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    What are the three most important criteria for choosing an independent regulator?

    • Low noise: The voltage stabilizer cannot generate noise or EMl that interferes with the surrounding RF system.
    • Low power consumption: This means high efficiency during operation, and low current in light load and standby states.
    • Small solution size: The voltage regulator must be integrated in a small package, and the external passive components must be few and small.

    What are the characteristics of fiber/fiber cable?

    1. Extremely wide frequency band, so it has great communication capacity. For example, there can be thousands of telephones in one fiber.
    2. The rate is high. The single-mode can reach 10-20Gbps, the total transmission rate in one optical cable can reach 4025Gbps, 1610Gbps, and the experimental system can reach 132*20Gbps.
    3. Excellent anti-magnetic field, anti-radio interference ability, very low bit error rate (10-9-10-10).
    4. No crosstalk, no noise, low loss, high confidentiality, not afraid of chemical corrosion.
    5. Small size, light weight, long relay distance, such as 5Gbps within 111km without repeater (repeater).

    Does digital control usually refer to the control mode of one of the three structures?

    • Analog system using digital programming.
    • Using a system controlled by a microcontroller.
    • Fully digital control.

    Handheld devices are portable devices that are operated by factory personnel.What are the four connection methods for handheld devices?

    1. HART handheld device or application program connected through factory automation network A handheld device that can be connected to the factory automation network can be connected to the factory automation network through some network technologies (such as WiFi). Like external factory automation servers, these handheld devices communicate with WirelessHART network devices through gateways. For a wirelessHART network, this type of handheld device acts like another host computer.
    2. HART handheld device connected to the device through an FSK module In this mode, the handheld device is directly connected to the device through an FSK module. in this mode. Handheld devices cannot access the WirelessHART network through their connected devices.
    3. WirelessHART handheld device connected to the WirelessHART network In this mode, the WirelessHART handheld device is a device in the WirelessHART network, which is partially restricted like other WirelessHART network devices, such as only communicating with network managers and gateways. This mode is used to configure keys for wireless handheld devices and to read diagnostic and system health information. This mode is also known as connecting as a network device.
    4. WirelessHART handheld device connected to a WirelessHART field device If a handheld device based on a WirelessHART connection is connected to a WirelessHART device through a WirelessHART network, it will be restricted to only communicate with its connected device. We will use a special configuration to ensure that the WirelssHART handheld is limited to communicating with directly connected devices at a time. This is referred to as connecting as a maintenance device. A handheld device operating in this manner must use a session between itself and the connected device to communicate.

    How to deal with complex signals?

    From the spectrum transformation relationship of the single-stage heterodyne receiver, it is known that the front-end circuit of the transceiver only processes the signal spectrum, and does not make any changes to the signal form and modulation method. completed in the terminal circuit. Whether it is the front end of the transmitter or the receiver, it usually works in a cascade of different parts. The functions performed by the cascaded parts usually include filtering (suppressing signals outside the channel where the useful signal is located), amplifying (adjusting the signal) level), mixing (changing the center frequency of the signal).
    Considering the local oscillator and multiplier in the mixer as two sub-modules inside a single module, the above three functions can be regarded as a single-input single-output system, and the frequency-domain characteristics of the receiver and transmitter can be regarded as no Bypassed signal processing chain. According to this idea, it is not possible to have many different topologies for receivers and transmitters. Its basic structure should be one or more band-pass filters, followed by an amplifier to adjust the signal level, and a multiplier to change the center frequency of the signal. Fundamental to transceiver design is the choice of filter bandwidth, amplifier gain, and mixer frequency. The choice of transceiver structure is nothing more than how many stages are used to combine these three modules.
    For designers of RF circuits, this technique has been used for at least 50 years, and the result is a large number of single-stage and multi-stage IF transmitters and receivers. In fact, the transceiver is not only a heterodyne structure, and the heterodyne receiver is not suitable for an integrated transceiver. When the carrier frequency is very high, the need for multi-level intermediate frequency is not suitable for integration. 
    The complex signal analysis method has been widely used in digital signal processing, and it is an important means to analyze the multi-path signal processing system as a single-path signal processing system. Receivers and transmitters using quadrature processing techniques are typical examples of such multipath signal processing. Using the complex signal analysis method, the circuit structure of multi-path signal processing can be regarded as a cascade system of signal processing modules with single input and single output. A variety of quadrature signal processing receiver and transmitter structures can be introduced.

    What is the energy of the inductive coupling system?

    Energy is obtained through the interaction between the electronic tag and the magnetic field of the reader.

    What are the characteristics of PRODAVE?

    OB85, OB86 are not started when a DP slave or PROFINET IO device is disabled, and no entries are made to the diagnostic buffer by the operating system. If DP slaves or PROFINET IO devices are disabled with SFC 12, when they fail, the operating system does not detect the failure and therefore does not start OB86 or the diagnostic buffer entry. A station failure can only be detected and written to the return value RET_VAL after the station has been reactivated.

    An optocoupler or relay is an isolation device that, if it meets the requirements, provides absolutely reliable isolation between separate intrinsically safe circuits.

    • Have suitable device ratings.
    • Before applying Um and ui to the device, it shall be subjected to the specified electric strength test.

    What are the working principles of deep circuits?

    • VTl etc. constitute an amplifier circuit. For the amplifier, it is required to have good working stability. One of them is that the quiescent current of the triode cannot be changed when the temperature changes, that is, the VTl base current cannot be changed with the temperature. Change, otherwise It’s the job stability. It is very important to understand the temperature characteristic of the amplifier to understand the working principle of the temperature compensation circuit composed of VDl.
    • The triode VTl has a bad characteristic related to temperature, that is, when the temperature rises, the base current of the triode VTl will increase. The higher the temperature, the larger the base current, and vice versa. Obviously, the temperature stability of the triode VTl is not good it is good. It can be seen that the poor temperature stability performance of the amplifier is caused by the temperature characteristics of the triode.

    What is the general structure of the electronically controlled anti-lock brake system?

    It is generally composed of wheel speed sensor, electronic controller, pressure regulator, ABS warning light and some relays.


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