Ten Daily Electronic Common Sense-Section 104

What is the principle of automatic line selection for single-phase ground faults in neutral point ungrounded systems?

The working principle of the software of the automatic grounding line selection device can be constructed by using the magnitude and direction characteristics of the fundamental zero-sequence current when the neutral point ungrounded system is grounded.

How to exit the exception execution program?

When the exception handler ends, the exception handler must perform the following operations: return to the instruction next to the instruction in which the exception occurred. That is, subtract the offset from the value in LR and move it to the PC, offset The amount varies depending on the type of exception, copy the value of the SPSR back to the CPSR. The interrupt disable control bit at the entry disposition bit is cleared.

What are the two meanings of the antenna port output power?

The output power of the antenna port may have two meanings: one is the total power of the antenna port; the other is the power of a certain channel of the antenna port.
In some systems, the total power of the antenna port is the same as the power of a signal at the antenna port, such as the GSM system. The maximum total power of the antenna port is the same as the maximum power of the main BCCH channel (Broadcast Control Channel, BCCH).
However, some systems, especially CDMA systems, have the problem that multiple channels share the total power. Therefore, the power of a certain channel of the antenna port is only a part of the total power.

What are the methods and reasons for solving the “cross effect” in the organic electroluminescence dynamic driving method?

The method to solve the “crossover effect” in the organic electroluminescence dynamic driving method is the reverse cutoff method, that is, a reverse voltage is applied to all the unselected organic electroluminescence pixels.
This is because the principle of organic electroluminescence is that current is injected into the pixel, and the recombination of positive and negative charge carriers forms luminescence. The reverse cut-off makes it impossible for the weak field drift current and diffusion current to pass through the pixel, which may form luminescence, thus effectively eliminating the crossover effect.
The organic electroluminescence display dynamic driving method utilizes the reverse cut-off method to effectively increase the contrast of the display screen and improve the quality of the display screen.

What kinds of finite state machine design tools does Synplify Pro offer?

Synplify Pro provides 3 finite state machine design tools, namely FSM Compiler, FSM Explorer and FSM Viewer.
Using these three finite state machine tools flexibly to analyze, compile and optimize FSM can make the synthesis result of FSM reach the best.

In infrared technology, which four areas are generally divided into infrared radiation?

In infrared technology, infrared radiation is generally divided into 4 regions. That is, the near-infrared region, the mid-infrared region, the far-infrared region and the extremely far-infrared region.

What is the aggregation port used for?

Trunk ports are often used between switches to extend VLANs.
If two users are connected to two switches in different parts of an office building, and must be in the same VLAN, a means of communicating with each other is required. Two switches can use a trunk port to pass 802.1Q (VLAN tagged) traffic from both sites.

What are the main features of the latest secondary side synchronous rectification control IC – NCP4303?

• Realize the synchronous rectification control of CCM, DCM and QR mode flyback converters.
• Accurate secondary side zero current detection technology.
• Automatically compensate the input with parasitic inductance.
• Typical 40ns turn-off delay from current sense input to drive output.
• The zero current detection terminal can withstand voltage up to 200V.
• The ultra-fast trigger interface is sent to the external signal to adapt to the CCM mode.
• It has a forbidden input and enters the standby or low power consumption mode.
• Adjustable minimum on-time independent of %c level.
• Adjustable minimum off time independent of %c level.
• 5A/2.5A peak current leakage and source level.
• The working voltage range of Vcc can be up to 30V.
• The gate drive voltage is internally clamped to l2V (NcP4303A) or 6V (NCP4303B).
• Low starting and standby currents.
• The maximum operating frequency can reach 500kHz.

What are the classifications of labels by energy source classification?

1. Active tags Active tags are also called active tags. Because the energy of active tag work does not come from the electromagnetic waves sent by the reader, but relies on the battery carried by itself. Therefore, the active tag can actively send data to the reader, and the life of the tag is limited by the battery capacity. Typically, active tags, sensor chips, and control circuits are integrated to work together to accomplish certain tasks. For example, the sensor chip sends the collected data to the reader through the active tag; then, the active tag executes the corresponding command of the reader through the control circuit. The working distance of active tags can reach tens of meters, or even hundreds of meters. Due to the long communication distance of active tags, relatively complex functions, and generally much larger storage capacity than passive tags, the price of active tags is much higher than that of passive tags. In the management of valuable assets, active tags can be used. In an environment with strong electromagnetic interference, the performance of active tags is much better than that of passive tags. Because the antennas of passive tags are usually relatively small, the tags transmit data by reflecting electromagnetic signals. The reflected signals are very weak and are easily interfered by electromagnetic signals in the environment. Active tags can enhance the ability to resist interference from the surrounding environment by broadcasting a strong signal, especially when the distance between the tag and the reader is relatively long. Since the energy of the active tag operation comes from the battery, the battery needs to occupy a certain space, so the size of the active tag is generally larger than that of the passive tag. To date, commercial passive tags (excluding antennas) can be as small as millimeters in length and as thin as a sheet of paper. Commercial active tags (without antennas) are about the size of a coin. Generally, active tags can be divided into two categories: wake-up active tags and beacon-type active tags. Wake-up active tags spend most of the time in an inactive state, a sleep state. When the tag receives the activation command from the reader, it will wake up. In the sleep state, the power consumption of the tag is very low, so as to prolong the life of the tag battery. This type of tag generally has a relatively large storage space. The tag stores the data in the storage area, waits for an appropriate time, and sends the data to the reader in a centralized manner. Such tags can be used for item tracking and the like. The beacon-type active tag is always in a working state and has no sleep state. Compared with wake-up active tags, the data transfer rate and storage space of such tags are much smaller. The tags reduce battery power consumption by limiting the data transfer rate. This type of label is also widely used due to the low cost of component construction. In the real-time positioning system, the beacon-type active tag sends signals to the reader regularly to help the reader obtain the position information of the object.
2. Passive tags Passive tags have no energy source themselves, and tags rely on the carrier signal emitted by the reflected reader to obtain working power. Because the energy obtained is very limited, the communication distance of passive tags is much smaller than that of active tags. Usually, the communication distance of passive tags is only a few meters, and the amount of data that can be transmitted is also very limited. Passive tags are mostly used in item statistics, transportation, tracking and other medical and anti-theft fields. Since the passive tag does not need to replace the battery, the structure is simple and the cost is low, which makes it very advantageous in some application scenarios. For example, the label placed in the human epidermal tissue is not allowed to replace the battery frequently, and it is more appropriate to use a passive label at this time. Passive tags and active tags can be combined with each other to complement each other. In the asset supply chain management solution, the use of passive tags can reduce costs in scenarios where the movement of items changes little and the requirements for security, perception, and storage are not high. In scenarios where the movement of items changes greatly, the security measures are complex, and the data storage capacity is required to be strong, active tags are used to ensure quality.
3. Semi-passive tags Semi-passive tags are a combination of active tags and passive tags. This tag will also contain a battery on the IC board. However, these batteries are only an auxiliary energy source. Similar to passive tags, semi-passive tags absorb energy from the carrier signal emitted by the reader to wake up the chip and transmit data to the reader. When the energy absorbed by the tag is not enough to maintain its working voltage, the auxiliary battery will provide working energy. Therefore, such tags are sometimes referred to as battery-assisted passive tags.

What is the network layer and the transport layer?

The network layer and transport layer work together to provide secure and reliable communication for network devices.