WO2011140732A1

WO2011140732A1 - Short-range communication method and system

Info

Publication number: WO2011140732A1
Application number: PCT/CN2010/073817
Authority: WO
Inventors: 肖德银
Original assignee: 国民技术股份有限公司
Priority date: 2010-05-10
Filing date: 2010-06-11
Publication date: 2011-11-17
Also published as: CN102244530A; CN102244530B

Abstract

A short-range communication method and system are provided. The method includes: according to a preset emission parameter, a card reader emits a low-frequency alternating magnetic field signal, of which the frequency includes at least the frequency points of low-frequency, f_Land f_H; a mobile radio frequency device receives, and detects the low-frequency alternating magnetic field signal at the frequency point f_L and the frequency point f_H, and magnifies the signal to a constant-amplitude voltage signal corresponding to the distance, adjusts the preset voltage threshold Vt to Vt+K*δ_HL；if the voltage signal is greater than or equals to Vt+K*δ_HL, then the preset valid distance space is entered, the mobile radio frequency device gets the identity information of the card reader, and transfers it to the card reader together with its own identity information; the card reader receives the information, compares whether the identity information in the information is identical to its own identity information, if they are identical then makes a card swiping deal with the mobile radio frequency device. By this method, the card swiping deals can be made for various mobile terminals without calibration, and the distance control effects are identical.

Description

Description of the book, a large communication method and system

The present invention relates to the field of communications, and in particular, to a short-range communication method and system. Background technique

With the popularization of mobile terminals, the application requirements for mobile terminal payment using mobile terminals are very urgent. At present, there are various implementation solutions, but each has its own disadvantages. At present, a radio frequency function (referred to as a radio frequency SIM card) is added to a subscriber identity module SIM (Subscr iber Ident module) card in a mobile terminal, or a short-range communication module is added on a mobile terminal motherboard to implement a mobile terminal near The method of communication, the latter is called NFC (Near Field Communication). The emergence of these methods makes the mobile terminal a super intelligent terminal that can be recharged, consumed, traded and authenticated, which greatly satisfies the market. Urgent needs.

Among them, the short-distance solution of the mobile terminal based on the radio frequency SIM card has received extensive attention with its advantages such as the single order and no need to change the mobile terminal. In this solution, the radio frequency SIM card adopts UHF (Ultra tra High Frequency) technology. Since UHF, especially the RF SIM card using the 2.4 GHz ISM common frequency band (ie industrial, scientific and medical frequency bands), the operating frequency is very high, the size of the antenna is small, and a small antenna can be placed in the SIM card to transmit enough Intensity signal, even if the radio frequency SIM card is embedded in the mobile terminal, the RF signal can still be transmitted from the mobile terminal. In the card reader, the industry's mainstream RF (Radio Frequency) transceiver chip can be used without additional amplification and reliable reception. The radio frequency signals of most mobile terminals, so that the mobile terminal can have the short-range communication function without any structural change to the existing mobile terminal. However, different mobile terminals have great differences in the transmission effect of radio frequency signals due to different internal structures. The radio frequency SIM card radio communication distance of a mobile terminal with strong transmission may reach a distance of several meters, and the radio frequency SIM card communication distance of a mobile terminal with weak transmission. Only a few centimeters can be reached. In order to avoid the huge difference in RF signal attenuation between different mobile terminals, the RF SIM card must be calibrated, that is, the attenuation parameters of the mobile terminal must be recorded into the card before use. The need for calibration is a major issue with RF SIM cards.

Another mobile payment technology NFC is based on the evolution of the contactless card technology based on the I S014443 standard The fundamental difference between the two is that they use a magnetic field of 13.56 MHz to transmit signals and energy. The main problems of NFC technology are:

1. The mobile terminal must be modified to achieve reliable two-way data communication. The magnetic field line of NFC cannot be integrated into the SIM card or SD card (Secure Di ta ta l Memory Card) /TF (TransFLa sh, flash memory) Cards for mobile terminals such as cards.

At the frequency of 13.56MHz, the reader and the card use the inductor and the coil to couple the signal and transmit the energy. The direction of the card reader to the card needs to transmit energy and the frequency modulation signal at the same time. The size of the upper receiving coil has higher requirements; the card is in the direction of the card reader, and the card relies on the short-circuit and the load modulation mode of the open card, instead of relying on external energy to directly transmit the field strength to transmit information to the card reader. Since the load modulation signal requires that the coupling coefficient between the card line and the card reader line is higher, the information transmitted by the card reader decoding card is facilitated, which further increases the size and area requirements of the antenna on the card. On the other hand, since the frequency of 1 3.56MHz is low, the size of the coupled coil is relatively large. In view of the above factors, NFC requires that the antenna cable in the mobile terminal is sufficiently large, and the size cannot be placed in a card for a mobile terminal such as an SIM card or an SD/TF card, and not only the metal and other conductive materials on the mobile terminal. Objects can seriously interfere with the receiving and load modulation effects of the antenna. In order to achieve good communication performance in near field communication, the mobile phone must be customized to optimize the effect of the antenna. The retrofit point is, for example, placing the multi-turn antenna of the card on the battery back cover of the mobile terminal, or guiding the antenna from the terminal main board to the back of the battery through a flexible PCB, the area of the antenna is equivalent to the size of the ordinary battery, and the back cover of the mobile phone Cannot be made of metal.

2. The 1 56 used by NFC requires calibration to be used for distance control.

Even if an NFC antenna can be replaced in any mobile terminal, because it uses a frequency of 1.56 MHz, the frequency signal will form a strong eddy current effect when encountering metal and other conductive objects, and the signal strength will follow the mobile terminal. The structure changes, so that a large fluctuation of the field strength is formed on the NFC card receiving antenna, and the uncalibrated distance control cannot be performed.

Figure 1 shows the voltage-distance curve of the test in the case where the coil receiving circuit is placed in various mobile terminals and the carrier is kept constant at the same 14443 P0S machine. The signal strength value is the necessary amplification of the receiving antenna induced voltage. After the value, the magnification remains constant, just pay attention to the relative change in intensity with distance. It can be seen that the field strength difference received by different terminals is > 30dB, and the field strength change from 1 cm to 10 cm in the same terminal is about 25 dB. The field strength change caused by the difference of the mobile phone has exceeded the terminal within the control range of l cm to 10 cm. Field strength changes, so the same threshold cannot be used Each terminal performs distance control, that is, no calibration distance control is possible. Summary of the invention

The technical problem to be solved by the present invention is to provide a short-distance communication method and system, so that a mobile terminal having various short-range communication functions can realize card payment transactions such as electronic payment without calibration, and the distance control effects of different mobile terminals are consistent. Improve the user's experience by improving the deviation of the swipe distance due to differences in individual terminals.

In order to solve the above technical problem, the present invention provides a short-range communication method for a short-range communication system including at least one card reader and at least one mobile radio frequency device, including:

Step a, the card reader transmits a low-frequency alternating magnetic field signal according to a preset transmission parameter, where the low-frequency alternating magnetic field signal carries identity identification information of the card reader, and the transmission parameter includes a frequency of the low-frequency alternating magnetic field signal. The frequency is equal to or less than the highest frequency f O of the system without calibration work, and the frequency includes at least 2 low frequency frequencies f\ and f _H , and the frequency point f\ is less than the frequency point f „;

Step b, the mobile radio frequency device receives, detects the low frequency alternating magnetic field signal at the frequency point f\ and the frequency point f _H at each distance point and amplifies the voltage signal with a constant amplitude corresponding to the distance, and calculates the frequency point f\ And the difference S _H L of the amplitude of the low frequency magnetic field signal received at the frequency point f _H , the preset voltage threshold Vt is adjusted to be V t+K* δ HL, where K is a preset adjustment coefficient, and Vt+K* δ HL is used as an adjusted voltage threshold to determine whether the terminal carrying the mobile radio frequency device enters a preset effective distance interval, and the voltage threshold Vt is the same for all terminals loaded with the mobile radio frequency device;

Step c, if the voltage signal corresponding to the received low frequency alternating magnetic field signal is greater than or equal to the adjusted voltage threshold Vt+K* S _H L, the terminal loaded with the mobile radio frequency device enters a preset effective distance Interval, the mobile radio frequency device acquires the identity identification information of the card reader from the received low frequency alternating magnetic field signal, and transmits the card identification device together with the identity identification information thereof to the card reader through the radio frequency channel;

Step d, the card reader receives the information transmitted by the mobile radio frequency device through the radio frequency channel, and compares whether the identity identification information of the card reader in the information is consistent with the identity information of the card, and if they are consistent, the identity information and the identity are The combination of the identification information of the mobile radio device is used as a combined address, and the mobile radio device performs a card transaction through the radio frequency channel.

