Juniper Systems Allegro 2 User Guide - Manual (Page 66)

62 Allegro 2 Rugged Handheld Owner’s Manual
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3.5 GNS – GNSS Fix Data. The GNS message contains
Time, Position Fix and related data for single or combined
navigation satellite systems (GNSS). If the data is
calculated from multiple satellite systems in differential
mode then several GNS messages are generated. The first
message with Talker ID “GN” will be followed by separate
messages with Talker ID “GP”, “GL” etc. to report the data
calculated from the individual systems. Only one GNS
message is generated in differential mode with SBAS.
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ZDA – Time & Date. The ZDA message provides UTC, day,
month, year and local time zone. The Local time zone is
presented by the number of hours and minutes that have
to be added to local time in order to get the UTC time.
Local zone is generally negative for East longitudes with
local exceptions near the International Date Line.
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GBS – RAIM GNSS Satellite Fault Detection. The GBS
message provides results of the Receiver Autonomous
Integrity Monitoring (RAIM) function. Given that the GNSS
receiver is tracking sufficient satellites to perform integrity
checks on the positioning quality of the position solution,
a message is required in order to report the output of
this process to other systems and advise the system
user. With the RAIM function in the GNSS receiver, the
receiver can isolate faults to individual satellites and not
use these in its position and velocity calculations. Also,
the GNSS receiver can still track the satellite(s) and easily
judge when returned within tolerance. This message is
used for reporting such RAIM information. To perform this
integrity function, the GNSS receiver must have at least
two observables in addition to the minimum required for
navigation. Normally these observables take the form
of additional redundant satellites. If only GPS, GLONASS,
etc. is used for the reported position solution the Talker ID
is “GP”, “GL”, etc. and the errors pertain to the individual
system. If satellites from multiple systems are used to
obtain the reported position solution the Talker ID is “GN”
and the errors pertain to the combined solution.
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DTM – Datum Reference. The DTM message provides the
current local geodetic datum and datum offsets from
the reference datum. The reference Datum cannot be
changed and is always WGS 84 for the NV08C receiver.