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Topic: Digital walkie talkie? (Read 3911 times) previous topic - next topic

sdh314


Hi guys,

Was bouncing around a few project ideas with a friend of mine, and we started talking about the possibility of making a digital walkie talkie based on Arduino/Xbee hardware.  I know plenty of analog devices have been made before, but what of a digital comms system?  I'm not too familiar with the hardware requirements of the MP for this - do the ATmega chips have sufficient grunt for the A/D and D/A processing?  The audio stream wouldn't need to be of particularly high quality (just enough to provide decent voice comms), but implementing some digital encryption would be good.  Would the Arduino be suitable for it?   Any comments from those with experience in this area would be appreciated. Ta!

sbright33

Done.  Great range!  1-way so far.  32khz oversampling.  Only 2 lines of code in loop(). 

Here's the hardware you need:
http://www.datasheetcatalog.org/datasheet/analogdevices/SSM2166S.pdf
It's a free sample.  The DIP socket is $3.  You already know what else to buy...
Questions?

I've made many improvements, but start simple right?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

sbright33

Mine is no different from a cheap wireless microphone, except in the following ways:

1. XBee can go to sleep when sound is below a threshold.  UNO can also, waking up to sample every 10s.  The average power is less than 1ma.  Try this with a wireless Mic 1/2mi away!

2. Other data can be sent too.  IR sensor, temp, light, jpg.

3. You can look for a signature in the frequency domain before sending.  There is enough processing power for this!  For example birds, a specific type of owl already sampled, male voices, a car engine idling, heater turning on, transient sounds like a door shutting.

4. You can talk back 2-ways like you want!

5. Do a FFT at 32khz and only send the results instead of the audio

6. Using Openlog you can make a tiny Spy Bug with a thumbnail sized lithium thionyl battery that lasts a YEAR!  Depending on how much talking is being done.  Try that with a voice recorder?

Which of these 6 features do you like?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

billroy

That's a very interesting chip, sbright33, thanks.  Puzzled they don't show a circuit with a microphone in it in the data sheet.

How much conditioning do you have to do to make a condenser style microphone input happy?  I presume you have to bias it, at least.  Did you find it needed pre-preamplification?

Would you perhaps be willing to share the circuit diagram?

-br
http://bitlash.net

sbright33

A resistor to 5V.  I used the circuit in the PDF above.  Works great!
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

Kevin117

#5
Jul 09, 2013, 05:39 pm Last Edit: Jul 09, 2013, 05:47 pm by Kevin117 Reason: 1
I am new to Arduino and XBee but old to electronics and programming. I found this topic via a search on XBee walkie-talkie.

My project is to try and build a digital walkie-talkie (packet switched) capable of mesh networking the audio packets. The application is caving (spelunking). Regular radios work like crap underground, are too bulky, use too much power, but most caving groups stay within a few dozen feet of each other. So data packets should be able to be relayed between each radio. So caver A in the front could talk to caver Z a couple of hundred/thousand feet behind/above/below, or whatever.

I'd like to fit the whole unit inside a helmet with the antenna mounted flush on the top outside surface. So it's small. Also VOX or voice commands would be very nice. The less wires and switches dangling them better. Waterproof naturally. 3-4 hour battery life min. The helmet has lamps on it. Possibly power sharing.

Any pointers, kits, circuits, code, comments would be greatly appreciated.

thank you

AWOL

I thought caverns used induction loops?

(This thread is two years old. Do you want me to split it and start a new thread?)
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

Kevin117

#7
Jul 09, 2013, 07:43 pm Last Edit: Jul 09, 2013, 08:17 pm by Kevin117 Reason: 1
Induction is used to communicate with the surface. I'm talking about between team members.

(Do whatever you think is best)

Kevin117

Here's a thought. What if I used a Bluetooth wireless headset (kind used with cell phones) that paired to a Bluegiga (or whatever) module as a base, connected to a XBee for mesh networking and range?

Just brainstorming here.

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