Qualified HDMI Cable Pass EMC
Nov 22, 2021
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According to foreign media techpowerup reports, recently, the German Federal Network administration, together with the Netherlands telecommunications department, Switzerland bakom and Sweden, jointly tested civil HDMI and coaxial cables. The test results show that a large number of products do not meet the requirements of EMC.
The four departments jointly tested 30 coaxial cables and 30 HDMI cables, of which only 11% of the product signal attenuation meets the requirements, and only 10% of the HDMI cables meet the acceptable EMC requirements, with a coupling attenuation of at least 50dB.
EMC electromagnetic compatibility means that the product is not easy to be disturbed by external electromagnetic waves, and will not actively release excessive electromagnetic waves to interfere with the surrounding equipment. Generally speaking, the EMC standard requires that the cable can resist EMI electromagnetic interference below the maximum value, and the released EMS shall not exceed a certain amount.
The most obvious example is that the poorly shielded USB 3.0 cable will release electromagnetic waves with a frequency of about 2.4GHz, which has never interfered with Bluetooth devices, 2.4G wireless keyboard and mouse and 2.4GHz Wi Fi working in the same frequency band. If the coaxial cable does not meet the EMC requirements, the electromagnetic wave released during transmission will affect the surrounding equipment. The European regulators have not disclosed the specific brands and models of the tested products, but the report points out that there is no significant difference between high-priced and low-priced cables. Most of the tested cables are between 1.5m-3m in length, but longer cables are bound to have worse performance. The four departments submitted a list of recommendations to the EU, proposing that standards organizations should strengthen the certification of HDMI and coaxial cables. In addition, these departments also want to test other types of cables, such as usb-c data cable, Ethernet cable, etc. The test results show that the overall quality of coaxial cable has deteriorated compared with the past.
The literal translation of EMC (electro magnetic compatibility) is "electromagnetic compatibility". It refers to the ability of the electromagnetic energy generated by the equipment to neither interfere with other equipment nor be interfered by the electromagnetic energy of other equipment.
The term EMC has a very broad meaning. Like a blind man touching an elephant, what you touch is very different from reality. In particular, electromagnetic phenomena contrary to the design intention should be regarded as EMC problems.
Electromagnetic energy detection, anti electromagnetic interference test, statistical processing of detection results, electromagnetic energy radiation suppression technology, natural electromagnetic phenomena such as lightning and geomagnetism, impact of electric field and magnetic field on human body, international standards of electric field strength, transmission channels of electromagnetic energy, relevant standards and restrictions are included in EMC.
It can be further explained as follows:
When we watch TV, if someone nearby uses household appliances such as hair dryer or razor, annoying snowflake stripes will appear on the screen. The electric rice cooker can't cook rice, the air conditioner is turned off, but it starts again after a while... These are common electromagnetic interference phenomena. More seriously, if the electromagnetic interference signal hinders the medical electronic equipment monitoring the disease or the flying aircraft, it will cause unimaginable consequences.
Electromagnetic compatibility (EMC) refers to the ability of equipment or system to meet the requirements in its electromagnetic environment and not produce intolerable electromagnetic interference to any equipment in its environment.
Therefore, EMC includes two requirements: on the one hand, the electromagnetic interference generated by the equipment in the normal operation process cannot exceed a certain limit; on the other hand, it means that the equipment has a certain degree of electromagnetic interference in the environment. The degree of immunity, that is, electromagnetic susceptibility.
The so-called electromagnetic interference refers to any electromagnetic phenomenon that can degrade the performance of a device or system. The so-called electromagnetic interference refers to the performance degradation of equipment or systems caused by electromagnetic interference.
Traditionally, EMC includes two aspects: EMI (electromagnetic interference) and EMS (electromagnetic susceptibility).
With the development of electrical and electronic technology, household appliances have become increasingly popular and electronic, radio and television, post and telecommunications, computers and their networks have become increasingly developed, and the electromagnetic environment has become increasingly complex and deteriorated. The electromagnetic compatibility of electrical and electronic products has become more and more popular in various countries The attention of the government and production enterprises. Since 1996 the European Community stipulated that electrical and electronic products must be affixed with the CE mark before they can be sold on the European Community market, all countries have taken corresponding measures. As a domestic appliance manufacturer, we must act as soon as possible to understand and improve the EMC performance of the product, and follow the new situation of EMC certification in order to gain the initiative in the market.