CN103023536B - Device, system and method used for detecting and transmitting low-frequency magnetic field signal and judging distance - Google Patents
Device, system and method used for detecting and transmitting low-frequency magnetic field signal and judging distance Download PDFInfo
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- CN103023536B CN103023536B CN201010166432.1A CN201010166432A CN103023536B CN 103023536 B CN103023536 B CN 103023536B CN 201010166432 A CN201010166432 A CN 201010166432A CN 103023536 B CN103023536 B CN 103023536B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/023—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring distance between sensor and object
Abstract
The invention relates to a device and a method used for detecting and transmitting close-range low-frequency magnetic field signals and judging distance. The device comprises at least one low-frequency sensor module used for sensing low-frequency signals, at least one amplifier used for amplifying the low-frequency signals, at least one analog-digital converter connected with the output end of the amplifier, and a digital processing module connected with the analog-digital converter, wherein the digital processing module is used for judging the intensity of original signals and accomplishing the signal detection and output. The invention further provides a system combining the close range detection and the radio-frequency high-frequency communication of the low-frequency alternating magnetic field, which comprises a radio frequency communication terminal and a close range radio frequency communication device, wherein the radio frequency communication terminal comprises the device used for detecting and transmitting the close-range low-frequency magnetic field signals and judging the distance and a radio frequency transceiver circuit. The device, the method and the system can accomplish the pre-amplification of the low-frequency weak signals, the analog-digital conversion, the field intensity detection and the data communication by a simple circuit structure, so that the reliable bidirectional distance communication can be realized without modifying a mobile terminal.
Description
Technical field
The present invention relates to the communications field, relate in particular between a kind of terminal and terminal, the detection of low frequency magnetic field signal and the apparatus and method of transmission while carrying out the controlled close-distance safety data communication of distance, the radio communication terminal (as mobile phone, PDA etc.) that particularly contains radio-frequency unit (as radio-frequency card) or there is close distance radio frequency communication function with close distance radio frequency communication equipment (such as POS machine or card reader; POS, i.e. Point of sales) distance control, magnetic field low frequency signal detects and the apparatus and method of transmission.
Background technology
Scientific and technological progress is today fast, people's life is also more and more convenient, wherein mobile payment industry is also arisen at the historic moment under such sight, nowadays, as long as being changed to a SIM card, mobile phone can realize mobile phone short-range communication, the appearance of this method make mobile phone become one can supplement with money, consume, the super intelligent terminal of transaction and authentication, greatly met the active demand in market.
This kind of SIM card, adopts the technology such as radio frequency UHF (Ultra High Frequency, hyperfrequency) to be embedded in mobile phone draw-in groove, without revising other structures, just can complete short-range communication and transaction.
But, due to the transmission otherness of UHF in different structure mobile phone, cause the mobile communication distance of different shielding propertiess to differ larger, far several meters, closely several centimetres, in concluding the business as swiping the card of public transport POS machine or subway gate, often the distance of can concluding the business is had to stricter restriction, to guarantee to avoid misoperation.That therefore, adjusts the distance has effectively been controlled to extremely urgent demand.
Prior art has existed a kind of low frequency alternating magnetic field closely to detect the system and method in conjunction with the communication of RF high frequency, has solved the problem that above-mentioned distance is controlled.This system is utilized low frequency alternating magnetic field, realizes card reader to the one-way communication of card, completes distance and controls and authentication, and recycling RF passage is realized the high speed communication between card reader and card.The feature of this system is without transformation mobile terminal, only needs to change SIM card/TF/SD card of terminal inner, can realize reliable two-way range communication.
Card reader transmitting low frequency alternating magnetic field signal, card only needs to receive this field signal, owing to being one-way communication, and by magnetic field, provides energy without card reader, therefore can, by receiving coil or other receiving circuit miniaturizations, be enough to put into SIM card/TF/SD card.Due to receive signal a little less than, in card, need to increase amplifying circuit.
In card, place RF transmission circuit in addition simultaneously, realize bidirectional high speed communication with the RF transmission circuit in card reader, as previously described, the antenna of RF circuit is very little, can be integrated into easily in SIM card/TF/SD card.
Utilizing low channel to realize distance detects and controls, card reader sends the unique ID r of self to card by low frequency half-duplex channel, clamping sends card reader together with the unique ID c that blocks self to by RF passage after receiving, thereby realize unique binding of card reader and card, i.e. the process of so-called mobile terminal access card reader.
Due to card reader and unique binding of card, the communication after access procedure adopts RF passage to carry out, and still can guarantee apart from the reliability of controlling and the reliability of communication.
In sum, no matter low frequency or the size of RF antenna all can be integrated in card adopts the mode of low frequency and RF combination to realize both-way communication, therefore without transformation mobile terminal simultaneously, only need to change SIM card/TF/SD card of terminal inner, can realize reliable two-way range communication.
