2, 炣 fuel technology May 31 news (Jiang Chenghua) determined to impact the high-end market of millet, once again to complete its charging technology upgrade. On May 31, Xiaomi announced two new records in the field of charging, the first 200W wired fast charge and 120W wireless fast charge. According to reports, 200W wired charging, only 8 minutes to complete 100% charging; 120W wireless charging, it takes 15 minutes to complete 100% charging.
3, the news, millet announced that the millet 11 Pro magic revision broke two chargesThe cable supports 200W power, and it takes only 8 minutes to fill the 4000mAh battery, and the cable charging has entered the 10-minute era for the first time. Specifically, taking the 4000mAh battery as an example, the 200W wired charge is charged to 10% in 44 seconds, 50% in 3 minutes, and 100% in 8 minutes.
1, for example, for the 6-10 layer memory module PCB design, choose 10/20mil (drilling /The pass hole is better, and for some high-density small size boards, you can also try to use 8/18Mil pass holes. Under the current technical conditions, it is difficult to use a smaller size of the hole (when the hole depth exceeds 6 times the diameter of the hole, it is impossible to ensure that the hole wall can be uniformly plated with copper); For the power supply or ground wire hole, you can consider using a larger size to reduce the impedance.
2, in the range of ravg 0~ 0.08m, the output power increases first and then decreases with the increase of coil turns; In the ravg range of 0.08~ 0.4m, the output power with the coil turnsThe number increase decreases first, then increases and then decreases again. For a fixed operating frequency, the quality factor Q mainly depends on the shape and size of the coil and the material used. Standard coil technologies (such as wire winding coils and PCB coils) generally specify quality factor values.
3, no matter what electronic products according to the reason, the fewer PCB layers, the worse the electrical performance. On the contrary, the more PCB layers, the better the electrical performance. In electronic products, the more PCB substrate layers, the better. Because the more layers of the PCB board, the more solid the foundation of the motherboard, the less interference between signals will be able to ensure the motherboardThe electronic components work normally in harsh environments without interference, and the longer the service life.
4, most of the host board is a 4 to 8 layer structure, but technically, the theory can do nearly 100 layers of PCB.
5, if some board guide holes appear on the front of the PCB board, but can not be found on the back, then it must be 6/8 layer board. If the same pilot hole can be found on both the front and back of the PCB board, it is naturally a 4-layer board. However, at present, many board manufacturers use another wiring method, that is, only some of the lines are connected, and the buried hole and blind are used in the wiring>1, First of all, not all of the wireless chargers on the market can be competent for watch charging. Many products do not clearly label the radiation value, which is somewhat worrisome. Since the radiation standard of wireless charging technology has not yet been perfected, we need to be concerned that the current regulatory requirements, such as the Electromagnetic Radiation Protection Regulations, stipulate that the electromagnetic radiation of the user in continuous contact with the wireless charger within 24 hours shall not exceed the specific absorption rate (SAR) limit of 0.02W/kg.
2, the test found that: using a high-sensitivity radiation tester, the radiation value of the wireless charger is between 150 and 180,While smaller than the 250-627 in front of a computer screen or the thousands when making a call on a mobile phone, the cumulative effect may not be negligible. At the same time, when wireless chargers, mobile phones, computers and other electronic devices are used together, the radiation value will increase significantly.
3, taking 1000mAh capacity lithium battery as an example to calculate the radiation of the wireless charger. 50% charging capacity is about 7~8Wh. If it is required to be full for about two hours, the maximum charging power should reach at least 1W (the maximum power of the GSM900 mobile phone is about 2W); Because the mobile phone wireless charging method is to place the phone above the charger rather thanInside, so the radiation leakage rate could be significant.
Modulation of AM signal refers to the ratio of signal amplitude to carrier amplitude. Ma is called the amplitude modulation coefficient, Umax represents the maximum value of the amplitude modulation envelope, and Umin represents the minimum value of the amplitude modulation envelope. Ma indicates the degree to which the carrier amplitude is controlled by modulation, and generally 0≤Ma≤1 is required so that the envelope of the AM wave can correctly represent the change of the modulated signal. The case of Ma1 is called overmodulation.
