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NMEA routing
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NMEA data can be routed from any input to any output. A default
route can be set as well as specific routing rules for individual NMEA
sentences.
Network data can be routed to any NMEA output, to be merged with
other NMEA data or to override this data. This enables automatic
switching between computer based navigation and GPS/instrument based
navigation. |
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NMEA filtering
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A flexible NMEA filter can be configured to pass or block
specific sentences from each input channel. This greatly reduces the
chance of an overflow and the resulting loss of data. Many GPS receivers
for instance, transmit an abundance of sentences every second,
accounting for 85% of the available bandwidth of the NMEA channel. By
blocking unwanted or unnecessary sentences, bandwidth is preserved for
other instruments. The filter can also be configured to reduce the rate
of specific NMEA sentences. |
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Flexible communication speed
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The communication speed of all inputs and outputs can be set from
4800 to 57600 Baud to allow connection of devices that operate at
non-standard (4800 Baud) communication speeds like integrated weather
sensors, gyrocompasses or AIS equipment. |
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SeaTalk® conversion
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When the SeaTalk -> NMEA option is enabled, one of the NMEA inputs becomes a SeaTalk® compatible input, offering conversion of the most common SeaTalk datagrams on a Raymarine® network into NMEA sentences. This data is combined with NMEA data
received on the other inputs. When Priority is enabled, SeaTalk data
can be assigned highest or lowest priority. |
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Real-Time forwarding
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Gyro- and fluxgate compasses produce NMEA sentences at a high rate (10
sentences/second or more). This can lead to a buffer overflow in the
multiplexer. Although this overflow is handled properly without data
corruption, it will lead to a delay of NMEA sentences of up to 20
seconds in extreme situations. This produces a severe problem for
autopilots, which cannot make proper course corrections when their
heading feedback is delayed for 20 seconds. The Real-Time option
prevents this delay by bypassing the buffer of that specific channel and
forwarding the data immediately to the multiplexer's NMEA output. As a
result, the heading is never delayed more than 0.2 to 0.5 seconds,
depending on the amount of other NMEA sentences passing through the
multiplexer. |
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Heading conversion
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This option converts a Magnetic Heading sentence (HDG) into a True
Heading sentence (HDT). If the originating magnetic heading sentence
contains a magnetic variation, it is used to calculate the true heading
before conversion. This feature is useful for certain equipment like
VDR's which need a true heading input, while the only available heading
source is a fluxgate, delivering a magnetic heading. |
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Priority
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With Priority enabled, similar NMEA sentences on different inputs are
only passed from the input with the highest priority. The Ethernet port
has the highest priority, followed by inputs 1 to 4, in descending
order. When for instance two GPS receivers are connected to inputs 1 and
2, and both transmit the same type of NMEA sentences, only those
received on input 1 are passed. An adjustable time-out ensures that
similar sentences from the GPS at input 2 are passed when the GPS at
input 1 stops sending these sentences.
Optionally, GPS sentences are checked for a valid status field,
causing automatic switchover when the primary GPS looses satellite
signal. |
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Channel information
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When this feature is switched on, the multiplexer will transmit a
proprietary NMEA sentence indicating on which input channel the
following NMEA sentence is received. Optionally, the multiplexer can
append NMEA V4.0 TAG block to each NMEA sentence to indicate its
originating input.
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Talker ID substitution
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Talker ID substitution changes the talker ID of incoming sentences. The
talker ID can be specified for each input channel. This option is useful
for software or instruments that expect a specific talker ID or to
distinguish between sentences from two similar instruments. |
