WO2011035516A1

WO2011035516A1 - Method and system for controlling radio frequency communication distance

Info

Publication number: WO2011035516A1
Application number: PCT/CN2009/075811
Authority: WO
Inventors: 余运波; 孙迎彤
Original assignee: 国民技术股份有限公司
Priority date: 2009-09-23
Filing date: 2009-12-22
Publication date: 2011-03-31
Also published as: CN102024290B; CN102024290A

Abstract

The present invention relates to a method for controlling radio frequency (RF) communication distance. Said method includes: corresponding relationship between communication distances and RF characteristic parameters is saved in an RF communication device beforehand, and a trigger threshold of echo field intensity variation is set, said RF characteristic parameters including said echo field intensity variation value and RF signal field intensity value; during communication between the RF communication device and an RF communication terminal, the RF communication device keeps detecting the current echo field intensity variation value and judging whether its absolute value has reached the trigger threshold of the echo field intensity variation; if yes, the next step is carried out; if not, the current step is repeated; the RF communication device obtains the current RF characteristic parameters, determines the current communication distance according to the corresponding relationship, and then judges whether the current communication distance is within the preset card swiping range; if yes, card transactions are permitted; if not, card transactions are not permitted. The present invention effectively reduces influence of individual RF communication terminal on distance control, and good stability and accurate distance control can be achieved.

Description

Method and system for controlling radio frequency communication distance

The present invention relates to the field of communications, and in particular, to a method and system for controlling radio frequency communication distance. Background technique

Radio frequency communication terminals, especially mobile phones, have become popular, and the radio communication terminals have the function of short-distance communication through transformation. The demand for functions such as electronic payment by using radio frequency communication terminals such as mobile phones is becoming more and more intense. Currently, user identification in mobile phones has appeared. The module (SIM) (Subscr iber Ident I ty Module) adds RF function (called RF SIM) or adds a short-range communication module on the mobile phone motherboard to realize the method of short-distance communication of the mobile phone. This method makes the mobile phone become a Super smart terminals for recharging, consuming, trading and identity authentication greatly meet the urgent needs of the market.

Among them, the RF SIM-based mobile phone proximity solution has received wide attention because of its simplicity and no need to change the mobile phone. In this solution, the RF SIM adopts UHF (Ultra tra High Frequency) technology to make the RF signal available. The mobile phone is transmitted out, so that the mobile phone can be equipped with a short-distance communication function without changing the mobile phone. However, different mobile phones have great differences in the transmission effect of radio frequency signals due to different internal structures. The communication distance of a mobile phone with strong transmission may reach a distance of several meters, and the mobile phone with weak transmission can reach several tens of centimeters. In mobile payment applications, such as bus and subway card swiping, there are usually strict requirements on the transaction distance to prevent users from accidentally brushing and causing losses. Therefore, mobile phone SIM-based mobile phones must be able to effectively control the effective range of their transactions while increasing the short-range communication function.

Among the existing radio frequency communication technologies, there is a contactless card technology based on the IS014443 standard capable of realizing transaction distance control, which is used for the non-contact card internal circuit by sensing energy from the card reader. Work, to achieve communication with the card reader; the basic principle of the technology to achieve distance control is that the RF energy can only be transmitted at close range, and this technology is difficult to apply to the SIM card: The SIM card area is small and embedded in Inside the mobile phone, the RF energy radiated by the card reader cannot communicate with the RF SIM through the mobile phone.

Another method for controlling the radio frequency communication distance of a mobile terminal in the prior art first establishes a corresponding near-field map for each type of radio frequency mobile terminal on the radio frequency control terminal by using a test method; and the current radio frequency mobile terminal detected by the detector array The matching degree between the field strength and the near-field spectrum obtained by the matching algorithm is compared; the obtained matching degree is compared with the preset threshold value of the corresponding type of radio frequency mobile terminal in the radio frequency control terminal, thereby judging the current Whether the distance between the RF mobile terminal and the RF control terminal is within the specified range. The method is more complicated; when the detector array is used to detect the near-field spectrum of the RF mobile terminal, it is difficult to achieve good isolation between the detectors, so that it is difficult to identify the spectrum. Summary of the invention

The technical problem to be solved by the present invention is to provide a method for controlling the radio frequency communication distance, which reduces the influence of the individual radio frequency communication terminal on the distance control, and improves the stability and the distance control accuracy.

In order to solve the above technical problem, the present invention provides a method for controlling a radio frequency communication distance, which is applied to a radio frequency communication system including a radio frequency communication device having an antenna array, wherein the antenna array includes a communication antenna and an echo detection antenna, The communication antenna transmits the radio frequency signal according to the set power, the echo detection antenna receives the echo radio frequency signal, the radio frequency communication device detects the echo field strength change value, and the radio frequency communication module in the radio frequency communication terminal receives the radio frequency signal and detects the radio frequency Signal field strength value, the method includes the following steps:

(a) preserving a correspondence between the communication distance and the radio frequency characteristic parameter in the radio communication device, and setting an echo field strength change trigger threshold, wherein the radio frequency characteristic parameter includes the echo field strength change value and RF signal field strength value; (b) in the communication process between the radio frequency communication device and the radio frequency communication terminal, the radio frequency communication device continuously detects the current echo field strength change value, and determines whether the absolute value of the echo field strength change value reaches the The echo field strength change trigger threshold, if yes, execute step (c), otherwise repeat step (b);

(c) the radio frequency communication device acquires a current radio frequency characteristic parameter, determines a current communication distance according to the correspondence, and then determines whether the current communication distance is within a preset swipe range, that is, whether it is less than a preset target control distance. If yes, the card transaction is allowed, otherwise the card transaction is not allowed.

Further, the above method may further have the following features. In the step (a), the correspondence relationship is obtained by a calibration process, where the calibration process is: the calibrator detects the radio frequency signals received by the radio frequency communication terminal at a plurality of predetermined distances. Field strength value PWj and echo field strength change value APWj, according to the periodic oscillation attenuation law fitting book - APW curve and book-PW curve, that is, the relationship between communication distance and echo field strength change value and communication distance and RF signal field A relationship curve of strong values, which is the corresponding relationship.

Further, the foregoing method may further have the following features. In the step (c), determining the current communication distance according to the corresponding relationship is specifically: the radio frequency communication device is based on the echo field strength change value Δ PW on the book-APW curve. Find the next corresponding book j value, and then find the corresponding RF signal field strength value PWj through the DWj value book-PW curve. If the field strength value PWc currently detected by the RF communication module is within the range of PWj ±P _A , Then, the communication distance is book j, and ΡΔ is the maximum receiving field strength error value of the preset RF communication module.

