Leica Geosystems Leica mojoXact Plus - Manual (Page 162)

162 Glossary of Terms, Leica mojoXact Plus
Appendix D Glossary of Terms
Almanac
Almanac data is used to predict which satellites are
visible, and thus shorten search times.
Base
A source of the correction signals for the RTK solu-
tion. May also be referred to as: base station, refer-
ence station and network reference station.
C/A code
The Coarse/Acquisition GPS code modulated on the
GPS L1 signal. This code is a sequence of 1023 pseu-
dorandom binary biphase modulations on the GPS
carrier at a chipping rate of 1.023 MHz, thus having
a code repetition period of one millisecond.
CAN bus
The Controller Area Network bus is a specialized
internal communications network that interconnects
components inside a vehicle.
A network inside a vehicle must meet specific
requirements: these include assurance of message
delivery, no conflict between messages, minimum
time for delivery, low cost, and ability to operate reli-
ably in an electrically noisy environment. Conven-
tional computer network technologies, such as
Ethernet, are rarely used in vehicles.
CDMA
Code-Division Multiple Access. CDMA refers to any of
a number of protocols used in second-generation
(2G) and third-generation (3G) cell phones. CDMA
uses multiplexing, which allows many signals to be
transmitted in a single channel. The frequency of a
signal is varied according to a code (defined pattern),
so that the signal can be picked up only by a receiver
that holds the same code.
CMR
Compact Measurement Record. This is an RTK
correction protocol.
Ephemeris
A list of positions or locations of a celestial object as
a function of time.
GPS
GPS is the short form of NAVSTAR GPS, which stands
for NAVigation System with Time And Ranging
Global Positioning System.
HSDPA
High-Speed Downlink Packet Access. HSDPA is a
protocol for cell phone data transmission. It is
referred to as a 3.5G technology (G stands for Gener-
ation). The HSDPA protocol provides download
speeds on a cell phone that are equivalent to ADSL
(Asymmetric Digital Subscriber Line) downloads on a
landline. HSDPA evolved from, and is an improvement
on, the W-CDMA protocol (a 3G protocol).
ISOBUS (ISO11783)
ISO11783 specifies a serial data network for control
and communications on forestry or agricultural trac-
tors, mounted, semi-mounted, towed or self-
propelled implements. Its purpose is to standardize
the method and format of transfer of data between
sensors, actuators, control elements, information
storage and display units whether mounted or part
of the tractor, or any implements.
Latitude
The angle between the ellipsoidal normal and the
equatorial plane. Latitude is zero on the equator and
90° at the poles.
Longitude
Longitude is the angle between the meridian ellipse
which passes through Greenwich and the meridian
ellipse containing the point in question. Thus, longi-
tude is 0° at Greenwich and is measured either east-
ward through 360° or eastward 180° and westward
180°.
NMEA
National Marine Electronics Association.
NMEA 0183 and NMEA 2000
NMEA 0183 and NMEA 2000 are combined electrical
and data specification for communication between
marine electronic devices such as echo sounder,
sonars, anemometer (wind speed and direction),
gyrocompass, autopilot, GPS receivers and many
other types of instruments.
NTrip (Network RTK)
Networked Transport of RTCM via Internet Protocol.
Post processing
The process of computing positions in non-real-time,
using data previously collected by GPS receivers.