Hi Folks,
I'm sure one of you out there will know the answer to this one.
Anyone any idea how well a 1.3GHz radio transmission will penetrate fresh
water. I build model subs and I know that standard 40MHz Radio control gear
works well down to ten feet or so. I'm thinking of mounting a black and
white TV camera on a sub. I've seen a transmission system that uses the
1.3GHz telemetry bands to carry a video feed, but I'm not sure how well it
will work.
So any help would be much appreciated - Oh and it is not that off topic the
Sub has two PICs in it, one for depth/attitude control the other for speed
control!
> Hi Folks,
> I'm sure one of you out there will know the answer to this one.
>
> Anyone any idea how well a 1.3GHz radio transmission will penetrate fresh
> water. I build model subs and I know that standard 40MHz Radio control gear
> works well down to ten feet or so. I'm thinking of mounting a black and
> white TV camera on a sub. I've seen a transmission system that uses the
> 1.3GHz telemetry bands to carry a video feed, but I'm not sure how well it
> will work.
>
> So any help would be much appreciated - Oh and it is not that off topic the
> Sub has two PICs in it, one for depth/attitude control the other for speed
> control!
>
> Andy
>
hmmm, my guess is you'll be lucky to get 1 inch! Probably have to
use something really powerful anyway... Are you sure you can't have a wire?
Don't take my word for it, but at 2 ghz with a high quality video and audio
transmitter/receiver (1 watt +/-) with 40 feet of air between them you can
block the signal with a sheet of paper. You need an unobstructed line of
sight path. With water, who knows, but I think lower frequencies would be
easier. There are a lot of low cost video transmitters in the 70 - 300 mhz
range. Check the security and surveillance web pages.
In real subs, they use LF(Low Frequency) or ULF(Ultra Low Frequency) to
carry signals through the water. It is also very high power, and poor
bandwidth. The
bandwidth problem is somewhat minimized by the use of codes, that get
expanded
on the receiving end... however..
If you want to use a camera, about your only option is to tie a balloon or
something
to an antenna to float it to the surface.
Craig
----------
> From: SHAWN ELLIS <spam_OUTspeTakeThisOuTMERC.RX.UGA.EDU>
> To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU
> Subject: Re: OT: Radio Transmission in Water
> Date: Wednesday, March 04, 1998 10:34 AM
>
>
> > Hi Folks,
> > I'm sure one of you out there will know the answer to this one.
> >
> > Anyone any idea how well a 1.3GHz radio transmission will penetrate
fresh
> > water. I build model subs and I know that standard 40MHz Radio control
gear
> > works well down to ten feet or so. I'm thinking of mounting a black and
> > white TV camera on a sub. I've seen a transmission system that uses the
> > 1.3GHz telemetry bands to carry a video feed, but I'm not sure how well
it
> > will work.
> >
> > So any help would be much appreciated - Oh and it is not that off topic
the
> > Sub has two PICs in it, one for depth/attitude control the other for
speed
> > control!
> >
> > Andy
> >
> hmmm, my guess is you'll be lucky to get 1 inch! Probably have to
> use something really powerful anyway... Are you sure you can't have a
wire?
> Anyone any idea how well a 1.3GHz radio transmission will penetrate
> fresh water. I build model subs and I know that standard 40MHz Radio
> control gear works well down to ten feet or so. I'm thinking of
> mounting a black and white TV camera on a sub. I've seen a
> transmission system that uses the 1.3GHz telemetry bands to carry a
> video feed, but I'm not sure how well it will work.
Andy:
It's unlikely to work real well at all. Is there any chance that
your sub could tow a floating antenna behind itself?
On Wed, 4 Mar 1998 21:57:31 -0000 Andy Shaw <EraseMEandy.shawspam_OUTTakeThisOuTVIRGIN.NET>
writes:
>Hi Folks,
>I'm sure one of you out there will know the answer to this one.
