There are many kinds of radio remote control, which can be realized by a capacitor or inductor three-point oscillation circuit. The transmitting part consists of a signal wave generating module and a carrier wave generating module, which is modulated and transmitted by a transmitting circuit, and the receiving part is demodulated by a demodulating module to obtain the desired signal wave. In order to prevent interference with other remote controllers, a group of encryption chips are added at the transmitter and receiver. If you want to do it yourself, pay attention to the high frequency carrier. Circuit diagram Baidu, n more.
Television, DVD, etc. It's all infrared
The signal is a pulse signal: one is that the number of pulses emitted when each key is pressed is different to distinguish different keys, but it is difficult to handle more keys. The other one is used more, and generally consists of one or two start pulses (with a wide width, which can almost reach 10MS), followed by 32 signal pulses, and finally an end pulse which is the same as the start pulse.
The signal uses pulse width to distinguish between 0 and 1. For example, if the pulse width is 1 .2ms, which means1,and 0.6ms means 0, then 32 pulse trains (four bytes) with 010/... can be formed. Infrared receivers are also very cheap, only 60 cents each.
You don't have to do it yourself. There are so many DVDs and VCDs, take any one.
Then take it to the oscilloscope to measure the waveform of each key, and use a single chip microcomputer to measure it if it is troublesome.