What is the multiplexer meaning? The multiplexer price

What is the multiplexer meaning? The multiplexer price
In a data communication system and computer network system, the bandwidth or capacity transmission media often exceeds the transmission of single signal needs, in order to effectively utilize the communication line, hope the multi-channel signal a channel transmission at the same time, this is called multiplexing (MultiplexiI1g). By multiplexing technology can bring a plurality of signals are combined for transmission on a physical channel, and can greatly reduce the cable installation and maintenance costs in long-distance transmission. Frequency division multiplexing FDM (Frequency Division Multiplexing) and time division multiplexing IBM (Time Di-vision MultiplexiIIg) is the two most common multiplexing technology.
1 frequency division multiplexing FDM
In the available bandwidth over a single physical channel required for original signal bandwidth situation, the total bandwidth of the physical channel is divided into a plurality of signal and the transmission bandwidth of the same individual (or slightly wider) sub channels, each channel signal transmission way, this is the frequency division multiplexing. Multiple original signal in frequency division multiplexing, to different sections of the signal spectrum to the physical channel spectrum by spectrum technology, even when the bandwidth of signals do not overlap each other, which can be modulated by different carrier frequencies to achieve. Frequency division multiplexing FDM an example is shown in Figure 2.12 (a), one of the 8 signal input to a multiplexer, different frequency with the multiplexer (f1~f8) modulation in each of the signals, and each signal to a carrier frequency which is the center of a certain bandwidth channel. In order to prevent the use of mutual interference, protect and bring the isolation of each channel, some do not use spectrum area protection zone.
2 time division multiplexing TDM
The bit rate of transmission media can be achieved if more than the required data rates can be used for data transmission, time division multiplexing TDM technology, is a physical channel is divided into several time slices allocated to multiple signal. Each time slice is occupied by a multiplexing signal, but unlike FDM, the same time to send multiple signals. Thus, cross utilization of each signal in time, can transmit a plurality of digital signal on a physical channel. This cross can be a level, can also be produced by the blocks of bytes or more information group cross. As shown in Figure 2.12 (b) in a multiplexer with 8 input, each input data rate is 9.616ps, then a capacity of 76.8kbps line can accommodate 8 signal source. Time division multiplexing four M scheme of the diagram, also known as synchronous time division multiplexing (Synchronous) TDM, its time slice are pre allocated, and is fixed, so the transmission of all kinds of signal source timing synchronization. In contrast, time slice asynchronous time division multiplexing 1DM allow dynamic allocation of transmission media. Time division multiplex TDM is not limited to the transmission of digital signals, can also cross transmission of analog signals. In addition, the analog signal, can sometimes take time division multiplexing and frequency division multiplexing technology used in combination. A transmission system can be divided into many sub channel, frequency, each sub channel reuse time-division multiplexing to subdivision. In the broadband local area network can be used in the hybrid technology.
T1 carrier Bell system using pulse code modulation of PCM and time division multiplexing technology of TDM, make the 24 sampled sound signal multiplexing a channel, its frame structure as shown in figure 2.13. 24 channel their rotation will be 8 bit digital signal encoded frame, 7 of whom were coded data, the eighth is the control signal. Each frame in addition to 24 × 8=192, plus a frame synchronization bit. So, a frame consists of 193 bits, each frame using the 125us time transfer, so the data transmission rate of T1 system for 1.544Mbps.
A, product description
In the same wire simultaneously with the same direction or reverse transmission of two video signal of the products, can effectively improve the utilization rate of cable, has the characteristics of clear image, easy installation, free debugging, stable and reliable.
Two, typical application
The equipment adopts 1, new projects, can be put to two video cable into a video cable, save cable usage;
2, renovation project, new increase point can use the new position next to the cable directly transmitted back, save wiring problem;
3, special use, need to complete the two-way video transmission, you can use a single coaxial cable to achieve two-way video transmission;
Three, product features:
1, dual unidirectional / video coaxial cable transmission of real-time hd;
2, the transmission distance can reach 800 meters, the equipment for the first road still can continue to pass 500 meters distance; (note the multi-core cable SYV75-5/3-2 and cable transmission distance is very short, about transmission trunk 500 meters)
3, built in ESD protection circuit;
4, free debugging, stable and reliable work;
5, the built-in filter circuit, isolation circuit, makes the image more clearly;