Therefore, how effectively to reduce circuit noise and the interference of ambient noise to low frequency signal, from low frequency signal, recover exactly data flow, realize card reader and card one-way communication, extract range information and effectively control the distance of its transaction and become current problem demanding prompt solution.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of for the method and apparatus of low frequency magnetic field input and transmission and Distance Judgment closely, for respond to low frequency signal, to low-frequency weak signal carry out pre-amplification, analog-to-digital conversion, field intensity detects and the apparatus and method of data communication.
The technical scheme that the present invention solves the problems of the technologies described above is as follows: a kind of device for low frequency magnetic field input and transmission and Distance Judgment, comprise at least one for respond to low frequency magnetic field signal low frequency induction module, at least one is for amplifying amplifier, at least one analog to digital converter being connected with amplifier out of low frequency induction signal and being connected with analog to digital converter and for judging that the intensity of primary signal and settling signal detect the digital signal processing module of output.
The invention has the beneficial effects as follows: utilize the structure of apparatus of the present invention, without transformation mobile terminal, only need to change SIM card/TF/SD card of terminal inner, can realize reliable two-way range communication.
On the basis of technique scheme, the present invention can also do following improvement.
Further, described low frequency induction module is induction coil, Hall element, or giant magnetoresistance.
Further, described amplifier adopts the mode of casacade multi-amplifier cascade.
Further, described amplifier is single-ended amplifier, can be also differential amplifier.
Further, in the casacade multi-amplifier of described cascade, every grade of input connects high-pass filtering circuit, every grade of output connection low-pass filter circuit, and amplifier is low imbalance and the long-pending amplifier of high gain-bandwidth.
The beneficial effect that adopts above-mentioned further scheme is that every grade of input and output side is introduced high pass and low-pass filtering, improves signal to noise ratio.
Further, described analog to digital converter adopts parallel A/D converter.
Adopt the beneficial effect of above-mentioned further scheme to be: to improve rear end digital module treatment effeciency.
Further, described analog to digital converter speed is greater than 1KSPS, and input range is that 0V is to analog to digital converter reference voltage.
Further, described analog to digital converter input front end is provided with the voltage follower being connected with amplifier.
Adopt the beneficial effect of above-mentioned further scheme to be: the simulation amplifying signal of stabilizing amplifier output, the voltage drift of avoiding A/D front end high resistant to cause, causes analog-to-digital conversion distortion.
Further, between described analog to digital converter and digital signal processing module, be provided with for digital signal being carried out to the digital spur filter of burr filtering.
The present invention also provides a kind of low frequency alternating magnetic field closely to detect the system in conjunction with the communication of radio frequency high frequency, comprise radio communication terminal and close distance radio frequency communication equipment, wherein, described radio communication terminal comprise as described in as arbitrary in claim 1 to 8 for the device of low frequency magnetic field input and transmission and Distance Judgment closely, and be connected for the radio-frequency (RF) transmit-receive circuit with close distance radio frequency communication equipment both-way communication for the device of low frequency magnetic field input and transmission and Distance Judgment closely with described.
It is a kind of for the method for low frequency magnetic field input and transmission and Distance Judgment closely that the present invention also provides, and method comprises:
Step a: measure magnetic induction module and the card reader that sends magnetic field at the induced voltage of different distance point the voltage amplitude value after amplifier amplification, determine the corresponding relation of voltage amplitude value and distance, and set up the corresponding table of range value and distance;
Step b: according to the swipe the card needs of distance of decoded low frequency signal transmitted data and control, in conjunction with signal to noise ratio requirement, form sluggish judgement voltage threshold by comparison threshold analog to digital converter output signal is adjudicated, obtain the code stream information of low-frequency magnetic place transmission; By comparison threshold, form non-sluggish judgement voltage threshold analog to digital converter output signal is adjudicated, obtain the distance feature information that transmit in low-frequency magnetic place;
Step c: signal after non-sluggish judgment condition judgement is sampled and obtained 0,1 code stream sequence, 1 signal proportion thresholding is set, in the time window length of setting, this code stream sequence is added up, when the shared code stream sequence of 1 signal ratio reaches preset ratio thresholding, think and enter set distance range, otherwise think and do not enter this distance range; Burst after sluggish judgment condition judgement is decoded, extract the code stream information of low frequency magnetic field, complete low frequency magnetic field signal one-way communication.
Further, in described step b, the corresponding table according to range value described in step a with distance, the requirement in conjunction with separating code distance, distance control, arranges the ratio thresholding of 1 signal and the comparison threshold in digital signal processing module is set.
Further, in described step b, use single, a plurality of single, a pair of, multipair comparison thresholds or its combination to extract magnetic field range information and code stream information.
Further, described a pair of comparison threshold is non-sluggish judgment condition, its method to set up is: the distance of establishing desired control is D1, search the corresponding table of range value and distance, obtaining the signal intensity amplitude that D1 is corresponding is+arrive-A1 of A1, the ratio thresholding that 1 signal is set is R1, according to A1 and R1, the level L1 of comparator is exported in setting, L2, meet in one-period, the percentage of time that fore device amplitude output signal is greater than L1 or is less than L2 equals R1, being greater than R1 enters in distance D 1 scope that described requirement controls, otherwise do not enter in the described scope that requires command range D1.
