Furuno VR-3000 Operator's Manual page 43

fields should be provided in following GNS sentences with talker Ids of GP, GL, etc. These
following GNS messages should have the latitude, N-S, longitude, E/W, altitude, geoidal
separation, mode, and HDOP fields null. This indicates to the listener that the field is
supporting a previous $GNGNS sentences to denote the number of satellites used from
that satellite system.
Example: A combined GPS/GLONASS receiver using only GPS differential corrections has
the following GNS sentence sent.
$GNGNS,122310.2,3722.425671,N,12258.856215,W,DA,14,0.9,1005.543,6.5,5.2,23*59<CR><LF>
Example: A combined GPS/GLONASS receiver using both GPS differential corrections and
GLONASS differential corrections may have the following three GNS sentences sent in a
group.
$GNGNS,122310.2,3722.425671,N,12258.856215,W,DD,14,0.9,1005.543,6.5,, *74<CR><LF>
$GPGNS,122310.2,,,,,,7,,,,5.2,23*4D<CR><LF>
$GLGNS,122310.2,,,,,,7,,,,3.0,23*55<CR><LF>
The Differential Reference station ID may be the same or different for the different for the
different satellite systems.
b) Age of Differential Data
For GPS Differential Data:
This value is the average age of the most recent differential corrections in use. When only
RTCM SC104 Type1 corrections are use, the age is that of the most recent Type1
corrections. When RTCM SC104 Type9 corrections are used solely, or in combination with
Type1 corrections, the age is the average of the most recent corrections for the satellites
used. Null field when Differential GPS is not used
For GLONASS Differential Data:
This value is the average age of the most recent differential corrections in use. When only
RTCM Type31 corrections are used, the age is that of the most recent Type31 correction.
When RTCM SC104 Type34 corrections are used solely, or in combination with Type31
corrections, the age is the average of the most recent corrections for the satellites used.
Null field when differential GLONASS is not used.
For Galileo Differential Data:
This value is the average age of the most recent differential corrections in use. When only
RTCM SC104 Type41 corrections are used, the age is that of the most recent Type41
corrections. When RTCM SC104 Type42 corrections are used solely, or in combination with
Type41 corrections, the age is the average of the most recent corrections for the satellite
used. Null field when differential Galileo is not used.
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