缩小ESP 32-Wroom-32D微控制器的经典蓝牙范围

Question

我正在研究ESP 32-Wroom-32D微控制器，并使用内置的经典蓝牙连接到android设备。目前，微控制器的范围约为70 m，我希望将其减小到5-6米左右。有什么可能的方法来减小蓝牙范围。请找到代码段。

#include "DHT.h"
#include "BluetoothSerial.h"
#include "BLEDevice.h"
#include <esp_bt.h>

#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run `make menuconfig` to and enable it
#endif

#define DHTPIN 23
#define DHTTYPE DHT22   // DHT 22

DHT dht(DHTPIN, DHTTYPE);
BluetoothSerial SerialBT;


void setup() {
  Serial.begin(115200);
  SerialBT.begin("ESP32"); //Bluetooth device name
  Serial.println("The device started, now you can pair it with bluetooth!");
  dht.begin();
  //esp_power_level_t(ESP_PWR_LVL_N12);
}

void loop() {

  if (SerialBT.available() == 0);
  esp_power_level_t(ESP_PWR_LVL_N12);
  Serial.println(ESP_PWR_LVL_N12);
  delay(2000);
  float f = dht.readTemperature(true);
    
  // Check if any reads failed and exit early (to try again).
  if (isnan(f)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }
  SerialBT.print(f);
  //Serial.println(f);

  delay(2000);
}