Further, the above method may further have the following features. In the step a, the frequency point f\ and the frequency point f _H are determined by the following steps: Step a, arbitrarily select a terminal or an obstacle, and if the card reader fixed the transmission parameter, keep the physical position of the terminal or the obstacle and the card reader fixed, and test the movement of the terminal or the obstacle. The frequency amplitude of the low frequency magnetic field signal at the frequency point f _t received by the radio frequency device is V _t , and the frequency point f _t is the lowest frequency point f _t . As the starting point, the lowest frequency point f _t . The voltage amplitude of the test signal to the low frequency magnetic fields as V _t. ;

Step a2, depicting V _t and V _t . The difference between the difference and the frequency f _t , taking the frequency f at the inflection point on the relationship curve is the maximum operating frequency f _M of the terminal or obstacle;

Step a3, and then select other typical terminals and obstacles, repeat step a1 and step a2, obtain a series of maximum operating frequencies of typical terminals and obstacles, and take the minimum frequency value of the series of maximum operating frequencies as the system has no calibration work. The highest frequency fO, taking a frequency point f\ that is less than fO, takes a frequency point f _H that is less than or equal to fQ, and makes the frequency point f _H greater than the frequency point f\.

Further, the above method may further have the following features. In the step a, the transmitting parameter further includes a modulation mode, an encoding mode, and a transmitting magnetic induction intensity amplitude Br, wherein the modulation mode, the encoding mode, and the transmitting magnetic induction intensity amplitude Br pass The following steps are selected:

Select any encoding method without an average DC component;

Select a carrier modulation mode with no modulation mode or no change in amplitude;

At a selected operating frequency F \ and f _H, modulation scheme and coding scheme, the selected first terminal and a typical noise within the mobile radio device is easy to realize a magnetic detection and amplification gain parameters, a test reader is not transmitting the low-frequency AC Moving the inherent noise voltage amplitude Vn of the detected voltage in the RF device under the condition of the variable magnetic field signal, and then measuring the detection voltage Vr in the RF device when the card reader transmits the low frequency alternating magnetic field signal by using the selected modulation and coding mode, and selecting the amplitude of the transmitted magnetic induction intensity The Br value makes Vr/Vn larger than SNR, and the SNR is the signal-to-noise ratio of the mobile radio device.

Further, the above method may further have the following features. In the step b, the preset adjustment coefficient K is determined by the following steps:

Step b11, testing the curve of the receiving voltage VL of the typical terminal and the obstacle at the selected working frequency point f\ and the receiving voltage V _H of the selected working frequency point f _H , the fluctuation range of the voltage VL is the fluctuation of the δ voltage V _H The range is δ _Η ;

Step Μ2, calculate the adjustment coefficient Κ, K value is equal to the ratio of SL to S _H L , and S _H L is equal to δ _Η minus the difference of 3.

Further, the foregoing method may further have the following features, in the step b, the preset power The voltage threshold Vt is determined by the following steps:

Step b21, determining a distance control target (Din, Dv) of the system, wherein Din represents a range of 0 ~ Din distance to ensure that the loaded mobile RF terminal device can swipe, Dv represents a range of distance fluctuation, and Din~Din+Dv is allowed in the range. Swipe, greater than Din+Dv is not allowed to swipe;

Step b22, determining that the error range of the voltage difference S at the frequency points f\ and f _H detected by the mobile radio device of the terminal caused by the card reader is δ _κ ;

Step b23, determining that the error range of the voltage difference S _H L at the detected frequency points f\ and f _H caused by the mobile radio frequency device itself is S _C ;

Step b24, determining, by the distance control target (Din, Dv), the fluctuation range of the detection voltage in the mobile radio frequency device is δ _τ , and δ _τ is equal to the average field strength obtained by the equivalent voltage distance curve formed by each typical terminal and the obstacle The voltage value of the slope of the attenuation curve is the difference between the voltage value corresponding to the point D i η on the curve and the voltage value corresponding to the point ( Din + Dv ), δ _τ = δ _c + δ _R ;

Step b25, under the selected transmission parameters, measure the voltage values of the typical terminals and obstacles at the frequency point f\ and the frequency point f _H , the transmission parameters including the frequency, modulation mode, and coding mode of the low frequency alternating magnetic field signal And emitting magnetic induction intensity amplitude Br;

Step b26, calculating the difference δ HL of the received voltage of the same terminal or obstacle at the frequency f\ and the frequency f _H ;

Step b27, calculating the receiving voltage V _L +K* δ _HL of the mobile terminal loaded with the mobile radio device at the frequency f\;

Step b28, the equivalent correction voltage curve formed by VL+K* S _H L of different mobile terminals, obtains the reference voltage distance curve, the intermediate value of the reference voltage distance curve correction curve, and the upper boundary and the lower boundary of the typical terminal curve The voltage amplitude is δ _τ /2;

Step b29, the detection voltage threshold Vt in the mobile radio device is selected, and the voltage value corresponding to the (Din+Dv/2) point on the reference voltage distance curve is the Vt value.

Further, the above method may further have the following feature, the frequency of the low frequency alternating magnetic field signal is in a special low frequency band or a low frequency band or a low frequency band, and the frequency range of the special low frequency band is 300 Hz - 3000 Hz, the very low frequency The frequency range of the frequency band is 3KHz ~ 30KHz, and the frequency range of the low frequency band is 30 KHz ~ 300KHz.

Further, the above method may further have the following feature, the frequency of the low frequency alternating magnetic field signal is 300 Hz to 50 kHz. Further, the above method may further have the following characteristics: the frequency of the low frequency alternating magnetic field signal is 500 Ηζ, 1 ΚΗζ, 1 · 5 ΚΗζ, 2 ΚΗζ, 2 · 5 ΚΗζ, 3 ΚΗζ, 4 ΚΗζ, 5 ΚΗζ, 10 ΚΗζ, 20 ΚΗζ or 30 ΚΗζ.

Further, the foregoing method may further have the following characteristics: the coding mode is a Manchester code, a differential Manchester code, or a return-to-zero code; and the modulation mode is an open key control method, a phase shift keying method, or a frequency shift keying method. .

In order to solve the above technical problems, the present invention also proposes a short-range communication system comprising at least one card reader and at least one mobile radio frequency device, wherein:

The card reader is configured to transmit a low frequency alternating magnetic field signal according to a preset transmission parameter, where the low frequency alternating magnetic field signal carries identity identification information of the card reader, and the transmission parameter includes a low frequency alternating magnetic field signal Frequency, which is equal to or less than the highest frequency f O of the system without calibration operation, and the frequency includes at least 2 low frequency frequencies f\ and f _H , the frequency point f\ is less than the frequency point f; and is also used to receive the movement The information transmitted by the radio frequency device through the radio frequency channel compares whether the identity information of the card reader in the information is consistent with the identity information of the card, and if they are consistent, the combination of the identity information of the card and the identity information of the mobile radio device As a combined address, performing a card transaction with the mobile radio device through a radio frequency channel;

The mobile radio frequency device is configured to receive, detect, and amplify a low-frequency alternating magnetic field signal at a frequency point f\ and a frequency point f H at each distance point, and amplify the voltage signal with a constant amplitude corresponding to the distance, and calculate the frequency at the frequency point. F \ amplitude and low frequency magnetic field signal frequency f _H of the received difference value S _H L, adjust the predetermined voltage threshold V t to _{V t + K * S H L} , where K is a predetermined adjustment coefficient to Vt +K* S _H L is used as an adjusted voltage threshold to determine whether the terminal loaded with the mobile radio frequency device has entered a preset effective distance interval, and the voltage threshold Vt is the same for all terminals loaded with the mobile radio frequency device And for acquiring the card reader from the received low frequency alternating magnetic field signal when the voltage signal corresponding to the received low frequency alternating magnetic field signal is greater than or equal to the adjusted voltage threshold Vt+K*S _H L The identification information is transmitted to the card reader through the radio frequency channel together with the identity information of the card; and is also used for card-swapping transactions with the card reader through the radio frequency channel.

Further, the above system may further have the following features, the card reader comprising at least one low frequency transmission line, at least one driving circuit, at least one encoding circuit, at least one first main processor, at least one radio frequency transceiver circuit, and at least one An RF antenna, the low frequency transmission line, a driving circuit, an encoding circuit, a first main processor, a radio frequency transceiver circuit, an RF antenna, and a serial connection in series; The mobile radio frequency device includes at least one low frequency magnetic induction circuit, at least one low frequency amplification circuit, at least one threshold determination and demodulation circuit, at least one second main processor, at least one radio frequency transceiver circuit and at least one radio frequency antenna, and the low frequency magnetic induction The circuit, the low frequency amplifying circuit, the threshold determining and demodulating circuit, the second main processor, the radio frequency transmitting and receiving circuit, and the radio frequency antenna are sequentially connected in series.

Further, the above system may further have the following feature: a modulation circuit is further disposed between the driving circuit of the card reader and the encoding circuit.