>
>Anyone any idea how well a 1.3GHz radio transmission will penetrate
>fresh
>water. I build model subs and I know that standard 40MHz Radio control
>gear
>works well down to ten feet or so.
I don't think it would work very well. The higher the frequency is, the
more the water will attenuate it. So the navy uses VLF to transmit to
their subs.
You may be able to control the sub over several hundred feet using some
sort of modulated sonar, but getting a TV image back is almost certainly
going to require a cable.
_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]
>On Wed, 4 Mar 1998 21:57:31 -0000 Andy Shaw <andy.shawspam_OUTVIRGIN.NET>
>writes:
>>Hi Folks,
>>I'm sure one of you out there will know the answer to this one.
>>
>>Anyone any idea how well a 1.3GHz radio transmission will penetrate
>>fresh
>>water. I build model subs and I know that standard 40MHz Radio control
>>gear
>>works well down to ten feet or so.
>
Mike Keitz wrote:
>I don't think it would work very well. The higher the frequency is, the
>more the water will attenuate it. So the navy uses VLF to transmit to
>their subs.
>
>You may be able to control the sub over several hundred feet using some
>sort of modulated sonar, but getting a TV image back is almost certainly
>going to require a cable.
>
How about a resonant periscope, 1.3 Ghz is 23cm so a quarter wave
will be around 4-5 cm, the water would make a nice ground plane
and you could tune for minimum vswr by diving a little. :-)
Thanks Brian,
Yeah I knew that things would get worse what I'm not sure about is what the
relationship is. Is it linear with frequency or worse :-( my guess would be
worse. To be honest this does not have to be able to work that deeply since
most of the time a model sub is probably only a few inches/feet under water.
The actual camera will probably be mounted lower down with the transmitter
as high up as I can get it. Anyway any advice would be welcome.
I think that the idea of using ELF or VLF will probably not float (Pun
intended). We live near one of these antenna and it's about 1/2 - 1
mile long. Probably the idea of a float bouy with a small antenna would
work.
PS I'm not an RF expert so take it with a handful of salt.
Just to throw in another possibility, there is a small window in the IR
spectrum that will transmit well through water. But please note that VLF
is the best way to go in water. The scroedinger wave equation can show
that any EM wave's propagation is a function of medium density and wave
frequency.
> Andy-
> In case you aren't RF aware, propagation actually goes down as frequency
> goes up. That's the basis of Shawn's guesstimate.
>
> Brian
> {Original Message removed}
Andy Shaw wrote:
>
> Hi Folks,
> I'm sure one of you out there will know the answer to this one.
>
> Anyone any idea how well a 1.3GHz radio transmission will penetrate fresh
> water. I build model subs and I know that standard 40MHz Radio control gear
> works well down to ten feet or so. I'm thinking of mounting a black and
> white TV camera on a sub. I've seen a transmission system that uses the
> 1.3GHz telemetry bands to carry a video feed, but I'm not sure how well it
> will work.
>
> So any help would be much appreciated - Oh and it is not that off topic the
> Sub has two PICs in it, one for depth/attitude control the other for speed
> control!
>
> Andy
Hi, Andy
the loss of 1.3 GHz in Water is very high (up to 70dB). The loss of
400MHz is only about 15 dB. I4ve tried to transmit with an RFM HX200
(916,5MHz) out of water and I had no success, after that i changed the
frequency to 433.92 MHz and it was much better. Remember: a microwave
oven works at 2.4GHz and most of the output will absorbed by water.
> is the best way to go in water. The scroedinger wave equation can show
> that any EM wave's propagation is a function of medium density and wave
> frequency.
>Just to throw in another possibility, there is a small window in the IR
>spectrum that will transmit well through water. But please note that VLF
>is the best way to go in water. The scroedinger wave equation can show
>that any EM wave's propagation is a function of medium density and wave
>frequency.
>
> - Dennis
Hi Dennis,
I think you are confusing density with the electromagnetic
properties of the material. And further confusing propagation
velocity with absorbtion.
The electromagnetic properties of the material determine the
absorbtion (attenuation).
