CN101807899A - Acoustic surface wave radio frequency tag with high coding capacity - Google Patents
Acoustic surface wave radio frequency tag with high coding capacity Download PDFInfo
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Abstract
The invention relates to an acoustic surface wave radio frequency tag which is characterized in that an interdigital transducer is manufactured on a piezoelectric substrate, and a series of reflecting gratings are arranged behind the interdigital transducer; the reflecting gratings can be arranged in one row or multiple rows; the time interval from the interdigital transducer to the reflecting pulse of the first reflecting grating is set as a blind area, and the position of the first reflecting grating is determined according to the size of the blind area; in order to correct the influence of the uncertain environment temperature, two or three reflecting gratings are arranged generally, wherein one or two phase delay time intervals among the reflecting gratings are accurately known under the specific standard temperature and are constants irrelevant to code values, and each phase delay time interval between other adjacent reflecting gratings is used for representing different tag codes; and the phase delay time intervals among the reflecting gratings are limited, are not definitely used for directly representing code values, and can be possibly used for self-checking, self-correction or anti-collision and other purposes of coded data. The invention can obtain maximal coding capacity under the same information space and frequency bandwidth.
Description
Technical field
This patent relates to acoustic surface wave radio frequency tag.
Background technology
Radio-frequency (RF) tag (RFID, Radio Frequency Identification) technology is a kind of technology of using noncontact tag, and it is by the automatic recognition objective object of radiofrequency signal and obtain related data.It is an important practical technology that adapts to information technology and development of information, has the major application prospect aspect the intelligent management of the automatic packages of highway charge automatically, logistics management, postal aviation, the numerous areas such as taking care of books, animal husbandry monitoring management, vehicle anti-theft of storing in a warehouse.For realizing that any project in the whole world has single said tag, labeling requirement realizes 64,96 even 128 codings.
Adopting the radio-frequency (RF) tag of surface acoustic wave (SAW) technology is a kind of radio-frequency identification method that does not use integrated circuit (IC) chip.Rfid system based on the SAW technology is made up of read write line and SAW label.The SAW label is made up of antenna, interdigital transducer and reflecting grating.The operation principle of SAW rfid system is similar to radar system: receive the wireless pulses request signal of read write line transmission when the interdigital transducer on the label (IDT) after, inverse piezoelectric effect according to piezoelectric, be converted to surface acoustic wave on piezoelectric substrate materials, this surface wave is just propagated to direction in piezo crystals.Through arriving reflecting grating after one period time of delay, part energy is reflected back toward IDT, another partly energy transmission continuation propagation forward.According to direct piezoelectric effect, the surface acoustic wave pulse that is reflected back toward IDT is converted into the signal of telecommunication once more and sends it back read write line by label antenna.Utilize time delay, amplitude, phase place or the frequency of reflection echo pulse can realize label coding.
Because SAW RFID and the essential distinction of IC-RFID on principle, they have different separately characteristics.SAW-RFID has the following advantages:
(1) the SAW label is pure passive, just reflects request signal passively.As long as SAW-RFID echo-signal energy surpasses receiver equivalence thermal noise power; IC tag then needs the radiofrequency signal energy supply, has only the energy of energy supply signal just can start working above behind the semiconductor rectifier voltage threshold.Therefore, SAW-RFID is bigger than IC tag read range, and the signal penetration capacity is strong, more is applicable on the body surface that is attached to metal or includes liquid.IC tag must be sticked on magnetic conduction objects such as ferrite overleaf, has increased cost.
(2) since the utilization of surface acoustic wave label be piezoelectric, the transition process that does not involve electronics in the semi-conducting material, therefore can under high and low temperature adverse circumstances such as (200-500 ℃), use, can bear strong x ray irradiation x (signal does not have significant change under the gamma-rays radiation of 10MRad intensity).
(3) reading speed is fast, can be used to discern high-speed moving object; The SOFIS surface acoustic wave system of Siemens company successfully is used for Oslo, Norway automobile gap bridge automatic fare collection system and the Munich, Germany navigation system that pulls in, can recognition speed reach 300 kms/hour high-speed moving object.