Further, the above system may also have the following features, the low frequency emission line 圏 being an enameled wire 圏 or a PCB wire 圏.

Further, the above system may further have the following feature: the number of turns of the low frequency transmission line is greater than

10 years old.

Further, the above system may further have the following feature: the number of turns of the low frequency transmission line is 50 ~ 500 圏.

Further, the above system may further have the following feature: the low frequency emission line is filled with a ferrite core or a core.

Further, the above system may further have the following feature: the cross-sectional area of the area surrounded by the low-frequency emission line 最 is wider than the cross-sectional width of the mobile radio frequency terminal.

Further, the above system may further have the following feature, the cross section of the area surrounded by the low-frequency emission line 至少 includes at least a circular area of 3 cm in diameter or a square area of 3 cm * 3 cm.

Further, the above system may further have the following features: the low frequency magnetic sensing circuit is a PCB wire 漆, an enamelled wire 圏, a Hall device or a giant magnetoresistive device.

Further, the above system may also have the following features, the mobile radio frequency device being placed in the mobile terminal.

Further, the above system may also have the following features: the mobile radio frequency device is placed in a SIM card, a UIM card, a US IM card, a TF card or an SD card in the mobile terminal.

Further, the above system may also have the following features: the mobile terminal is a mobile phone, a personal digital assistant PDA or a notebook computer.

Further, the above system may further have the following feature: the identity identification information is an identification code. The invention enables the credit card transaction such as electronic payment to be realized for various mobile terminals having the short-distance communication function without calibration, and the distance control effects of different mobile terminals are consistent, and the influence of the deviation of the card-swapping distance due to the difference of individual terminals is improved. The user experience. DRAWINGS

Figure 1 is a voltage-distance curve tested in the case where the coil receiving circuit is placed in various mobile terminals and the carrier is kept constant on the same 14443 P0S machine.

2 is a structural block diagram of a system for selecting a highest frequency f O of a system without calibration work in the short-range communication method of the present invention;

Figure 3 is a graph showing the attenuation curves of different obstacle frequencies and shielding characteristics;

4 is a voltage waveform diagram of a received voltage signal when an unmodulated direct baseband transmission is detected inside a mobile radio frequency device and a received voltage signal when sinusoidal FSK modulation is detected;

Figure 5 is a schematic diagram of a calculation method of a reference voltage distance curve;

6 is a structural diagram of a short-range communication system according to an embodiment of the present invention;

Figure 7 is a schematic diagram of a low frequency transmitting portion of the card reader;

8 is a schematic diagram of a format of a low frequency data frame of a card reader;

Figure 9 shows the voltage curves after 2k and 4K frequency correction;

Figure 10 is the attenuation curve of the 2k frequency mobile terminal;

Figure 11 shows the attenuation curve of the 4k frequency mobile terminal. detailed description

Firstly, the terminal appearing in the following text refers to a terminal loaded with a mobile radio device by default, and refers to a terminal that can be moved, that is, a mobile terminal, such as a mobile phone, etc., a distance card reader and a mobile radio device. The distance between the reader, that is, the distance between the card reader and the terminal loaded with the mobile radio device.

The invention aims at the distance control problem of the close-range transaction of the radio frequency device (especially the radio frequency card built in the terminal, such as the radio frequency S IM card) and the card reader device, and proposes a function of transmitting and transmitting with a low frequency alternating magnetic field and a radio frequency. A short-distance communication system comprising a signal transceiving function card reader and a corresponding mobile radio frequency device with a low-frequency alternating magnetic field induction receiving function and a radio frequency signal transceiving function, and a short-distance communication method corresponding to the system. The invention utilizes the attenuation inconsistency of the low frequency magnetic field signal of different frequency points to penetrate the mobile radio frequency device to identify the attenuation amount of the low frequency magnetic field signal of the mobile radio frequency device, and adjusts the gain of the received signal or the distance determination threshold according to the attenuation amount to achieve different movements. The effect of the RF device is consistent with the control. The high-frequency RF can effectively penetrate the terminal to complete the high-speed. Two-way communication for trading. The system determines the distance of the low frequency signal attenuation and automatically adjusts the gain of the receiving end or adjusts the distance judgment threshold by using a preset threshold and according to the difference in amplitude of the signals received by the mobile radio frequency device to complete the distance without calibration. Detection and control, that is, the card reader transmits two low frequency alternating magnetic field signals according to preset transmission parameters, and the mobile radio frequency device detects the magnetic field signal at each distance point and amplifies the voltage signal with a constant amplitude corresponding to the distance. Further preset threshold voltage Vt through door 2 and the detected voltage is different from a frequency difference _δ ΗΙ formed after compensation Vt + K * _δ ΗΙ threshold to determine whether to enter the terminal preset effective distance range (effective range section That is, the range of the card is allowed to be swiped. The voltage threshold Vt is the same for all terminals, and no calibration is required. The product compensation term K* S _H L is a fixed constant once two low frequency points are selected, and S is a pair of radio frequency devices. The difference between the low frequency frequency and the received signal voltage is used to automatically compensate the attenuation of the low frequency point by the mobile terminal. The invention combines the low-frequency one-way communication and the RF two-way communication to complete the unique binding of the card reader and the mobile radio device, and after binding, completes the bidirectional high-speed large-data communication through the radio frequency channel. The system of the invention can realize that the data communication distance (that is, the transaction distance) of the terminal (such as the mobile phone equipped with the radio frequency SIM card) containing the mobile radio frequency device and the card reader is reliably controlled within the specified range, and the terminal does not need to be calibrated. .

The principles and features of the present invention are described in the following description in conjunction with the accompanying drawings.

The short-range communication method of the present invention is applied to a short-range communication system including at least one card reader and at least one mobile radio frequency device, and includes the following steps of step &, step b, step c and step d, respectively The steps are specified:

Step a, the card reader transmits a low frequency alternating magnetic field signal according to a preset transmission parameter, and the low frequency alternating magnetic field signal carries the identity identification information of the card reader, wherein the transmitting parameter includes a frequency of the low frequency alternating magnetic field signal, and the frequency or less, no calibration of the system of the highest frequency f O, and the frequency comprises at least two low-frequency point F \ and f _H, frequency F \ is less than the frequency f ";

It should be noted here that the frequency of the low-frequency alternating magnetic field signal in this step refers to the frequency corresponding to the high-end frequency cut-off point of the 3dB bandwidth of the spectrum of the low-frequency alternating signal.

The lower the frequency of the low-frequency alternating magnetic field of adjacent frequency points, the difference between the attenuation of the two frequency points of various types of terminals can reflect the attenuation of the low-frequency point of the terminal, and the frequency selection system is used. As shown in Figure 2, the frequency points that meet this rule are selected to achieve non-calibrated distance control. Using a standard signal source to transmit a low frequency alternating magnetic field signal through a standard magnetic field emission line, in each typical The low frequency alternating magnetic field signal is received by the mobile terminal and the obstacle. The standard signal source is used to transmit the low frequency alternating magnetic field signal of the two frequencies through the standard magnetic field emission line, and the two frequencies are received within each typical mobile terminal and obstacle. The low frequency alternating magnetic field signal adjusts the transmission frequency until the frequency point f 0 is found, so that the attenuation of the frequency of the mobile terminal to the two frequency points does not increase, and the frequency is the highest frequency point f O of the system without calibration. Above this frequency point, the difference between the attenuation of the received signal of the mobile terminal on different frequencies and the attenuation of the low frequency point of the two frequency points by the mobile terminal cannot be proportional to the compensation of the distance threshold judgment, thereby making the distance The accuracy of the control is reduced.

2 is a structural block diagram of a system for selecting a maximum frequency f O of a system without calibration work in the short-range communication method of the present invention. As shown in FIG. 2, the frequency point selection system is composed of a signal source 505 and a low-frequency magnetic field emission line. The 504 is composed of a typical mobile terminal 501 and an obstacle, a signal strength tester 503 (a voltmeter, an oscilloscope, a spectrum analyzer, etc.), and the mobile terminal 501 has a low frequency receiving module 502 therein. Signal source 505 accurately produces signals of various frequencies, waveforms, and amplitudes. The principle of frequency point selection is: signal source 505 generates a sine wave signal of fixed amplitude frequency f, which is transmitted through transmission line 504, and low frequency receiving module 502 is placed inside selected typical mobile terminal 501 or obstacle, and received low frequency. The signal is connected to the signal strength tester 503 through a dedicated signal line, and the signal strength tester 503 tests the received voltage. Changing the distance of the mobile terminal can obtain a curve of the detected voltage of the mobile terminal or obstacle under the condition of frequency f (hereinafter referred to as a voltage distance curve), and changing the mobile terminal or the obstacle can obtain a curve of the plurality of terminals, changing A different curve can also be obtained for the frequency f.