Further, the above method may further have the following features, and the step (c) includes the following substeps:

(c 1 ) Calculate the absolute value of the current echo field strength change value, and subtract the absolute value of the current echo field strength change value from the RF signal field strength value in the current RF characteristic parameter to obtain the 4th dry erase 4 RF signal field strength PWca; (c2) Calculate the threshold PWag after canceling the interference on the DW-PW curve according to the set target control distance, specifically: the target control distance on the distance axis of the book-PW curve is the perpendicular to the distance axis, the perpendicular line The field strength corresponding to the intersection of the DW-PW curve is PWag;

(c3) When PWca is smaller than the judgment threshold Pwag of the above-mentioned 氐氐氐 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Otherwise, perform step (cl4);

(c4) Perform a near-field region judgment to determine whether the current RF signal field strength reaches a preset near-field field strength threshold. If the current communication distance is less than the target control distance, the card transaction is allowed, otherwise the card transaction is not allowed.

Further, the foregoing method may further have the following feature. In the step (c), determining the current communication distance according to the correspondence relationship is specifically: taking an absolute value of the echo field strength change value ΔP, and calculating A AP = Abs ( ΔΡ) - ΔΡ, Abs denotes the absolute value, draws the D- Δ ΔΡ curve according to the relationship between Δ ΔΡ and the communication distance, and sets the threshold A AP _g , if the current Δ ΔΡ is greater than the threshold △ The current communication distance of AP _g is near the distance range corresponding to the curve D- Δ ΔΡ trough.

Further, the above method may further have the following features, the radio frequency communication device is a POS machine, the radio frequency communication terminal is a mobile phone having a radio frequency communication module; and the radio frequency communication module is a radio frequency SIM card or a memory card with radio frequency communication function. .

In order to solve the above technical problem, the present invention also provides a system for controlling a radio frequency communication distance, including a radio frequency communication device and an RF communication terminal, wherein the radio frequency communication device has an antenna array, and the antenna array includes a communication antenna and an echo. Detecting an antenna, the communication antenna is configured to transmit a radio frequency signal according to a set power, the echo detection antenna is configured to receive a radio frequency signal and detect an echo field strength change value, and the radio frequency communication terminal is configured to receive the radio frequency signal and detect a radio frequency signal field strength value, wherein: the radio frequency communication device is configured to save a correspondence between a communication distance and a radio frequency characteristic parameter, and an echo field strength change trigger threshold, where the radio frequency characteristic parameter includes the echo field The strong change value and the RF signal field strength value are also used to continuously detect the current echo field strength change value during communication. When the current echo field strength change value reaches the threshold of the echo field strength change threshold, the current radio frequency characteristic parameter is obtained, the current communication distance is determined according to the corresponding relationship, and then the current communication distance is determined to be preset. Within the scope of the card, that is, whether it is less than the preset target control distance, if yes, the card transaction is allowed, otherwise the card transaction is not allowed.

Further, the above system may further have the following features, the radio frequency communication device is a POS machine, the POS machine includes a POS host and a card reader, and the card reader includes a card reader host and the antenna array. The POS host is configured to process service data during a card transaction process; the card reader host is configured to save a correspondence between a communication distance and a radio frequency characteristic parameter and an echo field strength change trigger threshold value, and is also used for During the communication process, the current echo field strength change value is continuously detected. When the current echo field strength change value reaches the echo field strength change trigger threshold value, the current radio frequency characteristic parameter is obtained, and the corresponding relationship is determined according to the corresponding relationship. The current communication distance, and then determine whether the current communication distance is within the preset credit card range, that is, whether it is less than the preset target control distance, and if so, the card transaction is allowed, otherwise the card transaction is not allowed.

Further, the system may further include the following: the radio frequency communication terminal includes a radio frequency communication module, where the radio frequency communication module includes a central processing unit CPU, a memory connected to the central processing unit CPU, a radio frequency transceiver circuit, and an interface circuit. And a radio frequency transceiver antenna connected to the radio frequency transceiver circuit, the radio frequency transceiver antenna and the radio frequency transceiver circuit are configured to receive a radio frequency signal, the central processing unit CPU is configured to detect a radio frequency signal field strength, and the memory is configured to save the radio frequency signal Field strength, the interface circuit is for communicating with other parts of the radio frequency communication terminal.

Further, the above system may further have the following features: the radio frequency communication terminal is one of a mobile phone, a PDA, and a netbook.

Further, the above system may also have the following features: the radio frequency communication module is a radio frequency SIM card or a memory card with radio frequency communication function.

Further, the above system may further have the following features, further comprising a calibrator, configured to detect a radio frequency signal field strength value PWj and an echo received by the radio frequency communication terminal at a plurality of predetermined distances. The field strength variation value Δ PWj is fitted according to the periodic oscillation attenuation law - Δ PW curve and - PW curve, that is, the relationship between the communication distance and the echo field strength change value and the relationship between the communication distance and the RF signal field strength value. The relationship curve is the corresponding relationship.

Further, the above system may further have the following features: The antenna array is distributed in a rectangular range by using a plurality of communication antennas and an echo detecting antenna to form a transmitting and receiving measuring surface.

The invention effectively reduces the influence of the individual of the radio frequency communication terminal on the distance control, has good stability and accurate distance control. DRAWINGS

1 is a structural diagram of an embodiment of a system for controlling radio frequency communication distance according to the present invention;

Figure 2 is a structural view of the card reader 500 of Figure 1;

3 is a schematic diagram of a propagation path of a radio frequency signal transmitted by the antenna array 501 of FIG. 1. FIG. 4 is a flowchart of a calibration process in an embodiment of a method for controlling radio frequency communication distance according to the present invention; FIG. Schematic diagram of relationship curve;

6 is a flow chart of determining a current communication distance in an embodiment of a method for controlling radio frequency communication distance according to the present invention;

7 is a structural view of an antenna array 501;

8 is a communication distance and echo field strength change value and an absolute value of the echo field strength change between the mobile phone and the antenna array based on the data shown in Table 1 and Table 2, and the field strength value of the RF signal received by the SIM card. Correspondence curve between them;

