| Author |
Explorist XL nmea output to vhf
|
|
|
| Hi. I am new to both groups and GPS. I have the Explorist Europe XL
hand held GPS and want to feed nmea data into my marine vhf. This is so
it knows a location and can send distress calls when I press the
button. The only output seems to be the USB link and I have stripped an
old USB lead and experimented with the wires but cant seem to get any
data input into the radio. I wondered if anyone had suceeded at this
and could give some advice. Thanx. Brian
| |
| Jim Townsend 2006-08-29, 10:33 am |
| brian wrote:
> Hi. I am new to both groups and GPS. I have the Explorist Europe XL
> hand held GPS and want to feed nmea data into my marine vhf. This is so
> it knows a location and can send distress calls when I press the
> button. The only output seems to be the USB link and I have stripped an
> old USB lead and experimented with the wires but cant seem to get any
> data input into the radio. I wondered if anyone had suceeded at this
> and could give some advice. Thanx. Brian
It's not as easy as connecting a wire from the USB cable to the
microphone :)
Most importantly, you can't send USB data blindly down a cable
like you can with serial data. USB is a two-way communications
protocol. In order for data to flow, the sending unit must see
special signals being being sent back in response.
You need a suitable host (ie a computer) on the other end of the
USB cable in order for USB devices to send data.
Since you're setting up your GPS/Radio combo to send data, I assume
there are stations somewhere to receive it.
The FIRST thing you should do is find out the correct format for the
positional data signals so these receiving stations can decode them.
You'll definitely need external equipment (ie modems etc) to do this.
| |
| brian 2006-08-29, 10:33 am |
|
Jim Townsend wrote:
> brian wrote:
>
>
> It's not as easy as connecting a wire from the USB cable to the
> microphone :)
>
> Most importantly, you can't send USB data blindly down a cable
> like you can with serial data. USB is a two-way communications
> protocol. In order for data to flow, the sending unit must see
> special signals being being sent back in response.
>
> You need a suitable host (ie a computer) on the other end of the
> USB cable in order for USB devices to send data.
>
> Since you're setting up your GPS/Radio combo to send data, I assume
> there are stations somewhere to receive it.
>
> The FIRST thing you should do is find out the correct format for the
> positional data signals so these receiving stations can decode them.
> You'll definitely need external equipment (ie modems etc) to do this.
Thank you Jim for your prompt reply. The vhf radio is a maine DSC type
that displays your current position on the screen. The position can be
entered manually at regular intervals or via an 'nmea in' cable
consisting of 2 wires designed to continuosly upload the data from
'any' gps (so it says). The idea is that the radio has a distress
button that sends out information to the coastguard automatically if
you press the big red button when you get in trouble - a bit like
sending a text message. The radio identifies itself by its uniqe
number and from that identifier the coatguard computer knows who it is
in trouble. But they also need the dsc to transmit the position at the
same time so they can come and help - hence the 'nmea in' cable. As the
only obvious data out source from the gps was the usb cable I worked
along those lines. Inside the usb cable are 4 wires and my guess was
that 2 (probably red and black) were power and the other 2 (green and
white) were probably data. But that was just a guess and I admit to
not being a trained electronics engineer. Any further thoughts would be
greatly appreciated. Thanx. Brian.
| |
| Jim Townsend 2006-08-29, 3:33 pm |
| brian wrote:
> Thank you Jim for your prompt reply. The vhf radio is a maine DSC type
> that displays your current position on the screen. The position can be
> entered manually at regular intervals or via an 'nmea in' cable
> consisting of 2 wires designed to continuosly upload the data from
> 'any' gps (so it says).
OK.. It's been a while since I followed marine radios. Back
then they were white and had a volume control, squelch and a
channel selector :-)
I did some browsing and see they have come a LONG way.
I should have done some research first before answering.
I downloaded a couple of owner's manuals for some advanced
DSC Uniden and Icom radios. I see the GPS not only indicates
your position on emergency broadcasts, but it can do other
things like suggest the best channels to use based on your
position.
All these radios have inputs for 'Optional GPS' but they
don't say exactly *which* units can be used.
I'm going to stand on my position that a GPS unit with USB can't
be used with your radio.
The NMEA standard calls for a SERIAL signal at 4800 Baud, 8 Bit,
no parity, one stop bit. USB is NONE of that.. It's a
*completely* different data format. Unless your marine radio
actually supports USB, your Explorist just won't work.
If you've used your GPS with a computer, you'll see that you
MUST install software that receives the USB data and maps it
to a pseudo COM port (which is serial). Once converted to
serial then the data is true NMEA and can be used by mapping
programs.
You may get away with an external USB to serial converter
such as in the link below.. It coverts USB to serial data.
http://www.usbgear.com/Y-105A.html
I would check with the seller or manufacturer of your radio
first. They should be able to give you specific details on
exactly what the radio wants.
Lots of luck :)
| |
| Jack Erbes 2006-08-30, 7:33 am |
| Jim Townsend wrote:
<snip>
> You may get away with an external USB to serial converter
> such as in the link below.. It coverts USB to serial data.
>
> http://www.usbgear.com/Y-105A.html
<snip>
That will not work. It will only receive data from a RS-232 serial port
and convert it for input on a USB port. That adapter requires drivers
for to be installed on the PC and when the adapter is plugged in, the PC
creates a virtual COM port. But plugging that into a serial port will
not create a USB port.
There are no adapters that I know of that do the conversion in the other
direction.
Calling that adapter a "USB to serial" adapter is a misnomer, it
actually should be called a "Serial to USB" adapter as that is what is
does. The IC in those adapters that does the conversion (Prologic
PL-2303 for example) is called a serial to USB bridge, why anyone would
want to turn that name around is beyond me.
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)
| |
| Jim Townsend 2006-08-30, 10:33 pm |
| Jack Erbes wrote:
> Jim Townsend wrote:
> <snip>
> <snip>
>
> That will not work. It will only receive data from a RS-232 serial port
> and convert it for input on a USB port.
You're right.. I called that link up quickly from a bookmark and didn't
read it fully.
| |
|
| Thats fantastic guys. Thank you for all your help on this. I had sent
an eamil to Magellen but have not recieved any reply. I will take the
unit back to the retailer and see what they say. Thanks again for all
your support.
Brian.
| |
|
| Thats fantastic guys. Thank you for all your help on this. I had sent
an eamil to Magellen but have not recieved any reply. I will take the
unit back to the retailer and see what they say. Thanks again for all
your support.
Brian.
| |
| Al Rodecap 2006-08-31, 10:33 am |
| brian wrote:
> Hi. I am new to both groups and GPS. I have the Explorist Europe XL
> hand held GPS and want to feed nmea data into my marine vhf. This is so
> it knows a location and can send distress calls when I press the
> button. The only output seems to be the USB link and I have stripped an
> old USB lead and experimented with the wires but cant seem to get any
> data input into the radio. I wondered if anyone had suceeded at this
> and could give some advice. Thanx. Brian
>
For some reason, I keep thinking that some of the older units were
serial only. I have an eXplorist 400 & it's USB but under the covers
(with the help of some software, does NMEA). Perhaps if you looked for
one of the older Magellan, Garmin, etc. it might work for your purposes.
Al
|
|
|
|