Operational Description

FCC ID: ZEROCR640

Operational Description

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FCCID_1764775

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

The USB Hub #1 is mainly used as a placeholder for future expansions. The USB hub #2 is used to connect the camera and the RFID to the USB upstream bus. The USB camera imager controls both the sounder and the lighting board through SPI and I2C respectively. The Lighting board is quite flexible to provide UV or IR or white illumination as requested by the imager. The RFID contactless reader drives two independent antennas. There is one antenna around the glass window. This antenna will be referred as antenna #1 in this document. The other antenna is behind the front face of the product. This antenna will be referred as antenna #2 in this document. Typically, both these antennas will be scanning for RFID passports – one at a time. High Speed USB Hub (#1 & #2): Device classification 2 port USB High speed hub Operating Voltage / Current 3.3V / 150mA Digital/Analog Digital circuitry Crystal Frequency 24 MHz PLL Multiplier x20 (480 MHz internal frequency) Data transfer rate 480Mbps Intentional Radiation No Software requirements USB host should have generic USB hub driver. All windows machine supports this USB hub class and it should start up right away. There are not application software requirements. Operational Description: High speed USB hub #1: This high speed USB hub is used for future extension of the product. High speed USB hub #2: This High speed USB hub provides USB connectivity to the RFID and the camera. It provides two USB downstream ports. One of the downstream ports is connected to a RFID full speed device and the other is connected to a 1.3 Mega pixel imager. Camera Imager: Device classification USB 2.0 High speed camera Operating Voltage / Current 5V / 150mA Digital/Analog Digital circuitry Crystal Frequency 24 MHz PLL Multiplier x20 (480 MHz internal frequency) Data transfer rate 480Mbps Intentional Radiation No 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

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. For normal operation camera application software like Amcap or IScap should be running. It should be noted that the lighting circuit is controlled by the imager. The right illumination could be selected appropriately by the imager circuit and this kind of arrangement helps the USB host software to control the illumination. The following diagram shows the internal blocks of the camera imager along with the lighting circuit. Fig 2: Camera imager internal block diagram

Lighting board: Device classification Boost regulator for lighting application Operating Voltage / Current 5V / 250mA Digital/Analog Analog circuitry Switching Frequency ~500KHz LED drive Voltage / Current ~25V / 20mA (Drives a string of IR, UV, White LEDs) Intentional Radiation No Software requirements None. Starts up as soon as power is applied Operational Description: The lighting board drives a set of IR, UV and white LEDs. The circuit is controlled by the imager circuit through I2C interface. The choice of IR/UV/White illumination is done by the host application and is handed down to the lighting board through the I2C interface. The lighting board has a step up DC-DC converter and current controlled LED drivers to accomplish the intended purpose. Sounder: Device classification Audible tone generator Operating Voltage / Current 3.3V / 20mA Digital/Analog Digital circuitry Operating Frequency 8 MHz Intentional Radiation No Software requirements None. Camera imager digital circuit controls the tone generator. The communication is through SPI interface operating at 100KHz. Operational Description: 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.

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 PLL Multiplier x6 (48 Mhz internal frequency) Data transfer rate 12Mbps Intentional Radiation No Software requirements Microsoft CCID smartcard driver is required. Only if the driver is loaded in the host machine the digital section will enable the RFID analog section. There are no application software requirements to get the RFID active. However, to reader RFID passport application software (like Golden reader tool) is required. RFID Contactless Reader – Analog Section Device classification RFID transceiver Operating Voltage / Current 5V / 150mA RFID protocol ISO14443 Type A and Type B Digital/Analog Analog circuitry Crystal Frequency 13.56 MHz PLL Multiplier None RF Data transfer rate 424 Kbps Intentional Radiation Yes Carrier frequency 13.56 Mhz +/- 7 KHz Sub Carrier frequency 847 KHz (max) Number of Antenna 2 Output power < 250 mW RF field strength 6 A/m (RMS) Software requirements Refer the RFID contactless reader - digital section software requirements Operational Description: The RFID contactless reader is a proximity reader that operates on 13.56 Mhz carrier frequency. It communicates to RFID passports using ISO14443 A/B protocols. The reader has two inbuilt antennas and it keeps switching the carrier between the two antennas, polling for RFID passports. The following diagram shows the internal blocks of the RFID reader.

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. The RFID reader uses loop antenna to radiate RF energy. The antennas are tuned to 50 Ohm impedance with a phase angle of +/- 10 degrees. The following diagram shows a simplified circuitry of the antenna. Fig 4: RFID loop antenna circuit The antenna board has two loop antennas tuned to operate at 13.56 MHz. Antenna #1 is around the glass window and antenna #2 is below the front face of the product. Variable capacitors are used in place of C1 and C2 so that the antenna could be tuned accurately during production. The following plots show a typical antenna impedance plots for both antenna #1 and #2.

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. The antenna switching and the polling sequence timing are shown in the following diagram.

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. It should be noted that the reader always does transceive operation. (i.e. Transmits command and receives or expects reception of data from the RFID passport). Hence, it is NOT possible to have the reader in transmit only or receive only mode.


Document Created: 2012-04-25 10:55:46
Document Modified: 2012-04-25 10:55:46
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