Figure 9 is the communication distance and echo field strength change value between the mobile phone and the antenna array, the absolute value of the echo field strength change, and the field strength value of the RF card received by the SIM card, and the RF signal field received by the RF SIM card after canceling the interference. A graph of the correspondence between strong values. detailed description

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

The invention utilizes the principle of radio frequency signal reflection superposition to solve the distance control problem in the radio frequency communication process. The principle of RF signal reflection superposition is as follows: When there is no interference in the electromagnetic field of the RF signal source, the field strength of the RF electromagnetic field will attenuate stably with increasing distance; and when there is interference, the interference will reflect the RF signal. The field strength of the RF electromagnetic field is characterized by the influence of signal reflection and other factors. The fluctuation period and the wavelength of the RF signal have a fixed relationship, which is represented by the RF signal source and the interferer at 0 or 180 degrees of the RF signal. The corresponding distance, such as the half-wavelength and its multiple distance range, is stable and the field strength is stable. When the distance of the RF signal is 90 degrees or 270 degrees, such as the quarter-wavelength range, the field strength is stably reduced.

According to this principle, the present invention designs a system capable of detecting signal attenuation changes. When a radio communication terminal such as a mobile phone communicates with the system, the radio frequency communication terminal such as a mobile phone becomes an electromagnetic field interference object, and the field strength of the current radio frequency signal is determined to be less than Whether the interference is enhanced or weakened can initially determine the possible distance range of the mobile phone from the RF communication device (ie, the RF signal source), and then assist in determining the specific distance interval by field strength attenuation or field strength variation attenuation, thereby judging and controlling the mobile phone. The communication distance between the RF communication terminal and the RF communication device.

The present invention provides a system for controlling a radio frequency communication distance, the system comprising a radio frequency communication device and a radio frequency communication terminal. Unlike the radio frequency communication system in the prior art, the radio communication device in the system for controlling the radio frequency communication distance of the present invention The antenna array includes a communication antenna and an echo detection antenna, wherein the communication antenna is configured to transmit a radio frequency signal according to a set power, and the echo detection antenna is configured to receive the radio frequency signal and detect an echo field strength change value. At the same time, the radio frequency communication terminal in the system for controlling the radio frequency communication distance of the present invention is configured to receive the radio frequency signal transmitted by the communication antenna and detect the field strength value of the received radio frequency signal. The radio frequency communication device in the system for controlling the radio frequency communication distance is also used for preserving the correspondence between the communication distance and the radio frequency characteristic parameter and the echo field strength change. The triggering threshold value, wherein the radio frequency characteristic parameter includes the above-mentioned echo field strength change value and the radio frequency signal field strength value, and is also used to continuously detect the current echo field strength change value during the communication process, in the current echo When the field strength change value reaches the threshold value of the echo field strength change threshold saved by itself, the current radio frequency characteristic parameter is obtained, and the current communication distance is determined according to the above-mentioned corresponding relationship saved, and then the current communication distance is determined to be preset. Within the scope of the card, that is, whether it is less than the preset target control distance, if yes, the card transaction is allowed, otherwise the card transaction is not allowed.

In the system for controlling the radio frequency communication distance, the correspondence between the communication distance and the radio frequency characteristic parameter stored in the radio frequency communication device can be obtained by calibration by the calibrator. Therefore, the system for controlling the radio frequency communication distance of the present invention can further include a calibrator. The calibrator is configured to detect the RF signal field strength value PWj and the echo field strength change value A PWj received by the RF communication terminal at a predetermined distance, and fit the book according to the periodic oscillation attenuation law-A PW curve and the book-PW curve. That is, the relationship between the communication distance and the variation of the echo field strength and the relationship between the communication distance and the field strength of the RF signal. The two relationship curves are the correspondence between the above communication distance and the radio frequency characteristic parameter.

The radio frequency communication device in the system for controlling the radio frequency communication distance of the present invention may be a P0S (Po int of Sa le) machine, where the P0S machine includes a P0S host and a card reader, and the card reader includes the read The card host and the antenna array described above, wherein the P0S host is used to process service data during the card transaction process; the card reader host is used to store the correspondence between the communication distance and the radio frequency characteristic parameter and the echo field strength change trigger gate The limit value is also used to continuously detect the current echo field strength change value during the communication process, and obtain the current radio frequency characteristic parameter when the current echo field strength change value reaches the echo field strength change trigger threshold value. The current communication distance is determined according to the foregoing correspondence, and then it is determined whether the current communication distance is within a preset credit card range, that is, whether it is less than a preset target control distance, and if so, the card transaction is allowed, otherwise the card transaction is not allowed. The card reader host can include a main processor CPU and a radio frequency transceiver circuit, and the card reader main processor CPU realizes the function of detecting the field strength value of the radio frequency signal received by the antenna array by controlling the radio frequency transceiver circuit.

The reader of the P0S machine is distributed with two or more antennas to form an antenna array according to a specific law. The column is divided into a communication antenna and an echo detection antenna, wherein the communication antenna can transmit the RF signal according to the required power, and can also receive the RF signal sent by the RF communication terminal such as a mobile phone, and can also detect the signal while receiving the RF signal. Field strength; the echo detection antenna is used to receive and detect the signal field strength transmitted by each communication antenna on the card reader, which is called the echo field strength; the card reader host can follow the echo field strength received by the echo antenna according to The specified requirements are stored and processed. The operations may include comparison, summation, absolute summation, variance, etc.; the reader may continuously transmit signals with some or all of the communication antennas while receiving back with the echo detection antenna. Wave the RF signal and measure the echo field strength at its current moment.

The calibrator can also include a card reader, has an antenna array consistent with the card reader in the POS machine, and corresponding radio frequency signal transceiving and simultaneous detection of the RF signal field strength function, and also records different distances with the radio communication terminal such as a mobile phone. In the case of the echo field strength measured by the calibrator antenna array and the RF signal field strength measured by the mobile phone RF SIM card. The calibrator can include a calibrator host and an antenna array consistent with the card reader, the antenna array is responsible for transmitting and receiving RF signals, and the calibrator host processes the RF signals (including detecting RF signal field strength values); the calibrator is provided with a card reader The high-level function makes the communication distance of the RF communication terminal such as the card reader and the mobile phone variable, and can communicate with the radio frequency communication terminal such as the mobile phone at several different set distances, and detect the different communication distances. The field strength of the RF signal and the field strength of the RF signal detected by the mobile phone or the RF SIM card are all recorded in the mobile phone or the RF SIM card.