In step a, the highest frequency f O of the system without calibration work and the system operating frequency f\, f _H are determined by the following steps:

Step 101: arbitrarily select a terminal or an obstacle, and if the card reader fixed the transmission parameter, keep the physical position of the terminal or the obstacle and the card reader fixed, and test the movement of the terminal or the obstacle. The frequency amplitude of the low frequency magnetic field signal at the frequency point f _t received by the radio frequency device is V _t , and the frequency point f _t is the lowest frequency point f _t . As the starting point, the lowest frequency point f _t . The voltage amplitude of the low frequency magnetic field signal tested is V _t . ;

Step 102, depicting V _t and V _t . Curve and frequency difference f _T, whichever is the relationship between frequency f of the inflection point on the curve for the terminal or the maximum operating frequency f obstacle _M;

Step 103, selecting other typical terminals and obstacles, repeating steps a1 and a2, obtaining a series of maximum operating frequencies of typical terminals and obstacles, taking the maximum operating frequency of the series The minimum frequency value is the highest frequency f O of the system without calibration work, taking a frequency point fL smaller than f O , taking a frequency point f _H less than or equal to fo, and making the frequency point f„ larger than the frequency point f\.

Before proceeding with this step 102, a preparatory work is required to select typical terminals and typical obstacles. The selection principle of a typical terminal is mainly selected according to the number of terminal metals or conductive structures. The more metal, the greater the attenuation. For example, plastic casing, metal casing, thick metal shell, thin metal shell, large-size terminal, small-sized terminal, etc. can be selected. The number of typical terminals is not strictly limited. The selection of typical terminals can basically cover the attenuation characteristics of the terminal to the low-frequency alternating magnetic field signals. In order to avoid the difference of individual mobile terminals, the mobile terminal model authentication can be added to the application, and the mobile terminal that needs to support the payment application is attempted to perform a card test to confirm that the attenuation characteristics of the mobile terminal of the model meet the requirements. Typical obstacles can be selected from different materials of standard shape plastic, aluminum, copper, iron, stainless steel and other mobile terminal common materials, placed between the card reader and the mobile radio device as an equivalent obstacle measurement attenuation of the mobile terminal effect.

So far, in the case of limiting the distance control target, the highest frequency f O of the system without calibration work is determined, and the adjacent frequency points and f _H that are easy to implement by the system are selected according to f O . The system can adopt the modulation method or the method of directly transmitting the baseband signal. The maximum frequency component of the system operation is as long as it is not greater than f O , and the distance control does not need to be calibrated.

An example is the process of determining f O . Figure 3 shows the attenuation curves of four typical obstacle frequencies from ΙΚΗζ to 125 kHz and the received voltage of the mobile RF unit. As shown in Figure 3, there are 3 obstacles that turn at the receiving voltage of the mobile device at a frequency of 15 kHz, that is, the attenuation is no longer decremented. Then f O=15KHz can be the maximum frequency of operation of the mobile terminal with the carrier as the typical obstacle.

In step a, the transmission parameters may further include a modulation mode, an encoding mode, and a transmitting magnetic induction intensity amplitude Br. The basic principle of selecting the transmission parameters is to ensure that the mobile radio frequency device detects and amplifies the low-frequency alternating magnetic field signal emitted by the card reader at various distance points, and the signal is a constant voltage signal corresponding to the distance. 4 is a voltage waveform diagram of a received voltage signal and a received voltage signal when a sinusoidal FSK modulation is detected in a non-modulated direct baseband transmission detected by a mobile radio frequency device, wherein a is a received voltage signal waveform when the baseband is transmitted without modulation. Figure, b is a waveform diagram of the received voltage signal when sinusoidal FSK modulation. As shown in FIG. 4, the detection voltage signal is a variable voltage signal including demodulation information, and the signal may be an AC voltage signal without a DC component, or a voltage signal having a DC component, and the constant amplitude means that the AC component changes the most. The amplitude is constant between different transmission symbols.

The modulation mode, coding mode and emission magnetic induction intensity amplitude Br in the transmission parameters are as follows Step all to step al3 is selected:

Step all, select any encoding method without average DC component, such as Manchester code, differential Manchester code, return to zero code, etc.

In step a2, a carrier modulation mode with no modulation mode or no change in amplitude is selected, and the carrier modulation mode can select any modulation mode with no change in amplitude. For example, the carrier can adopt a sine wave, a pulse, a triangular wave, etc., and the modulation mode can be selected as a switch. Keying method (00K), phase shift keying method or frequency shift keying method (FSK); when using no modulation method, the encoded baseband signal is directly transmitted by the transmitting line after being driven by the driving circuit;

Step a3, selecting the amplitude of the transmitted magnetic induction intensity Br, by: selecting the typical noise terminal and the easy-to-implement magnetic detection and amplification in the mobile radio device under the selected operating frequency, modulation mode and coding mode less than fO Gain parameter, test the inherent noise voltage amplitude Vn of the detection voltage in the mobile radio device under the condition that the card reader does not transmit the low frequency alternating magnetic field signal, and then measure the radio frequency when the card reader transmits the low frequency alternating magnetic field signal by using the selected modulation and coding mode. The detection voltage Vr in the device selects the amplitude of the transmitted magnetic induction intensity Br, so that Vr/Vn>SNR, SNR is the signal-to-noise ratio of the mobile radio frequency device. The selection of the SNR value is usually as large as possible, but too large will cause the reader to transmit too much power, which is difficult to implement. The typical value can be selected as SNR=10. When the SNR is determined, Br is determined by the above method.

Step b, the mobile radio frequency device receives, detects the low frequency alternating magnetic field signal at the frequency point f\ and the frequency point f _H at each distance point and amplifies the voltage signal with a constant amplitude corresponding to the distance, and calculates the frequency point f\ And the difference S _H L of the amplitude of the low-frequency magnetic field signal received at the frequency point f _H , and the preset voltage threshold Vt is adjusted to be Vt+K* δ HL, where K is a preset adjustment coefficient to Vt+K* δ HL As the adjusted voltage threshold, it is determined whether the terminal carrying the mobile radio frequency device enters a preset effective distance interval, and the voltage threshold Vt is the same for all terminals loaded with the mobile radio frequency device;

The coefficient K can be obtained by a test adjustment method.

In step b, the preset voltage threshold Vt is determined by the following steps 201 to 208: Step 201, determining the distance control target (Din, Dv) of the system, wherein Din represents the mobile radio frequency loaded within the range of 0 ~ Din distance The terminal device can swipe the card, Dv indicates the distance fluctuation range, and the Din~Din+Dv range allows the card to be swiped, and the Din+Dv is not allowed to swipe the card.

Step 202, determining that the error range of the voltage difference S at the frequency points f\ and f _H detected by the mobile radio device of the terminal caused by the card reader is δ _κ ;

Step 203, determining the detected frequency points f\ and f _H caused by the mobile radio frequency device itself The error range of the pressure difference S _H L is S _C ;

Step 204: Determine, by the distance control target (Din, Dv), a fluctuation range of the detection voltage in the radio device of the mobile terminal is δ _τ , where δ _τ is equal to an average field obtained by the equivalent voltage distance curve formed by each typical terminal and the obstacle The voltage value of the slope of the strong decay curve is the difference between the voltage value corresponding to the point D i η on the curve and the voltage value corresponding to the (Din+ Dv) point; then S _T = S _E + S _R .

Step 205: Under the selected transmission parameters, measure voltage values of typical terminals and obstacles at the frequency point f\ and the frequency point f _H , where the transmission parameters include the frequency, modulation mode, and coding mode of the low frequency alternating magnetic field signal. And emitting magnetic induction intensity amplitude Br;

Test f _H is shown at the mobile radio See Also shown in Figure 10, test f 2KHz RF received signal amplitude from different points within the mobile device case where the mobile terminal 10 kinds, as shown in FIG 11 = 4KHz mobile terminal 10 The device receives signal amplitudes at different distance points.

Step 206, calculating the difference δ HL of the received voltage of the same terminal or obstacle at the frequency f\ and the frequency f _H ;

As shown in Table 12, the difference δ _{HL of the} received voltages of the same terminal of 2ΚΗζ and 4ΚΗζ is calculated. The calculation result can be obtained: The stronger the signal received by the mobile terminal, the smaller the S _H L and the weaker the signal received by the mobile terminal. The larger the S _H L is.

Table 12 Differences between 2KHz and 4KHz received signals for different mobile terminals

Step 207, calculating a receiving voltage of the mobile terminal loaded with the mobile radio frequency device at the frequency point f\ V _L + K* δ _HL ;

According to the above 2KHz and 4KHz frequency point test voltage curve results, combined with FIG. 9 and FIG. 10, the 2KHz mobile radio frequency device receives the voltage fluctuation range as S.

