DSC to GPS Wiring Q's

Tasarsailor · 08 November 2005, 17:54

I added at Standard Horizon DSC radio to my RIB this summer. It's pretty sweet. It's the 1000 that is just a black box stowed in my console and then all of the radio's functions are a RAM+ speaker mic. I was able to wire the radio to the serial connection for my Garmin handheld (etrex vista) which has blue charts on it. I am able to send my position and the radio displays my position. (yes the etrex is microscopic... getting a 76cs next year)

My problem is that very few folks in the states have DSC (we don't have to be certified either) so I cannot find someone to send their postion to me. Standard Horizon suggests that the charting function (someone sending a postition to you) only works when utilized with a Standard Horizon mapping GPS. I think I have wired it correctly to accept a signal from the GPS but with no easy way to test it I can't tell if it works or not.

Has any wired up a DSC radio to an etrex? Other Garmin? If so are you able to display a position sent to you?

I may have to resort to chasing down a Coast Guard RIB and see if they have DSC. I am pretty sure those folks have all of their boats set up with DSC.

Thanks
Tony
Portland, Oregon USA

roycruse · 08 November 2005, 18:41

Have you wired up the both the transmit (TX) and recieve (RX) pins between the 2 systems - the bog standard way of connecting DSC to GPS is simply NMEA TX on GPS connected to NMEA RX on DSC this provides the DSC radio with your current position which is used in position reporting and distress alerts.

Some systems support additional functionality if you also connect the TX on the VHF to the RX on the GPS.

You then have the ability for automatic waypoint creation when position reports or distress alerts are recieved from the DSC radio.

To find out if this is possible with your equipment you need to check the NMEA specification for the two devices and compare them. You are looking for version numbers and sentence types.

My Garmin 178C chartplotter has the ability to recieve these position reports from a suitable radio - but unfortunately as far as i am aware my ICOM M421 is not able to transmit them so i have not actually seen it working...

Tasarsailor · 08 November 2005, 21:49

The radio has only 4 bare wires.

The wiring chart from the radio indicates that the 4 wires are:
1. NMEA in positive
2. NMEA in ground
3. NMEA out positive
4. NMEA out ground

My Garmin's wiring has also has 4 wires.
1. power positive
2. ground
3. NMEA in
4. NMEA out

So with a multi meter I located the appropriate wires on the Garmin serial connector then on the nifty little DIY serial connector for the radio connector I soldered the NMEA in and out ground wires together to connect to the single Garmin ground.

This seems to at least work in the direction of GPS to Radio. My position shows up on the radio screen and the time of day is also displayed properly.

I just can't confirm if the Radio to GPS will function as I imagine it should. I would expect that if my GPS receives an NMEA signal it will get added to my waypoint list automatically.

I may still just have to call the coast guard on my cell phone, give them my MMSI and see if they will send me a test. I should be able to test the all ships position send as well. Since, there are so few folks with DSC they may welcome a test run.

Thanks for the input.
Tony
Portland, Oregon USA

jwalker · 08 November 2005, 23:32

That all sounds about right.

I've got your MMSI, I'll call you tomorrow.

OceanEco · 09 November 2005, 01:58

I know some of the standard horizon radios can only transmit their position and not recieve other vessel's positions. Some of the higher end models can send and recieve positions with the dsc function. The lower end models do not have the recieving capabilities.

Tasarsailor · 09 November 2005, 14:44

The model I have is the Standard Horizon phantom PS1000 and has all of the features.

It's a pretty sweet unit. The main body of the radio is just a black box with no face. Only a single power button that you don't even really use. All of the function and display is on a speaker mic. It really cleaned up my console.

I am extremely pleased.

Tony

Jimbob · 09 November 2005, 17:43

get a mate or a marina to do it (the test that is)

Tasarsailor · 09 November 2005, 18:29

A soon as I can test it I will. Just can't find anyone with DSC. I spent two weeks in the San Jaun and Gulf Islands this summer and could find no one with a DSC to give it a go. The only DSC I found was an older unit and he didn't have it connected to a GPS so he couldn't try sending his position. (didn't have time to type one in manually) I am not even sure he had an MMSI anyway.

DSC is not even remotely prolific in the states. It has only been in the last year or so that affordable units were available. Previous to that it was only the high end units. It just hasn't been a priority for the general boating population. I think the proliferation of mapping GPS units among the general coastal boating population has increased the demand for DSC. Brits and Europeans spend a lot more time offshore in their recreational boats than North Americans.

There are so few DSC units out there that I'm not even sure if all of our commercial traffic is completely outfitted. I am pretty sure that our local law enforcement doesn't even have it.

I may have my boat out this weekend to do some crabbing at the coast. If I do I will try to phone the coast guard ahead of time to pass on my MMSI for a test.

Thanks
Tony

Tim M · 13 November 2005, 19:15

I wanted to connect my etrex up to my Navman 7100. Tested it but it didn't work; the two arn't compatable.

OceanEco · 13 November 2005, 19:34

If you are in the San Juans anytime soon let me know we are still out 5 days a week. Generally south end of San Juan. Our mmsi is 246345123

Tasarsailor · 14 November 2005, 16:39

Cool thanks for the mmsi I will make a note of it.

I won't likely be up there until next summer though.

I didn't get my boat out this weekend so I will have to wait to test it further.

I will repost when after I test it.

Thanks
Tony

Tasarsailor · 27 April 2006, 17:47

I finally got the word on DSC compatibility from Garmin.

The only garmin gps units that can receive a position and post to the map are the larger units.

Garmin says there is a hardware change that must be done to the non dsc compatible units to make it work. This hardware change is in place on larger units. I gave them some feedback regarding the complete lack of information on their website regarding DSC compatibility.

I was hoping just a firmware upgrade would eventually make it work. No dice.

The units I have tried so far are the etrex vista and a 76cs.

Here is the text of their answer:
"The GPSMap76CS will communicate with a VHF radio for the purpose of
transmitting your position during a distress call. The ability to input
another radio's position would require hardware changes within the unit that
increases its processor speed such as the larger marine units. I would be
more than happy to pass this along to the software engineers in regards to
making any updates that might make this feature available on the device. I
will also mention your suggestion about the minimal information available
about Garmin units and DSC compatibility. "

It still seems odd that it can send a position but not receive.

Good Luck