The radio frequency communication terminal in the system for controlling the radio frequency communication distance of the present invention may include a radio frequency communication module, where the radio frequency communication module includes a central processing unit CPU, a memory connected to the central processing unit CPU, a radio frequency transceiver circuit and an interface circuit, and a radio frequency transceiver antenna connected to the radio frequency transceiver circuit, wherein the radio frequency transceiver antenna and the radio frequency transceiver circuit are configured to receive the radio frequency signal, the central processing unit CPU is configured to detect the received RF signal field strength, and the memory is used to save the RF signal field strength, the interface The circuit is for communicating with other portions of the radio frequency communication terminal. The RF communication module can be a radio frequency SIM card or a memory card with radio frequency communication function, or other radio communication functions. Module. For example, in addition to the ordinary telecommunication card function and the radio frequency signal transceiving function, the radio frequency SIM card in the mobile phone can also detect the received RF signal field strength while receiving the radio frequency signal, and can store and calculate the field strength value. Processing, the operation may include comparison, addition and subtraction processing, and the like.

The system for controlling the radio frequency communication distance of the invention effectively reduces the influence of the individual of the radio frequency communication terminal on the distance control, has good stability and accurate distance control.

The radio frequency communication terminal may be one of a mobile phone, a PDA (Personal Data Center), and a netbook.

Based on the above system for controlling the radio frequency communication distance, the present invention also proposes a method for controlling the radio communication distance.

The method for controlling radio frequency communication distance of the present invention is applied to a radio frequency communication system including a radio frequency communication device having an antenna array, wherein the antenna array includes a communication antenna and an echo detection antenna, and the communication antenna transmits a radio frequency signal according to a set power, and the echo detection antenna Receiving the echo RF signal, the RF communication device detects the echo field strength change value, and the RF communication module in the RF communication terminal receives the RF signal and detects the RF signal field strength value. The method for controlling the RF communication distance includes the following steps:

Step 1: pre-correlate the correspondence between the communication distance and the radio frequency characteristic parameter in the radio frequency communication device, and set the echo field strength change trigger threshold value, wherein the radio frequency characteristic parameter includes the echo field strength change value and the radio frequency signal Field strength value;

In this step, the correspondence between the communication distance and the radio frequency characteristic parameter can be obtained through a calibration process. The calibration process is: The calibrator detects the RF signal field strength value PWj and the echo field strength received by the RF communication terminal at a predetermined distance. The variation value A PWj is fitted by the periodic oscillation attenuation law - Δ PW curve and the book - PW curve, that is, the relationship between the communication distance and the variation of the echo field strength and the relationship between the communication distance and the field strength of the RF signal. The relationship curve is the correspondence between the communication distance and the radio frequency characteristic parameters.

The radio frequency communication device may be a P0S machine, the radio frequency communication terminal may be a mobile phone with a radio frequency communication module, and the radio frequency communication module may be a radio frequency SIM card or a memory card with radio frequency communication function. For example, before the mobile phone communicates with the POS machine, it is necessary to measure and record the echo field strength received by the echo detection antenna in the antenna array of the reader under different distance conditions and the RF received by the mobile phone radio SIM card on different calibrators. Radio frequency characteristic parameters such as signal field strength; the calibrator determines a fixed correspondence relationship between the radio frequency characteristic parameter and the distance (for example, the relationship between the change value of the echo field strength and the distance, and the field strength value and distance of the radio frequency signal received by the radio communication terminal) And the radio frequency characteristic parameter and the fixed correspondence are recorded in the mobile phone or the radio frequency SIM card.

In advance, the threshold value of the echo field strength change of the P0S internal card reader can be set by experience or measurement, and recorded in the card reader of the RF communication device such as the P0S machine. By judging whether the current echo field strength change value reaches the preset field strength change trigger threshold value, it can be determined whether the mutual distance reaches the farthest detection distance, and if it is reached, the communication distance reaches the farthest detection distance, the P0S machine and the like The communication device initiates the communication distance determination process, otherwise it keeps detecting.

In order to maintain the consistency of the reader of the RF communication device such as the P0S machine and the reader of the calibrator, an initialization setting process can be added at the initialization of each card reader, and the threshold Δ P _g and the initial return are triggered during the calibration process. Wave field strength P. , and the calibrator preset distance during calibration can be achieved in the process. The process can include:

1) Determine the initial echo field strength P. : For each card reader, in the case that the space electromagnetic field does not have any interference, the communication antenna in the antenna array transmits the RF signal according to the set requirements, and the echo field strength detected by the echo detection antenna is set to the initial return. Wave field strength P. And recorded in a radio frequency communication device such as a P0S machine;

2) Determine the trigger threshold AP _g: According to the preset farthest detection distance, use the specified mobile phone as the interference object at the distance position of the radio frequency communication device such as the P0S machine, and measure the current field echo field strength change value AP _g And recorded in RF communication equipment such as POS machines.

3) Determining the calibrator preset distance can be achieved in the following two steps:

A) Selecting a number of card readers, using the designated mobile phone as an interference object, respectively measuring the echo field strength Pi under different distances from the card reader, and calculating A Pi = Pi - P0 , ( i = 1, 2, 3... n) ; respectively form a D - Δ Ρ curve, and Δ Ρ exhibits a periodic oscillating decay trend with distance D, which is the wavelength of the RF signal. The interval and number n of different distances Di can be selected according to the horses, for example, lcm can be selected as the interval, and the number n can be selected as 20;

B) Find the distance +Dj corresponding to the peak in the D - Δ Ρ curve and the distance -Dj , ( j = l, 2, 3... m ) corresponding to the valley, and calculate the average value as the calibrator The basis of the distance. In the actual system, the calibrator can select a partial distance to collect the RF signal received by the mobile phone and the echo detection parameters of the card reader. Where m value can be determined based on empirical or actual measurements, typically 3 or 4. The RF field card receiving field strength error range Ρ _Δ can be obtained by the following steps:

1) Pre-set the range of the target range of the swipe distance control, and calculate Ρ _Δ according to the attenuation range of the radio frequency signal according to the accuracy range. .

2) In the actual calibration process, the actual attenuation of the target mobile phone at different distances is actually corrected to obtain the final Ρ _Δ .

