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Old 04-04-2011, 18:13   #16
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Re: DSC

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Originally Posted by goboatingnow View Post
The key word is " position requests ". This is a specific feature that requests a DSC response from the receiver to send it's position. It has to be user replied to.
ok, I will have to learn about the position request feature.

But just by the way, I saw him do this in person and the reply was automatic. He did not touch the handheld, it was actually in the dinghy 100 yards away. So, somehow he has enabled it to automatically reply to this position poling.

But you are suggesting that without figuring out someone to do position poling with, there is no way for me to actually test the outbound ploter interface until or unless I get a real emergecy call. That somehow does not seem very sensible designwise.
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Old 04-04-2011, 18:28   #17
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Re: DSC

Evans and others, do NOT, repeat NOT, get a BOatUS MMSI, it is not valid for use in international waters or when you have an SSB on board and changing a MMSI is a nightmare. Which is why we haven't programmed our DSCs.
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Old 04-04-2011, 18:39   #18
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Re: DSC

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Originally Posted by Hannah on 'Rita T' View Post
Evans and others, do NOT, repeat NOT, get a BOatUS MMSI, it is not valid for use in international waters.
We actually have had an mmsi from the fcc for our sat c for years, but I accidentally let that license expire. So I just got a new fcc license with new number.

Regarding the position request feature - here is an ICOM ytube about it. A little bit of an icom ad, but does show how to use the position request. It suggests that 'auto reply' is the normal radio state (At least for icoms) but that you can turn the auto reply off. But this does look like a way to test my plotter hook up.

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Old 05-04-2011, 02:17   #19
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It's true that allmost all modern DSC radios have an auto response feature to reply to position requests.

Dave
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Old 05-04-2011, 05:08   #20
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Re: DSC

But it must be enabled by the user. The default setting is normally to NOT auto-acknowledge.

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Old 05-04-2011, 06:04   #21
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Re: DSC

Quote:
Originally Posted by Hannah on 'Rita T' View Post
Do NOT, repeat NOT, get a BOatUS MMSI, it is not valid for use in international waters or when you have an SSB on board and changing a MMSI is a nightmare. Which is why we haven't programmed our DSCs.
From the careful wording above I suspect that Evans' 'DSC friend' has done the same thing I have done: I have a MMSI associated with an FCC station license for Auspicious and have programmed that MMSI into the SSB and fixed VHF on board; I have a Boat/US MMSI for my dinghy that is programmed into my DSC handheld.

I found that between the fixed VHF Icom M601 and handheld VHF Standard Horizon HX850S when both were programmed with the same MMSI that one would switch channels properly when called by the other but not the other way round. I can't remember which one didn't behave properly. A Boat/US MMSI for the dinghy (and handheld dinghy radio) sorted that out nicely.

With an EPIRB, SSB DSC, fixed VHF DSC, SOLAS flares, yadda-yadda-yadda if I get to the point of depending on the handheld DSC for real help outside of USCG jurisdiction I have a whole bunch of troubles already. *grin*

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Originally Posted by estarzinger View Post
ok, I will have to learn about the position request feature.
I think there are two parts of the challenge: 1. Getting the radios to report position automatically and 2. determining what NMEA sentences the radio generates in response to the received position report. If you can't find a listing of the supported sentences you can figure it out for yourself. Hook the NMEA-out from the radio to a serial port on your laptop (or a serial-to-USB converter) and 'listen' to the NMEA output using a dumb terminal program. I use PuTTY which is overkill for this application but serves a number of other needs for me; it's free. You can get the pin-outs you need with Google. Send me a note if you need help.

Strictly speaking NMEA 0183 calls for an RS-422 serial interface, but it works fine almost all the time with RS-232.

Not all documentation matches the equipment so you may find yourself having to determine the as-built reality anyway, particularly for more obscure (at least at time of design and manufacture) functions.

Of course once you have figured out what the radio is transmitting you will have to figure out what the Furuno chart-plotter understands. The same setup will allow you to send hand-built NMEA sentences to the plotter to see how the plotter reacts.

sail fast and eat well, dave
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