Simulation using the finite cable TV coaxial cable signal transmission system known as the broadband coaxial cable. "Broadband" is the word comes from the telephone industry, refers to a wide frequency band than 4kHz. However, in computer networks, "broadband cable" means any use of the analog signal is transmitted to the cable network.
As the broadband network using a standard cable technology, use of the frequency band up to 300MHz (often to 450MHz); the use of analog signals need to be placed at the interface of an electronic device to the bit stream into the network is converted to analog signals, and the network output signal converted to bit-stream.
Broadband system is divided into multiple channels, usually occupy 6MHz television channel. Each channel can be used for analog TV, CD-quality sound (1.4Mb / s) or 3Mb / s digital bit stream. TV and data cables in a hybrid transmission.
Broadband systems and baseband system is a major difference: The coverage of the regional broadband system wide, so the need to periodically enhance analog amplifier signal. These amplifiers can only be one-way transmission signal, so if the amplifier between the computer, the Packet can not reverse transmission between computers. To solve this problem, people have developed two types of broadband systems: dual cable system and a single cable system.
1) Dual cable system
Dual-cable system has two identical cables laid side by side. In order to transmit data, computer data transmission via cable to the cable 1 to the root of the number of devices, that is the top device (head-end), then the top 2 via cable down the number of signal transmission along the cable. All the computers are sent through the cable 1, 2 reception via cable.
2) single-cable system
Another option is to cable each for the internal and external communications assigned different frequency bands. Low-frequency band to the top device for computer communications, receives the signal to move top of the high frequency band radio to the computer. In sub-section (subsplit) system, 5MHz ~ 30MHz band for communication within, 40MHz ~ 300MHz frequency band used for outgoing traffic. In the carve (midsplit) system, within the band is 5MHz ~ 116MHz, while the outgoing frequency band of 168MHz ~ 300MHz. This choice is caused by historical reasons.
3) There are many broadband system use. In the computer room can be assigned a dedicated permanent channel; other computer can control channel, to apply a temporary channel, then switch to the application to the channel frequency; also allows all computers to share one or a group of channels. Technically, broadband cable to send digital data than in the baseband (ie, single channel) cable is bad, but it has the advantage has been widely installed.