Step 2: During the communication process between the RF communication device and the RF communication terminal, the RF communication device continuously detects the current echo field strength change value, and determines whether the absolute value of the echo field strength change value reaches the echo field saved by itself. The strong change trigger threshold value, if yes, step 3 is performed. Otherwise, during the communication process, the communication antennas of the reader antenna array transmit radio frequency signals according to predetermined requirements, and receive communication RF signals from the mobile phone RF S-core, echo. The detecting antenna simultaneously detects the change value of the echo field strength; the mobile phone radio frequency SIM card also receives and measures the radio frequency signal from the card reader according to the predetermined requirement.

Since the radio frequency communication system has the consistency of receiving and transmitting, the process of detecting the radio frequency signal field strength of the radio frequency SIM card of the system for controlling the radio frequency communication distance can also be replaced by the reverse direction detecting process, that is, the radio frequency SIM card transmits the radio frequency according to the set power. Signal, communication antenna connection in the antenna array The RF field IM card can be used to detect the field strength of the RF signal. In this case, the RF SIM card does not have the RF signal field strength detection function: For example, when the antenna array communicates with the mobile phone, the RF SIM card of the mobile phone transmits the RF according to the required power. Signal, the communication antenna in the antenna array receives the radio frequency signal in turn or in turn, and detects the field strength value to form the receiving field strength of the communication antenna; the receiving antenna strength and the echo field strength variation value of the communication antenna constitute a radio frequency characteristic parameter, and the radio frequency characteristic parameter It also has a fixed correspondence relationship with the communication distance between the mobile phone and the antenna array, and the communication distance can be judged and controlled by searching the corresponding relationship by using the currently measured radio frequency characteristic parameters.

Step 3: The radio frequency communication device acquires the current radio frequency characteristic parameter, determines the current communication distance according to the correspondence between the communication distance and the radio frequency characteristic parameter saved by itself, and then determines whether the current communication distance is within the preset swipe range, that is, Whether it is less than the preset target control distance, if yes, the card transaction is allowed, otherwise the card transaction is not allowed.

In step 3, determining the current communication distance according to the correspondence relationship may be specifically as follows: The radio frequency communication device finds the next corresponding book j value on the DW-A PW curve according to the echo field strength change value, and then passes the book j value in the book- The corresponding RF signal field strength value PWj is found on the PW curve. If the field strength value PWc currently detected by the RF communication module is in the range of PWj ± P _A , the communication distance is book j, and Ρ _Δ is the preset RF communication module. The maximum received field strength error value. such as. The P0S machine obtains the book-Δ PW curve and the book-PW curve stored in the internal communication by communicating with the mobile phone, and finds the next corresponding book on the er-A PW curve according to the value of the echo field strength change value (Ρ - Ρ.). j value, according to the (P - P„) value, draw a horizontal line (cf. Fig. 5), and there may be multiple intersection points with the curve 602, the first intersection point is taken for the first time, and the second intersection point is taken for the second time. , and so on, through the book j value book - PW curve to find the corresponding RF S IM card receiving field strength PWj, if the current actual detection field strength value PWc of the RF S IM card is in the range of PWj ± Ρ _Δ , then judge The interference object is the target mobile phone, and the distance from the card reader is book j; otherwise, the next matching book j value described in this step is continued; if j is found that can match the two conditions, it is judged as non-target mobile phone interference. Object, continue to detect the echo field strength value.

The communication distance judgment can also take the eye diagram method to determine the auxiliary distance. This method can assist the judgment. Break the corresponding distance near the D- ΔΡ curve trough. The method utilizes the difference in physical position between different communication antennas in the antenna array. Therefore, in step 3, determining the current communication distance according to the corresponding relationship may also be specifically: taking the absolute value of the echo field strength change value Δ, and calculating Δ AP = Abs ( ΔΡ) - ΔΡ, Abs denotes the absolute value, draws the D-△ ΔΡ curve according to the relationship between Δ ΔΡ and the communication distance, and sets the threshold A AP _g if the current Δ ΔΡ is greater than the gate The limit value Δ AP _g is the current communication distance in the vicinity of the distance range corresponding to the curve D- Δ ΔΡ trough.

It is also possible to adopt a simpler interference cancellation method instead of the aforementioned distance determination method. The principle of the method is as follows:

In the actual system, the signal field strength received by the RF SIM card is easily affected by the relative angle and relative displacement between the target mobile phone and the P0S machine. As the distance increases, the relative angle and relative displacement are more and more affected. The distance judgment process in the above distance judgment method may lead to inaccurate distance control; in fact, the amplitude of the echo field strength change value (P - P.) is a comprehensive result of factors such as relative angle and relative displacement, and this information can be utilized. To offset part of the interference received by the RF SIM card receiving signal field strength. The current RF SIM card and the echo detection antenna detect the same signal source, so the two are affected by factors such as relative angle and relative displacement. The closer the mobile phone is to the P0S machine, the RF SIM card and the echo detection antenna are affected. The smaller the degree of influence, the farther the distance is, the greater the difference in the degree of influence between the two; the interference value detected by the echo is subtracted from the field strength value of the RF signal detected by the RF SIM card, that is, the variation of the echo field strength The absolute value of the relative angle and relative displacement can be greatly reduced in a relatively close range (such as half a wavelength).

Based on the above principle, the interference cancellation method can improve the accuracy of the distance control and simplify the distance control judgment process. The method uses the echo field strength change value to offset the relative angle and relative displacement of all or part of the RF SIM card signal receiving field strength. The interference of factors improves the accuracy of the distance control; in general, the target control distance is mostly within the half wavelength range of the RF signal.

Based on the interference 4 method, step 3 may include the following sub-steps:

Step 301: Calculate an absolute value of a current echo field strength change value, and use the current radio frequency characteristic parameter. The RF signal field strength value minus the absolute value of the current echo field strength change value, and the RF signal field strength PWca after canceling the interference is obtained;

Step 302: Calculate the threshold PWag after canceling the interference on the - PW curve according to the set target control distance, specifically: the target control distance on the distance axis of the book-PW curve is a perpendicular to the distance axis, and the perpendicular line The field strength corresponding to the intersection of the DW-PW curve is PWag;

Step 303, when PWca is less than the judgment threshold PWag after canceling the interference, further determining whether the current echo field strength change value Δ PW is less than 0, if yes, the current communication distance is less than the target control distance, allowing the card transaction, otherwise performing step 304;

Step 304: Perform a near-field region judgment, that is, determine whether the current RF signal field strength reaches a preset near-field field strength threshold. If yes, the current communication distance is less than the target control distance, and the card transaction is allowed, otherwise the card transaction is not allowed.