(4) the SAW label can combine with the surface acoustic wave sensing technology, when finishing identification mission, also can measure parameters such as temperature, pressure, acceleration, humidity and gas concentrations; Also can realize object localization by many readers.These those application for the condition that needs the while scorekeeping in the logistics transportations such as " intelligent tire " or food, medicine, blood are very suitable.
Present most of SAW-RFID adopts delay-line structure, promptly utilizes the different distance between transducer and each reflecting grating to form the reflected signal string, thereby determines its coding.Each reflecting grating can be arranged in delegation, also can come a plurality of passages.According to the EPC standard, the coding of radio-frequency (RF) tag often needs 64 even 96 codings, with realize the whole world arbitrarily article single said tag is arranged.For SAW RFID, adopt conventional on-off keying coding (OOK), pulse position (PPM) or phase code coded systems such as (PSK), on the substrate of finite length, can't realize above-mentioned code capacity requirement, become the one of the main reasons of restriction SAW label extensive use.
Can improve the code capacity of SAW-RFID with the way that increases reflecting grating quantity, can increase manufacturing cost so on the one hand, to such an extent as to and reflecting grating quantity too conference cause triple reflection to increase can't decoding, thereby be forced to reduce the reflection coefficient of every reflecting grating, so that increase the reflection loss reduction tag readable degree distance of label.So the different sign indicating number capacity that this method increased is extremely limited.Between the reflecting grating minimum spacing must be arranged, it depends primarily on the bandwidth of radio-frequency queries signal, according to the regulation of China's Wireless Management Committee and international relevant laws and regulations, has only 5MHz in the bandwidth that the 915MHz frequency range allows to use; The ISM band that is used for industry, scientific research and medical treatment is when 2.4-2.5GHz, and bandwidth allows to reach 40MHz.In order to increase the reliability of tag recognition, often outside the different sign indicating number capacity of necessity, also want the outer sign indicating number capacity of occupying volume.So the size of sign indicating number capacity not only will guarantee the different sign indicating number volumetric properties requirement of system, simultaneously also with reliability, cost with read other performances such as distance and link to each other.Increase substantially code capacity effectively and mainly contain two approach: the one, improve the resolution capability of pulse; Another is exactly to adopt coded system more efficiently to replace on-off keying coding (OOK), pulse position (PPM) or the phase code coded systems such as (PSK) of current routine.The former sees that application number is 200810154948.7 Chinese patent, and this patent is primarily aimed at the latter.
Through the existing Searches of Patent Literature is found, with respect to modes such as pulse amplitude coding, pulse position coding or impulse phase codings, a kind of jumbo high efficient coding mode put down in writing in U.S. Pat 6966493 " DESIGN OF GLOBAL SAW RFID TAG DEVICES " literary composition concentrated with being published in the Second International Symposium onAcoustic Wave Devices For Future Mobile Communication Systems meeting paper, and it utilizes pulse delay to encode in conjunction with phase place.Under the constant situation of occupied bandwidth, each packets inner also only has a time slot unlike the pulse position coding, but allow to have simultaneously a plurality of time slots place that pulse is arranged, and on envelope, allow between the time slot that two may be placed pulse and overlap, by the layout of surface acoustic wave reflecting grating, the time location and the phase position of modulating pulse simultaneously.Adopt this coded system efficiently to replace coded systems such as switch coding, pulse position or phase code commonly used can on the finite length substrate, improve code capacity greatly.But still there is following deficiency in this coded system:
(1) in the coding method that patent US 6966493 proposes, utilization be that the time location of pulse is in conjunction with phase position.Therefore, reflecting grating is placed on the possibility that there is many-valued difference position in the time slot groove position.Because be placed on the reflecting grating in certain time slot groove position, the position can move forward and backward one or several integer wavelength, still can have the phase place of appointment.
(2) though grouping is not the principal character of U.S. Pat 6966493, but if realize 12 groupings described in the Patent right requirement, must guarantee between two groupings a dead band, interval that can not be used to encode is arranged on the physical space, this greatly reduces code capacity.
