Proximity readers.
Proximity readers
Proximity technology has firmly won a leading place in professional access control systems, displacing magnetic and Wiegand readers, almost completely displacing Touch memory. This article discusses the operating principles of the readers and provides the characteristics of the Parsec readers.
There is nothing mysterious about this
Like all the technological wonders that surround us, Proximity readers rely on physical principles that are familiar even to schoolchildren. However, the same cannot be said about the signal processing algorithms in the reader circuit, which usually constitutes the «know-how» of manufacturers. Figure 1 explains the interaction of the card and the reader in the process of receiving the code entered into the card during its production.
The reader contains a generator, which usually operates at a frequency of 125 kHz and is loaded onto the reader antenna. The energy emitted by the reader antenna is received by the card antenna and powers the microchip located in the card. The latter modulates the signal in the card antenna with a code entered into the microchip at the manufacturing plant. The signal emitted by the card is received by the reader antenna, processed first by the analog part of the reader circuit, and then by the microprocessor located in the reader. The microprocessor checks the correctness of the code, converts it to the required format and sends it to the reader output, i.e. to the input of the access control system controller.
Code formats
With all the variety of data formats processed by access control system controllers, more than 80% of systems are oriented as the main or additional format Wiegand 26 bit. Nothing good can be said about this format except that it is a de facto standard, which forces all manufacturers to focus on it.
Considering the fact that many domestic developers cannot use this format due to the lack of detailed information, we provide its specification in Figures 2 and 3.
Table 1 provides a transcript for Figure 3.
Another popular interface format for access control systems is the Micro LAN bus format of the American company Dallas, according to which Touch memory keys operate. Unlike Wiegand 26, this format is well documented by the company in the literature, so we will not provide a description of it.
Because of the openness of the format, the cheapness of the readers, or some other higher considerations, but almost all Russian developers of access control systems focused on using the Micro LAN protocol in their controllers.
Now that most customers want to use Proximity technology, our manufacturers find themselves in an unpleasant situation when they refuse a generally good system due to outdated identification technology.
Parsec Readers
A fairly wide range of access control system equipment is produced under the Parsec trademark. In particular, these are autonomous ASC-xx series controllers and the ParsecLight network computerized access control system. At the same time, a whole range of Proximity readers for use in existing systems of both domestic and foreign production is sold under this trademark. In order to more easily navigate the types of readers, we will provide a diagram of their marking.
For example, the designation APR-03HW corresponds to a reader in design 3, designed to work with HID Corporation cards, and having a Wiegand 26-bit output interface. The appearance of the APR-OZhx, APR-04xx and APR-05xx readers is shown in Figure 4.
Special mention should be made of the APR-05xx reader, which is made in a stainless steel case and is intended for outdoor installation in cases where increased protection against vandalism is required.
The main characteristics of the readers are given in Table 2 below
It remains only to add that the retail price for all readers is about 200 dollars