Request for comments - acoustic remote control - Sub model remotely controlled by sounds

[fbradasc]

[color=#000000]I'm thinking to control the sub model by acoustic signals.

I've tought two ways to do that]

[tang]

I do not have the

I do not have the electrical knowledge to comment in a productive manner on this seemingly beneficial idea you've got here, but I would like to raise a question.

How would a number of modelers operate in the same lake at the same time? Currently, the use of different frequencies is made easy with preset crystals. Having the same level of organization among frequencies being used at any one time should be a primary goal.

[slats]

The idea seems interesting, but

The idea seems interesting, but what I am not following is why?
That is why would you want to control a sub acoustically, when radio signals work fine? -(Granted there are limitations regarding salinity of the water), but still not sure what the advantages are. Seems like a complicated way to do something that presently is simple.
Lots of luck.
John.

[fbradasc]

I've made some other researches

[color=#000000]I've made some other researches and I plan to use DTMF+ultrasounds, so to make the system usable by a number of modeler at the same time without interffering with each other.

An ultrasonic carrier will be FM modulated by the DTMF signal, the ultrasonic frequency can be chosen form a range spreading from 23KHz to 100KHz (the signal bandwidth should be less than 2KHz, so about 50 models can be controlled simultaneously without problems).

About why use sound to control the submarine models, well, the question should be]

[tang]

This is a whole new

This is a whole new dimension of possiblities! Unfortunitely, without knowing what DTMF stands for, I don't understand half of your post. Help!

[fbradasc]

DTMF stands for Dual Tone

DTMF stands for Dual Tone Multi Frequency, which means that each DTMF code consists of a pair of different frequencies played simultaneously.
They are the tones you ear when you compose a phone number, for each digit of the phone number a different DTMF tone pairs are played.
Each DTMF code can encode 4 bits of data so it can select 1 of 16 possible combinations.

[himszy]

Hi

Five questions]

[color=#FF0000]Hi

Five questions]

[guillermo pelaez]

The idea sounds innovative to

The idea sounds innovative to say the least.
How much bandwidth are we talking about? Would that be fast enough to give a micro an order in a timely manner (i.e. before the boat hit the bottom or the wall at the end of the pond).
Would not a powerful wireless modem work the same? I agree that the cost for a boxed product against a homemade project may be prohibitive.
An schematic would be really interesting.
I would just say, full ahead, good luck! And keep us posted, innovation is what progress is made of. And this could certainly be a new horizon for RC Underwater operations...
Cheers!

[fbradasc]

Hi

Five questions]
"Each DTMF code can

Hi

Five questions]

"Each DTMF code can encode 4 bits of data so it can select 1 of 16 possible combinations."

So in english you can have 16 channels?

With each DTMF code you can control 1 of 16 different ON/OFF switches. But you can send more than one DTMF code to extend the possibilities, i.e. you would like to make your sub dive up to a depth of 2 meters, regardless of the current depth, you will need to send 2 or 3 DTMF codes]Also how much would it cost?

I'm still in a design stage, but I think that 2 transceiver units, excluding the GB, will cost less than the GB itself.

So does it also have to work out how deep the pond is? If so isn't it going to keep looking at how deep the water is?

The sounds underwater will propagate in every direction at a speed of about 1480 metres per second. In few tens of metres will be almost no sound attenation. However the echo will be a problem.

Finally what if it reads your voice wrong? Goodbye sub

This is a misunderstanding. The commander will not speak to the model, but she/he will send to it DTMF codes. The DTMF codes will be interpreted by the model as commands.
When the model will receive a DTMF code it will send back to the remote control which will compare the replay with the command previously sent and if they are the same will proceed by sending a new command, otherwise it will resend the same command.

How much bandwidth are we talking about? Would that be fast enough to give a micro an order in a timely manner (i.e. before the boat hit the bottom or the wall at the end of the pond).

Each DTMF code needs to be "on air" (well on water for at least 52 milliseconds to be correctly interpreted, and between each DTMF code there's the need of a pause of 52 milliseconds, so each second can be transmitted about 9 codes correspondig to 36 bits. But you really need to transmit no more than 2 or 3 DTMF codes to send a particular command to the model, corresponding to less than 0.2 seconds.

Would not a powerful wireless modem work the same? I agree that the cost for a boxed product against a homemade project may be prohibitive.

I plan to put one of the two transceivers into the Trumpeter's Kilo or Seawolf model

An schematic would be really interesting.

I'm working on a preliminary draft, stay tuned.