How are the remote control signals received (what is the analog processing at the receiving side)?
A2 When remote control signals are received, these infrared signals have become more dispersed and weaker (the receptor photo diode’s output has a P-P value of several dozen μV), so a preamplifier must be used to amplify the infrared receptor photo diode’s output. Also, a bandpass filter is used to extract only the carrier frequency components, which are then detected and processed by a waveform shaper to obtain more accurate remote control signals. The type of remote control signal can be determined by measuring each signal’s on/off periods. A special-purpose preamplifier is used to simplify implementation of processing from preamplification to waveform shaping.
