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  1. The wireless technical parameters of the NB-loT module and the LoRa module are very similar, so their applicable fields have a high degree of overlap in theory, but the difference in networking methods determines that they cannot form a strong competitive relationship. Complementary, LoRa wireless technology has obvious defects in system capacity, speed, coverage capability and security controllability; NB-loT module has complex protocols, high power consumption, high traffic charges, poor regional coverage, and cannot be privatized and deployed. question. The difference between NB-loT technology narrowband transmission and LoRa wireless technology The main body of the network is not the same: NB-loT technology is based on the licensed spectrum, and the network is mainly formed by the three major operators. The flexibility of LoRa technology and the innovative awareness of Chinese companies have produced a variety of new operators, such as Giants like Alibaba are involved. The maturity of wireless technology solutions is different: LoRa technology started very early, and it is relatively mature in terms of technology and application, and there is strong support from the industry and financial circles, and more and more companies are joining the big environment. IoT application requirements are different: For enterprise applications, most customized projects will give priority to private networks such as LoRa modules based on considerations such as cost and data security. Most users prefer to build their own networks to securely store data. in their own hands.
  2. The GPRS wireless module is the abbreviation of General Packet Radio Service. It breaks through the way of thinking that the GSM network can only provide circuit switching. It is realized by adding corresponding functional entities and partially transforming the existing information base station system. Packet switching, the investment in this transformation is relatively small, but the user feedback data rate is very impressive. GPRS module (General Packet Radio Service) is a wireless communication module developed with data transmission technology based on Global System for Mobile Phones (GSM), which can be said to be the continuation of GSM. The GPRS wireless module is not different from the previous continuous transmission on the channel. The GPRS wireless module transmits in a packet (Packet) format, so the cost borne by the user is calculated by the unit of transmission data, not by its use. The whole channel, theoretically it's cheaper. The transmission rate of the GPRS module can generally be increased to 56bps or even 114Kbps. Since it is no longer necessary to add a communication intermediary converter to the current wireless application of the Internet of Things, the connection and transmission will be more convenient and easier. Therefore, users can choose to surf the Internet online, participate in video conferences and other interactive communication, and users on the same video network (VRN), even without dial-up Internet access, and continue to maintain a connection to the network. The general wireless packet service of the GPRS module is a wireless packet switching technology based on the GSM system. Packet switching technology, also known as (data) packet switching technology, divides the data transmitted by users into a certain length. The part of a separate area is called a packet, a technique for transmitting information by transmitting packets. It is a kind of exchange technology that realizes the communication between computers and computers through computers and terminals. The quality of transmission routes is not high and the network technology means is relatively simple. There is a packet header (packet header) in front of each packet to indicate which destination address the packet is sent to, and then the switch forwards each packet to the destination according to the address mark of each packet. This process is called packet switching.
  3. With the development of electronic products in the direction of lightness, thinness and smallness, PCBs are also developing towards high density and high difficulty, and the requirements of customers are getting higher and higher. The requirements for holes are also getting higher and higher. For example, there must be no solder resist ink entering the hole, causing tin beads to be hidden in the hole, no oil explosion, making it difficult to mount components, etc. PCB via hole plug purpose: to prevent tin from passing through the component surface from the via hole to cause a short circuit during PCB over-wave soldering, to avoid flux residue in the via hole, to prevent solder balls from popping out during wave soldering, causing short circuit, and to prevent surface solder paste The flow into the hole causes virtual welding, which affects the mounting, maintains the surface flatness, and meets the customer's characteristic impedance requirements. PCB plug hole requirements: copper in the via hole, solder mask can be plugged or not; there must be tin and lead in the via hole, there must be a certain thickness requirement (4um), no solder mask ink should enter the hole, causing the hole inside the hole. Hidden tin beads; through holes must have solder resist ink plug holes, opaque, and must not have tin circles, tin beads, and leveling requirements.
  4. As we all know, in every smart device, the chip plays a vital role. Whether it is a PC, a smart phone or a smart wearable device, the CUP is an indispensable core component. But for such a small thing, China is currently unable to effectively mass-produce it. Sometimes a thing is too small, it does not mean that it is easy to manufacture, let alone a chip, which requires nanoscale technology to control, which is beyond the reach of manpower. In an IC chip, the most important thing is the transistor, which is equivalent to the nervous system in the human brain. The more transistors, the faster the chip's operation speed. Therefore, how to put more transistors in such a small place has become a difficult problem. The basic unit of a chip - the transistor The so-called transistor is a semiconductor device commonly used in amplifiers or electronically controlled switches. Because of their fast response speed and high accuracy, they can be used for a variety of digital and analog functions, including amplification, switching, voltage regulation, signal modulation, and oscillators. Transistors can be packaged individually or in a very small area that can hold a hundred million or more transistors as part of an integrated circuit, which is why so many transistors can be integrated in a CPU. As early as 1929, then engineer Lillian Feld had obtained a patent for a transistor. However, due to the technical level of the year, transistors could not be manufactured. It wasn't until December 1947 that the world's first practical semiconductor device was fabricated at Bell Laboratories, and in its first experiments, the transistor was able to amplify audio signals by 100 watts, and was shaped like a matchstick. In 1950, the first "PN junction transistor" (the PN junction is the junction of the P-type and the N-type, the P-type has many holes, and the N-type has many electrons, which will be discussed below) finally came out. Today's transistors , most still belong to this PN junction transistor.
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