Weird Characters when I am transmitting and receiving datas from 2 HC-12 + 2 UNO

I am trying to transmit and receive datas at the same time by using 2 different HC-12 where each of them are connected to its own Arduino UNO. I am trying to send the DHT11 sensors of Temperature and Humidity values to each of them.

It is working well as long as it is one side transmitting the information. When I started both side to transmit and receive the information at the same time, there will be noises poping out in my Serial Monitor.

I uploaded 2 of my codes too. Help me pls!! =)

Pylonnnnn_2.ino (1.14 KB)

Pylonnn_1.ino (1.01 KB)

  if (Serial.available() > 1) { //Read from HC-12 and send to serial monitor
    String input = Serial.readString();
    mySerial.println(input);
  }

That is NOT what that code does.

SoftwareSerial mySerial(2, 3); //(TX, RX)

You did NOT connect a mySerial to those pins. Why did you then assign such a meaningless name to the instance?

Oppss… I uploaded the wrong file. The 2 codes of Transceiver A and B is the new one.

Transceiver_A.ino (1.52 KB)

Transceiver_B.ino (1.85 KB)