Direct Attach Cable, referred to as DAC, consists of two modules and one copper wire. It is often used in data transmission of short-range applications, such as adjacent cabinets or within cabinets. This article will introduce several key factors that affect the transmission performance of DAC direct attach cable.
1. Cable attenuation
Cable attenuation refers to the reduction or loss of signal energy that occurs during the transmission of information through a cable to a device. In the process of DAC cable transmission, as the frequency increases, the attenuation will increase. In addition to the increase in frequency attenuation, the temperature will also increase the attenuation of the cable. For every 10°C increase in temperature, the signal attenuation of the cable will increase by 4%.
2. Cable crosstalk
Crosstalk is also an important factor affecting cable performance. Crosstalk is a harmful interference signal that comes from the coupling effect between wire pairs. This type of noise can cause random changes in signal amplitude, which in turn limits the receiver’s ability to monitor changes in the signal waveform, thereby affecting the bit error rate and reliability of the transmitted signal.
3. Excessive bending of the cable
The bending of the cable will weaken the transmission signal, the cable is easier to bend, and the recovery ability after bending is relatively poor. In addition, the insulating part of the cable is of a foamed structure, which has poor mechanical properties, and is easily squeezed or stretched, and is distributed to deformation, which will destroy the foamed layer structure. Therefore, in the process of using DAC cables, we should try to avoid twisting and bending of the insulated core wires, which will bend the conductors and affect the performance.
4. Wiring environment
The use environment will also affect the performance and service life of the DAC cable. Factors such as excessive temperature, ultraviolet radiation, and excessive humidity will affect the transmission performance of the DAC cable. Therefore, we should lay out the cables under the eaves when laying out the cables outdoors. Keep away from light, moisture, and cool place.
5. Electromagnetic and radio frequency interference
Copper cables are most afraid of EMI/RFI (electromagnetic interference/radio frequency interference) when they are used. Although DAC cables are generally resistant to electromagnetic/radio frequency interference, we should also avoid potential source of interference.
6. Ground Connection
Proper grounding is the key to effective shielding. No or incorrect grounding may reduce the effectiveness of shielding. An ideal shield ground should have a single point of contact. When the interfering signal is coupled to the shield, the current will be directed to the ground, preventing the wire pairs under the shield from being affected.
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