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OCR640 – Operational Description
OCR640 is an USB connected passport reader which has a Camera Imager and a RFID contactless reader.
The camera is used to capture images by the host application, which then decodes the passport MRZ
data. The MRZ data is then sent to the RFID reader to authenticate with the RFID chip in the passport to
read the data. The following figure shows the hardware architecture of OCR640.
Fig 1: OCR640 Hardware Architecture
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Table of Contents
Summary of Contents for Access OCR640
- Page 1 OCR640 – Operational Description OCR640 is an USB connected passport reader which has a Camera Imager and a RFID contactless reader. The camera is used to capture images by the host application, which then decodes the passport MRZ data. The MRZ data is then sent to the RFID reader to authenticate with the RFID chip in the passport to read the data.
- Page 2 (480 MHz internal frequency) Data transfer rate 480Mbps Intentional Radiation Image resolution 2048 x 1536 (3.1 Mega pixel) Software requirements USB host should have Access IS camera drivers installed. The camera starts-up only if camera application software (like Amcap or IScap) is...
- Page 3 running. The camera shuts down when then application software is closed. Operational Description: The camera imager is a USB 2.0 high speed camera capable of streaming images at 3.1 Mega pixel resolutions. The data from the camera reaches the USB host through the USB high speed hub. It should be noted that the camera is in shutdown state when there is no application software running.
- Page 4 Sounder block is basically a small microcontroller that generates tones. The sounder controller receives commands from the camera digital circuit on which tone it has to play. With this kind of arrangement, the USB host software can access the sounder through the camera digital circuit.
- Page 5 RFID Contactless Reader RFID contactless reader contains both digital and analog section. Information on these two sections are provided below. RFID Contactless Reader – Digital Section Device classification USB full speed device Operating Voltage / Current 5V / 50mA Digital/Analog Digital circuitry Crystal Frequency 8 MHz...
- Page 6 Fig 3: RFID reader internal block diagram Note that there are two identical channels for driving antenna #1 and antenna #2. The RFID digital circuit controls both the antenna channels. The EMC filter provides the necessary attenuation to block higher frequency harmonics from reaching the antenna. The matching network along with the balun provides the required matching to a 50 Ohm antenna.
- Page 7 Z = 50 Ohm (+/- 3 Ohm) Ф = +/- 10 degree Fig 5: OCR640 Antenna #1 – Typical Impedance and Phase plot Z = 50 Ohm (+/- 3 Ohm) Ф = +/- 10 degree Fig 6: OCR640 Antenna #2 – Typical Impedance and Phase plot As said earlier, the RF energy is switched between the antennas one at a time, scanning for RFID passports.
- Page 8 Fig 7: RFID antenna switching and polling sequence Once a passport is detected the RFID reader exchanges data with it and stays locked on to the RFID passport. As long as the passport stays in the communicable range, the antenna switching/polling does not happen.