What (3) label that adopts among the patent US 6966493 utilized when decoding is the absolute position of each reflecting grating.In this coding method, the groove position ordinal number that first reflecting grating of each group reflecting grating or last reflecting grating are not fixed in the groove position.In order to determine the time slot groove position ordinal number at each reflected impulse place, must organize outside the reflecting grating during decoding, get a reflecting grating as a reference at this.Along with increasing of number of slots, depart from reference to reflecting grating position far away more, reflecting grating position, its evaluated error is big more, thereby reduces reliability, or has to reduce the space size of each grouping.
(4) do not provide the method for temperature-compensating.Because utilized information such as carrier phase in this coded system, and carrier phase is very responsive to the ambient temperature of label, patent US 6966493 does not propose the method for temperature-compensating.The carrier phase of supposing a reflection echo has the (+I that provides among the embodiment,-Q) four-quadrant, through processes such as design, forming label and actual demodulation, the phase place that demodulation obtains in no case can exceed the four-quadrant scope, otherwise will cause the label decoding error.And the change of label working temperature often makes all actual measurement phase places off-design value all of reflected signal.Along with the increase of temperature range, be provided with improperly if temperature-compensating or temperature-compensating are not set, just might cause surveying phase place and exceed four-quadrant, cause error code.Its result has reduced different sign indicating number capacity sharp thereby must set the enough big distance of being separated by between its groove position on the one hand in its design, and on the other hand, its spendable temperature range is subjected to great limitation.
(5) patent US 6966493 has adopted the coding system of fixation reflex grid numbers.When adopting the technology of this patent, can not limit the number of reflecting grating easily, thereby increase the sign indicating number capacity greatly.
Summary of the invention
In order to solve the above-mentioned weak point of prior art, the invention provides a kind of utilize carry out single pulsion phase time of delay (comprising integer part and fractional part) Methods for Coding (and patent US 6966493 be utilize phase place and pulse position the two).The present invention is achieved through the following technical solutions:
A kind of acoustic surface wave radio frequency tag; it is a series of reflecting gratings (reflecting grating can have 2 to 30) that are manufactured with interdigital transducer and come the interdigital transducer back on piezoelectric substrate; reflecting grating can be lined up 1 row or multirow (but as many as 4 row); the time interval the reflected impulse from interdigital transducer to first reflecting grating is provided with a blind area; determine the position of first reflecting grating according to the blind area size; in order to calibrate the influence of unfixed ambient temperature; often need to be provided with 2 or 3 reflecting gratings; make therebetween 1 or 2 phase retardation time interval under the specific criteria temperature for accurately known; be and the irrelevant amount of code value; each phase retardation time interval between other adjacent reflecting grating is used to represent different label codings; and the phase retardation time between these reflecting gratings is limited setting; these might not be used for the direct representation code value at interval, also may be as the self check of coded data; purposes such as self-correcting or anti-collision.
The phase retardation time between the described reflecting grating is meant that the phase retardation of surface acoustic wave reflected impulse echo under centre frequency of reflecting grating on two diverse locations is poor, and it comprises the complete cycle issue and the phase difference (fractional part of periodicity) of surface acoustic wave under this centre frequency.Fractional part for the periodicity that obtains appointment, when placing the reflecting grating in back, should compensate the transmission phase of the reflecting grating in front of the reflected phase will of this reflecting grating and 2 times, the phase retardation time that is used to encode between the reflecting grating is limited setting, comprises the restriction of three aspects:
(1) the phase retardation time interval value between per two reflecting gratings allows to exist certain error, and other the corresponding reflecting grating positions of phase retardation time institute outside the error range are unallowed in design;
The minimum phase retardation value Δ n that (2) two adjacent permissions are placed between the position of reflecting gratings is limited setting, and the fractional part of this phase retardation value is phase delay fractional part measure error level during greater than decoding; Simultaneously, phase delay integer part measure error level when phase retardation value integer part between the position of reflecting grating is placed in two permissions with identical phase retardation fractional part then greater than decoding, both cooperatively interact, can guarantee in the fractional part and integer part and both error ranges of measured phase delay, can only find a design load definite, that allow;
(3) no matter be coding reflecting grating usefulness and non-coding usefulness (temperature reference) at interval, the phase retardation time between per two adjacent reflecting gratings must not be less than certain minimum phase retardation time interval restriction, also must not be greater than certain maximal phase delay time lag, the influence that the bandwidth, adjacent signals lap that the minimum phase retardation time depends primarily on the wireless request signal of radio-frequency (RF) tag causes carrier phase and the phase error of permission, the minimum phase retardation time between the adjacent reflecting grating is designated as Δ N
Min=N
MinΔ n; And the maximal phase maximum phase error that can bear and label coding capacity requirement during temperature-compensating when depending on the label decoding time of delay is designated as Δ N
Max=N
MaxWhen Δ n, this maximal phase also may decode according to the impulse phase-locked loop mode time of delay, cause the maximum delay time of phase-locked loop losing lock to be determined.
