The question about the security of smart door locks has never stopped. Many people think that the security of smart door locks is not as expected. In fact, since the introduction of smart door locks, the R&D manufacturers have adopted a lot of technical means to improve the security of smart door locks. These technical means have effectively improved the security of smart door locks. Today, Xiaobian introduces you to the key technologies that have been adopted in the design in order to improve the security of smart door locks.
1. Line multiplexing technology
The intelligent monitor and electronic lock of the intelligent door lock are placed off-site, and the intelligent monitor supplies the power required by the electronic lock and receives the alarm information and status information sent by the smart lock. If the communication line and the power supply line are separated, it is necessary to increase the number of cable cores and increase the safety hazard. However, when the smart door lock adopts the line multiplexing technology, only one two-core cable is used to realize the transmission of power and information.
At the transmitting end, the electronic lock boosts the modulated data signal through the pulse transformer T and sends it out; at the receiving end, the pulse transformer T steps down the received data signal and sends it to the demodulator to reduce the carrier signal during transmission. Loss in the middle. In order to reduce mutual interference between communication and power supply, the selection of choke coil L and coupling capacitor C should be considered comprehensively.
Let the carrier frequency fo=400kHz, in order to ensure that most of the signal energy is transmitted to the receiving end, take L=33.7μHC1=0.047μF.
2, current monitoring technology
In order to prevent man-made damage to the communication line and the electromagnetic actuator from burning the coil due to excessive current flowing through the electromagnetic coil for some reason, current monitoring technology is adopted in the intelligent door lock design. The current monitor uses the MAX471 current-to-voltage conversion chip from MAXIM. The chip can convert the measured current I into a ground output voltage U, and has the characteristics of large measuring range, high precision, and the output voltage U and the measured current I are proportional. The current monitor output voltage is sent to the A/D converter. The MCU reads the A/D conversion result to know the current change in the line, and finds the abnormality in time by analysis and issues an alarm signal.
3. Data communication and preprocessing technology
The intelligent monitor receives the status information sent by the lock (including the opening and closing of the lock, the first password error, the second password error, the third password error, etc.), the current value flowing through the electromagnetic actuator coil, and Reading the supply current value of the communication line at that time, the three combine to form a data block, wherein the operation state occupies 1 byte, the supply current occupies 2 bytes, and the coil current occupies 2 bytes. The intelligent monitor is always in the receiving state during communication with the electronic lock.
4, intelligent analysis
The intelligent analysis and prediction technology is based on each received data block, compared with the recorded value of the previous similar data, analyzes the magnitude and trend of the current change caused by the operation, finds problems in time, and reports the management personnel. Improve the reliability of the entire system.
Smart door locks are developed along with the smart home industry. Smart door locks are one of the most popular smart home products, and their safety performance is constantly improving. It is worth noting that consumers must purchase regular smart door lock brands when purchasing smart door locks, and their safety is more secure.
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