When I got my second nmea device, i was excited -- "hook it up" the manual said
-- support said "yes; you just hook up all the nmea out with nmea in of the
other devices and visa versa" so I did.

It appeared to work. however, since I have some weird things recently
discovered, we've traced it down to the fact that the info I got was wrong; and
my understanding of nmea was woefully weak.

GPS: listens & talks (2 lines of each)
RADAR: listens & talks
navtex: listens only
autopilot: listens only
flowscan: listens only
VHF listen/talk

Navtex, Autopilot & flowscan need to listen to the gps
radar & gps need to listen & talk to each other
The VHF radio talks/listens to the gps.

AIS receiver is in the budget & will need to talk to the gps & radar.

From a few hours search; it seems I need multiple-multiplexers to make this work
"correctly" -- can anyone give me a hand?

-josh

Josh Assing wrote:
When I got my second nmea device, i was excited -- "hook it up" the manual said
-- support said "yes; you just hook up all the nmea out with nmea in of the
other devices and visa versa" so I did.

It appeared to work. however, since I have some weird things recently
discovered, we've traced it down to the fact that the info I got was wrong; and
my understanding of nmea was woefully weak.

GPS: listens & talks (2 lines of each)
RADAR: listens & talks
navtex: listens only
autopilot: listens only
flowscan: listens only
VHF listen/talk

Navtex, Autopilot & flowscan need to listen to the gps
radar & gps need to listen & talk to each other
The VHF radio talks/listens to the gps.

AIS receiver is in the budget & will need to talk to the gps & radar.

From a few hours search; it seems I need multiple-multiplexers to make this work
"correctly" -- can anyone give me a hand?

-josh


I have had exactly the same problem with (almost) exactly the same stuff
you have. Multiplexers did not fit the bill for me since their inputs
are usually limited to 4800bps while many NMEA sentences (like HDT)
should be transmitted much more frequently. In the end I managed by
intelligently coupling the nmea i/o ports on all my devices (most of my
devices have multiple NMEA in and out) and for the few connections I
couldn't 'fit' I wrote a WIN32 based program for the navigation computer
that combined the input from a few serial-USB converters into one serial
38k4 stream.
In any case, if you decide to go for NMEA multiplexers make sure they
support the speed you require.

For the PC end of things http://sourceforge.net/projects/com0com/
seems pretty interesting.

-- Tom.

On Tue, 15 Jul 2008 10:29:00 -0700, Josh Assing
wrote:

When I got my second nmea device, i was excited -- "hook it up" the manual said
-- support said "yes; you just hook up all the nmea out with nmea in of the
other devices and visa versa" so I did.

It appeared to work. however, since I have some weird things recently
discovered, we've traced it down to the fact that the info I got was wrong; and
my understanding of nmea was woefully weak.

GPS: listens & talks (2 lines of each)
RADAR: listens & talks
navtex: listens only
autopilot: listens only
flowscan: listens only
VHF listen/talk

Navtex, Autopilot & flowscan need to listen to the gps
radar & gps need to listen & talk to each other
The VHF radio talks/listens to the gps.

AIS receiver is in the budget & will need to talk to the gps & radar.

From a few hours search; it seems I need multiple-multiplexers to make this work
"correctly" -- can anyone give me a hand?

-josh

I have a Ratheyon radar and a Garmin 128 GPS. I bougt a Sitex AIS
standalone unit and it reads the data easily from the GPS - no
multiplexor, just bare wires.

regards
Peter

On Tue, 15 Jul 2008 10:29:00 -0700, Josh Assing
wrote:

When I got my second nmea device, i was excited -- "hook it up" the manual said
-- support said "yes; you just hook up all the nmea out with nmea in of the
other devices and visa versa" so I did.

It appeared to work. however, since I have some weird things recently
discovered, we've traced it down to the fact that the info I got was wrong; and
my understanding of nmea was woefully weak.

GPS: listens & talks (2 lines of each)
RADAR: listens & talks
navtex: listens only
autopilot: listens only
flowscan: listens only
VHF listen/talk

Navtex, Autopilot & flowscan need to listen to the gps
radar & gps need to listen & talk to each other
The VHF radio talks/listens to the gps.

AIS receiver is in the budget & will need to talk to the gps & radar.

From a few hours search; it seems I need multiple-multiplexers to make this work
"correctly" -- can anyone give me a hand?