The number of the resolving accuracy Δ n that is comprised from the minimum phase retardation time interval between the reflecting grating to the maximal phase delay time lag the reflecting grating is exactly each reflecting grating denotable different number of codes M=N at interval
Max-N
Min+ 1.Suppose that needing the code value of design is M
CCan be with M
CRepresent with the M carry, write as M
KM
K-1... M
2M
1Form.Units is M
1, M
1Value between 0 and M-1 between.So first encoding time delay is spaced apart (N
Min+ M
1-1) Δ n.Just can determine the position of next reflecting grating according to this value.Press M successively
2, M
3... determine reflecting grating, at last up to remaining space less than maximal phase delay time lag N
MaxΔ n.If but remaining space is still greater than minimum phase retardation time interval N
MinΔ n still can continue the placing reflex grid.Determined M before being located at this
JThe individual time interval, M so
J+1The carry digit of bit code just will be less than M.Continue the placing reflex grid like this, up to remaining space less than minimum phase retardation time interval N
MinTill the Δ n.The sign indicating number of choosing like this, for different code values, the phase delay at interval is apart from difference between each reflecting grating, and the reflecting grating number also may be different.The interval between the reflecting grating of with good grounds code value decision, lump together and form a code value string M
KM
K-1... M
2M
1, we can freely divide into groups in this code value string.Each reflecting grating not necessarily must divide into groups, even grouping also only is to stipulate that virtually which reflecting grating belongs to same group, does not have the isolation dead band that must be provided with physically between two adjacent set.
When label was decoded, the foundation of determining a certain code value was the phase retardation time between the two adjacent pulses, rather than the absolute position at pulse place.Code value is only relevant with the relative position of the related two adjacent pulses in this gap, and is irrelevant with its absolute position, also with forward and backward adjacent pulse outside the respectively location independent of other pulses.Because there are phase place 360 degree ambiguities in the phase retardation time when label decoding is measured, change number the complete cycle that promptly when decoding, can't accurately measure phase retardation.Resulting phase place is the fractional part of phase retardation in the time during Measurement Phase, and measure error is less, for example: percent several cycles.Obtain the complete numerical value of this phase retardation time, also must accurately estimate the value of the integer part of phase retardation time, but determine that the error of integer part value then is several cycles, even tens cycles or bigger.This label echo phase retardation resolving accuracy has determined the coding of adjacent permission with phase delay great interval should be arranged.For guaranteeing to determine accurately the phase retardation time of each reflection echo, need utilize application number is that 200810154948.7 Chinese patent improves the resolving accuracy of the phase delay of decoding.
Useful effect:
The beneficial effect of this patent mainly finds expression in, and under identical information space and frequency bandwidth (minimum spacing of adjacent pulse), obtains maximum code capacity.
For the ISM band that industry, scientific research and medical treatment are adopted, mainly contain near the several intervals of 2.4GHz, 920MHz and 434MHz.Centre frequency is lower, and available relative band is just narrower.Under narrower frequency band, owing to must separate enough distances between the adjacent pulse, and the size of substrate is limited, so general coded system all can only obtain very little different sign indicating number capacity, with regard to existing document, pursue jumbo method and all work is confined near the 2.4GHz centre frequency.Present embodiment 1 and embodiment 2 explanations utilize the present invention, even if near 920MHz, still can obtain enough big sign indicating number capacity on little substrate.In the 920MHz frequency range, obtain 64 of binary systems, even 128 capacity, still need only not too big chip and just can finish.
