The main function of the power amplifier driver is to further amplify the pre-processed signal and convert it into an analog signal to drive the entire speaker system. Since the AV amplifier is a transistor amplification method, the amplification module has the characteristics of small volume, low heat generation, and large current output compared with the tube amplifier. According to the different working modes of the output stage, it can be divided into A, B, AB, D, G and H, etc. Among them, Class AB and Class D amplifiers are commonly used in home theater amplifiers. These types of amplification methods have their own characteristics, and each of the subsequent amplification methods can be improved according to the shortcomings of the original types. For example, Class A has excellent linear performance with low distortion but high power consumption. Class B improves the power consumption problem, but it leads to the problem of large distortion. AB, G, and H balance the low distortion and low power consumption, while the D class improves the traditional analog amplification by digital amplification.
Class AB amplification is a commonly used method of AV amplifiers. It combines the characteristics of both Class A and Class B. The efficiency is higher than that of Class A amplifiers, and the distortion is smaller than that of Class B amplifiers. In terms of operating characteristics, the Class AB amplifier introduces a non-linear operating point that turns the two transistors on when the signal is close to zero and turns to the B mode when the signal is large. Here are some of the features of Class A and Class B amplifier circuits. Class A amplification occurs at the earliest time, and its working characteristic is that the output stage transistor is always on. The advantages of this type of amplifier are excellent linear output, low signal distortion, and the disadvantage of low performance, only 20% to 30%, and the rest are converted into heat, which requires a large heat sink. Therefore, Class A amplifiers are very large and heavy. The Class B amplification method was developed to overcome the lack of efficiency of the Class A method. The working characteristic is that two transistors are used, and the transistors of each output stage are turned on only for a half cycle of the signal waveform, and are used for positive and negative periods, respectively. The class B amplification method is characterized by a very good effect on the performance, low heat generation, but the disadvantages are also obvious, crossover distortion occurs, the linearity is not excellent, and the distortion is severe.
The class D amplification method is different from any of the amplification methods described above, and its working principle is to use the principle of PWM pulse modulation to express the amplitude of the analog signal by the density variation of the pulse digital frequency waveform. The switching frequency of the class D amplifier is much higher than the highest frequency of the original signal. After filtering by the LPF low-pass filter of the latter stage, the average value of the output waveform is consistent with the actual audio signal. Class D amplification actually adds the working principle of digital amplification. The output stage transistor is fully or completely disconnected during operation, and the Class D amplifier operates at up to 90% or more. The disadvantage of the class D amplification method is also very obvious, that is, the distortion is large, because in the process of modulation amplification, it will inevitably be different from the original signal. However, as the level of production of Class D amplifiers is getting higher and higher, the distortion problem that occurs during the modulation process is greatly reduced. Therefore, many AV amplifiers and post-stage power amplifiers use Class D amplification modules.
The overall structure of the Class G amplification method is the same as that of the AB class. Its working characteristic is to use two or more power supplies for low-signal low-level output. Since the power is supplied using a lower voltage power supply, the amplifier automatically switches to the appropriate supply voltage as the signal level increases. The Class H amplification method is developed on the basis of the G class. The operational characteristics are to predict and control the power supply voltage through an additional control circuit to minimize the voltage of the output stage without using multiple power supplies. The efficiency of these two types of amplification is significantly higher than that of class AB, but the disadvantage is that the design is more complicated, and also because of cost, it is not common in AV amplifiers.
Can you boost your WiFi signal with outdoor 4G CPE?
When you travel or go to some remote areas, you may be annoyed by poor reception. Is there any way to get a strong WiFi router signal outdoors in a 4G LTE network? Very good, outdoor 4G CPE router would be a good choice!
What is an outdoor 4G CPE router?
An outdoor 4G CPE router differs from a Wifi-only router in that it needs to be connected to a fiber optic network. The 4G CPE WiFi router can pick up the carrier's 4G LTE network signal and convert it into broadband and Wi-Fi. Just plug in your SIM card with your data plan and enjoy a stable and reliable WiFi signal with family and friends. This Outdoor CPE can be used in harsh environments. If you install your router outside or near a window in an area with a weak 4G signal, your device can receive a better 4G signal.
Second, what are the characteristics of outdoor 4G CPE router?
1. Better network for ODU and IDU
4G CPE outdoor routers include an outdoor unit (ODU) and an indoor unit (IDU). Help your device receive the best outdoor cellular signal through the ODU, and connect to the indoor WiFi router through the network cable to experience better network speed. As shown in the figure below, an outdoor LTE CPE (ODU) is installed outdoors and connected to an indoor Wi-Fi router (IDU) via a network cable. The entire 4G device is powered by POE. This data will be transmitted over the same Ethernet cable, eliminating the need to connect the ODU to a power outlet.
2. High-speed multi-user available
The outdoor 4G CPE features a built-in 4G LTE modem and a 5dBi high-gain antenna. LTE CAT4, download speeds up to 150Mbps, WiFi speeds up to 300Mbps, can connect 32 users at the same time. The high-gain antenna of the outdoor 4G CPE router enables it to have higher power and stronger signal transmission and reception capabilities than mobile phones. Therefore, the CPE router can receive the signal. If your phone can't receive a signal in some areas. Sometimes you also use your phone as a hotspot to share Internet access with your friends, right? Similarly, this 4G LTE CPE router allows 32 users to connect to WiFi at the same time, allowing more users to connect and receive a better signal than a phone sharing hotspot. In addition, the IDU has four Lan ports and can be connected to the device through network cables, which is also a backup mode of the Internet.
3. Excellent outdoor performance and design
On the one hand, outdoor LTE CPE is waterproof, UV resistant and corrosion resistant. It can be used at -20℃~60℃ operating temperature. Therefore, it is ideal for outdoor deployment. On the other hand, there are a variety of installation methods. CPE can be mounted on Windows or walls by mounting brackets. It is also possible to attach it to the antenna mast. In addition, the signal strength is displayed through the LED indicator to facilitate users to find the best location to get a better 4G signal.
4. Support different frequency bands
Outdoor 4G CPE supports a variety of frequency bands, including LTE-FDD, LTE-TDD, 3G WCDMA, and 2G GSM network bands. Meet the needs of different frequency bands in different regions and make full use of network resources.
5. Convenient management of CPE
Start the Web browser to log in to the Web management page. You can configure and manage the CPE easily. The web management system supports Linux. Provides functions such as WebUI management, Telnet, SSH terminal system status monitoring, NTP client, synchronization between devices and the system clock network, and configuration file import and export.
6. Applicable to various application scenarios
CPE is designed to provide ISP or operator with 4G LTE outdoor wifi router to facilitate network connection, whether at home, or in enterprises and remote areas, to bring users a wonderful network experience.
All in all, an outdoor 4G CPE router is an excellent choice for connecting to the Internet in remote areas and places where the signal is weak, the wired network is unreliable, or there is a lack of reliable WiFi. It's worth deploying outdoor CPE in rural, coastal, boat, caravan, campsite and remote areas to enjoy the best network speeds and outdoor activities! It can even reduce complex cabling deployments for home networks without the need to install a wired fiber network.
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Shenzhen MovingComm Technology Co., Ltd. , https://www.mcrouters.com