Further, in described digital signal processing module, a pair of comparison threshold is sluggish judgment condition, its method to set up is: if the distance that expectation is decoded is D2, search the corresponding table of range value and distance, the amplitude of variation that obtains D2 respective signal is+arrive-A2 of A2 that the amplitude that records most of noises generations is A3, and the level L3, the L4 that export to comparator are set, make should be greater than+A3 of L3, and be less than+A2; Be less than-A3 of L4, and be greater than-A2, allow decoding when distance is less than D2, otherwise do not allow decoding.
Further, in described step b, to using two output signals after paired non-sluggish judgment condition judges to carry out logic OR processing, after processing, obtain for extracting the digital signal of range information.
Further, in described step b, two output signals after using paired sluggish judgment condition to judge are carried out to sluggishness and process, after sluggish processing, obtain for extracting the digital signal of magnetic field code stream information.
Further, while using single comparison threshold to extract magnetic field code stream information, comparison threshold is set to amplifier input reference level; When using single comparison threshold output comparative level to extract magnetic field range information, comparison threshold method to set up is consistent with a pair of comparison threshold method to set up.
Further, the digital signal that described method is used a plurality of single comparison thresholds to export is more afterwards carried out the judgement of single distance and code stream, or uses the digital signal that multipair comparison threshold is exported more afterwards to carry out the judgement of single distance and code stream; The digital signal that described method is used a plurality of single comparison thresholds to export is more afterwards carried out the judgement of a plurality of distances and code stream, or uses the digital signal that multipair comparison threshold is exported more afterwards to carry out between a plurality of distances, a plurality of distance regions and the judgement of code stream.
Further, the digital signal that the digital signal that a plurality of single comparison thresholds of described method mixing use are exported more afterwards and multipair comparison threshold are exported is more afterwards carried out between a plurality of distances, a plurality of distance regions and the judgement of code stream.
Further, in described step c, comprise the step that the digital signal of input is carried out to burr filtering, then from the signal of filtering burr, decode low frequency magnetic field data flow.
Accompanying drawing explanation
Fig. 1 is the present invention for a kind of example structure figure of the device of low frequency magnetic field input and transmission and Distance Judgment closely;
Fig. 2 is the structural representation of induction coil induction low frequency mode of the present invention and single-ended input amplifier;
Fig. 3 is the structural representation of Hall element induction low frequency mode of the present invention and single-ended input amplifier;
Fig. 4 is the structural representation of giant magnetoresistance induction low frequency mode of the present invention and single-ended input amplifier;
Fig. 5 is the application example of induced signal difference input amplifier of the present invention;
Fig. 6 is the flow chart of embodiment of the present invention medium and low frequency signal detecting method.
Fig. 7 be in the embodiment of the present invention, record by experiment induction module is inserted to different mobile communication terminal, the corresponding relation schematic diagram of distance and low frequency induction signal amplitude value.
Fig. 8 is the inside basic block diagram of embodiment of the present invention analog to digital converter;
Fig. 9 is the schematic diagram that uses paired comparison threshold to adopt low frequency magnetic field signal detecting method to decode and process in the embodiment of the present invention;
Figure 10 is used paired comparison threshold to adopt low frequency signal detection method to carry out distance to control the schematic diagram of processing in the embodiment of the present invention;
Figure 11 is the schematic diagram that uses single comparison threshold to adopt magnetic field data low frequency signal detection method to decode and process in the embodiment of the present invention;
Figure 12 is used single comparison threshold to adopt low frequency signal detection method to carry out distance to control the schematic diagram of processing in the embodiment of the present invention;
Figure 13 is that a kind of low frequency alternating magnetic field of the present invention closely detects the system architecture diagram in conjunction with the communication of radio frequency high frequency.
In accompanying drawing, the list of parts of each label representative is as follows:
01: low frequency induction module
02: amplifier
03: analog/digital converter
04: digital logic module
05: comparator
06: the control module of analog to digital converter
07: analog to digital converter
08: data register
AIN: single-ended input signal
VINP: differential input signal anode
VINN: differential input signal negative terminal
VCM: common-mode voltage
Vref: reference voltage
VOUT: the outputting analog signal of amplifier afterbody
Ra1, Ra2, Ra3, Ra4, Ra5, R1, R2: resistance
R3, R4, R5, R6: Hall element internal components
C1, C2, C3, C4, C5, C6, C7, C8, C9, C10: electric capacity
L: induction coil
D0-Dn-1:ADC digital output
A: voltage follower
B: analog to digital converter nucleus module.
Embodiment
Below in conjunction with accompanying drawing, principle of the present invention and feature are described, example, only for explaining the present invention, is not intended to limit scope of the present invention.
