Has anyone attempted to connect their GPS unit to more than one
"listener", e.g. DCS radio, autopilot, laptop, radar, etc? If so, how
was it done? With hardware "expander"? Interested in any experiences.

Check out the seatalk module
http://www.marinecomputing.com/products/nmeaseatalk/
This will get you started.
Shane.

"Steve Zweigart" wrote in message
...
Has anyone attempted to connect their GPS unit to more than one
"listener", e.g. DCS radio, autopilot, laptop, radar, etc? If so, how
was it done? With hardware "expander"? Interested in any experiences.

"Steve Zweigart" wrote in message
...
Has anyone attempted to connect their GPS unit to more than one
"listener", e.g. DCS radio, autopilot, laptop, radar, etc? If so, how
was it done? With hardware "expander"? Interested in any experiences.

According to the NMEA standard, every talker (GPS) should be able to drive
up to four listeners. It is perfectly safe to feed the GPS output to more
than one input. The worst thing that could happen is that at a certain
number of listeners, the signal is loaded too much. But you won't break
anything. So just try it.

Meindert

Thanks!!! That's exactly the kind of info I was after!

Meindert Sprang wrote:
"Steve Zweigart" wrote in message
...

Has anyone attempted to connect their GPS unit to more than one
"listener", e.g. DCS radio, autopilot, laptop, radar, etc? If so, how
was it done? With hardware "expander"? Interested in any experiences.


According to the NMEA standard, every talker (GPS) should be able to drive
up to four listeners. It is perfectly safe to feed the GPS output to more
than one input. The worst thing that could happen is that at a certain
number of listeners, the signal is loaded too much. But you won't break
anything. So just try it.

Meindert

That's $250 US for a box with some connectors all wirenutted together
inside. "Optically isolated" means you can't see the wirenuts! There must
be a less expensive way...

Padeen


"Shane Child" wrote in message
...
Check out the seatalk module
http://www.marinecomputing.com/products/nmeaseatalk/
This will get you started.
Shane.

"Steve Zweigart" wrote in message
...
Has anyone attempted to connect their GPS unit to more than one
"listener", e.g. DCS radio, autopilot, laptop, radar, etc? If so, how
was it done? With hardware "expander"? Interested in any experiences.

"padeen" wrote in message
...
That's $250 US for a box with some connectors all wirenutted together
inside. "Optically isolated" means you can't see the wirenuts! There
must
be a less expensive way...

Well, an expander is bit more complicated than just a 'junction box'. It
contains an opto-coupler wich takes care of the optical- or galvanical
isolation. Next, there are a few buffers to give each output enough power to
drive the required four listeners per output. And then the power supply,
this might vary from a simple three-terminal regulator to a more expensice
DC/DC converter (also isolated). Put this on a PCB, stuff it in a box, add
the usual markups and there you are at a pricelevel of around $150. So
indeed, $250 is a bit over the top.

Meindert

Thanks for the explanation, Meindert. You've allayed my suspicions 1/2 way.
Padeen

"Meindert Sprang" wrote in message
...
"padeen" wrote in message
...
That's $250 US for a box with some connectors all wirenutted together
inside. "Optically isolated" means you can't see the wirenuts! There
must
be a less expensive way...

Well, an expander is bit more complicated than just a 'junction box'. It
contains an opto-coupler wich takes care of the optical- or galvanical
isolation. Next, there are a few buffers to give each output enough power
to
drive the required four listeners per output. And then the power supply,
this might vary from a simple three-terminal regulator to a more expensice
DC/DC converter (also isolated). Put this on a PCB, stuff it in a box, add
the usual markups and there you are at a pricelevel of around $150. So
indeed, $250 is a bit over the top.

Meindert

To take this thread a step further, in my "junkbox" are two Delorme
Earthmate GPS receivers formerly used with laptop computers. For some
reason, the output from these units does not convey location information
to my radio. (I have not yet tried it with the autotiller.) My guess
is that there's a baud rate problem. I'm not aware of adjustable
settings on the units, which are said to be NMEA compliant, but it seems
that there MUST be a way to switch from RS-232 to RS-422 in order to
utilize the NMEA output feature. I've found Delomre tech support to be
of absolutely no help with off-the-wall questions like this.

padeen wrote:
Thanks for the explanation, Meindert. You've allayed my suspicions 1/2 way.
Padeen

"Meindert Sprang" wrote in message
...

"padeen" wrote in message
...

That's $250 US for a box with some connectors all wirenutted together
inside. "Optically isolated" means you can't see the wirenuts! There

must

be a less expensive way...

Well, an expander is bit more complicated than just a 'junction box'. It
contains an opto-coupler wich takes care of the optical- or galvanical
isolation. Next, there are a few buffers to give each output enough power

to

drive the required four listeners per output. And then the power supply,
this might vary from a simple three-terminal regulator to a more expensice
DC/DC converter (also isolated). Put this on a PCB, stuff it in a box, add
the usual markups and there you are at a pricelevel of around $150. So
indeed, $250 is a bit over the top.

Meindert

"Steve Zweigart" wrote in message
...
To take this thread a step further, in my "junkbox" are two Delorme
Earthmate GPS receivers formerly used with laptop computers. For some
reason, the output from these units does not convey location information
to my radio. (I have not yet tried it with the autotiller.) My guess
is that there's a baud rate problem. I'm not aware of adjustable
settings on the units, which are said to be NMEA compliant, but it seems
that there MUST be a way to switch from RS-232 to RS-422 in order to
utilize the NMEA output feature.

This could indeed be caused by incompatibility between RS-232 and RS-422
levels, not to mention the fact that RS-232 is 'single ended' and RS-422 is
differential. If you want an explanation about connecting differential and
single ended devices, download a manual of my NMEA multiplexers. It contains
a page with drawings about how to connect devices with eachother. You can
find it on
http://www.shipmodul.com/datasheets/man_mpx-41_en.pdf
Look at page 3.

Meindert