LowPowerLab Forum

Hardware support => General topics => Topic started by: Alexander on December 28, 2017, 07:26:01 AM

Title: Sending audio to walkie-talkie
Post by: Alexander on December 28, 2017, 07:26:01 AM
Hello everyone,

Could anybody help to get to know how to transmit recorded audio from Monteino(RFM69) to regular LPD walkie-talkie?

Thank you!
Title: Re: Sending audio to walkie-talkie
Post by: Felix on December 28, 2017, 02:19:00 PM
These radios are OOK/FSK (digital communications). They are not appropriate for sending sound or other such media.
Title: Re: Sending audio to walkie-talkie
Post by: Alexander on December 29, 2017, 04:45:43 AM
Hi, but it possible : https://youtu.be/CdfbES_O9sw

The guy does it with AVR and RFM22B but I don't dare to ask for source code :)
Title: Re: Sending audio to walkie-talkie
Post by: perky on December 29, 2017, 09:02:04 AM
These LPD433 walkie talkies use F3E modulation, which are basically analogue FM. I don't think there's a hope of receiving that and decoding it, but I'm not sure what would happen if you sent a FSK modulated signal, which is basically a square wave, to an analogue FM receiver. The filters in the receiver may well extract the fundamental from the encoded square wave and produce something. Maybe modulating the frequency of the FSK with voice might be intelligabe the other end. It would mean using continuous mode or directly controlling the modulation digitally.

Mark.