Detection and the information communication of specific implementation low frequency magnetic field field intensity of the present invention, adopted a kind of structure by single-stage or cascade gain adjustable amplifier and analog to digital converter to complete collection and the response of information.The concrete amplifier that uses amplifies front end small-signal, and the input of the signal connection mode number converter after amplification transfers to digital module to carry out digital algorithm after analog-to-digital conversion, thereby realize distance, controls and communication.Below in conjunction with accompanying drawing, describe:
Fig. 1 has described the structure chart of the present invention for the device of low frequency magnetic field input and transmission and Distance Judgment, it comprises low frequency induction module 01, for amplifying the amplifier 02 of low frequency induction signal, the analog to digital converter 03 being connected with amplifier out, be connected with analog to digital converter 03 and for judging the intensity of primary signal and the digital signal processing module 04 that settling signal detects output.The present invention is used for the device collection of low frequency magnetic field input and transmission and Distance Judgment and amplifies faint low frequency signal, through analog-to-digital conversion, digital algorithm, finally completes distance control and transaction communication.
Figure 2 shows that a kind of a kind of structure example for the cascade gain adjustable amplifier that closely device of low frequency magnetic field input and transmission and Distance Judgment is used of the present invention.Cascade gain adjustable amplifier in this example, adopt single-ended input, the variation voltage AIN that induction coil L is coupled to by low frequency magnetic field Strength Changes is as shown in Figure 2 input to the 1st grade of amplifier negative terminal, 4 grades of modes that all adopt anti-phase amplification next, complete the pre-amplification of low-frequency weak signal altogether through 5 grades of inverting amplifiers.
In this example, high-pass filtering is introduced in every grade of input, and low-pass filter circuit is put in feedback control loop.C1/Ra1 in Fig. 2, C3/Ra2, C5/Ra3, C7/Ra4, C9/Ra5 is the RC high-pass filtering of every grade of input, along with the increase of frequency, condensance constantly reduces, and causes circuit gain to rise, and forms high-pass filtering, and C2/Rb1, C4/Rb2, C6/Ra3, C8/Rb4, C10/Rb5 is the RC low-pass filtering of every grade of feedback control loop, along with the increase of frequency, equivalence feedback impedance constantly reduces, and causes gain to decline, thereby forms low-pass filtering.In addition, the capacitor C 1 of the 1st grade of input plays every straight effect simultaneously, prevents that the DC differential pressure at induction coil two ends from causing signal to misplace large and error detection.The low-frequency cut-off frequency of every one-level determines by its RC high-pass filtering circuit, and high-frequency cut-off frequency is determined by its RC low-pass filter circuit.
In this example, every one-level multiplication factor is determined by corresponding Rb/Ra, and the total magnification after 5 grades of amplifications is Rb1*Rb2*Rb3*Rb4*Rb5/Ra1*Ra2*Ra3*Ra4*Ra5, in practical application, can according to circumstances to progression, increase and decrease.This common-mode voltage is selected half of amplifier power supply voltage, and amplifier adopts single power supply, also can according to circumstances select the mode of positive-negative power supply in application.Amplifier Rail to Rail (rail-to-rail), and possess low imbalance and higher gain bandwidth product.
What Fig. 2 showed is the mode that induction module adopts induction coil, according to circumstances also can adopt other the low frequency induction mode such as Hall element or giant magnetoresistance, as shown in Figure 3 and Figure 4.
Fig. 2 to 4 example has been described the mode that low frequency induction signal adopts single-ended input, according to applicable cases, also can select the mode of difference input, as shown in Figure 5, the 1st grade adopts difference input, Single-end output, the 1st grade of output introduced the passive low-pass filtering of RC, and rear level Four adopts the method for first order pole filtering, and input is introduced RC high-pass filtering, feedback end is introduced RC low-pass filtering, determines respectively lower-cut-off frequency and upper cut-off frequency.Common port is VCM (VDD/2), satisfaction induction signal take VDD/2 as axis symmetrical up and down, to avoid the distortion of waveform.The advantage of introducing the method is to increase common-mode rejection ratio, minimizing common-mode noise.What in this example, amplifier was selected is the amplifier of Single-end output, according to actual conditions, also can select difference input, the mode of difference output.
Fig. 6 is the flow chart of embodiment of the present invention medium and low frequency signal detecting method.The detection of low frequency signal comprises the steps:
Step 601, measures the range value that amplifies rear induced voltage in different distance;
Means by experiment, on different mobile phone terminals, measure magnetic induction module and the card reader that sends magnetic field at the induced voltage of different distance point the range value after amplifier amplification, and do corresponding record.
Step 602, sets up the corresponding table of range value and distance;
The measurement data of a plurality of terminals is processed, obtained the corresponding table of range value and distance.
Step 603, enters low frequency magnetic field data decode flow process;
Step 605, comparison threshold setting;
The expectation distance of decoding is D2, searches the corresponding table of range value and distance, and the amplitude of variation that obtains D2 respective signal is+arrive-A2 of A2, the amplitude that records most of noises generations is A3, level L3, the L4 of comparator exported in setting, makes should be greater than+A3 of L3, and be less than+A2; Be less than-A3 of L4, and be greater than-A2, allow decoding when distance is less than D2, otherwise do not allow decoding.