The following is an example of a radio frequency signal with a target control distance of 4 cm and a frequency of 2.4 GHz as an example to illustrate the distance judgment process of the interference cancellation method. The method can take the following steps:

(1) Calculate the absolute value of the current echo field strength change value. As shown in Table 1, the sum of the absolute values of the echo detection change values APWj transmitted by the respective communication antennas at different distances can be calculated to form a curve 603 in Table 1;

(2) PWca is formed by subtracting the absolute value of the current echo field strength change value from the signal field strength value received by the current radio frequency SIM card. The difference and the distance form a curve 604 in Table 1;

Table 1

(3) According to the set target control distance, the threshold PWag is determined after the cancellation of the interference in the book-PW curve stored in the mobile phone, specifically, the target control distance on the distance axis is the perpendicular to the distance axis, the perpendicular line The field strength corresponding to the intersection of the DW-PW curve (604) is PWag;

(4) When the PWca is less than the cancellation interference, the threshold Pwag is determined,

a) If the current echo detection change value (P-P0) is less than 0, the communication distance is judged to be within the target range; otherwise, the next step (ie, step b) is performed to determine the near-field region;

b) The judgment of the near-field region can adopt the traditional simple field strength judgment method, that is, directly judge It is judged whether the field strength of the received signal of the radio frequency SIM card reaches the near field strength threshold. The near field field strength threshold can be set by the calibration process.

In the process of judging distance, it is judged whether the interferer is the target mobile phone or not, and the field strength distribution equalization method can be used for auxiliary judgment to prevent malicious communication attacks. The method is: analyzing whether the field strength distribution balance of the RF signal transmitted by each communication antenna in the reader antenna array received by the current RF SIM card meets an expected value. As the distance increases, the difference in field strength of each communication antenna in the antenna array received by the radio frequency SIM card is reduced, so the field strength distribution balance value of the radio frequency signal becomes smaller, and the balance value of the field strength distribution is determined. The size can be determined by the approximate range of distance. There are many methods for calculating the distribution of field strength. The methods that can be used include variance, adjacent antenna difference, and packet antenna difference. The method for determining the field strength distribution equilibrium distance based on the difference of the packet antennas can be implemented by the following steps:

1) Grouped according to the physical distribution of each communication antenna in the antenna array. As shown in Figure 7, the communication antenna numbers can be grouped into 1, 2, and 3, and the numbers 4, 5, and 6 can be grouped into one group, and the numbers 7 and 8, 9 can be divided into groups and numbered 10 and 11. 12 divided into groups, divided into four groups;

2) The RF SIM card sums the received RF signals into four groups to form SUM1, SUM2, SUM 3 and SUM4;

3) The field strength distribution equilibrium is defined as PB = ( Abs ( SUM2-SUM1 ) + Abs ( SUM3-SUM2 ) + Abs ( SUM4-SUM3 ) + Abs ( SUM1-SUM4 ) ) / ( SUM1 + SUM2 + SUM3 + SUM4 ) ;

4) According to the target control distance range, the field strength distribution equalization corresponding to the target mobile phone is actually used as the threshold value. When the current field strength distribution balance value is greater than the threshold value, the judgment distance is within the target distance range, otherwise the distance is within the target distance range. Outside

5) The PB and the distance of different mobile phones also have a fixed correspondence relationship, and the PB-D curve can also be obtained by calibration, etc.; this curve can replace the book-PW curve of the calibration process in the communication distance judging method, and the book- △ PW curve fits to accurately determine the current communication distance;

6) Because the RF system has the characteristics of symmetry of transmission and reception, the field strength distribution is determined by distance The method can also use the radio frequency SIM card to transmit the antenna array to receive the packet judgment method to achieve the same effect.

Since the antenna array includes multiple antennas, the echo field strength detected by the echo detecting antenna and the signal field strength detected by the mobile phone radio frequency SIM card are multiple values, and in actual use, multiple values can be converted into one value. Easy to handle, simple methods are:

1) Accumulation sum method, this method can be used for echo field strength and signal field strength processing received by RF S IM card. That is, the field strength or field strength variation corresponding to each antenna is simply arithmetically accumulated;

2) Absolute value summation, this method can be used for echo field strength variation processing. That is, the variation of the echo field strength of each antenna is taken as an absolute value and then accumulated;

The distance control accuracy is related to the wavelength of the communication RF signal, and the control accuracy is approximately one quarter of the wavelength. For example, when communicating at a frequency of 2.4 GHz, the control accuracy is about 3 cm.

The antenna array can be distributed in a rectangular range by using multiple communication antennas and one echo detecting antenna to form a transmitting and receiving measuring surface, which is beneficial to reduce the interference of the RF signal measurement and improve the stability of the RF distance control. The antenna array may use four, six, eight, nine or twelve antennas equally spaced in a rectangular range, and the echo detecting antenna is arranged near the center of the rectangle, and the communication antenna in the antenna array transmits a signal. The echo detecting antenna on the antenna receives and detects the field strength of the radio frequency signal, and the increase in the number of antenna arrays and the increase in the distribution area are beneficial to improve the stability of the distance control.

The distance judgment in the distance control system can be realized by the processor in the card reader in the P0S.

The radio frequency communication terminal can also be a mobile phone with a short-range communication function module, that is, the short-range communication radio frequency chip is embedded in the mobile phone, and the same short-range radio frequency communication effect as the mobile phone with the radio frequency SIM card is realized.

The RF communication terminal can also be a PDA, a netbook, and other portable mobile devices.

The RF SIM card can also be a memory card with RF communication function and other RF communication modules. The method for controlling the radio frequency communication distance of the invention effectively reduces the individual pair distance of the radio frequency communication terminal Influence of control factors, good stability and accurate distance control.

The following is a specific system for controlling the radio frequency communication distance as an example, and the above-mentioned system and method for controlling the radio frequency communication distance are further described in detail.

1 is a structural diagram of an embodiment of a system for controlling radio frequency communication distance according to the present invention. As shown in FIG. 1, in the present embodiment, the system for controlling the radio frequency communication distance includes a mobile phone 100 including a radio frequency SIM card 200, a POS machine 300, and a calibrator 400. Both the POS machine and the calibrator include a card reader 500. The POS machine 300 communicates with the mobile phone 100 with the radio frequency SIM card 200 and the radio frequency characteristic parameter measurement through the card reader 500. The calibrator 400 is implemented by the card reader 500. Communication and radio frequency characteristic parameter measurement are performed with the mobile phone 100 with the radio frequency SIM card 200 under distance conditions.

