Keyestudio ESP32 Manual page 156

ESP32 Starter Kit
2. Working Principle
In this project, we often use a carrier of about 38K for modulation.
IR remote control system includes modulation, emitting and receiving. It sends data through modulating, which im-
proves the transmission efficiency and reduces the power consumption.
Generally, the frequency of carrier modulation is within 30khz~60khz(usually 38kHz). The duty cycle of the square
wave is 1/3, as shown below, which is decided by the 455kHz crystal oscillator on the emitting end. An Integer frequency
division is essential for crystal oscillator at this end, and the frequency coefficient usually evaluates 12. Therefore,
455kHz÷1237.9kHz38kHz.
38KH carrier (complete) emitting diagram:
Carrier frequency: 38KHz
Wave length: 940nm
Receiving angle: 90°
Control distance: 6M
152 Chapter 8. Arduino Tutorial