Step 607, relatively after judgement, output signal is sluggish processes;
Step 609, decodes to processing rear signal;
Decoder is decoded the signal after logical process according to coded format, obtains low frequency magnetic field traffic flow information.Decoder arranges digital spur filter can carry out burr filtering to the digital signal of input.
Step 611, completes the one-way communication of low frequency magnetic field signal;
By the application that after decoding, data are correlated with, complete the one-way communication function of low frequency magnetic field signal.
Step 604, enters apart from control flow;
Step 606, arranges 1 signal proportion thresholding and comparison threshold;
If the distance of desired control is D1, search the corresponding table of range value and distance, obtaining the signal intensity amplitude that D1 is corresponding is+arrive-A1 of A1, the ratio thresholding that 1 signal is set is R1, according to A1 and R1, the level L1, the L2 that export to comparator is set, meet in one-period, the percentage of time that fore device amplitude output signal is greater than L1 or is less than L2 equals R1, is greater than R1 and enters in distance D 1 scope that described requirement controls, otherwise do not enter in the described scope that requires command range D1.
Step 608, relatively after judgement, output signal logic OR is processed;
When using paired comparison threshold to obtain when carrying out the digital signal of Distance Judgment between card reader and card, this paired digital signal is proceeded as follows: after the output signal negate by the output signal after adjudicating by high comparison threshold and after adjudicating by low comparison threshold, carry out or operate, obtaining the digital signal for Distance Judgment.
Step 610, samples and obtains 0,1 data flow signal after step 608 logical process;
Step 612, is used Preset Time window to add up 0,1 data;
Preset Time window length, and 0,1 data in this time window are added up, calculate 1 proportion.
Step 614,616, compares statistics and set 1 signal proportion thresholding, completes Distance Judgment, realizes distance and controls.
Fig. 7 be in the embodiment of the present invention, record by experiment induction module is inserted to different mobile communication terminal, the corresponding relation schematic diagram of distance and low frequency induction signal amplitude value.
Table 1 is the mapping table of embodiment of the present invention medium and low frequency induced signal range value and distance.
| The distance of mobile communication terminal and card reader (cm) | Induced signal amplitude (dBmV) |
| 1cm | 52 |
| 2cm | 47 |
| 3cm | 40 |
| 4cm | 36 |
| 5cm | 30 |
| 6cm | 26 |
| 7cm | 21 |
| 8cm | 17 |
| 9cm | 11 |
| 10cm | 8 |
| 14cm | 5 |
Table 1
Figure 8 shows that the analog to digital conversion circuit basic framework of native system, the A/D of this example adopts the typical mode that successively compares type, comprises voltage follower A and analog to digital converter nucleus module B.Wherein voltage follower A, is mainly used to the simulation amplifying signal that stabilizing amplifier is exported, and the voltage drift of avoiding A/D front end high resistant to cause, causes analog-to-digital conversion distortion.Wherein common mode input port adopts the same common-mode voltage VCM of front-end amplifier.C10 is sampling capacitance, and capacitance is selected according to sampling rate.
In this example, select reference voltage Vref >=amplifier simulation amplifying signal VOUT, adopt the output of Parallel Digital amount, figure place is selected more than 8.
Fig. 9 is the schematic diagram that uses paired comparison threshold to adopt low frequency magnetic field signal detecting method to decode and process in the embodiment of the present invention;
DO shown in Fig. 9 is the output signal after digital to analog converter is changed amplifier input signal.High comparison threshold, low comparison threshold are according to separating code distance and arranging with the corresponding table of distance with reference to range value.DO2 is analog to digital converter output signal and the high comparison threshold output signal after relatively.DO3 is analog to digital converter output signal and the low comparison threshold output signal after relatively.DO4 is for carrying out the signal after sluggish processing to relatively rear signal DO2, DO3.This signal inputs to decoder for decoded data.Decoder can arrange digital spur filter can carry out burr filtering to this input signal, and decoder is decoded the signal after logical process according to coded format, obtains low frequency magnetic field traffic flow information.
Figure 10 is used paired comparison threshold to adopt low frequency signal detection method to carry out distance to control the schematic diagram of processing in the embodiment of the present invention;
DO shown in figure is the output signal after digital to analog converter is changed amplifier input signal.Its rangeability is from-A1 to+A1, and its corresponding distance is L.The L that supposes to adjust the distance controls, and first searches the corresponding table of range value and distance, obtains the signal amplitude value in this distance.The ratio thresholding that 1 signal is set is again R1.According to R1, arranging of high comparison threshold VG+, low comparison threshold VG-meets in one-period, and the percentage of time that fore device amplitude output signal is greater than VG+ or is less than VG-equals R1.To output signal DO2, DO3 after the judgement of paired comparison threshold carry out or process after obtain signal DO4, this signal is sampled, 0,1 data flow D5 after being sampled.In figure, in 0,1 data flow, dotted line frame represents default time window, setup times window length equals a signal period, in time window 0,1 signal are added up, obtain 1 signal proportion, the ratio thresholding of this ratio and 1 signal is compared, if be greater than ratio thresholding, think that induction module enters in distance L; Otherwise think and do not enter this distance.
