Z-1100 intercom

Regarding this walkie-talkie, the sound quality will be completely lost when the receiving end is separated by a thicker floor
for about 100 meters in the open area.
It can be changed, but there is no time to change it.
The boss can change it by himself. I will provide an idea.
The video is on the fifth floor. Receiving and transmitting on the first floor.
Why use a finished development board: too lazy to solder the chip.
Regarding legal issues: the power is legal and will not affect other normal city signals.
Up to six can be used together (maximum number of nrf24 networks)
2.4gHz signal , it is the same frequency as the drone remote control.
Don’t tell me that it is illegal or anything.
The program I made after checking it before doing it is to adjust a library. It is very simple.
The following is the code, written by Arduino IDE
 
#include < RF24.h>#include #include #include "printf.h" // General includes for radio and audio lib
RF24 radio(7,8); // Set radio up using pins 7 (CE) 8 (CS)RF24Audio rfAudio(radio,0); // Set up the audio using the radio, and set to radio number 0
int talkButton = 3;
void setup() { Serial.begin(115200); printf_begin( ); radio.begin(); radio.printDetails(); rfAudio.begin();
  pinMode(talkButton, INPUT);//sets interrupt to check for button talk abutton press
  attachInterrupt(digitalPinToInterrupt(talkButton), talk, CHANGE); //sets the default state for each module to receive rfAudio.receive();}
void talk(){ if (digitalRead(talkButton)) rfAudio.transmit(); else rfAudio.receive();}void loop(){}