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  • Ten Daily Electronic Common Sense-Section 122

    According to different access methods of PTN network users, what kinds of specific services can be divided into?

    TDM El service incoming from the base station, IMA El service incoming from the base station, and FE service incoming from the base station.

    What are the characteristics of the command system?

    The instruction system is a collection of various instructions that the microcontroller can execute. Users use the instructions to control the microcontroller to complete various complex functions such as calculation and control.
    Different families of microcontrollers usually have different instruction sets. Microcontrollers can directly recognize and execute machine instruction codes, but machine instruction codes are difficult for developers to memorize, and it is not convenient for program design, maintenance and transplantation.
    Therefore, the source program is usually written in assembly language or a high-level language such as C language, and then the assembly language or high-level language is compiled into machine instruction code by the assembler. The efficiency of assembly language compiled into machine instruction code is usually higher than that of high-level language such as C language.

    What is the base material of the strain gauge?

    The base of the strain gauge is used as the supporting layer of the grid wire, and at the same time has the function of electrical insulation.
    The material generally can use phenolic resin, epoxy resin, polyvinyl formal, polyimide and so on.

    What are the factors that affect the microprocessor power supply latency?

    1. Time required to reprogram the regulator.
    2. Can the DSP continue to execute any other code during the voltage change.
    3. Need to reprogram the peripheral. Such as a serial interface or an external memory interface to connect with peripherals that receive different clock sources. For example, a reduction in CPU clock frequency may require a reduction in the number of wait states for accessing external memory.
    4. The possibility of reprogramming the timer used to generate the OS clock time signal will affect the absolute correctness of the OS time base.

    What hardware interfaces does the WiFi hardware have embedded in the embedded system device?

    Generally speaking, there are three types of hardware interfaces for embedded system devices embedded in WiFi hardware: USB interface, SPI interface, and SDIO interface.
    The USB interface is limited to operation in the operating system mode, and the SPI interface and SDIO interface can be applied to both operating system and non-operating system environments.

    What are the basic components and functions of the five statement structures?

    1. A block statement is a combination of a series of parallel execution statements, and its function is to combine the parallel statements in the structure into one or more sub-modules.
    2. The process statement defines the sequence statement module, which is used to assign the signal value obtained from the outside or the internal operation data to other signals.
    3. The signal assignment statement assigns the processing result in the design entity to the defined signal or interface port.
    4. The subroutine call statement is used to call the procedure or function, and assign the obtained result to the signal.
    5. The component instantiation statement calls and explains the components generated by other design entities. And connect the ports of this component with other component signals or interface ports of high-level entities.

    What are the basic diagnostic steps for the three types of faults commonly found in automotive in-vehicle network systems?

    1. Understand the characteristics of the vehicle network system of the vehicle, including the transmission medium, the structure of several sub-network systems, etc.;
    2. Know whether there is a wake-up function and a sleep function, etc.;
    3. Check whether there is a fault in the vehicle power system, such as the output of the alternator Whether the waveform is normal (if it is not normal, it will cause signal interference failure), etc.;
    4. Check whether there is a fault in the link of the network system, and use the replacement method or the cross-line method to detect;
    5. If it is a node failure, only the replacement method can be used Carry out detection;
    6. Use the self-diagnosis function of vehicle network faults.

    What is a phase modulation fiber optic pressure sensor?

    The phase modulation optical fiber pressure sensor uses the optical fiber itself as the sensitive element.

    Where can a subroutine be defined in the VHDL program?

    Subroutines can be defined in 3 different places in a VHDL program: package, structure, and process.

    What are the analysis of the diode VDl temperature compensation circuit?

    1. The positive pole of VDl is connected to the DC working voltage y through R1, and its negative pole is connected to the ground wire through R2, so that VD1 is in a conduction state under the action of the DC working voltage 4-V. The main point to understand diode conduction is that the voltage on the positive pole is higher than the voltage on the negative pole.
    2. It is not feasible to use a 0.6V tube voltage drop after the diode is turned on to explain the role of VDl in the circuit. Because the DC operating voltage required by the base of VT1 can be achieved by adjusting the resistance of R1 and R2, there is no need to adjust the voltage of the base of VT1 by connecting the diode VD1 in series.
    3. The function of VDl in the circuit can be correctly explained by using the tube voltage drop temperature characteristic of the diode. Assuming that the temperature rises, according to the characteristics of the triode, the base current of VTl will increase a little. When the temperature rises, the tube voltage drop of the diode VDl will drop a little. The drop of the VDl tube pressure drop causes the VTl base voltage to drop a little, and as a result, the VTl base current drops. It can be seen from the above analysis that after adding the diode VD1, the original temperature increases to increase the base current of VT1. Now the VTl base current can be reduced a little by the VDl circuit. This plays the role of stabilizing the base current of the triode VTl, so VDl can play the role of temperature compensation.
    4. The poor temperature stability of the triode is also manifested in the process of temperature drop. When the temperature drops, the base current of the triode VTl will decrease, which is also a manifestation of poor temperature stability. After the diode VD1 is connected, when the temperature drops, its tube voltage drop slightly increases, which increases the DC operating voltage of the VT1 base. As a result, the VTl base current increases, which can also compensate the instability when the temperature of the triode VTl drops.


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