In order to specify the advantage of this patent, we adopt with patent US 6966493 examples in identical data so that compare.For present embodiment 3 and 4, be equivalent to M=(T-k+1) Δ n=75 Δ n in " DESIGN OF GLOBAL SAW RFID TAGDEVICES " literary composition, the situation of k=12.When adopting patent US 6966493 coding methods and having only the situation of a group, the code capacity that uses four reflecting gratings to obtain is 111930, C=log
2111930=16.77.The device of most of practicability often needs several groups.When adopt patent US 6966493 coding methods and two groupings are arranged or during four groupings code capacity be respectively 12528324900, C=33.54 and 1.57*10
20, C=67.In embodiment 3 and 4, the substrate length of employing is identical with two of patent US 6966493 coding methods groupings or four groupings respectively, and code capacity is along with the increase of information space, and advantage is more and more outstanding.
Also adopted two intervals in present embodiment 2, this is in order to cooperate the result of temperature-compensating.The reflecting grating position that temperature-compensating is used will be determined according to the temperature range that reality is used.Appropriate value can with temperature-compensating the inevitable error of introducing reduce to minimum.In order to adapt to the used reflecting grating position of appropriate temperature-compensating, this patent can optionally change own each interval space size, the flexibility that this also demonstrates the present invention and is had.
Description of drawings
Fig. 1 is the schematic diagram of the designed surface acoustic wave radio frequency identification label of the embodiment of the invention 1;
Fig. 2 is the schematic diagram of reflecting grating position of the surface acoustic wave radio frequency identification label of the embodiment of the invention 1;
Fig. 3 is the decoding process figure of surface acoustic wave radio frequency identification label;
Fig. 4 is the schematic diagram of the designed surface acoustic wave radio frequency identification label of the embodiment of the invention 5;
Embodiment:
Following embodiment elaborates to the present invention, and present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.
Embodiment 1
As shown in Figure 1, at 128 °-YXLiNbO
3Make on the piezoelectric substrate 101 and have the acoustic surface wave radio frequency tag 1 that patent of the present invention proposes coding method.Described radio-frequency (RF) tag 1 comprises interdigital transducer 201 and comes some reflecting gratings 202 (reflecting grating can have 2 to 40) of interdigital transducer back.Transducer 201 utilizes conventional interdigital transducer cascade to obtain better impedance matching as shown in Figure 1.The frequency range of wireless request signal is 920-925MHz.Reflecting grating 202 can be lined up 1 row or multirow.Position between these reflecting gratings 202 is a unit of measurement with the cycle of its echo surface acoustic wave 401 under centre frequency.(be two times of phase delay under the reflecting grating position institute respective center frequency.) reflecting grating 202A wherein, 202B, the phase retardation time between (or adding 202C) is fixed, and is used to calibrate the influence of unfixed ambient temperature.A Fixed Time Interval 301 is set the reflected impulse from interdigital transducer 201 to first reflecting grating 202A.Determine the position of first reflecting grating 202A according to described 301 size.The code value that will represent according to this label will determine the position of all the other reflecting gratings.
According to SAW propagating speed and used piezoelectric substrate length, can determine available space length.As shown in Figure 2, the left side is counted from transducer 201, to the right, supposes that reflecting grating 202C is on the possible position farthest, can calculate an available space length like this.This space length can be converted the shared time span of corresponding reflected impulse.The shared time of deduction Fixed Time Interval 301 and transducer 201 just can obtain available time span from this time span.Dotted line expresses possibility and places the position 200 of reflecting grating.Minimum phase retardation value 300 between two 200 is designed to
Substrate 101 up duration length for 8.5 mm lengths can be expressed as T=578 Δ n.
For fear of the phase mutual interference between the two adjacent reflected impulses, the position arrangement of reflecting grating must make minimum interval 302 between all adjacent reflected impulses greater than certain time interval.Described 302 interrelate with the bandwidth of wireless request signal.Get this value in the present embodiment and be n
Min=48 Δ n; Simultaneously, there is a maximum 303 in the time interval between the adjacent reflected impulse, gets this value n in the present embodiment
Maz=96 Δ n.Like this, as shown in Figure 2, after the position of reflecting grating 202B was determined, the reflecting grating in the 202B back can be placed on a series of possible positions, and this serial position is represented by each dotted line.Code value by this device determines that reflecting grating should be on wherein some positions in these a series of dotted lines.After in case the position of this reflecting grating is determined, can mark a series of dotted lines again again in its back, and according to code value determine its next reflecting grating the dotted line position that should locate.
