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Bishop, Robert H. - The Mechatronics Handbook [CRC Press 2002] Part 16

Tham khảo tài liệu 'bishop, robert h. - the mechatronics handbook [crc press 2002] part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | FIGURE 37.3 Example of a balanced data transmission. relatively inexpensive because for multiple signal lines only one common line is required however this type of interface is susceptible to induced and ground noise and is not suitable for high-speed communication over long distances. The ground noise is associated with voltage drop in a common return line while the induced noise comes from interfering electromagnetic fields. Both types of noise can come from external sources or from neighboring transmission circuits. A remedy can be the use of coaxial cable shielded cable and or the use of separate return lines for individual signals. These additional measures tend to increase the cost of the interface. The balanced differential transmission mode has much better noise immunity than the unbalanced mode. Two complementary signal lines carry the data signal. The implementation often involves two singleended drivers driving a twisted-pair transmission line. Figure 37.3 shows an example of balanced data transmission with two channels and five wires. As in Fig. 37.2 symbol D represents driver and symbol R receiver. Symbol T represents termination resistor. Use of a termination resistor at the receiver end of the transmission line is critical for high-speed communications over long distances as unterminated transmission lines can cause severe distortion of signals. Both induced and ground noises appear on both conductors as common-mode signals that are rejected by the differential receiver. The differential signals carrying data are amplified while the common-mode noise signals are suppressed. As a result the balanced data transmission lines can be used for longer distances with higher transmission rates. Both unbalanced and balanced interfaces shown in Figs. 37.2 and 37.3 represent two simplex interfaces which can form one full-duplex point-to-point see below communication channel. A good source of information on individual drivers and receivers is provided in the data