The process by which a TV receiver processes and responds to multiple infrared signals can be likened to a busy airport tower receiving and responding to signals from different aircraft. In this process, the TV remote control plays the role of an airplane, constantly sending signals to the TV “tower”.
First, each TV remote control sends out a specific coded infrared signal that corresponds to different keys on the remote control. When the user presses a key on the remote control, the chip inside the remote control detects the action and sends a coded sequence signal corresponding to the key. After the signal is amplified and modulated, the light-emitting diode (LED) at the front of the remote control is converted into an infrared signal to radiate outwards.
A television receiver, usually integrated inside a television set, contains components such as an infrared monitoring diode, amplifier, limiter, bandpass filter, integrated circuit, and comparator. When the receiver detects an infrared signal, the signal is first sent to the amplifier and the limiter, which controls the pulse amplitude at a certain level, ensuring that the signal can be received steadily regardless of the distance between the remote control and the receiver.
The signal then passes through a bandpass filter that only allows a signal from 30kHz to 60kHz, which is the frequency range used by most remote controls. Then, the signal enters the comparator through the demodulation and integration circuit, and the comparator outputs the high and low level to restore the signal waveform at the transmitting end of the remote control.
After receiving these signals, the central processing unit (CPU) will perform corresponding operations according to the code of the signal, such as changing the channel and adjusting the volume. It is as if the airport tower received the signal of the aircraft and instructed the aircraft to land or take off according to the signal.
In this process, if multiple remote controls are sending signals to the TV at the same time, the TV receiver needs to be able to distinguish and respond correctly to each signal. This is thanks to the fact that the signals emitted by each remote control are uniquely coded, similar to how each aircraft has a unique identification number. By parsing these codes, the TV receiver recognizes which remote control is sending the signal and performs the corresponding action.
For example, if one remote control signals a volume increase and the other signals a channel change, the TV receiver will perform a volume increase and channel change respectively based on these different codes.
In summary, the process of processing multiple infrared signals and responding to them by the TV receiver is a highly accurate and orderly process. It relies on the unique coded signal emitted by the remote control, as well as the complex circuit design inside the receiver, to ensure that the user’s instructions can be accurately executed even when multiple remote controls are operating at the same time.