Morse code communication using FM frequency

Thread Starter

StrawberryBro

Joined Mar 15, 2013
2
Hi, I'm new here, I have a little problem, I'll be grateful for the help. It happens that I want to modify the circuit of an FM audio transmitter, so that instead of transmitting audio can transmit a signal to turn off or turn on a switch, and the switch on and off an LED, the idea is to communicate using Morse code using the FM frequency. What could be modified to do this?. What could be change to a conventional radio receiver, so that instead of playing audio, will have a led (for morse code communication)?.

This is the transmitter diagram.



Thank you.
 
Why don't you just send audio (like an 800hz sine wave) into the mic portion of the circuit? Use a tone decoder on the FM receiver side to turn your LED ON and OFF so you can copy CW.

Marty
 

Thread Starter

StrawberryBro

Joined Mar 15, 2013
2
Why don't you just send audio (like an 800hz sine wave) into the mic portion of the circuit? Use a tone decoder on the FM receiver side to turn your LED ON and OFF so you can copy CW.

Marty
Hello my friend. Because I am new to electronics, so I'm a little frustrated, and for example, I still do not know where to place an oscillator, for wave.

One question: An oscillator is the only way to send a sine wave?

A constant frequency FM signal wont even be detected by the receiver as anything even remotely interesting.
Hello my friend. Nice to greet you and I'll be here to share knowledge on electronics and software also. And sorry but I did not understand what you mean.

A constant FM signal is not always detected by a receiver?
 

absf

Joined Dec 29, 2010
1,942
Hello my friend. Because I am new to electronics, so I'm a little frustrated, and for example, I still do not know where to place an oscillator, for wave.

One question: An oscillator is the only way to send a sine wave?
An oscillator doesnt have to be a sine wave generator. Pulses or square wave at 800 Hz would also work. Use a NE555 or LM555 and set it up as an astable oscillator would do the trick as well.

Are you using your FM radio as a receiver or you make your own dedicated FM receiver? You need a tone decoder using NE567 to decode the 800Hz tone and make it flash an LED or you can amplify the tone and play it on a speaker.

Allen
 

Papabravo

Joined Feb 24, 2006
12,511
Hello my friend. Because I am new to electronics, so I'm a little frustrated, and for example, I still do not know where to place an oscillator, for wave.

One question: An oscillator is the only way to send a sine wave?



Hello my friend. Nice to greet you and I'll be here to share knowledge on electronics and software also. And sorry but I did not understand what you mean.

A constant FM signal is not always detected by a receiver?
The basis of FM (Frequency Modulation) is that "information" is encoded in the signal my modulating (changing) the frequency. If the frequency of an FM signal is constant (not changing) then there is no information in the signal and consequently there is nothing for the receiver to detect. Is that clear enough?
 
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