Abstract:
Radio Frequency Identification (RFID) is a rising technology in the world nowadays. Many systems have already introduced and many systems are planned and will hopefully be implemented.
RF applications, such as television, cell phones and other devices that are used in many applications. The RFID (radio frequency identification) system is used for automatic detection of objects, using radio frequency.
The goal of project is to make something similar to the security system with a minimum range. The general goal is to produce RFID reader that is able to receive more than 1bit of data from the RFID Tag and to also design an oscillator to modulate the signal on the receiver side.
RFID is comparable in idea to bar coding. Bar code use a reader and coded labels that are attached to a card or any item, whereas RFID uses a reader and particular RFID devices that are attached to an item. Bar code uses optical signals to pass information from the label to the reader; RFID uses RF signals to pass information from the RFID system to the reader. The reader circuit provides 125 KHz carrier frequency, transmit that to tag, and detect the magnetic coupling from the tag. In order to understand this data we must remove the carrier frequency from the modulated signal. After removing the carrier frequency from the modulated signal we get the envelop frequency which can be magnified into something measurable. The main parts of this project are Transmitter stage, Half Wave Rectify and Filtering, Data Creation Stage and Power Supply. In transmitter stage RF Choke is used to filter out the upper harmonic frequencies found in the square wave output leaving the fundamental frequency (125 KHz). In half wave rectification the carrier frequency 125 KHz is separated from the modulated envelop because only envelop has the actual data. In filtering the low pass filter is used which allows the lower frequencies and eliminates the higher frequencies and 125 KHz carrier frequency.
