Simple underwater wireless communication

[girishpatil1234]

Hi all,
I want to make simple one to one underwater wireless communication using simple amplifier. Range of communication should be 50 to 70 meter.
If anybody has some idea about this or anybody have made this type of project, please share..
Thank You

 

[Diver300]

That can't be done with radio. Radio waves don't travel through water at all well. There are some short-range, low data rate communication systems that work with low frequencies.

You should be looking at sonic or ultrasonic communication systems.

 

[MikeMl]

Especially sea H2O

 

[Externet]

You need a full face diving mask to be able to vocalize.
You need a waterproof - pressure proof microphone installed near lips.
You need a waterproof - pressure proof second contact microphone worn attached to your throat to trigger a vox.
You need an ultrasonic transceiver, modulated by voice, with vox circuitry.
You need a waterproof - pressure proof omnidirectional piezo element transducer.
You need a circuitry to filter out bubble and breathing noises.
You need molded waterproof-depthproof jacks and plugs and canister for the electronics and battery.
You need a pool nearby for your tests.
You need a lot of time, patience and adrenaline to conquer maaaany unexpected failures. But has to be much easier today with internet for sourcing parts instead of a Thomas Register, and stamped mail communications from overseas.
I worked with the inventor of the first scuba intercom around 1972.

Today; I would attempt it by light modulation (UV?); but still need many of the above items.
I have not given too much tought to a simpler wimpy megaphone style, but not to be discarded at all.

 

[cowboybob]

Welcome to ETO, girishpatil1234!

Simple audio (speech), data or a combination of both?

 

[dr pepper]

Welcome.
I assume you cant just run a piece of bell wire here.
You might be able to get vlf radio to go that far, however it'll take some developing.
Will there be reasonably clear water when you need to communicate?, how about infra red or visible light (maybe a laser).

 

[Externet]

You can run wires, but with shortened life.
Infrared attenuates badly in water. Bluish performs much better. That is why the only color perceived at depth is bluish; if you are not a diver, perhaps you have seen videos.

----> **broken link removed**

 

[crutschow]

You can buy Scuba communicators that use ultrasonics for transmitting the voice signal.
Here's a discussion of underwater communication.

 

[girishpatil1234]

Dear all,

Thanks for your prompt and valuable response.

I want to use piezoelectric crystal here. I don't want to use any optical communication .
I am sharing simple block diagram in my mind.

Suppose I used the circuit as above and instead of loudspeaker I use piezoelectric crystal to transmit audio signal at the transmitter end.

Similarly at the receiver end I use Piezoelectric crystal to receive this signal and similar circuit as above to power the loud speaker.

Will it be ok or is there any wrong concept in it please guide me.

Thanks all...

 

[girishpatil1234]

Welcome.
I assume you cant just run a piece of bell wire here.
You might be able to get vlf radio to go that far, however it'll take some developing.
Will there be reasonably clear water when you need to communicate?, how about infra red or visible light (maybe a laser).

Dear Sir,
I am weak in optical communication, and I think it will require modulation and demodulation of signal so It will be difficult for me.
So I am thinking of simple power amplifier and transmitter and receiver for the signal.
medium will be sea water.
Thank you

 

[girishpatil1234]

Welcome to ETO, girishpatil1234!

Simple audio (speech), data or a combination of both?

Dear Sir,
I want to make simple audio communication. One man can speak with the other man thats it. There will not be any data communication.
Thank you

 

[girishpatil1234]

You need a full face diving mask to be able to vocalize.
You need a waterproof - pressure proof microphone installed near lips.
You need a waterproof - pressure proof second contact microphone worn attached to your throat to trigger a vox.
You need an ultrasonic transceiver, modulated by voice, with vox circuitry.
You need a waterproof - pressure proof omnidirectional piezo element transducer.
You need a circuitry to filter out bubble and breathing noises.
You need molded waterproof-depthproof jacks and plugs and canister for the electronics and battery.
You need a pool nearby for your tests.
You need a lot of time, patience and adrenaline to conquer maaaany unexpected failures. But has to be much easier today with internet for sourcing parts instead of a Thomas Register, and stamped mail communications from overseas.
I worked with the inventor of the first scuba intercom around 1972.

Today; I would attempt it by light modulation (UV?); but still need many of the above items.
I have not given too much tought to a simpler wimpy megaphone style, but not to be discarded at all.