The voltage fluctuation range received by the 4KHz mobile RF device is SL=16. 93C1B, then the K value is: K=SL/ ( δ _Η - δ _L ) = 8. 41/ ( 16.93-8.41 ) =0.99, then K The curve with the value 爹 positive frequency point 2ΚΗζ, as shown in Fig. 9, is the voltage curve after the positive correction. From this curve, it can be seen that the fluctuation range of the fluctuation range is less than the original 20% within the original fluctuation frequency f\.

Step 208: The equivalent correction voltage curve formed by the VL+K*S _H L of different mobile terminals is used to obtain the reference voltage distance curve and the intermediate value of the reference voltage distance curve correction curve, which is from the upper boundary and the lower boundary of the typical terminal curve. The voltage amplitude is δ _τ /2;

Step 209: The detection voltage threshold Vt in the mobile radio device is selected, and the voltage value corresponding to the (Din+Dv/2) point on the reference voltage distance curve is the Vt value.

Step d, the card reader receives the information transmitted by the mobile radio device through the radio frequency channel, and compares whether the identity information of the card reader in the information is consistent with the identity information of the card, and if they are consistent, the identity information and the identity are The combination of the identification information of the mobile radio device is used as a combined address, and the mobile radio device performs a card transaction through the radio frequency channel.

In the present invention, the frequency of the low frequency alternating magnetic field signal is in the ultra low frequency band or the low frequency band or the low frequency band, wherein the frequency range of the special frequency band is 300 Hz ~ 3000 Hz, and the frequency range of the very frequency band is 3 kHz ~ 30 KHz. The frequency range of the low frequency band is 30 KHz ~ 300KHz. Preferably, the frequency of the frequency alternating magnetic field signal may be 300 Hz to 50 kHz. Preferably, the frequency of the alternating magnetic field signal may be 500 Ηζ, 1 ΚΗζ, 1.5 ΚΗζ, 2 ΚΗζ, 2·5 ΚΗζ, 3 ΚΗζ, 4 ΚΗζ, 5 ΚΗζ, 10 ΚΗζ, 20 ΚΗζ or 30 ΚΗζ.

The short-distance communication method of the invention adopts a combination of low-frequency magnetic field one-way communication and high-frequency two-way communication of radio frequency electromagnetic field, thereby avoiding problems such as antenna problem caused by unique 13.56 MHz frequency point two-way communication and distance control in NFC system, and large difference in terminal signal attenuation. . In this method, the card reader utilizes The low-frequency unidirectional channel transmits its own unique identifier I Dr (ie, the aforementioned identification information) to the mobile radio device, and the mobile radio device attaches its unique identifier I Dc to the card reader through the RF bidirectional channel, and then transmits it back to the card reader, and reads The card device compares the correctness of the returned I Dr, which in turn enables the unique binding of the card reader to the mobile radio device. After the binding, the card reader and the mobile radio device use the RF bidirectional channel to realize high-speed and large-data communication until the transaction is completed.

The short-distance communication method of the present invention realizes that the data communication distance (ie, the transaction distance) of the radio frequency communication terminal (such as the mobile phone equipped with the radio frequency SIM card) containing the mobile radio frequency device and the card reader is reliably controlled within a prescribed range, and There is no need to calibrate the terminal, and the consistency of the swipe distance control of most mobile terminals is greatly improved.

The present invention also proposes a short-range communication system for implementing the above-described short-range communication method. The near field communication system of the present invention includes at least one card reader and at least one mobile radio frequency device, wherein:

a card reader, configured to transmit a low frequency alternating magnetic field signal according to a preset transmission parameter, where the low frequency alternating magnetic field signal carries identification information of the card reader, wherein the transmission parameter includes a frequency of the low frequency alternating magnetic field signal, The frequency is equal to or less than the highest frequency f O of the system without calibration work, and the frequency includes at least 2 low frequency frequencies f\ and f _H , the frequency point f*L is smaller than the frequency point f; and is also used for receiving the mobile radio frequency device through the radio frequency The information transmitted by the channel compares whether the identity information of the card reader in the information is consistent with the identity information of the card, and if it is consistent, the combination of the identity information of the identity and the identity information of the mobile radio device is used as the combined address, and the mobile The RF device performs a card transaction through the RF channel;

The mobile radio frequency device is configured to receive, detect, and amplify the low frequency alternating magnetic field signal at the frequency point f\ and the frequency point f H at each distance point and amplify the voltage signal with a constant amplitude corresponding to the distance, and calculate the frequency point fL and The difference S _H L of the amplitude of the low-frequency magnetic field signal received at the frequency f _H is adjusted to a preset voltage threshold Vt of Vt+K* S _H L, where K is a preset adjustment coefficient to Vt+K* S _H L is used as an adjusted voltage threshold to determine whether the terminal loaded with the mobile radio device enters a preset effective distance interval, and the voltage threshold vt is the same for all terminals loaded with the mobile radio device; and is also used for receiving and receiving When the voltage signal corresponding to the low-frequency alternating magnetic field signal is greater than or equal to the adjusted voltage threshold Vt+K* δ _HL , the identification information of the card reader is obtained from the received low-frequency alternating magnetic field signal, and is combined with its own The identification information is transmitted to the card reader through the radio frequency channel; and is also used for card transaction with the card reader through the radio frequency channel. The identity information may be an ID code.

It can be seen from the above that the card reader in the short-range communication system of the present invention has two basic functions of a low-frequency transmitting function and a radio frequency transceiving function, and it can be said that the card reader in the short-range communication system of the present invention has a low-frequency transmitting module and radio frequency transmitting and receiving. The module has two basic modules; the mobile radio frequency device in the short-range communication system of the present invention has two basic functions of a low frequency receiving function and a radio frequency transceiving function, and it can also be said that the mobile radio frequency device in the short-range communication system of the present invention has a low frequency receiving module. And two basic modules such as RF transceiver module.

The short-range communication system described above may be implemented by the following specific circuit: The card reader includes at least one low frequency transmission line, at least one driving circuit, at least one encoding circuit, at least one first main processor, at least one radio frequency transceiver circuit, and At least one radio frequency antenna, wherein the low frequency transmission line 圏, the driving circuit, the encoding circuit, the first main processor, the radio frequency transceiver circuit, the radio frequency antenna, and the serial connection in series; the mobile radio frequency device includes at least one low frequency magnetic induction circuit, at least one low frequency amplification a circuit, at least one threshold determination and demodulation circuit, at least one second main processor, at least one radio frequency transceiver circuit, and at least one radio frequency antenna, wherein the low frequency magnetic induction circuit, the low frequency amplification circuit, the threshold determination and demodulation circuit, the second main The processor, the RF transceiver circuit, and the RF antenna are connected in series in series. Preferably, in the above specific implementation circuit, a modulation circuit may be further disposed between the driving circuit of the card reader and the encoding circuit.

In the above specific implementation circuit, the low frequency transmission line 圏, the driving circuit and the encoding circuit (including the modulation circuit when modulating the circuit) in the card reader can be regarded as a component of the low frequency transmitting module, and the first in the card reader The main processor, the RF transceiver circuit and the RF antenna can be considered as components of the RF transceiver module in the card reader; the low frequency magnetic induction circuit, the low frequency amplification circuit and the threshold determination and demodulation circuit in the mobile RF device can be regarded as the low frequency receiving module. As a component, the second main processor, the radio frequency transceiver circuit, and the radio frequency antenna in the mobile radio device can be considered as an integral part of the radio frequency transceiver module in the mobile radio device.

Preferably, in the above specific implementation circuit, the low frequency emission line 圏 may be an enameled wire 圏 or a PCB 圏. Further, the number of turns of the low-frequency emission line 可以 may be greater than 10 圏. Preferably, the number of turns of the low-frequency emission line 50 is 50 to 500 圏. Preferably, the low frequency emission line is filled with a ferrite core or a core. Preferably, the cross-sectional area of the area surrounded by the low-frequency emission line 最 is wider than the cross-sectional width of the mobile radio frequency terminal. Preferably, the section of the area enclosed by the low-frequency emission line 至少 includes at least a circular area i having a diameter of 3 cm or a square area i of 3 cm * 3 cm. Preferably, the frequency magnetic sensing circuit may be a PCB wire, an enamelled wire, a Hall device or a giant magnetoresistive device.

In the present invention, the mobile radio frequency device may be placed in the mobile terminal, or may be placed in a SIM card, a UIM card, a USIM card, a TF card or an SD card in the mobile terminal. The mobile terminal can be a mobile phone, a personal digital assistant PDA or a laptop computer.