2 is a structural diagram of the card reader 500 of FIG. 1. As shown in FIG. 2, the card reader 500 includes an antenna array 501 and a card reader host 502, wherein the antenna array 501 includes a plurality of communication antennas 5011 and echoes. The antenna 5012 is detected.

3 is a schematic diagram of a propagation path of a radio frequency signal transmitted by the antenna array 501 of FIG. 1. As shown in FIG. 3, a plurality of communication antennas 5011 in the antenna array 501 transmit radio frequency signals according to a specified requirement (ie, according to a set power), and an antenna. The echo detection antenna 5012 and the RF SIM card 2QQ in the array 501 receive the RF signal and detect the RF signal field strength.

4 is a flow chart of a calibration process in an embodiment of a method for controlling radio frequency communication distance according to the present invention. As shown in FIG. 4, the calibration process may include the following steps:

Step 701: Set a distance between the card reader 500 and the mobile phone 100 in the calibrator 400. Step 702: Start the communication antenna 5011 in the antenna array 501 to transmit a radio frequency signal. Step 703, the echo detection antenna 5012 in the antenna array 501 Receiving the radio frequency signal, and detecting the field strength value of the currently received echo signal, and subtracting the initial echo field strength value P from the echo signal field strength value. Obtain the change value of the echo field strength and record it;

Step 704, the radio frequency SIM card 200 simultaneously receives the radio frequency signal transmitted by the communication antenna 5011 and detects the field strength value of the radio frequency signal, and records it; In step 705, it is determined whether the calibration process is finished, that is, whether all target distances are all measured, if step 701 is not repeated, otherwise step 706 is performed;

Step 706: Draw a corresponding curve 602 according to the relationship between the recorded echo field strength change value and the communication distance, and draw a curve 601 according to the relationship between the recorded radio frequency SIM card 200 detecting the absolute value communication distance of the RF signal field strength, according to the record. The relationship between the absolute value of the echo field strength change and the communication distance is plotted 603, and the curve 601, the curve 602, and the curve 603 shown in FIG. 5 are obtained, and the calibration process is completed.

6 is a flow chart of determining a current communication distance in an embodiment of a method for controlling radio frequency communication distance according to the present invention. As shown in FIG. 6, the following steps may be included:

Step 801, the card reader 500 in the POS machine 300 continuously activates the echo detecting antenna 5012 to detect the absolute value change of the echo field strength Abs ( P - P „ ) ;

Step 802, it is determined whether Abs (P-P.) exceeds the threshold AP _g , if step 801 is not repeated, otherwise proceeds to step 803;

Step 803, find the echo field strength change value (P-P.) in the curve 602, the next corresponding distance j;

Step 804, in the curve 601, the RF signal field strength value PWj detected by the radio frequency SIM card corresponding to the book j is found;

Step 805: Determine whether the RF signal field strength value PWc actually detected by the current radio frequency SIM card 200 is within the range of PWj±P _A. If not, go to step 803. If yes, go to step 806; Step 806, determine distance meter _k Current actual communication distance.

FIG. 一种 is a structural diagram of the antenna array 501. As shown in FIG. 7, the antenna array 501 includes 12 communication antennas 5011 and an echo detection antenna 5012.

Based on the antenna array shown in FIG. 7, the card reader host 502 alternately transmits a 2.4 GHz radio frequency signal through 12 communication antennas 5012 of the antenna array 501, and the echo detection antenna 5012 of the antenna array 501 receives the radio frequency signal and detects the strength of the radio frequency signal. , that is, the echo RF signal field strength P, when The former echo RF signal field strength P and the initial field strength P. The difference (P _ P.) is the echo field strength change value Δ PW.

1 is a mobile phone at a different height from the antenna array 501 shown in FIG. 7. The 12 communication antennas 5011 of the antenna array 501 transmit RF signals in turn, and the echo detection antenna 5012 simultaneously receives and measures the echo field strength variation. An example of the actual test data obtained, the data unit is dB.

2 is a mobile phone at a different height from the antenna array 501 shown in FIG. 7, 12 communication antennas 5011 of the antenna array 501 transmit RF signals in turn, and the RF SIM card 200 simultaneously receives and measures the absolute value of the received RF signal field strength. An example of actual test data, the data unit is dB.

Table 2

8 is a communication distance and echo field strength change value and an absolute value of the echo field strength change between the mobile phone and the antenna array based on the data shown in Table 1 and Table 1, and the field strength value of the RF signal received by the SIM card. Correspondence between the two corresponds to curves 602, 603, and 601, respectively. It can be seen from the curve 602 in Fig. 8 that the curve period is about 12 cm, which is consistent with the wavelength of the 2.4 GHz frequency.

Figure 9 is the communication distance and echo field strength change value between the mobile phone and the antenna array, the absolute value of the echo field strength change, and the field strength value of the RF card received by the SIM card, and the RF signal field received by the RF SIM card after canceling the interference The correspondence between strong values. The field strength curve 604 of the RF card received by the RF SIM card after canceling the interference is the difference between the field strength curve 601 of the RF SIM card receiving RF signal and the absolute value curve of the echo field strength variation 603. Based on the curve 604 and the curve 602, it can be judged by a simple distance.

The method and system for controlling the radio frequency communication distance of the invention have the advantages that the distance control is not affected by the individual factors of the radio frequency communication terminal, the stability is good, the distance control is relatively accurate, and is particularly suitable for a higher frequency band (such as UHF UHF, extremely high) Frequency SHF, etc.) Distance control of the communication system.

