Project - Morse Code FM Transmitter/Receiver and Decoder

Hi all

This is my first post and I'm also new to Arduino (I bet you hear this all the time)

I am putting together a project for my kids whom have shown a real interest in communications devices, specifically Morse Code. I want to encourage this and as normal I have over promised by saying I can deliver a self built Morse Code short range transmitter/receiver.

Scope: Two small self contained units, capable of transmitting and receiving Morse code over a short range (like 10 meters max, to stay within the law). Optional increase of scope to include visual decoder to help with training (but this depends on difficulty)

My research to date has been rather extensive and I have found lots of Arduino projects that include a Morse code transmitter or varying types, an FM receiver and a Morse Code decoder, but none seem to have done what I am proposing. Is this because what I am proposing is not possible for Ardunio or would be too complicated for a newbie.

So far I am considering the following equipment for each device

  • 1 x Arduino Uno
  • Elechouse v2.0 FM Radio Transmitter Module
  • FM RDA5807M FM Receiver Module
  • LCD 1602 Display
  • Active Buzzer
  • Buttons


  • Would I need two Arduino's per device, i.e. one to handle transmit, one to receive.
  • Is FM the way to go at all?, could I do the same thing with say an NRF24L01 module that is both transmit and receive, at the end of the day i am only trying to transmit/receive morse.

Any help and advice is greatly appreciated, thank you.

Why would you want to use FM to begin with? Lots of other radios available. Keep it simple, use a digital transmission. Send a message say 10-100 times a second, just a single byte. 0 for off, 255 for on. The moment the key is pressed, send 255s, when it's released, send 0s. On the other side the moment it receives a 255 switch on the buzzer, when it receives a 0 switch it off. That's all you have to do.

You send the messages continuously, so the other side knows the connection is there, and you can afford to lose some (wireless is inherently lossy).

An Arduino ought to be capable of decoding FM Morse, I did the same for a PICAXE some years ago.

The transmitter was a RFM22B module, receiver a UHF handheld with the audio being decoded into a logic 1 when the tone was present by a NE567 audio tone decoder. A PICAXE turned the 1s and 0s into characters for display on an LCD.

It worked well.

I wouldn't use entertainment FM frequencies.
Look at using a 433MHz transceiver. Best yet, it's totally 100% legal.

Don't believe 1km range. a few hundred feet probably.

And, yes, an Arduino can send and receive data like this in real time.

The first step is to decide if you are going to send an off-on audio tone through an FM transmitter, or just key the FM transmitter off and on. They are definitely not the same and an FM receiver WILL NOT receive an off-on signal unless it is audio. Yes, it will be received, but will be considered noise by the limiting circuitry in the receiver.