Dear Sir,
Thank You for your response.

Sir I have some doubt.
1) Is modulation necessary or will it be done without modulation?
I have electret mic, amplifier circuit, speaker and piezoelectric crystal.
I assembled the mic, amplifier and speaker It is working in the room.

Now my plan is to assemble another same circuit and use one as transmitter and one as receiver. In transmitter circuit there will be piezoelectric crystal in place of speaker and at the receiver end there will be piezoelectric crystal in place of mic.

Will it be able to transmit and receive the signal?
If you have any block diagram or circuit diagram in your mind, Please share I will try it.

Thank you

 

[girishpatil1234]

That can't be done with radio. Radio waves don't travel through water at all well. There are some short-range, low data rate communication systems that work with low frequencies.

You should be looking at sonic or ultrasonic communication systems.

Dear Sir,
I am using piezoelectric crystal for transmitting and receiving purpose.
Will it be ok?
I am not using any modulation here.
Thank you

 

[Tony Stewart]

Amplitude modulation of TX and Demodulation of Rx. is required.

Your concept wont work. More importantly the audio pickup , filtering and squelch (VOX) is essential, stated by Externet. A throat mic as used by jet pilots and ear buds is one option which I have used in an air suit where ambient noise is high which you will want to cut out of the transmission.

Also if you haven't read Crutschow's link do it next.

Modulation must be a more sophisticated single-sideband modulation, which transmits a single ultrasonic carrier signal to eliminate the reflection and multipath problems of AM.

Soon you will realize you have two choices;

1) learn much more in electronics or
2) buy a professional underwater single sideband, VOX operated Ultrasonic communication Transceiver.

 

[steveB]

Note, that if you did want to use optical communication, (I realize that you don't want to) you would want to use blue light.

 

[girishpatil1234]

Amplitude modulation of TX and Demodulation of Rx. is required.

Your concept wont work. More importantly the audio pickup , filtering and squelch (VOX) is essential, stated by Externet. A throat mic as used by jet pilots and ear buds is one option which I have used in an air suit where ambient noise is high which you will want to cut out of the transmission.

Also if you haven't read Crutschow's link do it next.

Modulation must be a more sophisticated single-sideband modulation, which transmits a single ultrasonic carrier signal to eliminate the reflection and multipath problems of AM.

Soon you will realize you have two choices;

1) learn much more in electronics or
2) buy a professional underwater single sideband, VOX operated Ultrasonic communication Transceiver.

Dear sir,
Thank you for your respnse.
It seems that modulation is essential in this project.
and noise elimination circuit should be added in it.
Thank you

 

[dr pepper]

You will have to use some modulation no matter what you do.
If you use ultrasound you could use amplitude modulation or frequency modulatiom, neither are particularly difficult, to get get noise reduction you could use a noise gate and a compressor/expander.
These days all this would probably be done digitally.

 

[audioguru]

A piezo mic and a piezo speaker produce very squeaky sounds. A real throat mic produces vowels only and is difficult to understand its speech because important consonant sounds in speech are missing.

 

[Externet]

... 1) Is modulation necessary or will it be done without modulation?
I have electret mic, amplifier circuit, speaker and piezoelectric crystal.
I assembled the mic, amplifier and speaker It is working in the room.

Now my plan is to assemble another same circuit and use one as transmitter and one as receiver. In transmitter circuit there will be piezoelectric crystal in place of speaker and at the receiver end there will be piezoelectric crystal in place of mic.

Will it be able to transmit and receive the signal?
If you have any block diagram or circuit diagram in your mind, Please share I will try it.

Thank you

Yes, modulating the resonant frequency of that particular piezoelectric crystal is necessary.
A piezoelectric crystal has a very narrow range uncapable of emitting or receiving intelligible audio.
One of the ´You need...´ is a pool for testing, not a room.

Go head, keep building your receiver...

For unidirectional communicator, coarse transmitter 'block' diagram:
Voice mic--->preamp--->filtering--->modulator
Throat mic--->preamp--->vox--->oscillator--->power amp--->piezo element
Coarse receiver block diagram:
Piezo--->preamplifier--->filtering--->demodulator--->audio amp--->earphone*

*Forgot that one on the 'You need' list, also waterproof-depthproof.

 

[audioguru]

In the transmitter or receiver, if the "speaker" can be heard by the microphone then you will have acoustical feedback howling because a sound will go around and around and around and around.