Modifying signal strenght of 433MHz

Using Arduino Project Guidance
1

Hello,

in my project I aim to create a "radio package" that is supposed to be found using a Baofeng UV-5R.

The setup is fairly siple: Arduino NANO, battery (or powerbank) and a 433MHz transmitter like this one: FS1000A 433 MHz RF Transmitter Module Pinout, Specifications, Equivalent & Datasheet

433MHz module is connected GND to GND on nano, DATA to D11 and VIN to A3 on nano.

The code is as follows:

#define SIGNAL 11


void setup() {
  pinMode(A3, OUTPUT);
  pinMode(SIGNAL, OUTPUT);  
}

void loop() {
 
    analogWrite(SIGNAL, 190); // send signal non-stop
    delay(300);
    analogWrite(A3, 255);  // turn transmitter on - full power
    delay(300);
    analogWrite(A3, 0);
    delay(300);
    analogWrite(A3, 150);  // turn transmitter on - less power
    delay(300);
    analogWrite(A3, 0);
    delay(300);
    analogWrite(A3, 100);  // turn transmitter on - little power
    delay(300);
    analogWrite(A3, 0);
    delay(1000);

}

I aimed to to modulate the signal strenght/transmission strenght in order to make three beeps. First one is loud and can be heard in the Baofeng at greater distance. Second beep is weaker and can be heard only if you approach the "package" closer. The third beep should be heard only if you stand close and at that point you need to search with your eyes.

I tried to send varying analogWrite signals to "give transmitter more or less power" to modulate signal strenght.

In other scenarios I tried to change the signal power by suppling VCC with digital imputs that went trough different value of resistors.

I also tried to modulate the "SIGNAL" analog value on analog pins.

Nothing really helps. The beep is either hearable regardless on the distance, or not hearable at all. This is the case for modifying VCC or modifying DATA. Both have the same result.

Could you suggest how to achieve my desired "radio package" if it is even possible?
Thank you all for help. I am looking forward to answer your questions.

2

Have you tried experiments with actual different Vcc supplied as opposed to using analogWrite()? You could use batteries and try a few valiea between the minimum where it works and the maximum allowed.

(How) are you smoothing the analog output?

a7

3

analogWrite() generates PWM signals of the same output voltage, but with varying on time.

The on time signal strength will be the same, unless the on time is too short for the transmitter to work properly.

4

By the specifications for the transmitter, it already modulates the signal strength to send the data package. Are you hearing that beep in your Baofeng FM device?
As the transmitter sends data at 10k bits per second, you can only change the length of the beep by changing the length of the data package being sent.