How to output GPS signal to a DSC radio?

[Moo]

Originally Posted by Dockhead

4. Connect a chart plotter with dedicated 0183 talker port to the radio with two wires. Or connect the radio to an N2K network if it has an N2K port. Job done, because the gear is all designed to be connected this way. You are suffering complications because you are using a computer rather than purpose made marine chart plotter.

This ^^^^^^^^


Basically if somebody has to ask how to make these connection there is no point bombarding them with technicalities (as much as some of us like technicalities ) It's got to be plug and play, off the shelf.

[GILow]

Originally Posted by smac999

If you are buying a new radio. Just Get one with built in gps.

The OP has already bought the radio.

[sdowney717]

Originally Posted by GILow

The OP has already bought the radio.

Yes, I needed a new radio. Its cheaper to buy one without GPS and add a GPS, I bought a GPS for $17, the radio was $83 off Amazon. So a little over $100. My computer was also cheap, way under $200 for every part, and it runs Linux Mint. I think $60 for monitor, $25 for MB with core2duo cpu, $15 for drive, cables maybe another $20, memory another $20, decent PCIE video card $40. Power supply I had already, case also had. And I had a decent out of the way spot for it. It is invisibly hidden behind the salon wall, behind a cabinet door, in a spot that the OEM had not crafted access. I have 20 foot run of USB 2.0 cable and 25 foot HDMI to the monitor.

On my chart table helm are left, next to the wheel, sits the monitor, usb hub keyboard, mouse all on a flat space of about 24" width and 28" depth. The monitor I drilled one hole in base at the back and screwed it down so it wont flop over. One screw lets me turn it too.

I have upgraded Pc motherboard twice, I buy older cheap ones off ebay, they are not too old, so I stay behind top rated speed, but its not needed to be the best.

When originally setting this up, I avoided using laptop, thought it was easily stolen and would have cost me a lot more money, plus not upgradable for cheap.

My ideal future upgrade would be NVME ssd drive and a faster MB

[Spot]

SD717, please let us know how the install goes. I agree that plug and play would be nice (Cobra's 'puck' is 50$ US) but I also like the whole DIY thing of getting A to talk to/listen to B without being beholden to a particular brand of device or to just save a little money.

[barnakiel]

Originally Posted by rgleason

There is another way to do this.
Use an old gps puck, determine the power wires and provide 5vdc, then determine which wire is nmea in on your radio and connect that to what you think is nmea out on the puck. If that does not work, switch the two nmea puck wires.

This gives your DSC radio a dedicated gps that is not dependent on any other equipment.

Except for a 12 to 5 V step down ...


An option: since the OP runs a machine, maybe there is a serial port on that machine (PC). Then this port can output the gps data for the radio.



b.

[rgleason]

Originally Posted by barnakiel

Except for a 12 to 5 V step down ...
An option: since the OP runs a machine, maybe there is a serial port on that machine (PC). Then this port can output the gps data for the radio.
b.

Sure the PC would work too, but it is more useful to me to have it all setup as a standalone sensor for VHF DSC, using a very small converter 12vdc to 5vdc. So small it is just taped to the wiring in back of the VHF.


When I turn the VHF on, position very shortly appears, ready for any emergency call. Reliant on no computer or loose connections.

[barnakiel]

Yes. The ways will differ depending on what one has at hand.


BTW. I am nearly sure a 12V vhf radio will not burn the puck. I say this as our gps can deliver position to our radio also when the gps is powered by batteries. And since these are 2x1.5Volt batteries I am very positive the 3 wire signal aka RS232 uses voltages lower than the radio itself. Using the same gnd wire does not imply the voltage is 12V even though the device may be 12V. They all have step downs inside to feed various chipsets that provide various functions.



So I think a vhf radio gps signal circuitry is only somewhere at 3.5V or thereabout.


But I am not sure what signal Volt level a RS422 device is (?)



Cheers,
b.

[Reefmagnet]

Originally Posted by barnakiel

Yes. The ways will differ depending on what one has at hand.