Get reflecting grating 202A that temperature correction uses and the time interval 307 between the 202B in the present embodiment and equal minimum interval 302 between the two adjacent reflected impulses just.Reflecting grating 202C is placed on from transducer 201 substrate one end farthest, then is equivalent to 530 Δ n to the space the reflecting grating 202C from the reflecting grating 202B that temperature correction is used.Other reflecting gratings can't be laid again in space between from 202A to 202B, and are coding region 700 between from 202B to 202C, can place the reflecting grating that expression information is used.But first position 200 of allow placing reflecting grating that expression information is used at least will with the 202B n of being separated by
Min(promptly 302); Last position 200 that may place reflecting grating that expression information is used and the 202C n at least of also will being separated by
Min(promptly 302) is k so can place the size in coding region 700 spaces of reflecting grating
TΔ n=434 Δ n.
From any one reflecting grating, the position of next reflecting grating is determined according to code value, a total K=(n
Max-n
Min+ 1)/and a Δ n=49 possible position, so the code value of label can be write as the numeral of 49 carries.Total code value M can be write as following form, M=M
JM
J-1M
2M
1It is the numeral of a J position, and wherein some carry digit of the right is 49.Value M according to units
1, can determine the position of in 49 possible positions, selecting this reflecting grating to lay.Then, press the value M of next bit
2Determine the value in next gap.By that analogy, arrive this interval remaining space less than K
MaxThe carry digit of the sign indicating number that the back is selected no longer is 49, will become with situation.But still can choose a spacing value, or determine next reflecting grating according to code value.But at this moment the carry digit of this bit code no longer is 49.With such method, can determine in information space that all reflecting gratings are corresponding to the due position of given code value M.As long as our code value can find corresponding gap or next reflecting grating position in different sign indicating number range of capacity.For the situation at present embodiment, k
T=434, K
Min=48, K
Max=96, can calculate different sign indicating number capacity is 2.9*10
10, or C=log
2(2.9*10
10)=34.7.
The label decoding process as shown in Figure 3.The foundation of determining a certain code value is the phase retardation time between the two adjacent pulses, rather than the absolute position at pulse place.There are phase place 360 degree ambiguities in label decoding when measuring, change number the complete cycle that promptly can't accurately measure phase retardation when decoding.Resulting phase place is the fractional part of phase retardation in the time during Measurement Phase, and measure error is less, for example: percent several cycles.Obtain the complete numerical value of this phase retardation time, also must accurately estimate the value of the integer part of phase retardation time, but determine that the error of integer part value then is several cycles, even tens cycles or bigger.This label echo phase retardation resolving accuracy has determined the coding of adjacent permission with phase delay great interval should be arranged.For guaranteeing to determine accurately the phase retardation time of each reflection echo, need utilize application number is that 200810154948.7 Chinese patent improves the resolving accuracy of the phase delay of decoding.Measure by group delay coding phase retardation integer part added that the phase retardation fractional part after the temperature-compensating obtains the phase retardation of every section coded message successively, and according to the respective coding rule decode and (or) information checking, self check.
Embodiment 2
The piezoelectric substrate material is identical with embodiment 1, and substrate length is 11.1 millimeters.Three reflecting grating positions of used temperature standard are also identical with embodiment 1.The value of selected Δ n, K
MinValue and K
MaxValue also identical with embodiment 1.In the present embodiment, interdigital transducer 201 is designed to a low-loss single phase unidirectional transducer.Reflecting grating 202B still is k to the coding region 700A between the reflecting grating 202C
aΔ n=434 Δ n.Different is to also have one section coding region 700B to the substrate end after 202C, can lay the reflecting grating of mask information.Used transducer is also the same with embodiment with the blind area.The up duration length T was 5087 cycles in the time of can being similar to embodiment and calculating substrate length and be 11.1 millimeters.So the size of information space is k among the coding region 700B
TbΔ n=229 Δ n.The different sign indicating number capacity that can calculate coding region 700B is 1.7*10
5, the coding region 700 total different sign indicating number capacity that two zones of 700A and 700B form together are 4.9*10
15Or C=log
2(4.9*10
15)=52.
