Design and Development of a Wireless Radio Frequency Identification Reader Communication System at UHF Band

Radio Frequency Identification (RFID) system has been widely used recently to replace a bar code system. The purpose of the RFID device is the same as a bar code device that provides a unique identifier data for an object. In the bar code device, the identifier data is printed on the object, while in the RFID device the identifier data can be stored and updated from time to time because it has a small size of memory chip or microprocessor located in its tag. Besides that, the RFID device does not need a line of sight to retrieve the data from the tag since it uses a magnetic wave or radio frequency wave at 134.2 KHz or 13.56 MHz to communicate between the reader and tag. The common RFID reader in the market nowadays is using a wire communication between the reader and the host computer. This limits the reader performance since it is not portable. To make it portable, the device can be connected to the Personal Digital Assistant (PDA) or Bluetooth wireless device, but the solutions are costly. In this thesis, the research is concentrated on the design and development of the communication system between the reader and the host computer. The communication between the RFID reader and the computer host is by using wireless and the communication is set to RS232 protocol. The system is operated at UHF 370 MHz band and it uses an amplitude shift keyed (ASK) modulation technique The system is established by modulating the amplitude of the high bit or bit ‘1’ of the signal at radio frequency wave at the UHF carrier wave. For the low bit or bit ‘0’ there is no radio frequency (RF) modulation taken place at the transmitter circuit, therefore the receiver does not receive any RF modulation wave from the RF transmitter reader and this is defined as low bit or bit ‘0’ at the receiver. This RFID wireless reader communication system can provide a good communication range in between 20 to 30 meters for line of sight or without line of sight. It is very useful for the outdoor such as tree tagging and electronic gardening applications. Furthermore, the designed RF transceiver is cost effective as compared to other RF transceiver modules available off the shelf and also from other wireless communication technologies such as Bluetooth or Wireless Fidelity (Wifi).

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