The simplest wireless communication

I am in the middle of building an installation. Two mannequins will have a simple conversation between them. When they talk, they just light up and produce an audio tone. But the main thing is that they dont interrupt each other and they take turns in talking. Ideally I want them to be independent, without any wires between them.

A friend of mine is helping me out with some custom electronics to detect the tone. We are now at prototype 2 and the audio filter works, but since the distance between the two mannequins may be variable, it proves to be hard to detect the tone further than a meter or two.

We still haven't given up on the idea, but I slowly start looking for planB, as I need to complete the project within the month.
I had a look online and I see these cheap wireless transmitters and receivers.

http://grobotronics.com/rf-link-transmitter-434mhz-2173.html#.U_ybmmNdBAY
http://grobotronics.com/rf-link-receiver-4800bps-434mhz-2171.html#.U_ybmmNdBAY

Has anyone used any of these before? Do you think they will be reliable for what I need? Basically I only need to transmit an on/off signal.

Also, I assume I will either have to find two pair of these working in different frequencies, or I will have to transmit a different character, so each mannequin doesn't listen to itself, right?

thank you

Also, I assume I will either have to find two pair of these working in different frequencies, or I will have to transmit a different character, so each mannequin doesn't listen to itself, right?

Could you make one of them a master and the other a slave?

  1. Master sends signal to say it is about to speak. Slave stops talking (if it was).

  2. Master talks.

  3. Master sends signal to say it has stopped speaking. Slave starts talking. Master waits for a period of time.

  4. Back to 1.

That way, you would only need communication in one direction.

hmmm yeah that's right... that could be a potential solution.
but I kind of like the idea of having two identical modules, running the same logic. Maybe later on I add a third or forth one.

I had a quick look to a tutorial about the arduino library and it seems that you establish a serial communication with which you can transmit a set of characters. Thinking about it, even if both operate in the same frequency... they can send and receive different characters for the on/off signal, don't you think?

I see there is also a transceiver. But looking at the spreadsheet, it may be a little more complicated to use. I don't see any arduino libraries for it.

http://grobotronics.com/rfm12b-s2-wireless-transceiver-915mhz.html#.U_ym5WNdBAY

How about you do it as if they were real people?
It could be simpler as well as more like what you are looking for.

  1. Use microphone to see if its quiet - if not wait a few seconds and repeat
  2. Talk for a while
  3. Pause for a while to allow the other person to start speaking

This thread has some info on using microphones and detecting tones:
http://forum.arduino.cc/index.php?topic=260989.0

If line of sight isn't a problem what about an infra-red LED/receiver pair on each unit?

Just spit balling.

A pair of xbees would do everything you said!

thanks for the suggestions guys

treva31:
How about you do it as if they were real people?

That's how the logic works. I've also added interrupts, if one person keeps talking for way too long, so they start competing.
The challenge at the moment is to know when the other person is talking and using just a mic means it will be triggered even with ambient sounds. This thing is going into an art exhibition that will hopefully be crowded at some point and with live music. It needs to be somewhat robust.

matmanj:
If line of sight isn't a problem what about an infra-red LED/receiver pair on each unit?

Actually I should give that another go, there will only be a few meters apart.
I have a pair of IR and did some initial tests a while ago, but I had trouble lighting up the LED in the right way to make the receiver trigger. That would probable be the cheapest solution.
Btw... In case I put it together and I find it doesn't reach due to distance, is it possible to amplify the LES brightness? If I put 2-3 LEDs in parallel, will it make it read further away?

Willyboielectro:
A pair of xbees would do everything you said!

Oh these are cool. These should definitely do the job, as they seem to offer a lot more than I need. I'll definitely consider them.

thanks a lot