Remote infrared (IR) works by transmitting invisible infrared light signals from a remote control to a receiving device, such as a TV, air conditioner, or home theater system. Here’s a breakdown of how it works:
**1. Infrared Light Transmission**
• The remote control has an **IR LED** (Light Emitting Diode) that emits infrared light when you press a button.
• This light pulses at a specific frequency, typically around **38 kHz**, to avoid interference from ambient light.
**2. Encoding the Signal**
• When you press a button, the remote’s microcontroller encodes the command into a digital signal (a sequence of ON/OFF pulses).
• This signal consists of:
• **A header pulse** (to signal the start of transmission)
• **A series of data pulses** (representing the button pressed)
• **A stop pulse** (to mark the end of the command)
• Different manufacturers use different encoding protocols, such as **NEC, RC5, or Sony SIRC**.
**3. IR Reception**
• The receiving device has an **IR sensor** (also called an IR receiver module), which detects the modulated IR pulses.
• The sensor demodulates the signal (removes the 38 kHz carrier frequency) and sends the raw digital data to a microcontroller.
**4. Decoding and Execution**
• The microcontroller in the receiving device deciphers the received data and determines which button was pressed.
• It then executes the corresponding action, like increasing the volume or changing the channel.
**5. Limitations of IR**
• **Line-of-sight required**: IR signals cannot pass through walls or solid objects.
• **Limited range**: Usually around **5 to 10 meters**.
• **Interference**: Sunlight, fluorescent lights, and other IR sources can interfere with transmission.
Remote infrared Sensor
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