In the case of microwave absorbtion, the absorbtion spectrum
relates more to the molecular structure.
Back to VLF, there is a VLF transmitter in Australia at
Exmouth Gulf on the West Coast which transmits to the Indian
Ocean. I think the frequency is just a few Khz. In any case
the antenna is over 1000 ft high! This system is used to
communicate with US submarines. I don't know if they
trnasmit video though. :-)
I'm usually silent but since i already tought of the dtmf idea a while
ago for another project and noticed it could not work, i had to say it.
The only problem with dtmf is the speed. the detectors cannot lock fast
enough to get a normal bandwidth (usually a couple of ms). A solution
would be High Speed DTMF (I heard of it but never looked it up).
I think the best way to go would be a cable to a floatin antenna. Then
you can get the equipment you want on the surface and the distance you
want. Only problem is crossing objects that are floating or submerged...
but it should work fine on the open.
+--------------------------+-----------------------+
| | ABL Canada inc. |
| Jacques Audette | 8550 Cote-de-Liesse |
| Hardware design | St-Laurent, Qc |
| Video Codecs | H4T 1H2 |
| | Tel: (514)344-5432 |
| RemoveMEjacques.audetteEraseMEEraseMEabl.ca | Fax: (514)344-5439 |
+--------------------------+-----------------------+
> ----------
> From: Alessandro Zummo[SMTP:RemoveMEazummospam_OUTKILLspamITA.FLASHNET.IT]
> Reply To: pic microcontroller discussion list
> Sent: Friday, March 06, 1998 7:30 AM
> To: RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU
> Subject: Re: OT: Radio Transmission in Water
>
> Il 05-Mar-98, Dennis Merrill scrisse:
>
>
> > is the best way to go in water. The scroedinger wave equation can
> show
> > that any EM wave's propagation is a function of medium density and
> wave
> > frequency.
>
> Just and idea.. what about using DTMF underwater?
>
> yes, i know.. i'm mad :-)
>
> --
>
> - *Alex* -
>
> http://freepage.logicom.it/azummo/
>
At 01:24 AM 3/7/98 +1000, you wrote:
>>Just to throw in another possibility, there is a small window in the IR
>>spectrum that will transmit well through water. But please note that VLF
>>is the best way to go in water. The scroedinger wave equation can show
>>that any EM wave's propagation is a function of medium density and wave
>>frequency.
>>
>> - Dennis
>Hi Dennis,
>
>I think you are confusing density with the electromagnetic
>properties of the material. And further confusing propagation
>velocity with absorbtion.
>
>The electromagnetic properties of the material determine the
>absorbtion (attenuation).
Yep, you're right. I probably shouldn't try to quote things from books
that have more than an inch of dust on them.... thanks for the
clarification! :)
> I'm usually silent but since i already tought of the dtmf idea a while
> ago for another project and noticed it could not work, i had to say it.
> The only problem with dtmf is the speed. the detectors cannot lock fast
> enough to get a normal bandwidth (usually a couple of ms). A solution
> would be High Speed DTMF (I heard of it but never looked it up).
I tought to use dtmf only for driving an r/c submarine,
surely not for other purposes... i could enlarge the tone
duration... anyway i should still evaluate the attenuation
of a sound in the water... if someone knows about
HSDTMF.. would be better :-)
Water conducts sound extremely well , better (and faster) than air.
I thinking in a very free form mode here but you could rip the
transducers off a couple of old fish finders and use em for tx and rcv.
units.
I think these guys operate above 30 KHz. You may be able to modulate
enough info on to the carrier to do slow frame video.
> From: Alessandro Zummo <EraseMEazummospamspamBeGoneITA.FLASHNET.IT>
> To: RemoveMEPICLISTKILLspamMITVMA.MIT.EDU
> Subject: Re: OT: Radio Transmission in Water
> Date: Friday, March 06, 1998 12:50 PM
>
> Il 06-Mar-98, Jacques Audette scrisse:
>
> > I'm usually silent but since i already tought of the dtmf idea a while
> > ago for another project and noticed it could not work, i had to say it.
