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Old 02-11-2011, 23:12   #1
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Postition Input to DSC Radio

I have just installed a new VHF with all DSC functions but have no GPS with the ability to feed the radio with the ship's position. I have two puck type GPS antennae, one for a laptop, using OpenCPN and another for a Yeoman plotter. I also have a standard Garmin GPS antenna for a now defunct plotter.
I don't particularly want to add more bits to the laptop and I only use the Yeoman intermittently.
Is there any way that I can connect either another puck antenna or the Garmin antenna directly to the radio or do I need some form of computing power to interpret the GPS signals?
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Old 03-11-2011, 14:24   #2
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If your gps puck has a serial output, like the Garmin gps18 lvc, or many handheld units, you can connect directly to the nmea input on your transceiver.

Chip
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Old 03-11-2011, 17:39   #3
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Re: Postition Input to DSC Radio

Antenna in itself will not do. You need something in between the antenna and the radio to create NMEA position sentences readable by the VHF.

Alas, check out what Garmin (antenna?) you have there as some pucks from Garmin that look like an antenna are in fact small receivers. Antenna can be known by looking at the kind of cable that comes out of your unit.

BTW I am not sure you need GPS for the radio to function properly. I think you need MMSI number for DSC functionality and GPS if you want GPS pos to be included in your DSC communication. Otherwise, I think, the radio will work OK.

b.
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Old 03-11-2011, 18:22   #4
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Re: Postition Input to DSC Radio

Hi, Thanks but I fear you are confirming what I already suspect. The Garmin antenna is one of the old fashioned mushroom ones, not a puck type.
You are right about the radio - it doesn't need the GPS to work but it's a comforting thought that, in an emergency, transmitting a correct position would be one less problem for an inexperienced crew member to worry about.
I have done this exercise once before on my last boat but that had a built in, GPS, similar to the Garmin 152 but without integrated antenna. If I could find something similar to that, I would invest in one but, apart from the Garmin 152, they all have fancy chart plotting capabilities, which I don't need, and cost a fortune.
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Old 03-11-2011, 19:03   #5
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Re: Postition Input to DSC Radio

Quote:
Originally Posted by galleyslave View Post

1) in an emergency, transmitting a correct position would be one less problem for an inexperienced crew member to worry about.

2) If I could find something similar to that, I would invest in one but, apart from the Garmin 152, they all have fancy chart plotting capabilities, which I don't need, and cost a fortune.
re 1: maybe in emergency you will want to do it yourself? just talking because methinks our DSC radio sends nothing once you push the red button ...

re 2:

You can get a cheapo 72H and it will do the job too (make sure, but I believe it has both data out and USB jacks),

OR

You can get something alike 17x or 18x and have a low-power solution that will deliver data to your radio or any other NMEA instrument.

Alas, in a small sailing boat I would go the 72H way - cheap, works and can be taken along while not sailing.

Cheers,
b.
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Old 04-11-2011, 07:22   #6
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Re: Postition Input to DSC Radio

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Originally Posted by barnakiel View Post
re 1: maybe in emergency you will want to do it yourself? just talking because methinks our DSC radio sends nothing once you push the red button ...
If you have it correctly connected to a GPS, and correctly register your MMSI number, then pushing the red button sends all of the information that the Coast Guard needs to confirm your emergency and respond--who you are, what kind of boat it is, where you are located. If your radio is sending nothing when you push the red button then you are wasting the real value of the DSC technology.
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Old 04-11-2011, 10:56   #7
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Re: Postition Input to DSC Radio

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If your radio is sending nothing when you push the red button then you are wasting the real value of the DSC technology.
Unfortunately, it is estimated that fewer than 10% of DSC radio's are enabled. Coast Guard statistics show that last year there were 263 DSC distress calls, compared to 15,882 voice calls on channel 16 and 7,285 calls via cell phone. Someone on another boating forum claimed that a radio without an MMSI programmed will still send out a distress call. That is not the case. Without an MMSI, the radio does not transmit anything and should give you an error beep.

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Old 04-11-2011, 15:14   #8
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Re: Postition Input to DSC Radio

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Originally Posted by denverd0n View Post
If you have it correctly connected to a GPS, and correctly register your MMSI number, then pushing the red button sends all of the information that the Coast Guard needs to confirm your emergency and respond--who you are, what kind of boat it is, where you are located. If your radio is sending nothing when you push the red button then you are wasting the real value of the DSC technology.
You misunderstood my intention. Maybe because I have mis-communicated the message. Off course I am too of the opinion that having a DSC radio and not using its DSC functionality is pretty pointless.

I clarify:

E.g., SH2100, instruction manual, states as per attached jpg.

Now, to me, it reads 'press the button' then 'press the button again'.

I am not sure if this is how it really works, or maybe pressing the damn button just once will work the same. SH manual has been apparently translated from Japanese with some help from Google Translate.

But what I do know, is that I would rather send the DSC Mayday myself than delegate the possibly less than intuitive process to an inexperienced crew member.

BTW to further clarify the matter, GPS link is a good thing but not technically required to send a DSC distress communication. On the other hand MMSI is technically required and if no MMSI is input then the DSC communication will not work - meaning the red button will not work either.

This is what I gleaned from some units. It is possible there are some major differences between manufacturers.

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Old 05-11-2011, 18:16   #9
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Re: Postition Input to DSC Radio

One jury-rig would be to buy a Standard Horizon HX-851 handheld. It's charging station has NMEA0183 wires. SO as long as the HX is in the station, you'll have position since the HX has its own GPS receiver. It also allows full checkout of all DSC functionality short of an actual distress call. One should use the same MMSI for both the fixed unit on a boat and its handheld.

You might be able to cobble together a USB-to-Serial connection from your PC to the radio but that almost sounds hard.
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