2.4G and 5G are different protocols used by wireless networks. 2.4G refers to 2412MHZ-2472MHZ in the country, which can be divided into 13 full channels, while 11 channels are regulated in the United States. 5G is 5725MHZ~5825MHZ in this country, 4 channels.

When the distance to the router is the same, the 5G signal is weaker than the 2.4G signal, which is determined by the physical characteristics of electromagnetic waves: the longer the wavelength, the less attenuation, and it is easier to bypass obstacles and continue to spread. The 5G signal has a high frequency and short wavelength, while the 2.4G signal has a low frequency and a long wavelength.···

Spread Spectrum Communication, that is, spread spectrum communication technology (Spread Spectrum Communication), its basic characteristic is that the bandwidth of the signal used to transmit information is much larger than the bandwidth of the information itself.

M2M (Machine to Machine) is a machine-to-machine communication technology, in a broad sense, M2M (Man to Machine), the Internet of Things is to connect objects (including machines) together. Obviously, M2M is an important part of the Internet of Things to connect objects. It is impossible to connect objects to form a huge Internet of Things without M2M technology. M2M technology and products are i···

The wireless communication module is a key link connecting the perception layer and the network layer of the Internet of Things. It belongs to the underlying hardware link and is irreplaceable. There is a one-to-one correspondence between the wireless communication module and the Internet of Things terminal.

DTU is the full name of GPRS data transmission unit. At present, there is actually a clearer agreement on GPRS DTU in China: GPRS DTU is a GPRS wireless device specially used to transmit serial port data through GPRS network.

NB-IoT (Narrow Band Internet of Things, NB-IoT) is an emerging technology of the cellular-based narrowband Internet of Things in the IoT field. It supports the cellular data connection of low-power devices in the wide area network. It is also called low-power wide area network ( LPWA).

The Internet of Things connects all the machines and equipment on the production line. Users can view the status of the equipment and production progress anywhere, providing mobile users with real-time manufacturing data. However, as more and more devices are connected to the Internet and a large amount of data is transmitted, a lot of pressure is placed on the network and cloud systems. In order ···

When the communication distance is tens of meters to thousands of meters, the RS-485 serial bus standard is widely used. RS-485 uses balanced transmission and differential reception, so it has the ability to suppress common mode interference. The standard value of the maximum transmission distance of the RS-485 interface is 4000 feet (about 1219 meters), which is actually up to 3000 meters. In add···

COM口是串行通信端口，简称串口。一般来说，我们看到两个物理标准。D型9针插头，加4针杜邦排针，是USB转TTL串口的小板，可通过USB进行扩展。对于使用不带COM的笔记本电脑或台式电脑的嵌入式工程师来说，它是必不可少的工具。除了使用串口向单片机下载程序外，它也是辅助调试程序的神器。