Small wireless audio system EMC rectification
Generally speaking, such a small wireless audio system, in addition to the analog part, or the 2.4GHz wireless transmitter and receiver part, the other rarely appear unqualified circuit. However, with the development of science and technology, this criterion or the theory of earth has ceased to exist. Take this type of wireless system case now and analyze a set of rectification plans with excessive radiation. 1, first analyze the test data, and compare the use of AUX radiation test data, BT mode radiation test data, Host only radiation test data, and even replace a different mobile phone, or different locations, first qualitatively determine the source of noise, or the sound system That part of the electromagnetic launch? (1) After careful test data comparison, it was found that this sound input 1KHz signal under the AUX Ipod mode, the test result is very good, and the frequency point of Fail can hardly be seen. (2) Host only mode is also unqualified in BT mode (3) There was no significant difference in data changes when using different mobile phones, signal sources, or changing the Setup mode. (4) Connect BT without song, test failed After a comparative analysis, the tests were all unqualified in this wireless audio system as long as it was under BT enabled mode or state. This illustrates that there is basically no major problem with pre-signal processing, subsequent power amplification, or structural parts. 2. After preliminary EMC rectification launch was initially positioned as part of the BT, we continued to disassemble and compared the detection of the BT circuit using the near-field probe and concluded that the conclusion was completely consistent with the preliminary theoretical analysis. In order to accurately confirm the problem points appear in the BT section. 3, rectification program (1) Near BT control post-pole power amplification section To stanby signal adds a 0.01uf capacitor to ground (2) Near-BT control post-pole power amplifier To mute signal Add a 0.01u capacitor to ground (3) Near BT control LED Bluetooth connection success Color display LED signal Add a 0.01uf capacitor to ground After adding the above rectification plan, it is no longer necessary to re-test the harmonics. The highest point frequency of 245 MHz PK has a 5.5 dB margin. 4. Conclusion Whether the product is an analog or digital circuit, or any other product whose previous experience is qualified without problems, as long as it complies with the list of product ranges within the scope of the relevant standards, we all need to pass rigorous laboratory tests and record detailed test data. In order to ensure the objective and scientific certification quality. 10Kv Steel Pole,Metal Pole,Metal Pole Barns,Metal Poles For Fence Jiangsu Baojuhe Science and Technology Co.,Ltd. , https://www.galvanizedsteelpole.com