Figure 11 is the schematic diagram that uses single comparison threshold to adopt magnetic field data low frequency signal detection method to decode and process in the embodiment of the present invention;
DO shown in figure is that digital to analog converter carries out the output signal after analog-to-digital conversion to amplifier input signal.Comparison threshold is set to amplifier input reference level.Relatively, signal directly inputs to decoder as decoder supplied with digital signal.Decoder arranges digital spur filter can carry out burr filtering to this input signal.Decoder is decoded the signal after logical process according to coded format, obtains low frequency magnetic field traffic flow information.
Figure 12 is used single comparison threshold to adopt low frequency signal detection method to carry out distance to control the schematic diagram of processing in the embodiment of the present invention;
DO shown in Figure 12 is the output signal after digital to analog converter is changed amplifier input signal.Its rangeability is from-A1 to+A1, and its corresponding distance is L.The L that supposes to adjust the distance controls, and first searches the corresponding table of range value and distance, obtains the signal amplitude value in this distance.The ratio thresholding that 1 signal is set is again R1.According to R1, arranging of comparison threshold VG meets in one-period, and the percentage of time that fore device amplitude output signal is greater than VG equals R1.Output signal DO1 after relatively adjudicating is sampled, 0,1 data flow DO2 after being sampled.In figure, in 0,1 data flow, dotted line frame represents default time window, setup times window length equals a signal period, in time window 0,1 signal are added up, obtain 1 signal proportion, the ratio thresholding of this ratio and 1 signal is compared, if be greater than ratio thresholding, think that induction module enters in distance L; Otherwise think and do not enter this distance.
It is evident that, when using a pair of comparison threshold, in digital signal processing module, a pair of comparison threshold is non-sluggish judgment condition, its method to set up is: the distance of establishing desired control is D1, search the corresponding table of range value and distance, obtaining the signal intensity amplitude that D1 is corresponding is+arrive-A1 of A1, the ratio thresholding that 1 signal is set is R1, according to A1 and R1, the level L1 of comparator is exported in setting, L2, meet in one-period, the percentage of time that fore device amplitude output signal is greater than L1 or is less than L2 equals R1, being greater than R1 enters in distance D 1 scope that described requirement controls, otherwise do not enter in the described scope that requires command range D1, to using two output signals after paired non-sluggish judgment condition judges, carry out logic OR processing, after processing, obtain for extracting the digital signal of range information, in digital signal processing module, a pair of comparison threshold is sluggish judgment condition, its method to set up is: if the distance that expectation is decoded is D2, search the corresponding table of range value and distance, the amplitude of variation that obtains D2 respective signal is+arrive-A2 of A2, the amplitude that records most of noises generations is A3, level L3, the L4 of comparator exported in setting, makes should be greater than+A3 of L3, and be less than+A2, be less than-A3 of L4, and be greater than-A2, when distance is less than D2, allow decoding, otherwise do not allow decoding, two output signals after using paired sluggish judgment condition to judge are carried out to sluggishness and process, after sluggish processing, obtain for extracting the digital signal of magnetic field code stream information.
It is evident that, the digital signal that also can use a plurality of single comparison thresholds to export is more afterwards carried out the judgement of single distance and code stream, or uses the digital signal that multipair comparison threshold is exported more afterwards to carry out the judgement of single distance and code stream; The digital signal that described method is used a plurality of single comparison thresholds to export is more afterwards carried out the judgement of a plurality of distances and code stream, or uses the digital signal that multipair comparison threshold is exported more afterwards to carry out between a plurality of distances, a plurality of distance regions and the judgement of code stream; Also can mix the digital signal of using digital signal that a plurality of single comparison thresholds export more afterwards and multipair comparison threshold to export more afterwards carries out between a plurality of distances, a plurality of distance regions and the judgement of code stream.
Figure 13 is that a kind of low frequency alternating magnetic field of the present invention closely detects the system architecture diagram in conjunction with the communication of radio frequency high frequency, as shown in the figure: system comprises radio communication terminal and close distance radio frequency communication equipment, radio communication terminal comprises low frequency alternating magnetic field signal receiving circuit, be connected with low frequency alternating magnetic field signal receiving circuit for the device of low frequency magnetic field input and transmission and Distance Judgment closely, and be connected for the radio-frequency (RF) transmit-receive circuit with close distance radio frequency communication equipment both-way communication with the device for low frequency magnetic field input and transmission and Distance Judgment.
During work, close distance radio frequency communication equipment transmitting low frequency alternating magnetic field signal, radio communication terminal receives this field signal by low frequency alternating magnetic field signal receiving circuit, and be transferred to the device for low frequency magnetic field input and transmission and Distance Judgment, finally utilize radio-frequency (RF) transmit-receive circuit and close distance radio frequency communication equipment to realize two-way range communication.