The principle of the short-range communication system of the present invention will be described below:

1. The highest frequency of the system without calibration work f O The selection method and device have been described in the content of the aforementioned short-range communication method, and will not be described here;

2. The principle of distance measurement and control is as follows:

The card reader continuously transmits a low-frequency alternating magnetic field signal not higher than the selected frequency f\ and f„ according to the distance control target with the set transmission parameter, and the data carries the data by modulation or direct baseband transmission. Frame, the data frame contains the unique identification code Idr of the card reader (of course, other identification information). When the mobile terminal loaded with the mobile radio device is placed around the card reader, the low frequency alternating magnetic field signal penetrates the terminal. Reaching the internal mobile radio frequency device, the mobile radio frequency device detects the magnetic field signal at each distance point and amplifies the voltage signal with a constant amplitude corresponding to the distance, when the amplitude of the voltage is lower than the preset within the card and adjusts the compensation after receiving The voltage threshold Vt+K* δ _H L indicates that the terminal does not enter the effective swipe distance range, and the card is not allowed to be swiped; when the voltage amplitude is higher than the preset in the card and adjusts the supplemented receiving voltage threshold Vt+K* δ HL, indicating that the terminal enters the predetermined valid card swipe range of the card reader, and the low frequency receiving circuit in the mobile radio device (refers to the aforementioned low frequency magnetic induction circuit, low frequency amplifying circuit and door) The judgment and demodulation circuit starts the decoding process to obtain the unique identification code IDr of the card reader. On the other hand, the distance between the voltage signal after the magnetic field conversion in the mobile radio device and the card reader and the mobile radio device exists. The relationship is determined by the converted equivalent voltage distance curve. According to the correspondence, the distance between the mobile radio device and the card reader can be determined by the voltage, thereby indirectly determining the mobile terminal and the card reader. Distance Vt and parameter K and emission parameters are set once, once the setting is in use, no changes are required.

3. The process principle of the mobile radio device accessing the card reader:

The mobile radio device access card reader mainly includes a unique binding process of the card reader and the mobile radio device. The binding process is illustrated here: the mobile radio device removes the card reader unique identification code IDr from the low frequency signal and transmits it to the second main processing module in the mobile radio device, and the second main processing module moves the radio device. Unique identification code IDc together with the received IDr, transmitted and received by RF The module sends the card reader to the card reader. After the card reader receives the IDr (IDc) returned by the mobile radio device, the mobile radio device with the ID code IDc is correctly returned to the card reader IDD, which is the transaction. The only communication terminal. Since the IDr encoding ensures that the identification codes of other card readers around the card reader are different at this time, the mobile radio device with the ID code IDc confirms that it has unique communication with the card reader whose ID code is IDr. At this point, the mobile radio device and the card reader realize a unique binding, and the two parties uniquely identify each other through the (IDr, IDc) combined address. The binding communication process uses the RF channel for interaction without error. After the mobile radio device is successfully accessed, the distance control process is completed, and the subsequent transaction process can be performed on the RF channel until the transaction ends.

4. Trading process:

The card reader and the mobile radio device establish a reliable and unique communication link through the RF channel. Based on the link, the two parties can implement the process required for identity authentication and other transactions required for the transaction. All of these processes are performed through a fast RF channel. Since the completion of the aforementioned process ensures that access can only be achieved within a predetermined distance, the entire transaction process is also within a limited range of communication.

The invention is further illustrated by the following examples.

FIG. 6 is a structural diagram of a short-range communication system according to an embodiment of the present invention. As shown in Fig. 6, the system consists of two parts: a card reader device 1 QQ and a mobile radio device 2QQ, which is placed inside the mobile terminal and interacts with the terminal through the communication interface of the mobile terminal.

The card reader 100 is composed of the following modules: a first main processor 101, which is responsible for the low frequency and high frequency control of the card reader and other protocol processing, and the first main processor 101 is directly connected to the external communication interface through the interface circuit 102; The encoding circuit 108 is responsible for bit-by-bit encoding of the low-frequency frame data, and the modulation circuit 107 is responsible for modulating the encoded-output symbol stream to form a modulated signal to the driving circuit 106, and the encoded signal is directly sent to the driving circuit without modulation. The driving circuit 106 is responsible for driving the low-frequency transmitting line 圏105 to generate the low-frequency alternating magnetic field 301; and the low-frequency transmitting module consisting of the low-frequency transmitting line 圏105, the driving circuit 106, the modulating circuit 107 and the encoding circuit 108, and the transmitting field strength value thereof It can be changed and set; the low frequency transmission line 圏105 is usually composed of a plurality of turns of a specific shape of the wire; the RF transceiver circuit 103 receives and transmits the RF signal through the RF antenna 104.

The mobile radio device is composed of the following modules: a second main processor 201, which is responsible for the control of low frequency and radio frequency modules and other protocol processing, and is also responsible for communication with the mobile terminal; the SIM/TF/SD card module 202 is the SIM/ of the mobile terminal. TF/SD card body module, which specific module is determined by the card type; low frequency magnetic The sensing circuit 207 is composed of a PCB wire 漆, an enameled wire 圏, a Hall device, a giant magnetoresistive device or other circuit component capable of sensing a magnetic field change, and is responsible for sensing the low frequency alternating magnetic field signal 301 and converting it into an electrical signal; the low frequency amplifying circuit 206 Responsible for amplifying the electrical signal detected by the low frequency magnetic induction circuit to obtain a low frequency magnetic detection voltage signal 303; the threshold determination and demodulation circuit 205 is responsible for determining the low frequency magnetic detection voltage signal 303 according to a preset threshold Vt+K* δ _H L , Reaching the threshold Vt+K* δ HL does not demodulate and does not allow the card to be swiped, and reaches the threshold Vt+K* S _H L to demodulate the signal, and the demodulated signal is sent to the second main processor 201; the RF transceiver circuit 203 passes The RF antenna 204 is responsible for performing RF two-way communication with the RF transceiver module of the card reader.

The system performs distance detection and control without calibration by a preset threshold determination method, that is, the card reader 100 transmits a low frequency alternating magnetic field signal 301 according to a preset transmission parameter, and the mobile radio frequency device 200 receives the magnetic field signal and converts it into a low frequency. The magnetic detection voltage signal 303 is used to determine whether the terminal enters a preset effective distance interval by setting and adjusting the compensated threshold Vt+K* δ HL. The calculation method of the threshold Vt+K* S _H L is all The terminals are the same and do not need to be modified for different terminals (so-called calibration). The unique binding of the card reader 100 and the mobile radio frequency device 200 is completed by the combination of the low frequency one-way communication and the RF two-way communication, that is, the card reader 100 transmits the unique identifier IDr to the mobile radio device 200 by using the low frequency one-way channel. The mobile radio frequency device 200 adds the card's own unique identifier IDc to the IDR through the RF bidirectional channel, and then returns the card ID to the card reader 100. The card reader 100 compares the correctness of the IDR, thereby implementing the card reader 100 and the mobile radio device 200. The only binding. After the binding, the two-way high-speed large data communication is completed through the RF channel.

In this embodiment, the specific working process of the short-range communication system is as follows:

(1) First, select the basic parameters of the system operation, including RF frequency, no calibration low frequency frequency f*L, f„, reader transmit parameters, mobile RF device receive voltage threshold Vt, parameter K.

1. RF frequency selection

The frequency of the above RF communication usually adopts the 2400 ~ 2483MH 2.4G ISM frequency band to achieve high-speed communication and good penetration to the terminal, and other frequency points such as 433MHz, 900MHz, 5GHz, etc. can also be used.

2. No calibration low frequency frequency point f;, f _H selection

The above method is used to determine the low-frequency uncalibrated working frequency points f\ and f _{H of the system} . For a typical GSM mobile communication terminal, distance control in the range of 0 ~ 10 cm is required, f\, f _H frequency points are usually less than 125 KHz, and typical values include 500 Hz. , ΙΚΗζ, 1.5KHz, 2KHz, 2.5KHz, 3KHz, 5KHz, 10KHz, 12KHz, 14KHz, 16KHz, 18KHz, 20KHz, 22KHz, 24KHz, 48KHz, and the like.

3. Selection of the reader's transmission parameters

The transmission parameters mainly include the modulation mode, the coding mode and the amplitude of the transmitted magnetic induction intensity Br. Figure 7 is a schematic diagram of the low frequency transmitting portion of the card reader. Referring to Fig. 6, the low frequency transmitting circuit of the card reader is composed of a driving circuit 106, a modulating circuit 107 and an encoding circuit 108, and the low frequency modulated signal driven by the driving circuit 106 is output to the low frequency transmitting line 圏105.

The modulation circuit 107 can employ a variety of modulation methods:

1) Carrier modulation mode modulation: The baseband signal generated by the encoding circuit 108 modulates the carrier through the modulation circuit 107. The carrier can be a sine wave, a square wave, a triangle wave, etc., and the modulation can be switched frequency shift keying 00K, phase shift keying, frequency Shift keying FSK or the like, the modulated signal is loaded into the low frequency emission line 圏105 through the driving circuit 106;

2) no carrier direct baseband transmission: the baseband signal generated by the encoding circuit 108 is directly loaded to the low frequency transmission line 圏 105 through the driving circuit 106;

3) Other modulation methods: Since the system of the present invention uses the threshold judgment method for distance control, the modulation method should not adopt amplitude modulation, and any modulation method capable of keeping the detection voltage amplitude in the mobile radio frequency device substantially constant during the transmission process can be used for the present invention. Invented near field communication system;

The encoding circuit 108 can employ a variety of encoding methods:

1) Manchester encoding: Bit 1 is encoded as two symbols 01, and bit 0 is encoded as 10.