>
> > The only problem with dtmf is the speed. the detectors cannot lock fast
> > enough to get a normal bandwidth (usually a couple of ms). A solution
> > would be High Speed DTMF (I heard of it but never looked it up).
>
> I tought to use dtmf only for driving an r/c submarine,
> surely not for other purposes... i could enlarge the tone
> duration... anyway i should still evaluate the attenuation
> of a sound in the water... if someone knows about
> HSDTMF.. would be better :-)
>
>
> --
>
> - *Alex* -
>
> http://freepage.logicom.it/azummo/
Well we've discussed everything else...... how 'bout pee, and a
trained dog. I'll leave you to imagine the mechanics.........
I like the concept of the sound waves, what was said about 30kHz?
I remember they used to pipe in underwater music at the local pool,
I little 8 inch speaker could be heard over the entire area.
I'd just be a bit concerned about the poor marine life that has to listen
to this man's stereo. Can't whales, dolphins, etc hear this freq?
> From: Paul B. Webster VK2BZC <paulbSTOPspamspam_OUTMIDCOAST.COM.AU>
> To: spamBeGonePICLISTSTOPspamEraseMEMITVMA.MIT.EDU
> Subject: Re: OT: Radio Transmission in Water
> Date: Monday, March 09, 1998 3:55 PM
>
>
> Well, this gives some clues about why in this age of aeronautics,
> major military powers still have large submarine fleets, doesn't it?
>
> Of all the options quoted, I'd consider the visible light. IR may be
> OK, I don't know. Even the sun doesn't feel very warm underwater!
>
> Cheers,
> Paul B.
>
> Humor:
>
> Well we've discussed everything else...... how 'bout pee, and a
> trained dog. I'll leave you to imagine the mechanics.........
>
> I like the concept of the sound waves, what was said about 30kHz?
> I remember they used to pipe in underwater music at the local pool,
> I little 8 inch speaker could be heard over the entire area.
>
> I'd just be a bit concerned about the poor marine life that has to listen
> to this man's stereo. Can't whales, dolphins, etc hear this freq?
>
> Craig
>
> ----------
> > From: Paul B. Webster VK2BZC <KILLspampaulbspamBeGoneMIDCOAST.COM.AU>
> > To: EraseMEPICLISTEraseMEMITVMA.MIT.EDU
> > Subject: Re: OT: Radio Transmission in Water
> > Date: Monday, March 09, 1998 3:55 PM
> >
> >
> > Well, this gives some clues about why in this age of aeronautics,
> > major military powers still have large submarine fleets, doesn't it?
> >
> > Of all the options quoted, I'd consider the visible light. IR may be
> > OK, I don't know. Even the sun doesn't feel very warm underwater!
> >
> > Cheers,
> > Paul B.
a couple of days ago you where talking about howe high above the
electical groundplane you had to be when you where using cm waves.
now you are talking about transmitting with the ground all around you
very intelligent.
whats next transmitting from inside a Faradays cage perhaps.
science is beutiful.read something about density and wavespreading
and ohms law.the higher frequency you use the better short it will be
try a very low frequency and perhaps you get something to play with.
sorry for my bad typing.i am not a deskclerk.
> Water conducts sound extremely well , better (and faster) than air.
> I thinking in a very free form mode here but you could rip the
> transducers off a couple of old fish finders and use em for tx and rcv.
> units.
> I think these guys operate above 30 KHz. You may be able to modulate
> enough info on to the carrier to do slow frame video.
The question is: where can i get them and how can i protect
any other emitter from water without loosing it's capabilities...
part 0 1320 bytes I made a little PC that fits inside of the Kynar cylinder, and
provides two stages of amplification, and bandwidth trim. Once
it is in place, I mold it into a urethane shape that fills all voids.
The urethane is waterproof and is transparent to sound.
Great hydrophone. I have dozens of the boards, if anyone is
interested.
