We know that in just a few years, dial-up Internet access has risen from 14.4Kbps to 56Kbps, however, due to the quality of the phone lines, 56Kbps should be the limit for a typical modem. To get a faster connection, you have to go through a different route, so in recent years various kinds of broadband access services have appeared one after another.
So what is broadband? In fact, there is no very strict definition, generally to the current dial-up rate of 56Kbps as the upper limit for the demarcation of 56Kbps and its access to the following is called "narrowband", above the access to be categorized as "broadband".
Some people can't help but ask: what about ISDN, is ISDN broadband? ISDN is not broadband? But because it can provide much faster than the general Modem dial-up access services, and there have been a certain number of users, it is necessary to recognize the "earliest broadband-ISDN".
ISDN
ISDN (Integrated Service Digital Network) is a digital telephone link system. ISDN is the earliest accepted form of broadband Internet access, and in addition to its 128Kbps transfer rate, ISDN also allows users to surf the Internet and talk on the phone at the same time. This is a great attraction for users who love to surf the web but also have a lot of phone calls to make.
Strictly speaking, ISDN can't be considered a popular product to solve the problem of insufficient bandwidth for users to access the Internet, because the fastest transmission rate is only 128Kbps. However, in addition to Internet access, more ISDN users are interested in the simultaneous use of voice and data transmission. Therefore, point-to-point communication is a very popular area for ISDN, such as video conferencing systems for cross-county companies, telemedicine systems for hospitals, and distance learning for schools.
Today's broadband
Today's world is developing rapidly, and the Internet has changed people's lives; the successive introduction of broadband (broadband) technology has greatly improved Internet access speeds, and its irreplaceable role in our network life is also having a greater and greater impact on ------. "The speed of light, the capacity of the sea," this is what broadband has been committed to pursuing. This is the goal that broadband has been striving for this year. So far, the total number of Internet users in China is close to 30 million. China Telecom in accelerating the construction of CHINANET backbone network at the same time, increase the development of fiber-optic high-speed broadband metropolitan area network, from a long-term strategic point of view, to build a complete and unified broadband network platform.
The fiber-optic cable backbone ring of telecommunication metropolitan area network in major cities has been spread all over the city's main arteries and lots, and broadband access nodes have been set up in the main nodes to facilitate users' access to provide users with real-time video-on-demand, network TV, video phone, e-commerce, distance education, network karaoke, telemedicine, remote monitoring and other information services.
The construction and remodeling of broadband network has approached us, while its corresponding product information and sales channels are not satisfactory. This site is so born, this site mainly to introduce you to the technology of broadband, market information. To assist people from all walks of life and enterprises to better utilize the broadband technology, from the slow speed of the Internet to free themselves from the trouble, swim in the global network, faster and better to find information, online video playback, on-demand online video, so that the online video games more smoothly.
Bandwidth:
Monitor Terminology Explained
Bandwidth is an abbreviation for the bandwidth of a monitor's video amplifier passband, which refers to the maximum total number of pixels swept across the screen by an electron gun per second, measured in MHz (megahertz). On the surface, the bandwidth can be obtained by simply multiplying the line frequency by the horizontal resolution. In reality, however, the number of pixels swept horizontally and vertically by the electron gun during scanning is higher than the theoretical value, so as to avoid signal attenuation at the edges of the scan and make the image equally clear all around.
Horizontal resolution is about 80% of the actual scanning value, vertical resolution is about 93% of the actual scanning value, so the bandwidth is calculated as follows: bandwidth = horizontal resolution / 0.8 × vertical resolution / 0.93 × field frequency. Or bandwidth = horizontal resolution × vertical resolution × field frequency × 1.344. For example, in the mode of 1024 × 768 @ 85Hz, the bandwidth is 1024 × 768 × 85 × 1.344 = 89.84199868mhz. The larger the value of the bandwidth, the better the performance of the monitor.
The higher the bandwidth, the lower the inertia, the faster the response, the higher the frequency of the signal allowed to pass through, the lower the signal distortion, which reflects the resolution capability of the monitor. Compared to line frequency, bandwidth is more comprehensive and directly reflects monitor performance. It is one of the more important factors contributing to the variation in monitor performance.
Bandwidth determines the range of information that a display can process, which is the frequency range that a particular electronic device can handle. The operating frequency range is limited as early as the circuit design, and because high frequencies produce radiation, the design of high-frequency processing circuits is more difficult and much more expensive. Enhancing the high frequency processing capability can make the image clearer. Therefore, wide bandwidth can handle higher frequencies and better images. Each resolution corresponds to a minimum acceptable bandwidth. If the bandwidth is less than the acceptable value for that resolution, the displayed image will be blurred by loss and distortion.
Network bandwidth
Bandwidth, also known as bandwidth, is the amount of data that can be transmitted in a fixed amount of time, i.e., the amount of data that can be passed through a transmission pipe. In digital devices, bandwidth is usually expressed in bps, which is the number of bits per second that can be transmitted. In analog equipment, bandwidth is usually expressed in terms of cycles per second or Hertz Hz. Bandwidth is especially important for Basic Input/Output System (BIOS) devices, such as fast disk drives, which can be hampered by low-bandwidth buses.