What is the difference between PCM and PCB?

Although they are just one letter apart, they are two completely different beings.

PCM (pulse-code modulation), pulse code modulation, is a modulation method or refers to the circuit that realizes this modulation method. This modulation method is to convert an analog signal into a digital code stream by A/D, and then modulate the carrier signal according to certain coding rules for transmission or emission. It is the standard form of digital audio in computers, CD-ROMs, digital telephones and other digital audio applications.

PCB (printed circuit board), printed circuit board, also known as printed wiring board, is an important electronic component, is the support body of electronic components, is the carrier of the electrical connection of electronic components, is the electronic equipment used to carry and connect the electronic components of the board-like parts. Because it is made by electronic printing technology, it is called "printed" circuit board.

PCM:
Pulse Code Modulation is the conversion of a time-continuous, value-continuous analog signal into a time-discrete, value-discrete digital signal for transmission over a channel. Pulse code modulation is the process of sampling an analog signal, then quantizing and coding the amplitude of the sample value. It is a combination of mathematics, physics and chemistry, which is a sampling technique as a theorem, sampling, quantization and coding of continuously varying analog signals produced by the process of digital signals.
PCM has the advantages of one bit variability, volatility, scaling, fast read speed, fast random storage; fast write/erase speed and no separate erase step Conclusion

PCB:
PCB consists of an insulating backplane, connecting wires and pads for assembling and soldering electronic components, and serves the dual purpose of conducting wiring and insulating the backplane. It can replace the complex wiring, realize the electrical connection between the components in the circuit, not only simplify the assembly of electronic products, welding work, reduce the traditional way under many disadvantages. Printed circuit board has a good product consistency, it can use standardized design, is conducive to mechanization and automation in the production process. At present, the printed circuit board has been extremely widely used in the manufacture of electronic products.

PCB is categorized according to the number of circuit layers, which can be divided into single-sided board, double-sided board and multilayer board. Common multilayer boards are generally 4-layer boards or 6-layer boards, and complex multilayer boards can reach dozens of layers; according to the classification of hard and soft, it can be divided into rigid circuit boards and flexible circuit boards, hard and soft combined boards. According to the upstream and downstream of the industrial chain to categorize, can be divided into raw materials, copper-clad boards, printed circuit boards, electronic product applications.
PCB has the advantages of densification, high reliability, designability, production, testing, assembly and maintenance.

However, the layout of components and the placement of wires are important to get the best performance from electronic circuits. In order to design PCBs with good quality and low cost. Generally, they are optimized in terms of layout, wiring, and pads, which are the principles that should be followed when designing PCBs.

In short, although they all belong to the field of electronics, but are two different kinds of existence, PCM is more focused on the knowledge of mathematics and computer reserves, such as high numbers, line generation, probability theory, signals, etc.; and PCB more inclined to circuit hardware reserves, such as electrical components, collectors, devices and so on.

PCM circuits generally have to be contained in PCBs, which may contain PCM circuits.

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