No. AM signalThe modulation system is the ratio of signal amplitude to carrier amplitude. m refers to the adjustment system, the greater the adjustment system, the greater the contrast, not the bigger the better, but to find a suitable state.
FM is frequency modulation. AM is Amplitude Modulation, AM and FM are two different Modulation modes of radio carrier signal, (Amplitude Modulation) and (Frequency Modulation) abbreviation, that is, amplitude modulation and frequency modulation.
AM on a radio is Amplitude Modulation, that is, amplitude modulationMake. FM on a radio is Frequency Modulation, or frequency modulation. AM Amplitude Modulation (AM) is amplitude modulation. Amplitude modulation, also known as medium wave, is in the range of 530-1600khz. Amplitude modulation is an electrical signal that changes the amplitude of the sound from high to low. The transmission distance is far, but it is greatly affected by weather factors, and it is suitable for inter-provincial radio broadcasting.
AM refers to the amplitude modulation of the signal. Amplitude modulation is a process in which the amplitude of the sinusoidal carrier varies linearly with the modulated signal. AM AM can be usedCoherent demodulation, the modulated signal can be recovered by multiplying the carrier by the low-pass filter and making certain adjustments in amplitude. In addition, the envelope detection method can also be used for AM signal under the condition of 1max () mtm.
Frequency modulation is to encode information by making the instantaneous frequency of the carrier change with the signal, and the emergence of frequency modulator/makes this technology widely used in broadcasting, navigation and other equipment. The characteristic of frequency modulation is that the carrier amplitude remains unchanged and the vibration frequency changes with the signal, so it has the advantages of strong anti-interference ability, wide band/frequency hopping wave and high power utilization /, but the service radius is relatively limited.
Frequency modulation refers to the frequency of the sound represented by the radio wave frequency of the broadcast signal, one100 use particularly high frequency radio waves, usually 88MHz to 108MHz. Amplitude modulation refers to the frequency of sound represented by the amplitude of radio waves, and radio waves of various bands can be used, usually divided into long wave (China does not have), medium wave, short wave.
It is a modulation method that makes the instantaneous frequency of the modulated wave vary with the modulated signal. The circuit to realize this modulation method is called frequency modulator, which is widely used in frequency modulation broadcasting, television sound, microwave communication, phase-locked circuit and frequency sweep meter. The basic requirements of frequency modulator are large frequency shift, good frequency modulation characteristics and small parasitic amplitude modulation.
Frequency modulationInstantaneous frequency offset The Angle modulated according to the instantaneous value function of a given modulated signal. The function is usually linear. That is, the frequency of the high-frequency carrier is not a constant, but a modulation mode that changes within a certain range with the modulation signal, and its amplitude is a constant. Amplitude modulation: Modulation in which the carrier amplitude changes as a function of the instantaneous value of a given modulated signal. The function is usually linear. The invention relates to a modulation method, belonging to baseband modulation.
1, in frequency modulation, the frequency modulation coefficient is usually greater than 1, and the amplitude modulationThe coefficient is less than 1 (more than 1 is overtuned, which will be seriously distorted), so the band width of the FM wave is much larger than the band width of the AM wave.
2, the difference: the radio frequency modulation (FM) and amplitude modulation (AM) difference is the received radio wave modulation method is different, frequency modulation is the instantaneous frequency change of the carrier to represent the information of the modulation mode, and AM is the amplitude of the carrier changes with the signal modulation mode. Frequency modulation, full name "frequency modulation". Modulation method in which the instantaneous frequency of the carrier changes according to the change law of the desired transmitted signal.
3, different frequency modulationSound machine: FM refers to the general FM broadcast 76-108MHz, which is 85-108MHz in China. AM radio: AM for short, is actually a combination of (long, medium and short) waves. In general, for ordinary radio, AM only refers to the medium wave. The range is 530-- 1600KHz. The received radio wave modulation method is different frequency modulation radio: frequency modulation is the instantaneous frequency change of the carrier to represent the modulation mode of information.