Sound Comunication

Troberg

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To be quite honest, I don't see the point. It's in every way inferior to wifi and bluetooth. Also, it will, at best, work at old style telephone line modem speeds.
 

maso1975

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Troberg Hi, thanks for answering,

in my case, I would like to do something like packet radio, and can send text strings between two android audio connected to a transceiver, could be for example a sending android gps position through the transceiver to another without any other infrastructure that the transceiver and the android, with wifi repeaters would need, plus how easy it would have a transceiver and a smartphone to put lock the system.



greetings.
 

sorex

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To be quite honest, I don't see the point. It's in every way inferior to wifi and bluetooth. Also, it will, at best, work at old style telephone line modem speeds.
the only benefit would be the lack of extra hardware (wifi) or clumsy setups (blutooth, tether etc...)

but it's far from new, it's just the principle of a modem connection but using speakers instead of a wire between the two.

I wonder how many resends it does because it couldn't get the right data due to lame speakers/mics or background noise.
 

Troberg

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but it's far from new, it's just the principle of a modem connection but using speakers instead of a wire between the two.
Which was pretty much how the first modems worked. You put the handset from a normal phone on the modem box, which had a speaker and a microphone, and the transmission was acoustic. I think it had something to do with the phone companies not allowing the connection of equipment not sold by them.
 

sorex

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more like "you are not allowed to modify our infrastructure in any way for personal profit"

so they left how it was and just placed the horn on that horn holder microphone/speaker thing, pretty legal like that :)
 

maso1975

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Hello everyone, and thank you for your interest in this matter,

is that it is not new, my intension is not to invent anything, if not do something like this in B4A with code that can change, precisely one of the problems is that where I would like to use (and now I will expose the idea that I have) is that no wifi infrastructure, telephony or to repeat data.

I'll give an example of why I want to do something like this, a couple of friends and I went for a walk through a forest close to home, from a point there is no signal or wifi telephony, radio pmr446 got along one of them was lost, and although we could talk to explain was dende not know, although I had the smartphone did not know how to use the GPS of this to give us their location, after about 20 minutes we found it and thankfully everything was left in a fright.

It occurred to me that if the smartphone also carry in your pocket a small cable to connect the smartphone to the radio pmr446, and a program with just one click could convey the position of this, we could have found him sooner.

This is an example, but ne can think of several other things I could do with something like that, precisely because something simple and does not require too much hardware thanks to technology that is at alcanse of most people today.
 

Cableguy

Expert
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Well, I forsee a few obstacles/difficulties to this...

- the tone alphabet choice has to be very careful as well as radio frequency and modulation. ..
- no radio transmission is noise free, especially walkies...

I admit, your idea is quite good... you may need how ever a coupling circuit...

[P.S.: I remember seeing a few years ago an automatic morse coder... the user entered the message through a keyboard and then the message was converted and sent as audio... you could use it that way...]
 

Troberg

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Licensed User
Use the touch tone dialing system, should work well.

However, if the person who is lost, as in the scenario above, can't figure out the GPS, can he use this setup?
 

KMatle

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Anonymous used some sort of mailboxes/fax with tone dial/accoustic modem in to spread informations to countries cut from the internet.

I often thought of alternativ communication ways. Maybe we can share some ideas about it.
 

Troberg

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Yeah, Pirates Without Borders dis something like that as well. I think they also did things like setting up amplified wifi stations near borders.
 

maso1975

Member
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Anonymous used some sort of mailboxes/fax with tone dial/accoustic modem in to spread informations to countries cut from the internet.

I often thought of alternativ communication ways. Maybe we can share some ideas about it.
why I opened this thread to share ideas and develop something like this.

I think I'll start using this example http://www.b4x.com/android/forum/threads/fft-fast-fourier-transform-library.6989/page-3, and make a loop where you can read something like one second recording for them often, I have not very clear but I start out there.
 

Troberg

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Licensed User
Yeah, FFT would probably be the way to go. Use one frequency to clock the transmission (state change for every bit) and another for data. It will work, though not very fast. If you want faster transmission, you'll have to use several frequencies to send several bits in parallel.
 

maso1975

Member
Licensed User
We only need text to transmit. So it's fast enough. But we need to transmit it a long distance...
This is where the transceiver enters to transmit over long distances, once the App can encode / decode a headphone cable to the transceiver is only necessary, activating the vox transceiver, this transmit when the app starts to play a sound through the earpiece, I've also seen one very simple circuits that can connect to the headphone output to the ptt is active transceiver, in the pictures below an example of how to connect android systems APRS is.

AD3-APRSDroid.jpg
x_aprsdroid_xperia_uv3r.jpg
 
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