-josh

One Very Important Rule: you can only have _one_ "talker" on an NMEA
circuit, but can have several listeners. It looks like you will need
a multiplexer to combine the GPS, Radar and VHF output data into one
talker feed that everything listens to. (but you may have problems if
something repeats everything it hears, as well as sending its own data
- there are some intelligent muxes that can filter data to prevent
this causing a problem)

Note that normal NMEA-0183 data is sent at 4800 baud, while AIS data
is normally sent at 38400 baud - they can't coexist on the same
circuit. My Raymarine C80 chartplotter/radar display can accept AIS
data at 38400 on its serial port, while the GPS and other NMEA-0183
data goes into the SeaTalk system via a Raymarine NMEA=SeaTalk
interface box.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

Herodotus wrote:
...
I have a Ratheyon radar and a Garmin 128 GPS. I bougt a Sitex AIS
standalone unit and it reads the data easily from the GPS - no
multiplexor, just bare wires.

I have several GPS units that _talk_ to a laptop running Capn 8.3 and to a
Furuno radar display. The GPS units are wired so that the output can be
switched from one unit to the next, permitting only one _talker_ on the
circuit (i.e., NMEA 0183 compliant). The GPS units can also be switched to
bypass the laptop and _talk_ directly to one of several autopilots, and to
the Furuno when the laptop is not in use (e.g., offshore passages).

I like electronic toys and now want to add an AIS receiver (looking at the
Smart Radio models) since Capn 8.3 is able to receive and display AIS
information. I think I "get" the wiring requirements for the AIS, but am
puzzled by one aspect: does the AIS receiver need an _additional_ GPS data
source if I am already supplying GPS data to Capn 8.3. In other words, if
Capn 8.3 is getting GPS sentences from, say, the Garmin GPS, and I somehow
feed it the sentences from the Smart radio, will these data be combined to
achieve the desired outcome, the display of AIS information on the Capn 8.3
chart display?

Hope this question is not too poorly put.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://home.comcast.net/~kerrydeare

"Armond Perretta" wrote in message
. ..
I like electronic toys and now want to add an AIS receiver (looking at the
Smart Radio models) since Capn 8.3 is able to receive and display AIS
information. I think I "get" the wiring requirements for the AIS, but am
puzzled by one aspect: does the AIS receiver need an _additional_ GPS data
source if I am already supplying GPS data to Capn 8.3. In other words, if
Capn 8.3 is getting GPS sentences from, say, the Garmin GPS, and I
somehow
feed it the sentences from the Smart radio, will these data be combined to
achieve the desired outcome, the display of AIS information on the Capn
8.3
chart display?

No, I think you got that a bit wrong. Here is the setup I use:
GPS output input SR161 AIS Receiver output input PC (combined AIS/GPS
data at 34,600 Baud).

Armond,

I have almost the same set up as do you. I have installed a Brookhouse
multiplexer so that I do not have to switch NMEA talkers on and off. The
GPS(Furuno 7000), Autopilot(Simrad Robertson AP20 with 3000x box), and the
fathometer (Furuno RD30 with Airmar transducer) all feed into the
multiplexer. The multiplexer then feeds out to the GPS, Radar Position
(Furuno 1721M2), Radar Compass, Autopilot, & Depth and the computer. The AIS
receiver(Milltech SR161 with antenna splitter) I feed straight into the
computer with the Cap'n software. The computer get GPS data from the
multiplexer and AIS data from the AIS receiver. It all works great.

I believe that Milltech now has a multiplexer that will handle the AIS data
but I have had mine for a few years.

Cheers

Ansley Sawyer
SV Pacem

On Jul 16, 7:53*am, "claus" wrote:
...
No, I think you got that a bit wrong. Here is the setup I use:
GPS *output input SR161 AIS Receiver output input PC (combined AIS/GPS
data at 34,600 Baud).

AFIK, the SR161 needs the gps so it knows what the packet timing will
be. This might help:
http://www.milltechmarine.com/images...ate-Wiring.pdf

-- Tom.

Ansley W. Sawyer wrote:
...
I have almost the same set up as do you. I have installed a Brookhouse
multiplexer so that I do not have to switch NMEA talkers on and off.
The GPS(Furuno 7000), Autopilot(Simrad Robertson AP20 with 3000x
box), and the fathometer (Furuno RD30 with Airmar transducer) all
feed into the multiplexer. The multiplexer then feeds out to the GPS,
Radar Position (Furuno 1721M2), Radar Compass, Autopilot, & Depth and
the computer ...

I think I am getting somewhere now thanks to your explanation, but still a
few questions. Why first feed GPS info into the multiplexer, than out from
the multiplexer back to the GPS? To allow route and waypoint uploads to the
GPS?

... The AIS receiver(Milltech SR161 with antenna splitter)
I feed straight into the computer with the Cap'n software. The
computer get GPS data from the multiplexer and AIS data from the AIS
receiver. It all works great.

This is I believe the question I am trying to address. Are you saying that
by feeding GPS data and AIS data _separately_ into Capn 8.3, they are
combining in the Capn software to properly display AIS info on the chart?

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://home.comcast.net/~kerrydeare