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  • Ten Daily Electronic Common Sense-Section 78

    What are the basic transmission components of PWE3?

    User Equipment, Carrier Border Router, Access Link, Pseudo-Wire or Virtual Link, Repeater, Tunnel, Encapsulation, PW Signaling Protocol, Quality of Service QoS.

    What is harmonic current?

    When the non-sinusoidal periodic current function is expanded according to the Fourier series, its frequency is the general term for each sinusoidal component whose frequency is an integer multiple of the original periodic current frequency. The harmonic current whose frequency is equal to k times the frequency of the original cycle current is called the k-th harmonic current, and the harmonic currents whose k is greater than 1 are also collectively called the higher harmonic current.
    Harmonic current is a general term for each sinusoidal component whose frequency is an integer multiple of the frequency of the original periodic current. The non-sinusoidal periodic current is represented in the form of a Fourier series, where the frequency is a general term for each sinusoidal current component whose frequency is an integer multiple of the frequency of the original non-sinusoidal periodic current.

    What is the LTC3555/LTC3555.1?

    The LTC3555/LTC3555.1 are highly integrated power management and battery charger ICs for Li-ion or Li-polymer battery applications.

    What aspects can I consider when choosing a Resistors?

    • In order to meet the requirements of low noise, metal film resistors or wirewound resistors with small excess noise should be used for the resistors passing through the current. Resistors with the same resistance value and the same temperature r have the same thermal noise. In this case, reducing the excess noise is the only way.
    • Consider the frequency range in which the resistor operates. Wirewound resistors and thin film resistors are spiral-shaped in production, and have larger inductance than synthetic carbon resistors (except for special inductor resistors). Through the magnetic coupling of the inductance, it is easy to make external noise pass through the low-noise resistor. In addition, the resistor also has distributed capacitance, and the impedance presented by the resistor varies with frequency, especially when it is used at high frequencies (above 500kHz). This will affect the performance of the circuit. In experiments, we found that the noise of the resistor is also related to the rated power. When two resistors of the same type and the same resistance value consume the same power, the noise of the resistor with the larger rated power is usually smaller. This is not difficult to explain, two resistors of the same type and the same resistance value. When they consume the same amount of power, they generate the same amount of heat. Since the heat dissipation conditions of the resistor with a larger rated power are better, its temperature must be lower than that of the resistor with a smaller rated power, and the corresponding thermal noise will be smaller.

    What are the brightness adjustment techniques?

    • Pulse width modulation.
    • Frequency modulation.
    • Bit angle modulation.

    What are the characteristics of the Audi A6 car comfort system LIN bus?

    1. One master unit connects to multiple slave units
    2. One master unit connects multiple sensors
    3. The data exchange between each LIN bus is realized by the master unit via the Comfort System CAN bus

    What functions does the RF module perform?

    • The radio frequency energy is generated by the radio frequency oscillator, part of the radio frequency energy is used for the reader, and the other part is sent to the electronic tag through the antenna, which activates the passive electronic tag and provides energy for it.
    • Modulate the signal sent to the electronic tag to the carrier frequency signal of the reader to form a modulated transmission signal, which is transmitted through the antenna of the reader.
    • Demodulate the echo signal returned by the electronic tag to the reader, extract the signal sent by the electronic tag, and amplify the electronic tag signal.

    What are the advantages of the DS18B20 digital temperature sensor?

    DS18B20 is a digital temperature sensor with single bus interface, which has the advantages of small size, low power consumption, strong anti-interference ability and simple microcontroller interface.

    What are the characteristics and application scope of repair equipment maintenance methods for electrical control equipment?

    1. Ex-post (passive) repair
    2. Preventive (active) maintenance
    3. Condition maintenance
    4. Maintenance prevention
    5. Retrofit maintenance

    What are the data types of VHDL?

    Constants, signals and variables are the most important data types in VHDL, which represent certain physical meanings respectively.


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