Trimble Outdoors SK8 - Manual (Page 199)

Lassen-SK8 Embedded GPS Module Glossary-1
Glossary
This section defines technical terms and abbreviations used in this manual. It includes terms from the field
of GPS technology.
2-D Two Dimensional. A 2-D position is defined as latitude and longitude.
Altitude is assumed to be fixed.
2-D GPS mode A procedure of determining a 2-D position using signals received from
the best (or only) three available GPS satellites. Altitude is assumed to be
known and constant. A 2-D position solution will only be determined if
signals from three or more satellites are available.
2 dRMS Twice the distance root mean squared. The error distance within which
95% of the position solutions will fall.
3-D Three Dimensional. A 3-D position is defined as latitude, longitude, and
altitude.
3-D GPS mode A procedure of determining a 3-D position using signals received from
the best (or only) four available GPS satellites. A 3-D position solution
will only be determined if signals from four or more satellites are
available.
almanac A reduced-precision subset of the ephemeris parameters. Used by the
receiver to compute the elevation angle, azimuth angle, and estimated
Doppler of the satellites. Each satellite broadcasts the almanac for all the
satellites in the system.
ASCII American Standard Code for Information Interchange. A standard set of
128 characters, symbols and control codes used for computer
communications. ASCII characters require 7 bits of data to send, but are
often sent 8 bits at a time with the extra bit being a zero.
asynchronous
communication A method of sending data in which the bits can be sent at random times.
Data transmission is not synchronized to a clock. With asynchronous
transmission, each character is transmitted one at a time with a “start” bit
at the beginning and one or more “stop” bits at the end. Any amount of
time can elapse before the next character is sent. \
auto GPS mode A procedure of automatically determining either a 2-D or 3-D position
using signals received from GPS satellites. The solution automatically
transitions between 2-D and 3-D depending on the number of satellites
available, the PDOP of the available satellites, and the defined PDOP
switch value. (See PDOP and PDOP constellation switch).
azimuth angle The angle of the line-of-site vector, projected on the horizontal plane,
measured clockwise from true North.