2) Differential Manchester coding: There are two bit symbol sequences: 01 and 10, bit 1 coding is different from the previous symbol sequence, bit 0 is the same, or vice versa.

3) Other coding methods: Since the system of the present invention uses the threshold judgment method for distance control, the low-frequency modulation signal must maintain the average value stable, and the encoded sequence cannot contain the DC component, and any coding method with an average DC component of zero after coding can be used. A near field communication system for use in the present invention.

After determining the modulation mode and the coding mode, the aforementioned method is used to determine the amplitude of the magnetic induction intensity Br of the card reader. The process of adjusting Br is actually a process of adjusting parameters such as the number of turns, wire diameter, and shape.

4. Mobile RF device receiving voltage threshold Vt threshold adjustment parameter K selection

The card receiving threshold voltage Vt and the parameter K are determined by the foregoing method. The selection of the above parameters is one-off. Once selected, there is no need to change the work.

(2) Secondly, the system workflow after the working parameters are determined is as follows:

Step A1 00: Distance measurement and control process. The first main processor 101 of the card reader 100 generates a data frame containing the unique identification code I Dr of the card reader, and sends it to the encoding circuit 108 for encoding. The encoded signal is modulated by the modulation circuit 107 or not. The modulation is directly sent to the driving circuit 106, and the modulation voltage is sent to the low-frequency transmitting line 圏1 05. By setting the frame format, modulation and coding mode and driving capability in advance, the transmission line 圏1 05 continues with the set intensity Br. The low frequency alternating magnetic field signal 301 of the specified parameter is cyclically transmitted in accordance with the above frame format. When the mobile terminal is placed around the card reader, the low frequency alternating magnetic field signal 301 penetrates the terminal to reach the internal mobile radio frequency device 200, and the low frequency magnetic induction circuit 207 in the mobile radio frequency device 200 detects the low frequency magnetic signal and converts it into an electrical signal. After being amplified by the low frequency amplifying circuit 206, the low frequency magnetic detecting voltage 303 is obtained. When the amplitude of the voltage is less than (or greater than) the adjusted receiving voltage threshold value Vt+K*S _H L, the card is not allowed to be swiped; when the magnitude of the voltage is greater than or equal to After (or less than or equal to) the adjusted receiving voltage threshold value Vt+K* S _H L , indicating that the terminal enters the predetermined valid card swipe range of the card reader, and the low frequency receiving circuit starts the decoding process to obtain the unique identification code of the card reader. Dr. On the other hand, there is a corresponding relationship between the voltage signal after the magnetic field conversion in the mobile radio frequency device and the distance between the card reader and the mobile radio frequency device, and the relationship is determined by the voltage-distance curve, and according to the correspondence, The distance between the mobile radio device and the card reader is determined by the voltage, thereby indirectly determining the distance between the mobile terminal and the card reader. The above-mentioned original threshold value Vt is the same for all terminals, and there is no need to correct for each terminal, that is, there is no need to know the calibration, so the above process is a distance measurement and control process without calibration;

The frame format in step A1 00 is defined as follows:

Figure 8 is a schematic diagram of the low frequency data frame format of the card reader. As shown in Figure 8, the low frequency data frame of the card reader is divided into the following fields:

Sync code: 8 bits, usually FFH, for frame synchronization;

Control field: 8 bits, used to provide de-frame information of frame data, such as length, data type, etc., may be reserved for expansion;

I Dr: N bits, the unique identifier of the reader, specified by the control field;

CRC: Check the control domain, I Dr, using CRC checksum or other means.

The frame format described above is only an example, and does not limit the frame format actually employed by the present invention. In principle, any frame format including a card reader that can uniquely recognize the card reader can be used. Unique identifier can be used The length of the random number can also be used by all readers to manually assign a unique code, or other way to generate an identification code.

Step A2QQ: The process of the mobile radio device accessing the card reader: The mobile radio device access card reader mainly includes the unique binding process of the card reader 100 and the mobile radio device 200, which actually indicates that the card reader and the mobile radio device are located. The unique binding process for mobile terminals. The internal low frequency receiving circuit of the mobile radio frequency device 200 solves the card reader unique identification code Idr and transmits it to the first main processor 201 in the mobile radio frequency device, and the module adds the unique identification code Idc of the mobile radio frequency device together with the received Idr. And transmitting to the card reader 100 through the RF transceiver circuit 203 and the RF antenna 204 in the mobile radio device, and the internal RF antenna 103 and the RF transceiver circuit 104 of the card reader receive the (IDr, IDc) returned by the mobile radio device, and then transmit the signal to the first A main processor 101 processes, and the first main processor 101 confirms that the mobile radio device whose identification code is IDc correctly returns the card reader IDr, which is the only communication terminal of the transaction. Since the IDr code ensures that the identification codes of other card readers around the card reader are different at this time, the card whose ID is IDc confirms that it has unique communication with the card reader whose ID code is IDr. At this point, the mobile radio device and the card reader implement a unique binding, and the two parties uniquely identify each other through the (IDr, IDc) combined address. The binding communication process uses RF channels for interaction without error. After the mobile radio device is successfully connected to the card reader, the distance control process is completed, and the subsequent transaction process can be performed on the RF channel;

The mobile radio device unique identification code IDc in step A200 is a unique identification code pre-stored in the non-volatile memory (NVM) in the mobile radio device, or a sufficiently long random number generated in the mobile radio device.

Step A300: The transaction process. The card reader 100 and the mobile radio device 200 establish a reliable unique communication link through the RF channel, on the basis of which the two parties can implement the authentication required for the transaction and the processes required for other transactions. All of these processes are done through a fast RF channel until the end of the transaction. Since the completion of the foregoing steps A100 ~ A200 ensures that the mobile radio device 200 can only complete access within a predetermined distance, the entire transaction process is also within a limited distance to complete the transaction. The transaction process is a mature P0S machine processing flow, which is not described in detail in the present invention.

The low frequency signal detecting circuit 207 in the mobile radio frequency device 200 can generally be constructed by using a PCB wire 漆, an enameled wire 圏 or a Hall device. The detecting circuit is not limited to these components, and in principle any magnetic field change can be converted into an electrical signal. Sensors can be used with this module, the only restriction being that it can be placed inside the card. The system of the invention realizes the distance detection and control by using the low frequency alternating magnetic field, and realizes the one-way communication between the card reader and the mobile radio frequency device, and realizes the reliable binding of the terminal by using the RF channel combined with the low frequency communication, and simultaneously realizes the card reader by using the RF channel. High-speed data communication between mobile radios. It has the following characteristics: 1. It is possible to realize reliable two-way distance communication by simply replacing the internal SIM card/TF/SD card in the terminal without replacing the mobile terminal; 2 the card reader transmits low-frequency alternating magnetic field signals, moving The radio frequency device only needs to receive the magnetic field signal. Because it is one-way communication, and the card reader does not need to provide energy through the magnetic field, the receiving line or other receiving circuit can be miniaturized enough to put the mobile radio device into the SIM card/TF/ In the SD card; 3. Due to the weak received signal, the amplifier circuit needs to be added in the mobile RF device. In addition, the RF transceiver circuit is placed in the mobile RF device at the same time, and the RF transceiver circuit in the card reader realizes bidirectional high-speed communication. As described above, the antenna of the RF circuit is small and can be easily integrated into the SIM card/TF/SD card. Inside.

The highest frequency point f O selected according to the method of the present invention, and the frequency points f*L, f _H below the f O suitable for the design, the system operates below the frequency point without calibration, as an extension, the system Working above the f O frequency point is not absolutely impossible. The possible effect is that the performance is degraded, the accuracy of the distance control is reduced, and the calibration of the cartridge may be required. These applications do not fundamentally conflict with the principles described in the present invention. , just an extended application of performance changes.

The near field communication system of the invention realizes that the data communication distance (ie, the transaction distance) of the radio frequency communication terminal (such as the mobile phone equipped with the radio frequency SIM card) containing the mobile radio frequency device and the card reader is reliably controlled within the prescribed range, and Calibrate the terminal.

With the system and method of the present invention, two adjacent low frequency frequencies f\, f _H which are lower than the highest frequency point f O without calibration work are selected, and low frequency intersections with f*L and f _{H are used} . The variable magnetic field is used for distance measurement and control, and the influence of the structural difference between the mobile terminals can be reduced to the fluctuation range required by the distance control target, thereby realizing the non-calibrated distance control. Using the low-frequency frequency points f\ and f _H to identify the magnitude difference of the signal received by the mobile radio device at different mobile terminals to identify the magnitude of the attenuation of the low-frequency signal by the mobile terminal, and correspondingly gain compensation or threshold adjustment to achieve different mobile terminal distance judgment thresholds. A consistent method achieves the goal of consistent card swipe.