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 method for controlling a radio frequency communication distance, which is characterized in that it is applied to a radio frequency communication system including a radio frequency communication device having an antenna array, wherein the antenna array includes a communication antenna and an echo detection antenna, and the communication antenna is set according to The radio frequency signal is transmitted by the fixed wave, the echo detecting antenna receives the echo radio frequency signal, the radio frequency communication device detects the echo field strength change value, and the radio frequency communication module in the radio frequency communication terminal receives the radio frequency signal and detects the field strength value of the radio frequency signal. The method includes the following steps:

(a) preserving a correspondence between the communication distance and the radio frequency characteristic parameter in the radio communication device, and setting an echo field strength change trigger threshold, wherein the radio frequency characteristic parameter includes the echo field strength change value and RF signal field strength value;

(b) in the communication process between the radio frequency communication device and the radio frequency communication terminal, the radio frequency communication device continuously detects the current echo field strength change value, and determines whether the absolute value of the echo field strength change value reaches the The echo field strength change trigger threshold, if yes, execute step (c), otherwise repeat step (b);

The method for controlling a radio frequency communication distance according to claim 1, wherein in the step (a), the correspondence relationship is obtained by a calibration process, wherein the calibration process is: the calibrator detects a plurality of predetermined distances The RF signal field strength value PWj and the echo field strength change value Δ PWj received by the RF communication terminal are fitted to the book-Δ PW curve and the PW curve according to the periodic oscillation attenuation law, that is, the communication distance and the echo field strength change value. The relationship between the relationship curve and the communication distance and the field strength of the RF signal is the corresponding relationship.

The method for controlling the radio frequency communication distance according to claim 1 or 2, wherein in the step (c), determining the current communication distance according to the correspondence relationship is specifically: the radio frequency communication device according to the echo field The strong change value APW finds the next corresponding book j value on the book-APW curve, and then finds the corresponding RF signal field strength value PWj through the book j value book-PW curve, if the field currently detected by the RF communication module The strong value PWc is in the range of PW j ± P _Δ , then the communication distance is DWj, and ΡΔ is the maximum receiving field strength error value of the preset RF communication module.

The method for controlling radio frequency communication distance according to claim 1 or 2, wherein the step (c) comprises the following substeps:

(c 1 ) Calculate the absolute value of the current echo field strength change value, and subtract the absolute value of the current echo field strength change value from the RF signal field strength value in the current RF characteristic parameter to obtain the 4th dry erase 4 RF signal field strength PWca;

(c2) Calculate the threshold PWag after canceling the interference on the DW-PW curve according to the set target control distance, specifically: the target control distance on the distance axis of the book-PW curve is the perpendicular to the distance axis, the perpendicular line The field strength corresponding to the intersection of the DW-PW curve is PWag;

The method for controlling the radio frequency communication distance according to claim 1 or 2, wherein in the step (c), determining the current communication distance according to the correspondence relationship is specifically: changing the echo field strength value Δ is taken as an absolute value, and Δ ΔΡ = Abs ( ΔΡ ) - ΔΡ is calculated. Abs is taken as an absolute value, and a D- Δ ΔΡ curve is drawn according to the relationship between Δ ΔΡ and the communication distance, and a threshold value Δ ΔΡ _{8 is set} . If the current ΔΡ is greater than the threshold Δ AP _g then the current communication distance is in the curve D- Δ Δ The vicinity of the distance range corresponding to the P wave valley.

The method for controlling a radio frequency communication distance according to claim 1, wherein the radio frequency communication device is a POS machine, the radio frequency communication terminal is a mobile phone having a radio frequency communication module, and the radio frequency communication module is a radio frequency S. IM card or memory card with radio frequency communication function.

A system for controlling a radio frequency communication distance, comprising: a radio frequency communication device and an radio frequency communication terminal, wherein the radio frequency communication device has an antenna array, wherein the antenna array includes a communication antenna and an echo detection antenna, The communication antenna is configured to transmit a radio frequency signal according to a set power, where the echo detection antenna is configured to receive the radio frequency signal and detect a change value of the echo field strength, and the radio frequency communication terminal is configured to receive the radio frequency signal and detect the field strength value of the radio frequency signal. , among them:

The radio frequency communication device is configured to save a correspondence between a communication distance and a radio frequency characteristic parameter and an echo field strength change trigger threshold, where the radio frequency characteristic parameter includes the echo field strength change value and a radio frequency signal field strength The value is also used to continuously detect the current echo field strength change value during the communication process, and obtain the current radio frequency characteristic parameter when the current echo field strength change value reaches the echo field strength change trigger threshold value. Determining the current communication distance according to the correspondence, and then determining whether the current communication distance is within a preset credit card range, that is, whether it is less than a preset target control distance, and if so, allowing the card transaction, otherwise the card transaction is not allowed.

The system for controlling the radio frequency communication distance according to claim 7, wherein the radio frequency communication device is a POS machine, the P0S machine includes a POS host and a card reader, and the card reader includes a read. a card host and the antenna array, the POS host is configured to process service data during a card transaction process; and the card reader host is configured to save a correspondence between a communication distance and a radio frequency characteristic parameter and a change in echo field strength The trigger threshold is used to continuously detect the current echo field strength change value during the communication process. When the current echo field strength change value reaches the echo field strength change trigger threshold, the current RF is obtained. Determining a current communication distance according to the corresponding relationship, and then determining whether the current communication distance is within a preset credit card range, that is, whether it is less than a preset target control distance, and if so, allowing a credit card transaction, otherwise the credit card transaction is not allowed. .

The system for controlling the radio frequency communication distance according to claim 7, wherein the radio frequency communication terminal comprises a radio frequency communication module, and the radio frequency communication module comprises a central processing unit cpu connected to the central processing unit CPU. a radio frequency transceiver circuit and an interface circuit, and a radio frequency transceiver antenna connected to the radio frequency transceiver circuit, the radio frequency transceiver antenna and the radio frequency transceiver circuit are configured to receive the radio frequency signal, and the central processing unit CPU is configured to detect the field strength of the radio frequency signal. The memory is configured to store the RF signal field strength, and the interface circuit is configured to communicate with other portions of the RF communication terminal.

The system for controlling radio frequency communication distance according to claim 7, wherein the radio frequency communication terminal is one of a mobile phone, a PDA, and a netbook.

The system for controlling radio frequency communication distance according to claim 9, wherein the radio frequency communication module is a radio frequency SIM card or a memory card having a radio frequency communication function.

The system for controlling radio frequency communication distance according to claim 7, further comprising a calibrator, wherein the calibrator is configured to detect a radio frequency signal field strength value PWj received by the radio frequency communication terminal at a predetermined distance and back Wave field strength change value A PWj , according to the periodic oscillation attenuation law fitting book - Δ PW curve and book - PW curve, that is, the relationship between communication distance and echo field strength change value and the relationship between communication distance and RF signal field strength value A curve, the relationship is the corresponding relationship.

The system for controlling radio frequency communication distance according to claim 7, wherein the antenna array is distributed in a rectangular range by using a plurality of communication antennas and an echo detecting antenna to form a transmitting and receiving measuring surface. .