A contactless smart card uses the same radio-based technology as the proximity card, with the exception of the frequency band used: it uses a higher frequency (13.56 MHz instead of 125 kHz), which allows the transfer of more data, and communication with several cards at the same time. A contactless card does not have to touch the reader or even be taken out of a wallet or purse. Most access control systems only read serial numbers of contactless smart cards and do not utilize the available memory. Card memory may be used for storing biometric data (i.e. fingerprint template) of a user. In such case a biometric reader first reads the template on the card and then compares it to the finger (hand, eye, etc.) presented by the user. In this way biometric data of users does not have to be distributed and stored in the memory of controllers or readers, which simplifies the system and reduces memory requirements.
In the 1-to-many mode a user presents biometric data such as a fingerprint or retina scan and the reader then compares the live scan to all the templates stored in the memory. This method is preferred by most end-users, because it eliminates the need to carry ID cards or use PINs. On the other hand, this method is slower, because the reader may have to perform thousands of comparison operations until it finds the match. An important technical characteristic of a 1-to-many reader is the number of comparisons that can be performed in one second, which is considered the maximum time that users can wait at a door without noticing a delay. Currently most 1-to-many readers are capable of performing 2,000–3,000 matching operations per second.
An important feature for memory card readers is the speed with which they can transmit data. Readers with USB 3.0 compatibility will be faster than USB 2.0 technology (as long as your computer has a USB 3.0 port). As mentioned earlier, there are various types of memory cards, so having a reader than can communicate with more than one interface will be beneficial, especially if you find yourself using multiple memory cards.
Most card readers are highly portable and versatile in their ability to read more than one type of memory card. The most common types of memory cards are Secure Digital (SD), microSD, SDHC, microSDHC, CompactFlash (CF), Memory Stick (MS), MS Duo, Mini SD, and MMC. Before buying a reader, make sure it's compatible with the memory card you are using.
No matter what is going on in your life right now, a psychic reading can help you discover and maintain your peace of mind and tranquility. During your call, you will have the opportunity to ask questions and get answers to the things that have been on your mind lately. As a result of your session, you will gain an appreciation for how things in the past are affecting you and the likely future outcome of this situation.
Biometric templates may be stored in the memory of readers, limiting the number of users by the reader memory size (there are reader models that have been manufactured with a storage capacity of up to 50,000 templates). User templates may also be stored in the memory of the smart card, thereby removing all limits to the number of system users (finger-only identification is not possible with this technology), or a central server PC can act as the template host. For systems where a central server is employed, known as "server-based verification", readers first read the biometric data of the user and then forward it to the main computer for processing. Server-based systems support a large number of users but are dependent on the reliability of the central server, as well as communication lines.