I've just fitted a Raymarine C120 with a NASA AIS. I also have a new
DSC VHF to fit & was hoping to use the GPS via NMEA from the Raymarine
to give a position n the VHF however the system setup will only let me
have AIS or NMEA as Output. Is there any way around this? Any advise
in lay mans terms please.

"darlo 61" wrote in message
...
| I've just fitted a Raymarine C120 with a NASA AIS. I also have a new
| DSC VHF to fit & was hoping to use the GPS via NMEA from the Raymarine
| to give a position n the VHF however the system setup will only let me
| have AIS or NMEA as Output. Is there any way around this? Any advise
| in lay mans terms please.

The problem is the baud rate. If you configure the C120 for AIS, the
baudrate of both input and output NMEA port becomes 38400 bps. The C120 will
still send the NMEA data, including GPS, but the baudrate of 38400 is too
high for the DSC VHF radio. It only accepts 4800bps. The only way to resolve
this is to use a device which can 'convert' the baudrate from 38400 to 4800
bps or buy a cheap GPS mouse as a dedicated GPS for the VHF. The latter also
has the advantage that your VHF radio still receives lat/lon when the C120
is switched off and that you have a backup GPS with lat/lon readout on the
radio LCD. Baudrate conversion is possible with a NMEA multiplexer like the
Miniplex of Shipmodul or the one my company makes:
http://www.brookhouseonline.com/pdf%...egration_1.pdf
http://www.brookhouseonline.com/pdf%...egration_2.pdf
http://www.brookhouseonline.com/pdf%...egration_3.pdf

Wout

On 9 Mar, 20:21, "WBH" wrote:
"darlo 61" wrote in message

...
| I've just fitted a Raymarine C120 with a NASA AIS. I also have a new
| DSC VHF to fit & was hoping to use the GPS via NMEA from the Raymarine
| to give a position n the VHF however the system setup will only let me
| have AIS or NMEA as Output. Is there any way around this? Any advise
| in lay mans terms please.

The problem is the baud rate. If you configure the C120 for AIS, the
baudrate of both input and output NMEA port becomes 38400 bps. The C120 will
still send the NMEA data, in'l'cluding GPS, but the baudrate of 38400 is too
high for the DSC VHF radio. It only accepts 4800bps. The only way to resolve
this is to use a device which can 'convert' the baudrate from 38400 to 4800
bps or buy a cheap GPS mouse as a dedicated GPS for the VHF. The latter also
has the advantage that your VHF radio still receives lat/lon when the C120
is switched off and that you have a backup GPS with lat/lon readout on the
radio LCD. Baudrate conversion is possible with a NMEA multiplexer like the
Miniplex of Shipmodul or the one my company makes:http://www.brookhouseonline.com/pdf%...egration_3.pdf

Wout

Thanks for that, we do have a spare GPS so we'll use that, though it
seemed like a nice idea to have everything intergrated.

Graeme

"WBH" wrote in
:

The only way to resolve
this is to use a device which can 'convert' the baudrate from 38400 to
4800 bps

Wouldn't this soon be overrun with data pouring in at 38400 and dripping
out at 4800? If there's a lot of AIS targets, is 4800 fast enough to keep
the converter memory from being overrun??

In article ,
Larry wrote:

"WBH" wrote in
news:fr1hee $bjk$1@ lust.ihug.co.nz:

The only way to resolve
this is to use a device which can 'convert' the baud-rate from 38400 to
4800 bps

Wouldn't this soon be overrun with data pouring in at 38400 and dripping
out at 4800? If there's a lot of AIS targets, is 4800 fast enough to keep
the converter memory from being overrun??

Larry, your assuming that the data is a continuous stream from the 38K
data source. This is a BIG Assumption, and I would bet that the data is
burst or packetized, and the actual 38K thru-put is actually less than
that of the 4800 NEMA thru-put. If you were right and the 38K data was
Streaming, then I suspect that only a fraction of that data is required
represent the AIS information, when converted to the NEMA 4800 required
Sentence Structure, and the Multiplexer, would FIFO, and buffer, the
data, using internal registers, since NEMA updates only happen about
once a second anyway.

maybe our Multiplexer Friend, Miendert SP could enlighten us on the
subject, if he is still reading the newsgroup.....