According to above description, the present invention can complete low-frequency weak signal pre-amplification, analog-to-digital conversion, and field intensity detects and data communication.
The foregoing is only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.
Claims (21)
1. one kind for the device of low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, comprise at least one for respond to low frequency magnetic field signal low frequency induction module, at least one is for amplifying amplifier, at least one analog to digital converter being connected with amplifier out of low frequency induction signal and being connected with analog to digital converter and for judging that the intensity of primary signal and settling signal detect the digital signal processing module of output;
This device is used for closely low frequency magnetic field input and transmission and Distance Judgment, specifically comprises:
Step a: measure magnetic induction module and the card reader that sends magnetic field at the induced voltage of different distance point the voltage amplitude value after amplifier amplification, determine the corresponding relation of voltage amplitude value and distance, and set up the corresponding table of range value and distance;
Step b: according to the swipe the card needs of distance of decoded low frequency signal transmitted data and control, in conjunction with signal to noise ratio requirement, form sluggish judgement voltage threshold by comparison threshold analog to digital converter output signal is adjudicated, obtain the code stream information of low-frequency magnetic place transmission; By comparison threshold, form non-sluggish judgement voltage threshold analog to digital converter output signal is adjudicated, obtain the distance feature information that transmit in low-frequency magnetic place;
Step c: signal after non-sluggish judgment condition judgement is sampled and obtained 0,1 code stream sequence, 1 signal proportion thresholding is set, in the time window length of setting, this code stream sequence is added up, when the shared code stream sequence of 1 signal ratio reaches preset ratio thresholding, think and enter set distance range, otherwise think and do not enter this distance range; Burst after sluggish judgment condition judgement is decoded, extract the code stream information of low frequency magnetic field, complete low frequency magnetic field signal one-way communication.
2. device according to claim 1, is characterized in that, described low frequency induction module is induction coil, Hall element, or giant magnetoresistance.
3. device according to claim 1, is characterized in that, described amplifier adopts the mode of casacade multi-amplifier cascade.
4. according to the device described in claim 1 or 3, it is characterized in that described amplifier is single-ended amplifier or differential amplifier.
5. device according to claim 3, it is characterized in that in the casacade multi-amplifier of described cascade that every grade of input connects high-pass filtering circuit, every grade of output connects low-pass filter circuit, and amplifier is low imbalance and the long-pending amplifier of high gain-bandwidth.
6. device according to claim 1, is characterized in that, described analog to digital converter adopts parallel A/D converter.
7. according to claim 1,3,5 or 6 arbitrary described devices, it is characterized in that, described analog to digital converter speed is greater than 1KSPS, and input range is that 0V is to analog to digital converter reference voltage.
8. according to claim 1,3,5 or 6 arbitrary described devices, it is characterized in that, described analog to digital converter input front end is provided with the voltage follower being connected with described amplifier.
9. device according to claim 1, is characterized in that, is provided with for digital signal being carried out to the digital spur filter of burr filtering between described analog to digital converter and digital signal processing module.
10. a low frequency alternating magnetic field closely detects the system in conjunction with the communication of radio frequency high frequency, comprise radio communication terminal and close distance radio frequency communication equipment, it is characterized in that, described radio communication terminal comprise as described in as arbitrary in claim 1 to 8 for the device of low frequency magnetic field input and transmission and Distance Judgment closely, and be connected for the radio-frequency (RF) transmit-receive circuit with close distance radio frequency communication equipment both-way communication for the device of low frequency magnetic field input and transmission and Distance Judgment closely with described.
11. 1 kinds for the method for low frequency magnetic field input and transmission and Distance Judgment closely, and method comprises:
Step a: measure magnetic induction module and the card reader that sends magnetic field at the induced voltage of different distance point the voltage amplitude value after amplifier amplification, determine the corresponding relation of voltage amplitude value and distance, and set up the corresponding table of range value and distance;
Step b: according to the swipe the card needs of distance of decoded low frequency signal transmitted data and control, in conjunction with signal to noise ratio requirement, form sluggish judgement voltage threshold by comparison threshold analog to digital converter output signal is adjudicated, obtain the code stream information of low-frequency magnetic place transmission; By comparison threshold, form non-sluggish judgement voltage threshold analog to digital converter output signal is adjudicated, obtain the distance feature information that transmit in low-frequency magnetic place;
Step c: signal after non-sluggish judgment condition judgement is sampled and obtained 0,1 code stream sequence, 1 signal proportion thresholding is set, in the time window length of setting, this code stream sequence is added up, when the shared code stream sequence of 1 signal ratio reaches preset ratio thresholding, think and enter set distance range, otherwise think and do not enter this distance range; Burst after sluggish judgment condition judgement is decoded, extract the code stream information of low frequency magnetic field, complete low frequency magnetic field signal one-way communication.
