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Old Jul 28, 2013, 06:41 PM
Registered User
Liverpool, UK
Joined Aug 2004
111 Posts
Yes 35mhz works okay in FRESH water. Tried a scratch built sub in a Loch in Scotland once that was saline, dependant on the exact location and time of tide. Worked great on the surface. Ended up going for a swim

Kev

If there's been some revolution recently and there's a system that will work in sea water would someone please post? (and no, I'm not up to building an ELF station!)
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Old Jul 28, 2013, 07:54 PM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
I am looking into the possibility of making a system that would work in salt water, though this is in the very initial stages of conceptual development. Possibly a few years away till I even get around to a prototype.

Adam
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Old Jul 28, 2013, 11:54 PM
TheyreComingToTakeMeAway!
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USA, ID, Coeur D'Alene
Joined Dec 2003
5,405 Posts
just for fun, i recently tried this out at the lake, i used a spektrum dx6i and ar6300 receiver. it lost signal about 3-4 inches under the surface at about 35 feet out. not viable for anything underwater.
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Old Jul 30, 2013, 07:19 AM
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United States, ME, Bar Harbor
Joined Sep 2005
391 Posts
An example of signal penetration, or lack there of: My house has wire lathe plaster walls. My portable phone uses 2.4 ghz. My phone will not reach it's base 70 feet away.
Frequencies will have to drop significantly to manage any H2O penetration. If we lose 75mhz we will be very expensive targets.
Jonathan
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Old Sep 18, 2013, 04:24 PM
BabyBootLegger
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United States, CA, Alameda
Joined Nov 2010
649 Posts
I don't know if this works on all 2.4GHz radios but a Jeti DC-16 2.4GHz radio trainer out PPM plug can be connected to a 75MHz transmitter module for use with model submarines. The telemetry system will still work, as long as you use Jeti telemetry components.
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Old Sep 18, 2013, 05:35 PM
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Joined Jul 2004
270 Posts
Since everything is going 2.4,,, I hope the FCC lifts it's ban on 72 and let it be used for surface. Where I live I could get away with it. no one would know. too many farmers around here that would never spend even 10 cents on RC. I hope that in the country areas they would allow 72 . I have a really good 72 radio that would be an awesome Sub radio. but won't do it. though I would love to.
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Old Oct 01, 2013, 03:31 PM
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Joined Oct 2004
496 Posts
Hey , I just stumbled over here from the sailplane forums out of curiosity and found this thread . Here's a news flash : It's not even a good idea to use 2.4 in the RAIN .
Some have learned it the hard way
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Old Oct 31, 2013, 11:23 PM
beginning night flyer
RCpilotwantabe's Avatar
Anacortes,WA
Joined Dec 2007
482 Posts
so I have a silly question and i figured id ask it here, will 433mhz (UHF) work underwater or will it still get reflected?
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Old Nov 02, 2013, 12:22 AM
Michigan, USA
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Joined Apr 2008
66 Posts
Quote:
Originally Posted by RCpilotwantabe View Post
so I have a silly question and i figured id ask it here, will 433mhz (UHF) work underwater or will it still get reflected?
Two points:

1) 433 MHz would probably not work well for Radio Control - wouldn't penetrate water very far, and

2) 433 MHz is NOT a legal band in the US for Radio Control. ham license or not.

Dan
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Old Nov 02, 2013, 01:56 PM
beginning night flyer
RCpilotwantabe's Avatar
Anacortes,WA
Joined Dec 2007
482 Posts
Ok thank you. I will do some further reading then.
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Old Nov 02, 2013, 05:14 PM
Tygum Lagoon Terror
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Australia, QLD, Regents Park
Joined Mar 2007
3,454 Posts
There are 4XX MHz systems available marketed as LRS systems mainly for FPV planes

Long range systems

Just the first link that popped up

as for there usefulness in underwater RC boating

Nick
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Old Nov 02, 2013, 08:18 PM
Michigan, USA
Roedj's Avatar
Joined Apr 2008
66 Posts
From FCC 15.231

TITLE 47--TELECOMMUNICATION

CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION

PART 15_RADIO FREQUENCY DEVICES--Table of Contents

Subpart C_Intentional Radiators

Sec. 15.231 Periodic operation in the band 40.66-40.70 MHz and above 70 MHz.

(a) The provisions of this section are restricted to periodic
operation within the band 40.66-40.70 MHz and above 70 MHz. Except as
shown in paragraph (e) of this section, the intentional radiator is
restricted to the transmission of a control signal such as those used
with alarm systems, door openers, remote switches, etc. Continuous
transmissions, voice, video and the radio control of toys are not
permitted.
Data is permitted to be sent with a control signal. The
following conditions shall be met to comply with the provisions for this
periodic operation: (emphasis mine)

NO radio control in the 420-450 MHz band period - ham license or not.

Dan
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Old Nov 02, 2013, 09:29 PM
Tygum Lagoon Terror
nick_75au's Avatar
Australia, QLD, Regents Park
Joined Mar 2007
3,454 Posts
All well and good.
Info was for the benefit of information NOT the fact of whether it is legal or not.
As this forum has members from all over the world I thought the information could be useful

Cheers
Nick
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Old Nov 03, 2013, 06:21 AM
Man from Atlantis
Sub culture's Avatar
London
Joined Nov 2003
882 Posts
Interesting the way that legislation is worded.

If the data was not continuous e.g. was sent say every say 50ms, then you wouldn't be breaking any regulations by using bands within the prohibited frequencies. Is that correct?

Back in the analogue days that would have been difficult to achieve, but these days, it shouldn't be too tough.
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Old Nov 03, 2013, 10:56 AM
Michigan, USA
Roedj's Avatar
Joined Apr 2008
66 Posts
Quote:
Originally Posted by Sub culture View Post
Interesting the way that legislation is worded.

If the data was not continuous e.g. was sent say every say 50ms, then you wouldn't be breaking any regulations by using bands within the prohibited frequencies. Is that correct?

Back in the analogue days that would have been difficult to achieve, but these days, it shouldn't be too tough.
You're going to make me work for this, aren't you?

I'm not a lawyer nor do I play one on TV (the telly). Having said that, I would define an intermittent signal as one having no periodic nature. Your idea of pulsing the signal on and off at a predetermined rate would, by definition, be periodic.

And except for your acknowledgment of my superior logic, let's end this now, please.

Dan
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Last edited by Roedj; Nov 03, 2013 at 11:01 AM. Reason: spelink
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