The waveform coding method used mainly has two basic forms with sine wave, that is, composed of many points, each point corresponds to a voltage, v=data* reference voltage *1\/2n,(2n means 2 to the power of n, n is the number of ad, there are 8, 12 bits. 16-bit)data is a numeric code:
1: Store a period of analog data in the memory, use high-precision oscillation source to interrupt the source of the interrupt single chip microcomputer, single chip microcomputer in the interrupt read the data memory corresponding data, send DA chip, after amplification to send LC resonant circuit, get the voltage amplitude you want continuous AC signal.
2: The speed of the MCU can not keep up with the addition counter to accumulate the oscillator source pulse, the cumulative value as the data memory address, the oscillation pulse as the data memory to read the signal, control the data memory output data, send DA conversion, amplification, and drive the LC resonant circuit.
If the single chip microcomputer is used to control the frequency division of the oscillation source, the signal of any period can be output. The other waveforms are similar! (Of course, there is no need for square wave) speech coding is to encode analog speech signals, convert analog signals into digital signals, thereby reducing the transmission rate and digital transmission, the basic methods of speech coding can be divided into waveform coding, parametric coding (sound source coding) and mixed coding. Waveform coding is formed by sampling, quantization and coding the waveform signal of analog voice in time domain.