User's Guide

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user’s position yield would be decreased by the vertical
component of the PDOP ( for example, if the user is
collecting data under canopy).
L1
The primary L-band carrier used by GPS satellites to
transmit satellite data.
L2
The secondary L-band carrier used by GPS satellites to
transmit satellite data.
L5
The third L-band carrier used by GPS satellites to
transmit satellite data. L5 will provide a higher power
level than the other carriers. As a result, acquiring and
tracking weak signals will be easier.
MSAS
MTSAT Satellite-Based Augmentation System. A
satellite-based augmentation system (SBAS) that
provides a free-to-air differential correction service for
GPS. MSAS is the Japanese equivalent of WAAS, which
is available in the United States.
Multi-Frequency GPS
A type of receiver that uses multiple carrier phase
measurements (L1, L2, and L5) from different satellite
frequencies.
Multipath
Interference, similar to ghosts on a television screen
that occurs when GPS signals arrive at an antenna
having traversed different paths. The signal traversing
the longer path yields a larger pseudorange estimate
and increases the error. Multiple paths can arise from
reflections off the ground or off structures near the
antenna.
MEA
National Marine Electronics Association. NMEA 0183
defines the standard for interfacing marine electronic
navigational devices. This standard defines several
'strings' referred to as NMEA strings that contain
navigational details such as positions. Most CHC GPS
receivers can output positions as NMEA strings.