BTW. I am nearly sure a 12V vhf radio will not burn the puck. I say this as our gps can deliver position to our radio also when the gps is powered by batteries. And since these are 2x1.5Volt batteries I am very positive the 3 wire signal aka RS232 uses voltages lower than the radio itself. Using the same gnd wire does not imply the voltage is 12V even though the device may be 12V. They all have step downs inside to feed various chipsets that provide various functions.



So I think a vhf radio gps signal circuitry is only somewhere at 3.5V or thereabout.


But I am not sure what signal Volt level a RS422 device is (?)



Cheers,
b.

+5 volt is the range from memory, but this is in no way related to the power supply requirements of the device. There may be some confusion with the NMEA 2000 standard which does include power distribution for transducers. NMEA 0183 does not.

[Moo]

Originally Posted by barnakiel

But I am not sure what signal Volt level a RS422 device is (?)



Cheers,
b.

RS 422 signal levels are 2 > 6V



Power supply to the unit could be anything of course.

[rgleason]

https://en.wikipedia.org/wiki/RS-232#Voltage_levels

[GILow]

Originally Posted by rgleason

https://en.wikipedia.org/wiki/RS-232#Voltage_levels

I think there may be some confusion here. There are the signalling voltages defined by the various standards such as RS422 but there is also the question of the supply voltage required for the puck to operate. In this case the OP linked a puck that needs 5 volts to power the device. I would assume the actual NMEA output would be at the correct voltages.

[Moo]

Originally Posted by rgleason

https://en.wikipedia.org/wiki/RS-232#Voltage_levels

Yerrr that is why RS232 (your standard computer serial) sometimes doesn't work with NMEA0182 (now in the later versions close to RS422). There is some overlap but they are not the same.



GiLow.... I'm not confused but maybe I have added to it by pointing out some awkward facts


To re-enforce ... Supply voltage to the device is not specified in RS232/422/485 or NMEA0183 (at least not for puck devices in the latter case)

[Tupaia]

The OP seems to be making something simple more complicated.
If you have a GPS puck connected to your PC/OpenCPN are you saying that you are going to use this as your primary navigation aid?


Surely a standalone (12v) GPS or a Multi output unit including AIS from Quark would solve all of the issues.


Relaying on a GPS puck connected to a PC for DSC purposes will likely result in a Distress call failing because of lack of a fix.

[sdowney717]

Originally Posted by Tupaia

The OP seems to be making something simple more complicated.
If you have a GPS puck connected to your PC/OpenCPN are you saying that you are going to use this as your primary navigation aid?


Surely a standalone (12v) GPS or a Multi output unit including AIS from Quark would solve all of the issues.


Relaying on a GPS puck connected to a PC for DSC purposes will likely result in a Distress call failing because of lack of a fix.

It might or might not. Cetainly if the computer quits working.
I use a small puck on the PC as my primary nav aid. It sits dry out of the rain under the 3 forward windows, I am on a powerboat. It works very well and cost $7, gets a cold fix fast.
This is the one. I use it with Linux Mint.
https://www.aliexpress.com/item/3280...69154c4dh88Qge

I bought this one for the new radio, I paid $17.50 2 days ago, price just went up, I wonder why, tariffs?
https://www.aliexpress.com/item/3291...4de64c4dzX7ecZ

[Tupaia]

Originally Posted by sdowney717

It might or might not. Cetainly if the computer quits working.
I use a small puck on the PC as my primary nav aid. It sits dry out of the rain under the 3 forward windows, I am on a powerboat. It works very well and cost $7, gets a cold fix fast.
This is the one. I use it with Linux Mint.
https://www.aliexpress.com/item/3280...69154c4dh88Qge

I bought this one for the new radio, I paid $17.50 2 days ago, price just went up, I wonder why, tariffs?
https://www.aliexpress.com/item/3291...4de64c4dzX7ecZ

You are asking software engineers to fit lightbulbs what you have is a hardware issue.

The solution to your hardware problem is here.

Connect your GPS to your VHF radio | The Ensign magazine