BTW, I am wondering if there is any garbage attached. I called
Microsoft, and they gave me their version of how to suppress it
in Outlook 97. If they are right, email private, and I will reveal
all.
>BTW, I am wondering if there is any garbage attached. I called
>Microsoft, and they gave me their version of how to suppress it
>in Outlook 97. If they are right, email private, and I will reveal
>all.
>Attachment Converted: C:\WINDOWS\DESKTOP\Re OT Radio Transmission in W
>
> -----Original Message-----
> From: PIC microcontroller discussion list
> [@spam@PICLIST@spam@spam_OUTMITVMA.MIT.EDU]On Behalf Of Alessandro Zummo
> Sent: March 10, 1998 12:40
> To: spamBeGonePICLISTKILLspamMITVMA.MIT.EDU
> Subject: Re: OT: Radio Transmission in Water
>
>
> Il 10-Mar-98, The Jacky's scrisse:
>
> > Water conducts sound extremely well , better (and faster) than air.
> > I thinking in a very free form mode here but you could rip the
> > transducers off a couple of old fish finders and use em for tx and rcv.
> > units.
> > I think these guys operate above 30 kHz. You may be able to modulate
> > enough info on to the carrier to do slow frame video.
>
> The question is: where can I get them and how can I protect
> any other emitter from water without loosing it's capabilities...
I believe most emitters are piezo, which is real easy to find. Look in o
ne
of the recent electronics now issues, they have a hydrophone project. The
emitter consisted of a piezo element epoxied in a bottle cap or something
like that. TTYL
> provides two stages of amplification, and bandwidth trim. Once
> it is in place, I mold it into a urethane shape that fills all voids.
> The urethane is waterproof and is transparent to sound.
Great solution! maybe i'll try..one day or another...
--
>>
>> The question is: where can I get them and how can I protect
>> any other emitter from water without loosing it's capabilities...
> I believe most emitters are piezo, which is real easy to find. Look
in one
> of the recent electronics now issues, they have a hydrophone project. The
> emitter consisted of a piezo element epoxied in a bottle cap or something
> like that. TTYL
You might consider using a fiber-optic cable (the cheaper grade should work
o.k.). Off the shelf video transmitters/receivers (over fiber) can be purchased
for $200.00 to $300.00 ea. Hey... Maybe you could put a bobber and a hook on
the line and reel in the big ones - a remote control fishing pole!
> Hi Folks,
> I'm sure one of you out there will know the answer to this one.
>
> Anyone any idea how well a 1.3GHz radio transmission will penetrate fresh
> water. I build model subs and I know that standard 40MHz Radio control gear
> works well down to ten feet or so. I'm thinking of mounting a black and
> white TV camera on a sub. I've seen a transmission system that uses the
> 1.3GHz telemetry bands to carry a video feed, but I'm not sure how well it
> will work.
>
> So any help would be much appreciated - Oh and it is not that off topic the
> Sub has two PICs in it, one for depth/attitude control the other for speed
> control!
>
> Andy
You might consider using a fiber-optic cable (the cheaper grade should work
o.k.). Off the shelf video transmitters/receivers (over fiber) can be purchased
for $200.00 to $300.00 ea. Hey... Maybe you could put a bobber and a hook on
the line and reel in the big ones - a remote control fishing pole!
> Hi Folks,
> I'm sure one of you out there will know the answer to this one.
>
> Anyone any idea how well a 1.3GHz radio transmission will penetrate fresh
> water. I build model subs and I know that standard 40MHz Radio control gear
> works well down to ten feet or so. I'm thinking of mounting a black and
> white TV camera on a sub. I've seen a transmission system that uses the
> 1.3GHz telemetry bands to carry a video feed, but I'm not sure how well it
> will work.
>
> So any help would be much appreciated - Oh and it is not that off topic the
> Sub has two PICs in it, one for depth/attitude control the other for speed
> control!
>
> Andy
MERC.RX.UGA.EDU>
