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communication

Printed From: Yachts and Yachting Online
Category: Keelboat classes
Forum Name: Keelboat news and development
Forum Discription: All the latest developments for yachts
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=745
Printed Date: 10 May 25 at 3:21pm
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com


Topic: communication
Posted By: Peter Rhodes
Subject: communication
Date Posted: 05 Jun 05 at 3:58pm
to avoid paying satelite phone fees would it be possable to get an internet conection on a boat by conecting a laptop to a short wave / ssb radio with another at home conected to a computer, would it be possable to do this digitally to avoid data changing interferance etc or would it have to be through a modem?



Replies:
Posted By: brys
Date Posted: 14 Jun 05 at 12:34pm

Really don't know. about the first part of your question

But second bit about modems is easy:-

 basic computing knowledge says:

MODEM = MOdulator/DEModulator

ie A modem converts digital pulses in your computer into radio frequency or telephony system compatible signals......or vice versa (for outgoing and incoming signals)

It provides and modulates a carrier signal for broadcast and then demodulates the received signal (strips out the carrier) leaving the digital information....that can then be processed by software, be it text, pictures or speech data

Whatever MODEM you use your end there has to be a compatible one the other!

For you to use Radio to transmit your data you would need a radio frequency modem and the receiver would need a modem of the same type tuned to receive the broadcast frequency....As with any radio broadcast it would not be private, anyone caple of picking up the signal (and equipped with the same type of modem) could intercept your messages, data etc.unless you employed some very sophisticated encryption software!

Hope this helps?



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Never enough time for sailing


Posted By: Peter Rhodes
Date Posted: 14 Jun 05 at 4:37pm

I thought a modem was an anologue/digital converter

anyone know of one of these forum things for hamateur radio enthusiasts?



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Posted By: Stefan Lloyd
Date Posted: 14 Jun 05 at 5:33pm

Originally posted by Peter Rhodes

I thought a modem was an anologue/digital converter

Well yes, in effect it is. And then it puts the analogue signal over a phone line or radio connection, exactly as Brys described. Whether you are going over a phone line or a radio chanel, you need something to take your 32-bits (or whatever) and serialise them into one stream so they can go over the channel.

If you want to use short-wave for an internet connection, yes I think there are people on uk.rec.sailing who do it. If you ask nicely, you may get a sensible answer out of them. There are some knowledgable people there and also some fairly strange ones.

 



Posted By: Peter Rhodes
Date Posted: 14 Jun 05 at 8:16pm
what is uk.rec.sailing dosn't look like a website adress, nor does it work as one?

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Posted By: Stefan Lloyd
Date Posted: 15 Jun 05 at 7:44am

It's a web Usenet forum. Sorry but since you were asking for one I assumed you'd know how to access them. Via http://www.dejanews.com - www.dejanews.com is one simple way.

A newsreader is a better one but needs a bit of setup: for example Outlook. From Internet Explorer, Tools -> Mail and News -> Read News. You will need to know the address of your ISP's NNTP server to set it up. Use dejanews if this sounds too complicated.



Posted By: alex650
Date Posted: 15 Jun 05 at 7:19pm

There plenty of ways to get email via SSB radio (globally) - all for free.

Try looking at http://www.sailmail.com/ - http://www.sailmail.com/  as although they provide a service, they also have plenty of technical information about how to go about this.

cheers

alex



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http://650.org.uk/650/yellowfin/main.html - 2007 Mini Transat campaign - follow Alex's campaign news...


Posted By: Peter Rhodes
Date Posted: 15 Jun 05 at 7:39pm
so the radio transmitter is not a modulator even though it modulates a carier wave so that it caries information and a radio reciver is not a demodulator by seperating these out again?

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Posted By: Stefan Lloyd
Date Posted: 16 Jun 05 at 8:16am

If you like, yes. But since most radio transmitters modulate analogue information, not digital, it is not relevant to your original question.

Do you have a point or are you just being argumentative? If the latter, you'd be really at home on uk.rec.sailing.



Posted By: Peter Rhodes
Date Posted: 16 Jun 05 at 12:12pm
so to send digital radio signals I need special equipment

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Posted By: Stefan Lloyd
Date Posted: 16 Jun 05 at 1:20pm
Yes. Take a look at the link Alex provided.



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