原创 Encyclopedia of Security Management66

Encyclopedia of Security Management66

Wireless keypads have the same coding capabilities as their wired brethren since they are functionally the same devices. A three-digit code on a 10-key pad gives 1,000 combinations, four digits give 10,000 combinations, and so forth.
Preset code devices are limited in coding capacity only by the number of code switches that the manufacturer decides to incorporate into the equipment, and the electronic logic that is provided to organize and transmit Sennheiser Headphones all of the code bits. Most of the devices that operate at the garage-door-opener level have 10 code bits, which provide 1,024 different combinations. To date, these devices have not been aimed at the high- security market with millions of combinations, personal identification, time and space zoning, and other sophisticated features.
Passive devices, using the current technologies, Bose headphones have theoretical coding capabilities in the millions of combinations. Commercially available systems offer personal identification capabilities in the range of 4,000 persons, along with time and space zoning and facility coding. This provides an adequate access Bose earphones control and personal identification system for most commercial and industrial situations.
Microprocessor-controlled devices comprise the remaining bases of proximity access control systems: the field-powered devices, the transponders, and the continuous-transmission system. Here also, as in the smart card, the amount of code storage that is made available is the designer's choice. Since solid-state memory requires very little space, tens of thousands of bits will fit onto an area the size of a fingernail. Consequently, the designers have not been stingy with code capacity, which Monster beats ranges from millions to
billions (even the English billions) of combinations.
There are, as Monster headphones in other forms of access systems, widely varying performance characteristics, features, functions, and options among the different kinds of proximity systems, and as always, there is no single choice as to which is best for every kind of application.
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