New High Frequency Communication Protocol Listening Circuit
A high-frequency communication and circuit technology, applied in the field of new high-frequency communication protocol listening circuits, can solve the problems of no energy source, weak fundamental signal, and difficult demodulation.
Active Publication Date: 2015-11-25
SHANDONG HUAYI MICRO ELECTRONICS
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Problems solved by technology
Since the card is passive in the system and has no energy source itself, the information is transmitted by modulating the 847kHz subcarrier, the fundamental wave signal is weak and difficult to demodulate
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[0017] Combine below Figure 1-3 The present invention is described in further detail.
[0018] The novel high-frequency communication protocol listening circuit of the present invention includes two parts: a data acquisition circuit and a data processing system. The data acquisition part is built by analog components to complete signal acquisition, filtering, conversion and other operations; the data processing part is composed of FPGA, EEPROM, etc., to complete signal decoding, storage and communication with the host computer, receive commands from the host computer, and transmit data to the host computer machine operation.
[0019] According to the 14443 protocol, the carrier of all signals is a sine wave signal of 13.56MHz. The modulation method from the card reader to the smart card is 100% ASK mode, and the modulation method from the smart card to the card reader is, on the 13.56MHz carrier signal, first modulate an 847KHz sub-carrier signal, and then on the sub-carrie...
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The invention belongs to the field of design of high-frequency circuits, in particular to a novel high-frequency communication protocol monitoring circuit for monitoring interaction data of a non-contact intelligent card and a card reader. The novel high-frequency communication protocol monitoring circuit comprises a data acquisition circuit and a data processing system, wherein the data acquisition circuit comprises an induction antenna, an automatic gain control circuit, a bandpass filter, judgment circuits, an amplifier and an FPGA (Field Programmable Gate Array) decoding module; the induction antenna is connected with the automatic gain control circuit, two input ends of the automatic gain control circuit are respectively connected with the bandpass filter and the judgment module, the bandpass filter is connected with the other judgment circuit through the amplifier, output ends of the two judgment circuits are connected with the FPGA decoding module; and the data processing system is a system on a chip, which is built on an FPGA. According to the invention, the characteristic of weak return signals of the card is fully considered, the signal sent by the card reader and the signals sent by the card are demodulated, and uploaded to an upper computer after processed by the FPGA; and the monitored data storage function is realized.
Description
technical field [0001] The invention belongs to the field of high-frequency circuit design, in particular to a novel high-frequency communication protocol interception circuit for intercepting interactive data between a non-contact smart card and a card reader. Background technique [0002] The non-contact smart card is a kind of data transmission and exchange through the electromagnetic induction of the coil by plastic-sealing the induction coil and the IC chip in a card. Because there is no physical contact between the smart card and the card reader during the communication process, and a certain transmission distance is allowed, various failures caused by physical contact are avoided, and it is convenient to use. This solution involves a widely used non-contact based on the 14443ISO protocol. smart card. Contactless smart cards are used in access control, micropayment, social security cards, etc. With the replacement of bank cards and the improvement of people's security...
Claims
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IPC IPC(8): G06K7/00
Inventor 沈国新
Owner SHANDONG HUAYI MICRO ELECTRONICS