NMEA out from pc??

contessaman

contessaman

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okay, so I have nearly finished building my all singing 12 volt on board pc for navigation. the gps receiver is one of the USB SIRF star ones - works incredibly well. One thing has just crossed my mind - the NMEA input to the DSC VHF which currently comes from a garmin GPS, can I somehow drive this from the pc? I know that one can knock up an NMEA input to a pc using the serial port but is it possible to drive the VHF from the USB GPS via the PC? all my efforts to build a 12 volt PC with a 12" screen that only takes 2 amps will be in vain if I have to have another gps receiver running at the same time..
ta

contessaman.
 
Have a look at this Here

It may work . You could just buy an old GPS Receiver an wire it to the radio . This has the benefit of a backup should your onboard pc decide that its time for the blue screen of death and a reboot says the hard drive is not responding :eek:

Either that or write yourself an application that will run on the task bar and send out a NMEA String that your radio can understand :eek: but then you are totally reliant on one PC :eek:
 
contessaman said:
all my efforts to build a 12 volt PC with a 12" screen that only takes 2 amps will be in vain if I have to have another gps receiver running at the same time..
Click to expand...

A quick google reveals that a random GPS "mouse" draws 90mA. Is that really going to break the power budget?

Assuming your VHF displays lat/long on its screen, a separate GPS input to it seems like an elegant solution for backup as well as easier to do.

Pete
 
A quick google reveals that a random GPS "mouse" draws 90mA. Is that really going to break the power budget?
Click to expand...

What's more is that all Bluetooth GPS mice have rechargeable batteries with about 17-20 hour battery life. So no power drain at all for most journeys.
 
contessaman said:
okay, so I have nearly finished building my all singing 12 volt on board pc for navigation. the gps receiver is one of the USB SIRF star ones - works incredibly well. One thing has just crossed my mind - the NMEA input to the DSC VHF which currently comes from a garmin GPS, can I somehow drive this from the pc? I know that one can knock up an NMEA input to a pc using the serial port but is it possible to drive the VHF from the USB GPS via the PC? all my efforts to build a 12 volt PC with a 12" screen that only takes 2 amps will be in vain if I have to have another gps receiver running at the same time..
ta

contessaman.
Click to expand...

Sorry not got much time but short answer is YES. Get a USB to Serial converter from say Maplin and this will allow you to output RS232 from your laptop - then follow the instruments wiring diagrams
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if the GPS source for your setup is a USB device then you need to output on either an RS232 port on the laptop ( is there one ) or via a USB to serial converter.

In addition you will have to 'intercept' the incoming serial stream before it gets to your nav software and echo it out onto the new serial port.

The suggested GPSGate 2.6 software MAY work, I suggest contacting the distributor. Not sure if it will work with non wireless serial streams.

There is another product ( several actually ) usually called 'serial port splitter' in fact here's one.
 
are you not putting all your eggs in one basket, we run a gps laptop on a 12 inch touch screen but we also have back up g.p.s. and 2 radios and 2 depth sounders
 
prv said:
A quick google reveals that a random GPS "mouse" draws 90mA. Is that really going to break the power budget?

Assuming your VHF displays lat/long on its screen, a separate GPS input to it seems like an elegant solution for backup as well as easier to do.

Pete
Click to expand...

I agree. the GPS mouse drives the computer and as you rightly say uses milliamps. but alas If I bought a second one of these (agree with thoughts on backup too) a USB GPS mouse will not drive the VHF. Not directly. Proper 'boaty' stand alone GPS receivers seem to take a lot more juice. I have a phillips AP navigator which is old but great, that is my backup. but it does take about 700ma so the plan was only to use this if the pc one failed. not to have it running at the same time.
Its a shame you cant get a little GPS mouse that offers an NMEA output rather than have a USB or Ps2 plug on it.
 
davo said:
are you not putting all your eggs in one basket, we run a gps laptop on a 12 inch touch screen but we also have back up g.p.s. and 2 radios and 2 depth sounders
Click to expand...

Yes but you dont have them all switched on at once!!
You are preaching to the converted on redundancy. Got a separate GPS. and a hand held VHF with an adapter to plug into masthead antenna. Only one echo sounder but it does have a pair of x'ducers. The thing here is my VHF bleats at me if there is no GPS signal, and I want it to have one. Its currently fed off the fixed GPS but why run this and the pc together?
 
Stoaty said:
Its a shame you cant get a little GPS mouse that offers an NMEA output rather than have a USB or Ps2 plug on it.
Click to expand...

Um - surely you can! That's exactly what I was suggesting you get. I admit I didn't have a specific product in mind, but I thought I'd seen loads of these in the past.

EDIT: Here's one.

Pete
 
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We have similar Epia based computer system using usb gps and PcPlotter software. For the DSC radio we use a Furuno GP30 GPS. There were several reasons for this

1 Furnuno unit is stand alone GPS so when the computer is off this unit only draws less than 3w and with range of voltage 10.8 to 31.2VDC and can still output to VHF.

2 we use it as our anchor alarm again low power when on all the time.

3 if Rikaline gps fails we have cable to plug into computer.

4 unit was cheap to buy as it is now regarded as redundant.
 
prv said:
Um - surely you can! That's exactly what I was suggesting you get. I admit I didn't have a specific product in mind, but I thought I'd seen loads of these in the past.

EDIT: Here's one.

Pete
Click to expand...

thats the perfect solution! so gps #1 will be pc with usb gps receiver.
Gps #2 will be vhf with this little receiver you provided link to.

then if(when?) pc one fails the vhf will be the standby gps - you can read the lat and long off the VHF screen which is fine for a stanby. makes you wonder why modern vhf/dsc sets dont come with one of these microscopic gps recevers built in since they cost pence...
 
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