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Introduction and Difference Between Active Optical Cable (AOC) and Direct Attach Cable (DAC)

Ⅰ. What is AOC?


(1) AOC is an active optical cable. Also AOC is a digital power amplifier cable, composed of semiconductor materials (two optical transceivers and leakage cable). Digital amplifier cable is mainly used in big data centers, computers with excellent performance, large capacity storage equipment and other mechanical equipment for high-speed transmission and reliable interconnection transmission. AOC applications are electrical sockets that meet industry standard requirements. By using the electric-opto-electric conversion inside the cable, the cable can carry out efficient and stable data transmission.


(2) Advantages of active optical cable(AOC):


a. Wider bandwidth for testing transmission characteristics, which can make the freight volume of the application system reach 40Gbps, without external equipment or upgraded mechanical equipment.

b. Compared with the general speed cable, AOC active optical cable is lighter in weight, and has smaller volume.

c. Strong ability to shield interference signals: AOC active optical cable transmits laser welding data signals according to the optical fiber, and the optical fiber line material is the electrolytic medium of the insulation layer, which is not easy to be harmed by interference signals.

d. Disadvantages: it has higher cost compared with DAC.


Ⅱ. What is direct attach cable(DAC)?


DAC is a high-speed connection cable, also known as data transmission copper cable. The port number of this cable cannot be changed, and the control module head cannot be separated from the copper cable. DAC copper cable is the most common direct cable connecting servers and the Internet in storage areas of big data centers. DAC copper cables for data transmission can be divided into two categories: microwave sensor copper cables and digital power amplifier copper cables. Among them, the copper cable of microwave sensor has high application frequency. Due to its high cost performance and fast transmission speed, it shows the best solution for short route transmission. DAC cables, microwave sensors and digital power amplifiers are generally used for network switches in the main room of big data centers.


Ⅲ. What is the difference between active optical cable and direct attach cable?


(1) Firstly, AOC is composed of integrated photoelectric devices. The signal transmission process is that the a-end module converts electrical signals into optical signals, and the optical signals are transmitted to the B-end module by fiber jumper, and then the B-end module converts optical signals into electrical signals. However, DAC directly connected cable is different. It uses silver-plated conductor and foamed insulated core wire as materials, adopts wireline pair shielding and total shielding, and transmits signals as electrical signals without the process of photoelectric signal conversion.


(2) Secondly, the transmission distance of active optical cable is longer, and it is not subject to electromagnetic interference and electromagnetic shielding, and the transmission stability is strong, while the transmission distance of high-speed line will be relatively short.


(3) Finally, the direct attach cable(DAC) is larger in volume and weight than AOC active cable. Both active cable and direct attach cable can be used to transmit signals between network devices. DAC directly connected cables are of both active and passive types. The longest transmission distance of active copper cable is longer than that of passive copper cable, while AOC is active. Active refers to the need for power supply, and passive does not need, active devices can be used to amplify and transform signals, and passive devices generally only for signal transmission.


(4) DAC direct attach cable and AOC active optical cable are generally used for switches and servers in data center rooms. DAC is generally used for interconnection between devices in cabinets due to its short transmission distance, while AOC active optical cable has a relatively long transmission distance, so it is widely used for interconnection between devices in cabinets. To connect equipment rooms of two data centers, single-mode optical modules and single-mode optical fiber jumpers are required.


AOC and DAC are widely used, although their materials and main uses are different. So how should the customer choose? First, master the pros and cons of both, and then buy according to demand.