FIG. 9 is a conversion equivalent voltage distance curve tested by a coil receiving circuit placed in various mobile terminals and transmitted by a signal source through a low frequency transmission line 恒定 under a constant magnetic field of 2 KHz and 4 KHz. As shown in FIG. 9, it is an example of a voltage correction distance curve of a plurality of typical terminals at a frequency of 2 KHz and 4 KHz. The signal strength value is the value of the receiving antenna induced voltage after necessary amplification, and the magnification is maintained. Constant, just pay attention to the relative change in intensity with distance. It can be seen from Fig. 9 that the field strength difference between the terminals is <2.5 dB, and the field strength variation range of each terminal in the range of 1 to 10 cm reaches 15 dB, regardless of the fluctuation of the field strength of the card reader and the detection circuit of the mobile radio frequency device. The error, the mobile RF device end adopts a unified original threshold Vt, and the automatically adjusted Vt+K* S is used to judge whether each terminal is within the target distance range, and the distance control error is approximately lcm between the terminals. The range greatly improves the consistency of the distance control effects of different mobile terminals.

The short-range communication system of the invention enables the credit card transaction such as electronic payment to be realized for various mobile terminals having the short-range communication function without calibration, and the distance control effects of different mobile terminals are consistent, and the card-swapping distance is improved due to different terminal individual differences. The bias affects the user experience.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

Claim

A short-range communication method for a short-range communication system including at least one card reader and at least one mobile radio frequency device, comprising:

The short-range communication method according to claim 1, wherein in the step a, the frequency point f*L and the frequency point f _H are determined by the following steps:

Step a, arbitrarily select a terminal or an obstacle, and if the card reader fixed the transmission parameter, keep the physical position of the terminal or the obstacle and the card reader fixed, and test the movement of the terminal or the obstacle. The frequency amplitude of the low frequency magnetic field signal at the frequency point f _t received by the radio frequency device is V _t , and the frequency point f _t is the lowest frequency point f _t . As the starting point, the lowest frequency point f _t . The voltage amplitude of the low frequency magnetic field signal tested is V _t . ; Step a2, depicting V _t and V _t . The difference between the difference and the frequency f _t , taking the frequency f at the inflection point on the relationship curve is the maximum operating frequency f _M of the terminal or obstacle;

The short-range communication method according to claim 2, wherein in the step a, the transmission parameter further includes a modulation mode, an encoding mode, and a transmitting magnetic induction intensity amplitude Br, wherein the modulation mode, the coding mode, and The amplitude of the transmitted magnetic induction intensity Br is selected by the following steps:

Select any encoding method without an average DC component;

The short-range communication method according to claim 1, wherein in the step b, the preset adjustment coefficient K is determined by the following steps:

Step b11, testing the curve of the receiving voltage VL of the typical terminal and the obstacle at the selected working frequency point f\ and the receiving voltage V _H of the selected working frequency point f _H , the fluctuation range of the voltage VL is SL, the voltage V _H The fluctuation range is δ _Η ;

In step bl2, the adjustment coefficient Κ is calculated, and the K value is equal to the ratio of SL to S _H L , and S _H L is equal to the difference of δ _Η minus 3.

The short-range communication method according to claim 1, wherein in the step b, the preset voltage threshold Vt is determined by the following steps:

Step b22, determining a frequency point f\ detected by the mobile radio device of the terminal caused by the card reader The error range of the voltage difference S at f _H is δ _κ ;

Step b23, determining that the error range of the voltage difference S at the detected frequency points f\ and f _H caused by the mobile radio frequency device itself is S _C ;

Step b24, the fluctuation range is determined within the mobile radio device detects a voltage of _{_δ} τ, δ τ is equal to the distance curve by the equivalent voltage terminal and is typically formed of an obstacle having an average field strength obtained by the distance control target (Din, Dv) The voltage value of the slope of the attenuation curve is the difference between the voltage value corresponding to the point D i η on the curve and the voltage value corresponding to the point ( Din + Dv ), δ _τ = δ _c + δ _R ;

The short-range communication method according to claim 1, wherein the frequency of the low-frequency alternating magnetic field signal is in an ultra-low frequency band or a low-frequency band or a low-frequency band, and the frequency range of the ultra-low frequency band is 300 Hz. ~ 3000Hz, the frequency range of the very low frequency band is 3KHz ~ 30KHz, and the frequency range of the low frequency band is 30 KHz ~ 300KHz.

The short-range communication method according to claim 6, wherein the frequency of the low-frequency alternating magnetic field signal is 300 Hz to 50 kHz.

The short-range communication method according to claim 6, wherein the frequency of the low-frequency alternating magnetic field signal is 500 Ηζ, 1 ΚΗζ, 1.5 ΚΗζ, 2 ΚΗζ, 2·5 ΚΗζ, 3 ΚΗζ, 4 ΚΗζ, 5 ΚΗζ, 10 ΚΗζ, 20 or 30.

The short-range communication method according to claim 3, wherein the coding mode is a Manchester code, a differential Manchester code, or a return-to-zero code; and, the modulation mode is an on-off key Control method, phase shift keying method or frequency shift keying method.

10. A near field communication system comprising at least one card reader and at least one mobile radio frequency device, wherein:

The mobile radio frequency device is configured to receive, detect, and amplify a low-frequency alternating magnetic field signal at a frequency point fL and a frequency point f H at each distance point and amplify the voltage signal with a constant amplitude corresponding to the distance, and calculate the frequency point f \And the difference S _H L of the amplitude of the low-frequency magnetic field signal received at the frequency f _H , adjust the preset voltage threshold Vt to Vt+K* S _H L, where K is the preset adjustment coefficient to Vt+K* S _H L is used as an adjusted voltage threshold to determine whether the terminal loaded with the mobile radio frequency device enters a preset effective distance interval, and the voltage threshold vt is the same for all terminals loaded with the mobile radio frequency device; Obtaining the identity information of the card reader from the received low frequency alternating magnetic field signal when the voltage signal corresponding to the received low frequency alternating magnetic field signal is greater than or equal to the adjusted voltage threshold Vt+K*S _H L And transmitting it to the card reader through the radio frequency channel together with its own identification information; and is also used for swiping transactions with the card reader through the radio frequency channel.

The short-range communication system according to claim 10, characterized in that

The card reader includes at least one low frequency transmission line, at least one driving circuit, at least one encoding circuit, at least one first main processor, at least one radio frequency transceiver circuit, and at least one radio frequency antenna, the low frequency transmission line, driving Circuit, coding circuit, first main processor, radio frequency transceiver circuit, radio frequency antenna, serial connection in series;

The mobile radio frequency device includes at least one low frequency magnetic induction circuit, at least one low frequency amplification circuit, at least one threshold determination and demodulation circuit, at least one second main processor, at least one radio frequency transceiver circuit and at least one radio frequency antenna, and the low frequency magnetic induction The circuit, the low frequency amplifying circuit, the threshold determining and demodulating circuit, the second main processor, the radio frequency transmitting and receiving circuit, and the radio frequency antenna are sequentially connected in series.

The short-range communication system according to claim 10, characterized in that a modulation circuit is further provided between the drive circuit of the card reader and the encoding circuit.

The short-range communication system according to claim 10 or 11, wherein the low-frequency emission line 圏 is an enameled wire 圏 or a PCB 圏.

The short-range communication system according to claim 13, wherein the number of turns of the low-frequency radiation 大于 is greater than 10 圏.

The short-range communication system according to claim 14, wherein the number of turns of the low-frequency radiation ray is 50 to 500 。.

The short-range communication system according to claim 13, wherein the low-frequency radiation ray is filled with a ferrite core or an iron core.

The short-range communication system according to claim 13, wherein the cross-sectional area of the area surrounded by the low-frequency radiation ray is wider than the cross-sectional width of the mobile radio frequency terminal.

The short-range communication system according to claim 13, wherein the cross section of the area surrounded by the low-frequency radiation ray includes at least a circular area of 3 cm in diameter or a square area of 3 cm * 3 cm.

The short-range communication system according to claim 1, wherein the low-frequency magnetic circuit is a PCB coil, an enamelled wire, a Hall device or a giant magnetoresistive device.

A short-range communication system according to claim 10, wherein said mobile radio frequency device is placed in a mobile terminal.

The short-range communication system according to claim 10, wherein the mobile radio frequency device is placed in an SIM card, a UIM card, a US IM card, a TF card or an SD card in the mobile terminal.

The short-range communication system according to claim 20 or 21, wherein the mobile terminal is a mobile phone, a personal digital assistant PDA or a notebook computer.

The short-range communication system according to claim 10, wherein the identity identification information is an identification code.