12. according to described in claim 11 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, in described step b, corresponding table according to range value described in step a with distance, requirement in conjunction with separating code distance, distance control, arranges the ratio thresholding of 1 signal and the comparison threshold in digital signal processing module is set.
13. according to described in claim 11 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, in described step b, use single, a plurality of single, a pair of, multipair comparison thresholds or its combination to extract magnetic field range information and code stream information.
14. according to described in claim 13 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, described a pair of comparison threshold is non-sluggish judgment condition, its method to set up is: the distance of establishing desired control is D1, search the corresponding table of range value and distance, obtaining the signal intensity amplitude that D1 is corresponding is+arrive-A1 of A1, the ratio thresholding that 1 signal is set is R1, according to A1 and R1, the level L1 of comparator is exported in setting, L2, meet in one-period, the percentage of time that fore device amplitude output signal is greater than L1 or is less than L2 equals R1, be greater than in distance D 1 scope that R1 enters described desired control, otherwise do not enter in the scope of described desired control distance D 1.
15. according to described in claim 13 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, described a pair of comparison threshold is sluggish judgment condition, its method to set up is: if the expectation distance of decoding is D2, search the corresponding table of range value and distance, the amplitude of variation that obtains D2 respective signal is+arrive-A2 of A2, the amplitude that records most of noises generations is A3, level L3, the L4 of comparator exported in setting, makes should be greater than+A3 of L3, and be less than+A2; Be less than-A3 of L4, and be greater than-A2, allow decoding when distance is less than D2, otherwise do not allow decoding.
16. according to described in claim 14 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, in described step b, to using two output signals after paired non-sluggish judgment condition judges to carry out logic OR processing, after processing, obtain for extracting the digital signal of range information.
17. according to described in claim 15 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, in described step b, two output signals after using paired sluggish judgment condition to judge are carried out to sluggishness and process, after sluggish processing, obtain for extracting the digital signal of magnetic field code stream information.
18. according to described in claim 13 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, while using single comparison threshold to extract magnetic field code stream information, comparison threshold is set to amplifier input reference level; When using single comparison threshold output comparative level to extract magnetic field range information, comparison threshold method to set up is consistent with method described in claim 16.
19. according to described in claim 13 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, the digital signal that described method is used a plurality of single comparison thresholds to export is more afterwards carried out the judgement of single distance and code stream, or uses the digital signal that multipair comparison threshold is exported more afterwards to carry out the judgement of single distance and code stream; The digital signal that described method is used a plurality of single comparison thresholds to export is more afterwards carried out the judgement of a plurality of distances and code stream, or uses the digital signal that multipair comparison threshold is exported more afterwards to carry out between a plurality of distances, a plurality of distance regions and the judgement of code stream.
20. according to described in claim 13 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, the digital signal that the digital signal that a plurality of single comparison thresholds of described method mixing use are exported more afterwards and multipair comparison threshold are exported is more afterwards carried out between a plurality of distances, a plurality of distance regions and the judgement of code stream.
21. according to described in claim 11 for the method for low frequency magnetic field input and transmission and Distance Judgment closely, it is characterized in that, in described step c, comprise the step that the digital signal of input is carried out to burr filtering, then from the signal of filtering burr, decode low frequency magnetic field data flow.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
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| CN201010166432.1A CN103023536B (en) | 2010-05-10 | 2010-05-10 | Device, system and method used for detecting and transmitting low-frequency magnetic field signal and judging distance |
| PCT/CN2010/073764 WO2011140731A1 (en) | 2010-05-10 | 2010-06-10 | Device, system and method for low-frequency magnetic field signal detecting, transmission and distance estimating |
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| CN201010166432.1A CN103023536B (en) | 2010-05-10 | 2010-05-10 | Device, system and method used for detecting and transmitting low-frequency magnetic field signal and judging distance |
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| CN105228081A (en) * | 2015-08-21 | 2016-01-06 | 联想(北京)有限公司 | A kind of information processing method and electronic equipment |
| CN109917335B (en) * | 2019-03-29 | 2021-04-20 | 北京经纬恒润科技股份有限公司 | Method and device for calibrating received signal strength |
| CN114124257B (en) * | 2021-09-29 | 2024-04-19 | 武汉船舶通信研究所（中国船舶重工集团公司第七二二研究所） | Signal quality evaluation device and signal quality evaluation method |
| CN113872709B (en) * | 2021-10-14 | 2023-10-24 | 上海橙科微电子科技有限公司 | System for continuously monitoring presence or absence of high-speed signal |
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| CN103023536A (en) | 2013-04-03 |
| WO2011140731A1 (en) | 2011-11-17 |
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Inventor after: Sun Yingtong Inventor after: Yu Huan Inventor after: Zhao Hui Inventor after: Liu Yong Inventor after: Liao Weijun Inventor after: Huang Zhen Inventor after: Wang Haixiang Inventor after: Jiang Yu Inventor before: Wang Haixiang Inventor before: Jiang Yu |