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  • Ten Daily Electronic Common Sense-Section 127

    What is the antenna lobe in the pattern?

    The lobes other than the main lobe in the antenna lobes are called side lobes or side lobes.
    The side lobe level refers to the ratio of the maximum value of the side lobe to the maximum value of the main lobe, denoted as FSLL.

    How to choose a varactor?

    1. Varactor diodes are generally used in resonant networks to replace traditional variable capacitors. Therefore, there must be a sufficient Q value (the ratio of the inductive reactance or the Yi anti-bow circuit resistance when the tuned circuit resonates, the larger the Q value, the better the circuit selectivity). Obviously, as the frequency increases, the Q value will gradually decrease. Measure the frequency when this definition Q=1 is cut ll two frequency, when using, the working frequency should be lower than j two cut l Bu frequency. At the same time, pay attention to the variable capacity ratio to meet the tuning needs, and the maximum reverse voltage should be greater than the maximum value of the voltage applied at both ends.
    2. Also pay attention to the variation range of junction capacitance and IU capacitance.
    3. Using varactor: the pole tube is ft, and the interaction between the DC control power of the varactor_pole tube and the DC power supply system of the oscillating circuit should be avoided. Inductors or fire resistors are usually used to isolate the two.
    4. The operating point of the varactor diode should be selected appropriately, that is, the DC reverse bias voltage should be selected appropriately. Generally, varactor diodes with large relative capacity changes and small reverse partial calluses are selected.

    What are the audio ADC related modules?

    1. Stereo ADC
    2. Audio recording selector
    3. Recording gain
    4. Automatic level control

    What is the composition of ISDN?

    Terminals, terminal adapters, network terminal equipment, line terminal equipment and switching terminal equipment, etc.

    What is the tunnel technology?

    From the point of view of network communication, this is equivalent to installing a virtual serial port gateway locally. When accessing any operation of the serial port, the gateway will convert it into Ethernet network protocol. Then send it out through the network cable. After the data packet reaches the destination through the network, the destination gateway converts it into a pure serial port protocol and sends it to the local serial port. This “protocol A. Protocol B. Protocol A” protocol combination mode is called tunnel (Tunnel) technology.

    What is the security and confidentiality of smart card communication?

    1. Change, delete, and add information content.
    2. Change the source or destination of information.
    3. Change the order of information groups/items.
    4. Reusing once sent or stored information.
    5. Tampering with receipt.

    What is the development trend of LED display?

    • High brightness, full color. Since the appearance of blue and pure green LED products, the cost has been reduced rapidly year by year, and they have already met the conditions for commercialization.
    • Standardization and normalization. After the maturity of materials and technology and the basic balance of market prices, the standardization and normalization of LED display screens will become a new trend in the development of LED display screens.
    • Diversified product structure.

    What are the two main types of oxygen sensors for automobiles?

    There are mainly two types of oxygen sensors for automobiles: zirconia type (Zr02) and titanium oxide type (Ti02).

    What is the difference between Thumb and ARM instructions?

    • The specific differences between Thumb instructions and ARM instructions are generally as follows:
      1. Jump instruction
      2. Data processing instruction
      3. Single register load and store instruction, batch register load and store instruction

    What constitutes a reader?

    Composed of radio frequency signal transmitting unit, high frequency receiving unit and control unit.


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