Embodiment 3
The piezoelectric substrate material is identical with embodiment 1.The device centre frequency is 2.44GHz in the present embodiment, and bandwidth is 40MHz.Interdigital transducer 201 is designed to a low-loss single phase unidirectional transducer that constitutes based on high order harmonic component.Value between the position 200 of permission placement reflecting grating is got the Δ n=6.1 cycle.The minimum phase retardation time interval value 302 of adjacent pulse is got n
Min=12 Δ n, adjacent pulse maximal phase delay time lag value 303 is got n
Max=24 Δ n, the size in coding region 700 spaces is k
TΔ n=172 Δ n.Can obtain yard capacity by the coding method of this patent is 72243061840, C=log
272243061840=36.07.
Embodiment 4
Situation is identical with embodiment 3, and just the size in coding region 700 spaces changes k into
TΔ n=344 Δ n.Can obtain yard capacity by the coding method of this patent is 1.4*10
22, C=73.57.
Embodiment 5
The piezoelectric substrate material adopts YZ-LiNbO
3The device centre frequency is 2.44GHz in the present embodiment, and bandwidth is 40MHz.As shown in Figure 4, interdigital transducer 201 is designed to two low-loss single phase unidirectional transducer series connection.Value Δ n between the position 200 of permission placement reflecting grating, the value n in the minimum phase retardation time interval 302 of adjacent pulse
Min, and the value n of adjacent pulse maximal phase delay time lag 303
MaxAll identical with embodiment 3.The size in coding region 700 spaces is k
TΔ n=344 Δ n.In coding region 700 spaces, the reflecting grating present embodiment that is in line among the embodiment 4 changes into and is arranged in two row, and the reflection coefficient of the reflecting grating of every row can be than increasing among the embodiment 4.As required, can artificially virtually four or five adjacent reflecting gratings be incorporated into is a group 500, and then all reflecting gratings among this embodiment can be divided into four groups.
Claims (5)
1. acoustic surface wave radio frequency tag, it comprises: be produced on interdigital transducer and some reflecting gratings on the piezoelectric substrate material, it is characterized in that: the time interval the reflected impulse from interdigital transducer to first reflecting grating is provided with a blind area; Reflecting grating can be in line to four lines, has two or three reflecting gratings to be used to calibrate the influence of unfixed ambient temperature, and each the phase retardation time interval between all the other adjacent reflecting gratings is used to represent different label codings; The phase retardation time between described two adjacent reflecting gratings must not limit less than certain minimum phase retardation time interval, also must not be greater than certain maximal phase delay time lag; The integer part of the minimum phase retardation value between the position of reflecting gratings and fractional part separately measure error level should be respectively greater than decoding the time is placed in two adjacent permissions on piezoelectric substrate.
2. the radio-frequency (RF) tag of surface acoustic wave techniques according to claim 1, it is characterized in that: the phase retardation time interval between the described adjacent reflecting grating is represented different label codings, in case the reflected impulse of first reflecting grating was determined apart from the phase retardation time interval of interdigital transducer, the position of each reflecting grating is unique definite by the surface acoustic wave reflected impulse echo and the phase retardation difference of adjacent previous echo under centre frequency of this reflecting grating later on, allow to have certain error, but other the corresponding reflecting grating positions of phase retardation time institute outside the error range are unallowed in design; Described phase retardation might not be used for direct representation label code value at interval, also may be used as self check, self-correcting or the anti-collision of temperature-compensating, coded data.
3. the radio-frequency (RF) tag of surface acoustic wave techniques according to claim 1 is characterized in that: the minimum phase retardation value that two adjacent permissions are placed between the position of reflecting gratings is limited setting: the fractional part of described phase retardation value is phase delay fractional part measure error level during greater than decoding; Phase delay integer part measure error level when simultaneously, described phase retardation value integer part between the position of reflecting grating is placed in two permissions with identical phase retardation fractional part then greater than decoding.
