It is indeed a really nice project idea! I hope Tobie can make it work! AFAIK, There are several store and forward packet radio satellites in orbit. These will accept packet messages (transmitted on VHF or UHF freqs) from ground stations and then allow other users in different locations (anywhere in the orbital coverage of the satellite) to receive the data at a later time. How large is the boat? The amount of signal power needed for the satellite depends on the satellite,and since I have never done this, I am not sure of the typical amounts needed. I would guess ,thought, that there is at least one such satellite which would get a good enough signal from a couple of watts into a small yagi. There has been a push for a long time in amateur radio to launch some satellites which had such good antennas and receivers to be able to get a usable signal from 5 watts into an omnidirectional antenna, but I don't know if any are currently in operation. Could you handle an antenna which was about 1.5 meters long and 0.3 meters wide? What are your weight limits like? Could you deal with having a pair of motors to point the antenna and a computer with tracking program to point it properly? Sean At 02:41 PM 10/19/00 -0500, you wrote: >I for one, think this is a super-cool project. > >I've been waiting for the ham radio types to come in, who know more about >the radio side, and especially what is legal. For that kind of range, you >need either a short-wave radio that will skip, or a transmitter that can >talk to a satellite. > >For the short-wave approach, the ham guys might know how you can legally >have a remote-operated transmitter off in international waters operating on >a short-wave ham band. If you put it up using a standard modulation scheme >and publish its frequency and transmission schedule, you can probably get a >lot of help in receiving the reports, with receivers scattered about both >sides of the ocean. > >It will take a few watts to push a signal across the ocean, but the message >need only be a few milliseconds long. 50 bytes at 1200 baud is 417 >milliseconds. You should be able to use less than 50 bytes, and possibly a >higher bit rate as well. I would run the transmitter from a bank of low-esr >capacitors that were charged up from whatever power supply you're using for >motors, etc. If it transmits, say, every 4 hours, and has a 50% probability >of being received each time, then you will get an average of three position >reports per day. The probability of getting them all goes way up if you >have 10 receivers at different positions. > > > -----Original Message----- > > From: Tobie Horswill [mailto:thorswil@EXMACHINA.QC.CA] > > Sent: Thursday, October 19, 2000 1:15 PM > > To: PICLIST@MITVMA.MIT.EDU > > Subject: Re: [OT]: Long range position feedback anyone ? > > > > > > Hi Roman, > > > > Well actualy, the boat is still in the making ... I'm > > building it just > > because I like the idea of a totally closed and autonomous > > system, I don't > > have the money to travel and the "hi-tech message in a bottle" idea is > > something I've been thinking of for some time. The boat should start > > somewhere off the Canadian east cost and head for France, > > Spain or Portugal > > and then come back. It'll be saving daily position logs to > > EEPROM so I can > > plot it's course but still, I'd like to have a real-time > > position feedback > > if possible ... And no, I don't do this often, this is the > > first time. :-) > > > > Regards, > > > > Tobie Horswill > > thorswil@hotmail.com > > > > > > ----- Original Message ----- > > From: "Roman Black" > > To: > > Sent: Thursday, October 19, 2000 1:53 PM > > Subject: Re: [OT]: Long range position feedback anyone ? > > > > > > > Hi Tobie, > > > > > > I'm fascinated, why do you have a little boat roaming around > > > the middle of the atlantic ocean? Do you do this often? :o) > > > -Roman > > > > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > "[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other > > "[BUY]:","[AD]:" =Ads > > > > > > > > > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other >"[BUY]:","[AD]:" =Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: "[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads