"图解PCM原理及其应用技术：采样，量化和编码操作详解"

The Principle of PCM (Pulse Code Modulation) is based on three essential operations: sampling, quantizing, and coding. Over the years, various techniques have been developed to carry out these functions effectively. In this overview, we will discuss the main methods used in PCM transmission. Sampling is the process of converting continuous analog signals into discrete digital signals. By measuring the amplitude of the analog signal at regular intervals, known as sampling rate, we can obtain a series of discrete values that represent the original signal. This method ensures that a continuous signal can be accurately represented in digital form. Quantizing involves assigning numerical values to the sampled amplitude values. These values are then rounded off to the nearest level within a predetermined range, known as quantization levels. The goal of quantization is to reduce the number of bits required to represent the signal while maintaining an acceptable level of signal quality. Coding is the final step in PCM, where the quantized values are encoded into binary digits for transmission. Each amplitude value is represented by a sequence of 8 binary digits, allowing for efficient storage and transmission of the signal. This coding scheme is essential for ensuring that the original analog signal can be accurately reconstructed at the receiving end. Overall, PCM is a versatile and efficient method for transmitting analog signals over digital communication channels. By combining sampling, quantizing, and coding techniques, PCM allows for the accurate representation of speech signals in telephone-quality communication. The principles of PCM play a vital role in modern communication systems, ensuring clear and reliable transmission of audio signals.