--
Bruce in alaska
add path after fast to reply

"Larry" wrote in message
...
| "WBH" wrote in
| :
|
| The only way to resolve
| this is to use a device which can 'convert' the baudrate from 38400 to
| 4800 bps
|
| Wouldn't this soon be overrun with data pouring in at 38400 and dripping
| out at 4800? If there's a lot of AIS targets, is 4800 fast enough to keep
| the converter memory from being overrun??
|


The "baudrate conversion" is for the data stream coming FROM the C-series
(or E-series). This data stream does not contain AIS data. I agree that
potentially there is always the risk that if you input NMEA data at 38400,
4800 will not provide enough bandwidth to output that same data, but the
C-series output is GPS and instrument data and the total volume is unlikely
to exceed the 4800 bandwidth. The multiplexer's buffering takes care of the
input volume peaks that may occur.
Also, if the baudrate conversion input port receives a full data stream
including AIS, the Brookhouse multiplexer automatically filters out that AIS
data for the same reason. This situation does not normally occur if
connected to a C or E-series, but Brookhouse multiplexers have several
baudrate conversion options and one of them (option 3) involves feeding the
full data stream into the baudrate conversion input buffer. The purpose of
this is that the NMEA data is also available at 4800 bps to feed standard
(4800) listeners. In this case the AIS data is filtered out automatically.
Read more he
http://www.brookhouseonline.com/pdf%...%20Options.pdf

Wout

"WBH" wrote in
:


"Larry" wrote in message
...
| "WBH" wrote in
| :
|
| The only way to resolve
| this is to use a device which can 'convert' the baudrate from 38400
| to 4800 bps
|
| Wouldn't this soon be overrun with data pouring in at 38400 and
| dripping out at 4800? If there's a lot of AIS targets, is 4800 fast
| enough to keep the converter memory from being overrun??
|


The "baudrate conversion" is for the data stream coming FROM the
C-series (or E-series). This data stream does not contain AIS data. I
agree that potentially there is always the risk that if you input NMEA
data at 38400, 4800 will not provide enough bandwidth to output that
same data, but the C-series output is GPS and instrument data and the
total volume is unlikely to exceed the 4800 bandwidth. The
multiplexer's buffering takes care of the input volume peaks that may
occur. Also, if the baudrate conversion input port receives a full
data stream including AIS, the Brookhouse multiplexer automatically
filters out that AIS data for the same reason. This situation does not
normally occur if connected to a C or E-series, but Brookhouse
multiplexers have several baudrate conversion options and one of them
(option 3) involves feeding the full data stream into the baudrate
conversion input buffer. The purpose of this is that the NMEA data is
also available at 4800 bps to feed standard (4800) listeners. In this
case the AIS data is filtered out automatically. Read more he
http://www.brookhouseonline.com/pdf%...nversion%20Opt
ions.pdf

Wout



Thanks. Too bad there's no computing that could parse it.

"Bruce in alaska" wrote in message
...
Larry, your assuming that the data is a continuous stream from the 38K
data source. This is a BIG Assumption, and I would bet that the data is
burst or packetized, and the actual 38K thru-put is actually less than
that of the 4800 NEMA thru-put. If you were right and the 38K data was
Streaming, then I suspect that only a fraction of that data is required
represent the AIS information, when converted to the NEMA 4800 required
Sentence Structure, and the Multiplexer, would FIFO, and buffer, the
data, using internal registers, since NEMA updates only happen about
once a second anyway.

maybe our Multiplexer Friend, Miendert SP could enlighten us on the
subject, if he is still reading the newsgroup.....

Still reading... every day :-)

The C and E series displays do not pass AIS data to it's output, only the
standard instrument data is sent out, which 'fits' into a 4800 baud channel.

Meindert