Glossary
1PPS
Pulse-per-second. Used in hardware timing. A pulse is generated in conjunction
with a time stamp. This defines the instant when the time stamp is applicable.
almanac
A file that contains orbit information on all the satellites, clock corrections, and
atmospheric delay parameters. The almanac is transmitted by a GNSS satellite to
a GNSS receiver, where it facilitates rapid acquisition of GNSS signals when you
start collecting data, or when you have lost track of satellites and are trying to
regain GNSS signals.
The orbit information is a subset of the ephemeris/ephemerides data.
base station
Also called reference station. In construction, a base station is a receiver placed
at a known point on a jobsite that tracks the same satellites as an RTK rover, and
provides a real-time differential correction message stream through radio to the
rover, to obtain centimeter level positions on a continuous real-time basis. A
base station can also be a part of a virtual reference station network, or a
location at which GNSS observations are collected over a period of time, for
subsequent postprocessing to obtain the most accurate position for the location.
BeiDou
The BeiDou Navigation Satellite System (also known as BDS) is a Chinese satellite
navigation system.
The first BeiDou system (known as BeiDou-1), consists of four satellites and has
limited coverage and applications. It has been offering navigation services
mainly for customers in China and from neighboring regions since 2000.
The second generation of the system (known as BeiDou-2) consists of 14
satellites in a combination of geostationary, inclined geosynchronous, and
medium earth orbit configurations. It became operational with coverage of
China in December 2011. However, the complete Interface Control Document
(which specifies the satellite messages) was not released until December 2012.
BeiDou-2 is a regional navigation service which offers services to customers in
the Asia-Pacific region.
A third generation of the BeiDou system is planned, which will expand coverage
globally. This generation is currently scheduled to be completed by 2020.
broadcast server
An Internet server that manages authentication and password control for a
network of VRS servers, and relays VRS corrections from the VRS server that
you select.
carrier
A radio wave having at least one characteristic (such as frequency, amplitude, or
phase) that can be varied from a known reference value by modulation.
carrier frequency
The frequency of the unmodulated fundamental output of a radio transmitter.
The GPS L1 carrier frequency is 1575.42 MHz.
carrier phase
Is the cumulative phase count of the GPS or GLONASS carrier signal at a given
time.
SPS985 GNSS Smart Antenna Getting Started Guide 29
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General