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Old 14 April 2012, 06:26   #51
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that must get carried by some other frequency or somthing to travel that far
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Old 14 April 2012, 06:41   #52
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so does that equation apply to the way dsc works too?
Yes. The digital signal actually has slightly more range than the analog voice signal, about 15% or so.
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Old 14 April 2012, 06:46   #53
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that must get carried by some other frequency or somthing to travel that far
This occurs in certain atmospheric conditions - when there is a high pressure system in place and there is little wind. The radio signal gets trapped below a certain altitude, about 1000' if I remember correctly, and this allows it to travel further. It involves temperature inversions and super-refraction - gobbledegook to most people, including me.
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Old 14 April 2012, 06:53   #54
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so basicly the same as an am signal using the ionisphere to bounce off,i believe charged from particles that have been discharged by solar flars from the sun? thus carrying it further,
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Old 14 April 2012, 07:43   #55
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so as previously discussed if you have a series of boats using dsc over a 30mile distance,say 10 boats 3 miles apart will that not get 30mile using the others as a repeater
Class D dsc sets can't relay messages
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Old 14 April 2012, 08:01   #56
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Yup! dsc uses the VHF band,... but it only transmits at 2w
I can't argue this as I don't have any evidence to the contrary but I've never heard this before and it sounds extremely daft IMHO
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Old 14 April 2012, 08:27   #57
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I can't argue this as I don't have any evidence to the contrary but I've never heard this before and it sounds extremely daft IMHO
I might be getting confused with AIS which is 2W, so I'm willing to stand corrected
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Old 14 April 2012, 08:40   #58
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I might be getting confused with AIS which is 2W, so I'm willing to stand corrected
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To prevent overloading of the available bandwidth, transmission power is restricted to 2 W, giving a range of about 510 mi.
Consider yourself corrected
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Old 14 April 2012, 09:11   #59
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Consider yourself corrected
See, you CAN educate pork after all
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Old 14 April 2012, 12:01   #60
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Hello

From my recent experience I'd certainly go for DSC unit if you can.

The point above about the DSC data signal going further seems very true here, where we have patchy VHF coverage due to cliffs and a fragmented pattern of islands.

I've just set up the DSC unit on my RIB and the DSC signal got through to both Aberdeen and Shetland coastguards 100% even in places where my voice signal was weak.

In an emergency, that DSC distress data packet (complete with the GPS locational data from the chart plotter) could I'm sure be a life saver, especially as all you need is that long press of the red button, even where a voice signal may be unreadable. Plus if I came to grief, it's great to know there's such an easy way for crew to call for help too when they may be flustered.

Plus the DSC "test call" function is a really quick and easy way to be reassured that the system is working in a discreet way.

Of course, it depends where you are, but I'm sure pleased I went for a DSC unit.

Hope this helps

Steve
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