4. the radio-frequency (RF) tag of surface acoustic wave techniques according to claim 1 is characterized in that: when described label decoding, the foundation of determining a certain code value is the phase retardation time between the two adjacent pulses, rather than the absolute position at pulse place.
5. the radio-frequency (RF) tag of surface acoustic wave techniques according to claim 1, it is characterized in that: described interdigital transducer is low-loss single phase unidirectional transducer or high order harmonic component transducer, or their combination.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102243715A (en) * | 2011-07-08 | 2011-11-16 | 中国人民解放军96411部队 | Piezoelectric ceramic novel label, and identification system and identification method for piezoelectric ceramic novel label |
| CN102708394A (en) * | 2012-04-17 | 2012-10-03 | 重庆大学 | SAW (surface acoustic wave)-based passive temperature tag and SAW-based passive temperature tag reader |
| CN104200262A (en) * | 2014-09-09 | 2014-12-10 | 北京中讯四方科技股份有限公司 | Large-capacity surface acoustic wave radio frequency tag |
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| CN105180982A (en) * | 2015-08-27 | 2015-12-23 | 中电科技德清华莹电子有限公司 | Surface acoustic wave delayed reflection type wireless sensor system having anti-collision function |
| CN105890661A (en) * | 2016-05-10 | 2016-08-24 | 全球能源互联网研究院 | Multi-physical-parameter sensor based on multi-channel surface acoustic wave |
| CN109782215A (en) * | 2018-12-11 | 2019-05-21 | 南京航空航天大学 | A kind of indoor positioning based on surface acoustic wave techniques and identifying system and its positioning and recognition methods |
| CN111060900A (en) * | 2018-10-17 | 2020-04-24 | 中国科学院声学研究所 | Distance measuring device and method based on multi-band phase information of surface acoustic wave device |
| CN113029582A (en) * | 2021-03-10 | 2021-06-25 | 南京航空航天大学 | Aero-engine torque detection system and detection method based on surface acoustic wave label |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102243715A (en) * | 2011-07-08 | 2011-11-16 | 中国人民解放军96411部队 | Piezoelectric ceramic novel label, and identification system and identification method for piezoelectric ceramic novel label |
| CN102708394A (en) * | 2012-04-17 | 2012-10-03 | 重庆大学 | SAW (surface acoustic wave)-based passive temperature tag and SAW-based passive temperature tag reader |
| TWI501158B (en) * | 2013-08-16 | 2015-09-21 | ||
| CN104200262A (en) * | 2014-09-09 | 2014-12-10 | 北京中讯四方科技股份有限公司 | Large-capacity surface acoustic wave radio frequency tag |
| CN105180982A (en) * | 2015-08-27 | 2015-12-23 | 中电科技德清华莹电子有限公司 | Surface acoustic wave delayed reflection type wireless sensor system having anti-collision function |
| CN105180982B (en) * | 2015-08-27 | 2018-07-20 | 中电科技德清华莹电子有限公司 | Saw delay reflection-type wireless sensor system with anti-collision |
| CN105890661A (en) * | 2016-05-10 | 2016-08-24 | 全球能源互联网研究院 | Multi-physical-parameter sensor based on multi-channel surface acoustic wave |
| CN111060900A (en) * | 2018-10-17 | 2020-04-24 | 中国科学院声学研究所 | Distance measuring device and method based on multi-band phase information of surface acoustic wave device |
| CN111060900B (en) * | 2018-10-17 | 2022-04-05 | 中国科学院声学研究所 | Distance measuring device and method based on multi-band phase information of surface acoustic wave device |
| CN109782215A (en) * | 2018-12-11 | 2019-05-21 | 南京航空航天大学 | A kind of indoor positioning based on surface acoustic wave techniques and identifying system and its positioning and recognition methods |
| CN113029582A (en) * | 2021-03-10 | 2021-06-25 | 南京航空航天大学 | Aero-engine torque detection system and detection method based on surface acoustic wave label |
| CN113029582B (en) * | 2021-03-10 | 2022-04-05 | 南京航空航天大学 | Aero-engine torque detection system and detection method based on surface acoustic wave label |
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