User's Guide

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satellites. Normally set to 10 degrees to avoid
interference problems caused by buildings and trees,
and multipath errors.
Ephemeris/Ephemerides
A list of predicted (accurate) positions or locations of
satellites as a function of time. It contents a set of
numerical parameters that can be used to determine a
satellite’s position.
Available as broadcast ephemeris or as postprocessed
precise ephemeris.
Epoch
The measurement interval of a GPS receiver. The epoch
varies according to the measurement type: for
real-time measurement, it is set at one second; for
post-processed measurement, it can be set to a rate of
between one second and one minute. For example, if
data is measured every 15 seconds, loading data using
30-second epochs means loading every alternate
measurement.
Firmware
The program inside the receiver that controls receiver
operations and hardware.
GLONASS
Global Orbiting Navigation Satellite System. GLONASS is
a Soviet space-based navigation system comparable to
the American GPS system. The operational system
consists of 21 operational and 3 non-operational
satellites in 3 orbit planes.
GNSS
Global Navigation Satellite System.
GSOF
General Serial Output Format. A Trimble proprietary
message format.
HDOP
Horizontal Dilution of Precision. HDOP is a DOP value
that indicates the accuracy of horizontal
measurements. Other DOP values include VDOP
(vertical DOP) and PDOP (Position DOP).
Using a maximum HDOP is ideal for situations where
vertical precision is not particularly important, and the