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

"Peter Bennett" wrote in message
news
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,

The SR161 can be used to consolidate incoming NMEA positional data from a
GPS with the AIS NMEA data into a combined high-speed data stream on a
single serial port.

In that scenario there is no need for any multiplexer.

"claus" wrote in message
. ..

"Peter Bennett" wrote in message
news
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,

The SR161 can be used to consolidate incoming NMEA positional data from a
GPS with the AIS NMEA data into a combined high-speed data stream on a
single serial port.

In that scenario there is no need for any multiplexer.

Forgot to add the link to the Wiring diagram for connecting a GPS into the
AIS receiver using a Single Serial Port on the Computer:

http://www.milltechmarine.com/images...ng-diagram.pdf

On Jul 18, 11:24*am, "claus" wrote:
"Peter Bennett" wrote in message

news
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,

The SR161 can be used to consolidate incoming NMEA positional data from a
GPS with the AIS NMEA data into a combined high-speed data stream on a
single serial port.

In that scenario there is no need for any multiplexer.

Right - just to clarify a couple of things:
1. AIS Receivers do not need GPS signals to output AIS sentences. They
work independent of GPS.
2. With the SR161/SR162, you can feed GPS (or any other NMEA data)
into the AIS receiver at 4800 baud on pin 3 and the receiver will
combine the data with the AIS sentences and output the combined
datastream out the single serial port at 38400 baud on pin 2 with a
common ground on pin 5. We sell a cable to do this and also include
the wiring diagram to build your own. See:
http://www.milltechmarine.com/images...ng-diagram.pdf


Doug Miller
Milltech Marine

On Jul 18, 11:48*am, Doug Miller wrote:
...
Right - just to clarify a couple of things:
1. AIS Receivers do not need GPS signals to output AIS sentences. They
work independent of GPS.
2. With the SR161/SR162, you can feed GPS (or any other NMEA data)
into the AIS receiver at 4800 baud on pin 3 and the receiver will
combine the data with the AIS sentences and output the combined
datastream out the single serial port at 38400 baud on pin 2 with a
common ground on pin 5. We sell a cable to do this and also include
the wiring diagram to build your own. See:http://www.milltechmarine.com/images...ng-diagram.pdf

Doug Miller
Milltech Marine

Cool. I'm in the market for an SR 161. Does it help the unit any to
have a GPS feed or does it just pass the data through. I can imagine
how the unit might take advantage of knowing the packet timing, but I
don't know if does.

-- Tom.

On Jul 18, 6:30*pm, " wrote:
On Jul 18, 11:48*am, Doug Miller wrote:
...

Right - just to clarify a couple of things:
1. AIS Receivers do not need GPS signals to output AIS sentences. They
work independent of GPS.
2. With the SR161/SR162, you can feed GPS (or any other NMEA data)
into the AIS receiver at 4800 baud on pin 3 and the receiver will
combine the data with the AIS sentences and output the combined
datastream out the single serial port at 38400 baud on pin 2 with a
common ground on pin 5. We sell a cable to do this and also include
the wiring diagram to build your own. See:http://www.milltechmarine.com/images...ng-diagram.pdf

Doug Miller
Milltech Marine

Cool. *I'm in the market for an SR 161. *Does it help the unit any to
have a GPS feed or does it just pass the data through. *I can imagine
how the unit might take advantage of knowing the packet timing, but I
don't know if does.

-- Tom.

GPS does affect AIS perfofrmance but of course you'll need a GPS for
your nav package in order to calculate collision information (e.g.
distance from you, closest point of approach and time to closest point
of approach).

On Jul 20, 8:59*am, Doug Miller wrote:
...
GPS does affect AIS perfofrmance but of course you'll need a GPS for
your nav package in order to calculate collision information (e.g.
distance from you, closest point of approach and time to closest point
of approach).

Thanks for that. Just to be clear, I have GPSes on my system and the
computer that will run my AIS software already has GPS positioning
data. What I think you are saying is that I should route one of the
GPSes through the SR161 when I install it to make the 161 work
better. Is that right?

Cheers,

-- Tom.

Doug Miller wrote in news:f31faed5-6a54-4b92-999a-
:

http://www.milltechmarine.com/images...ng-diagram.pdf

Thank you. I didn't know it did that....

The SR161 can be used to consolidate incoming NMEA positional data from a
GPS with the AIS NMEA data into a combined high-speed data stream on a
single serial port.

In that scenario there is no need for any multiplexer.


but how does it talk to other non-high speed nmea devices then?

"Josh Assing" wrote in message
...
The SR161 can be used to consolidate incoming NMEA positional data from a
GPS with the AIS NMEA data into a combined high-speed data stream on a
single serial port.

In that scenario there is no need for any multiplexer.


but how does it talk to other non-high speed nmea devices then?

The AIS only "talks" with either
a)a PC with chart plotting software that can show AIS or
b) directly to a chartplotter that can show AIS.

For example, on our boat the SR161's combined output goes to a PC with
Coastal Explorer software. In turn, Coastal Explorer and the PC outputs NMEA
(4800 Baud) to our Raynav Chartplotter and from there to all other
instrumentation onboard via RayMarine's proprietary Seatalk network.

Hope this helps. If I could I would send you a diagram - but I don't have a
scanner.... :-(