Electronic – arduino – How to Arduino send an RF signal at 433 MHz

arduinofrequencyRF

I am asking this question primarily to learn.

I have learned that Hz is the number of cycles in one second.

Taking that into consideration I have tried the following examples.

Example 1

void loop() {     
  digitalWrite(3,HIGH); // make pin 3 have a voltage of ~ 5V
  delay(500); // wait 0.5 seconds
  digitalWrite(3,LOW); // make pin 3 have a voltage of ~ 0V
  delay(500); // wait 0.5 seconds
}

This code has a frequency of 1 Hz because voltage is .5 seconds up and .5 down. My voltmeter shows .99999 Hz

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The duty cycle is 50% because the voltage is half of the time up and half of the time down.

Example 2

void loop() {     
  digitalWrite(3,HIGH); // make pin 3 have a voltage of ~ 5V
  delay(90); // wait 0.09 seconds
  digitalWrite(3,LOW); // make pin 3 have a voltage of ~ 0V
  delay(10); // wait 0.01 seconds
}

This code has a frequency of 10 Hz because every cycle is .1 seconds (90 ms + 10 ms). In 10 cycles you will reach 1 second. The duty cycle of this code is 10%.

The following examples are basically the question:

Example 3

void loop() {     
  digitalWrite(3,HIGH); // make pin 3 have a voltage of ~ 5V
  // Do not delay
  digitalWrite(3,LOW); // make pin 3 have a voltage of ~ 0V
  // Do not delay
}

If I run this code, my voltmeter shows a frequency of 112,000 Hz or 112 kHz:

enter image description here

I believe that is the highest frequency I can get. I am not delaying in between cycles. Why is it that when I google the frequency of Arduino Uno it says:

enter image description here

Example 4

Google is probably correct and the frequency is 16 MHz for Arduino. If that is true, then how can an Arduino send a 433 MHz frequency? I want to buy this:

enter image description here

When I now set delay as in Example 3, the highest frequency I could obtain was 112 kHz (with a k). How is it possible to send a 433 MHz frequency (with an M)?

Best Answer

The short answer: It doesn't.
Arduino doesn't send anything close to that high. It can only send a lower frequency (lower bitrate) signal over a 433MHz CARRIER frequency (or any other frequency for that matter) by using another device/module which generates a very high frequency (radio frequency) in order to communicate via radio waves.
The 433MHz in this case is NOT THE RATE OF DATA/BITS, but a frequency of the radio signal over which the data is transmitted/received.
Your question shows a lack of knowledge about the meaning of, and the difference between, processor clock frequencies, speed of processing, data rate, and "carrier" frequencies as the means of radio communication, so you should read and learn more about basic computer processing and its related terms, and about the means and ways of transmitting information over radio waves.
Basically, the carrier/radio frequency is modulated/changed by the information/data you want to transmit, so it is those changes that represent the information.
Based on the type of change, there 3 basic types of modulation.
Amplitude Modulation (AM), Frequency Modulation (FM), Phase Modulation (PM).
With AM, the carrier frequency is kept stable/same, while the amplitude/power of the carrier frequency is varied to transmit information.
FM keeps the carrier amplitude the same (at maximum) while the frequency changes up and down a certain amount represent information.
PM is similar to FM, and it carries information by phase-shifting the carrier frequency.

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