-second is a pulse that is output by the receiver
precisely once a second and is used for hardware
s
y
nchronization.
Activation Activation refers to a feature added through a one-time
purchase. For features that require recurring fees, see
Subscription.
aRTK aRTK is a Hemisphere GNSS exclusive service that uses
Atlas to extrapolate the last RTK correction during an RTK
outage so that the length of time an RTK position can be used
after an RTK outa
g
e is extended.
Atlas Atlas is a subscription-based service provided by Hemisphere
to achieve sub-decimeter accuracy after a twenty-minute
convergence period without the need for a base station or
datalink.
Base Station The Base Station is a receiver placed over a familiar point.
The base station then provides real-time observations and
sends these to nearby RTK rovers via UHF radio or the
internet.
BeiDou BeiDou is a Chinese satellite-based navigation system.
Datalink Datalink is the device used to send RTK or DGNSS
corrections from a base station to one of more rovers.
Common datalinks are UHF radio or Ntrip
(
see Ntrip
)
.
DGPS/DGNSS Differential GPS/GNSS refers to a receiver using Differential
Corrections.
Differential Corrections A method of improving precision of a GNSS rover. Two GNSS
receivers placed in a nearby area will have similar error. A
base station is placed over a known point. Since the actual
position of the base station is known, error can be calculated,
and corrections can then be applied to nearby rovers. This
differs from RTK
(
see section on RTK
)
.
Dual-Frequency Dual-Frequency use both L1 and L2 signals from GPS
satellites, G1 and G2 signals from GLONASS satellites, and
B1 and B2 signals from BeiDou satellites. Single frequency
receivers will onl
y
use L1, G1, and B1.
EGNOS European Geostationary Navigation Overlay Service
(EGNOS) is a satellite-based augmentation system (SBAS)
that provides free differential corrections over satellite in parts
of Europe.