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.
Alternative: RF vs. IR
Some remotes use radio frequency (RF) or Bluetooth instead of IR, allowing them to work through walls and over longer distances.
