Now most people have access control cards and swipe in and out. The strange thing is, why do we sometimes see cars automatically open before they reach the door, and sometimes we have to open the access card near the swipe door?
There is a signal sensing distance between high frequency and low frequency access cards.
What is the difference between high and low frequency in access cards? Card Cube briefly introduces them:
What is the difference between high frequency and low frequency in access cards?
The induction distance of high-frequency cards is farther, while low-frequency cards are closer, with different radiation distances. According to the difference of frequency and distance, the induction distance of high frequency card is farther. For example, if a parking lot uses a UHF card, the car can open automatically before it arrives. Access cards, bus cards and other low-frequency cards have a shorter induction distance, and need to be close to 1cm can only be inducted internally.
① high frequency card operating frequency: 13.56MHz induction distance of about 1cm, like the high frequency card used in the Anlibao ZM1298 fingerprint lock. Enterprise / campus card, bus stored value card, highway toll, parking, community management, etc.
② low frequency card is the frequency of 100-125KHz induction distance of 1cm in the internal, induction needs to be very close. Low frequency cards are mainly used for attendance access control hotel door locks animal tags product production management.
According to the Institute of Electrical and Electronics Engineers (IEEE) developed a spectrum classification table.
?30~3000 frequency low kHz.
?300~30,000 frequency medium kHz, ?300~30,000 frequency medium kHz, ?300~30,000 frequency medium kHz
?3~30MHz frequency range.
?30~3000 frequency range MHz why high frequency, ?30~3000 frequency range MHz
? Frequency range of 300~1000MHz or higher is UHF.
(a) Compared with low frequency signals, high frequency signals change very quickly and have sudden changes.
Low frequency signal changes slowly and has smooth waveform.