GB2285557A - Code responding system utilizing a variation of reflectance of a transmitted electromagnetic wave - Google Patents
Code responding system utilizing a variation of reflectance of a transmitted electromagnetic wave Download PDFInfo
- Publication number
- GB2285557A GB2285557A GB9425459A GB9425459A GB2285557A GB 2285557 A GB2285557 A GB 2285557A GB 9425459 A GB9425459 A GB 9425459A GB 9425459 A GB9425459 A GB 9425459A GB 2285557 A GB2285557 A GB 2285557A
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- Prior art keywords
- code
- responder
- electromagnetic wave
- generating
- accordance
- Prior art date
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
- G01S13/78—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/75—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors
- G01S13/751—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors wherein the responder or reflector radiates a coded signal
- G01S13/756—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors wherein the responder or reflector radiates a coded signal using a signal generator for modifying the reflectivity of the reflector
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- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar Systems Or Details Thereof (AREA)
Description
2285557 CODE RESPONDING SYSTEM UTILIZING A VARIATION OF REFLECTANCE OF A
TRANSMITTED ELECTROMAGNETIC WAVE The present invention relates to a code responding system in which a code responder responds to an electromagnetic wave transmitted from an interrogator upon its reception by generating a fixed or variable code. For example, the invention may be used to identify a moving body in a non-contact manner by detecting a codt such as an ID code assigned to a code responder mounted on the moving body by performing, for instance, radio communication with the moving body.
Conventionally, there have been proposed several code responding systems in which an ID code is assigned to a code responder mounted on a moving body, and an interrogator is allowed to identify, by its ID code, the moving body that responds to an electromagnetic wave transmitted from the interrogator. In one code responding method, an ID code is stored in a semiconductor memory incorporated in the code responder. In another method, a resonance circuit incorporated in the code responder is caused to resonate at its own resonance frequency.
However, in the case of using a usual semiconductor memory, a battery is needed for a backup purpose. In the case of using a E 2 PROM, a battery is also needed for writing and 1 reading operations. The incorporation of a battery increases the size and cost of the code responder. It may be conceivable to f orgo a battery by supplying energy to a memory and a CPU in the code responder by using an external electromagnetic wave.
However, in view of regulations on the radiation electric power, this is not practical; that is, a sufficient amount of energy is not obtained, prohibiting a long-distance communication.
On circuit is are needed responders To the other hand, the method of using the resonance also deficient in that more resonance frequencies for setting Qf ID codes as the number of code to be identified increases.
solve the above problems, the present applicant has proposed a code responder which is compact and does not need a is battery, and which is composed of delay elements f or generating time- series pulses in response to a pulse signal sent from an interrogator and a code generator for generating a particular code based on the time- series pulses (Japanese Unexamined Patent Publication No. Hei. 4-259876).
However, in the above configuration, the pulse signal sent from the interrogator attenuates in the code responder to make a final output very weak. Therefore, when the interrogator and the responder are distant froin each other, the interrogator cannot correctly detect a code based on a response fropt the responder.
2 1 1 The present invention has been made in view of the above problems in the art, and has an object of providing a code responding system which can improve the code detection accuracy on the interrogator side by changing the reflectance of an electromagnetic wave being transmitted from the interrogator in accordance with an inherent or variable code generated in the code responder.
According to a first aspect of the invention, a code responding method comprises the steps of:
generating a single pulse upon reception of an electromagnetic wave; converting the single pulse to time-series pulses; generating a coded signal based on the time-series pulses in accordance with a code associated with a code responder; and responding to the electromagnetic wave by changing a reflectance of the electromagnetic wave in accordance with the coded signal.
According to a second aspect of the invention, a code responder comprises:
means for receiving an electromagnetic wave; means for generating a single pulse when the receiving means receives the electromagnetic wave; means for generating time-series pulses by sequentially delaying the single pulse; - 3 1 coding means for generating a coded pulse train based on the time-series pulses in accordance with a code associated with the code responder; and means for changing a reflectance of the electromagnetic wave by changing an impedance, as viewed f rom the receiving means, of the code responder in accordance with the coded pulse train.
According to a third aspect of the invention, a code responding system comprises:
at least one code responder comprising: means for receiving an electromagnetic wave; means for generating a single pulse when the receiving means receives the electromagnetic wave; means for generating time-series pulses by sequentially delaying the single pulse; coding means for generating a coded pulse train based on the time-series pulses in accordance with a code associated with the code responder; and means for changing a reflectance of the changing an impedance, as viewed from the code responder in accordance with and comprising:
electromagnetic wave by the receiving means, of the coded pulse train; an interrogator means for transmitting the electromagnetic wave; means for receiving a reflection wave that is reflected from the code responder; and - 4 means f or detecting the code by demodulating a temporal variation of the received reflection wave.
In the drawings:
Fig. 1 is a block diagram showing the total configuration of a code responding system according to an embodiment of the present invention; Fig. 2 is a block diagram showing a specific example of the code responding system of Fig. 1; Fig. 3 is a timing chart showing an operation of the system of Fig. 2; Fig. 4 is a Smith.chart showing an impedance of each matching circuit; Fig. 5 is a block diagram showing the total configuration of a code responding system according to another embodiment of the invention; Fig. 6 is a block diagram showing a specific example of the code responding system of Fig. S; Fig. 7 is a timing chart showing an operation of the system of Fig. 6; Fig. 8 is a circuit diagram showing a configuration of a signal conversion circuit; and Fig. 9 is a block diagram showing the total configuration of a code responding systeni according to a further embodiment of the invention.
- j Fig. 1 shows the total configuration of a code responding system according to an embodiment of the present invention. In this code responding system, radio communication is performed between an interrogator 1 and a code responder 4 that moves together with, for instance, a moving body on which it is mounted. The interrogator 1 is equipped with an interrogator controller 2 for controlling modulation, demodulation and other operations, and an interrogator antenna 3 for emitting an electromagnetic wave.
The code responder 4 has a responder antenna 5 for receiving an electromagnetic wave transmitted from the interrogator antenna 3. The received electromagnetic wave is sent to a demodulation circuit 7 via an impedance matching circuit 6 (hereinafter referred to simply as "matching circuit 6"). Based on the electromagnetic wave thus supplied, the demodulation circuit 7 generates a single pulse, which is supplied to a delayed pulse generator 8. Having a plurality of delay elements 9a-9z for sequentially delaying the single pulse, the delayed pulse generator 8 produces, at output taps 10a-10z, a plurality of pulses deviated in time from one another.
Provided to generate a code that is assigned to the code responder 4 by performing a coding operation based on the pulses generated above, a coder 11 has switching terminals 12a12z to which the respective pulses are supplied from the output taps 10a-10z. In Fig. 1, the terminals 12a, 12c and 12z are 6 1 closed, and the terminal 12b is open. While a pulse supplied to a closed switching terminal appears on an output line 13, a pulse supplied to an open switching terminal does not. In this manner, a pulse train appears on the output line 13 in accordance with switching states of the switching terminals 12a-12z; that is, a pulse coding operation on the time axis is performed.
A modulation circuit 14 and an impedance matching circuit 15 (hereinafter referred to simply as "matching circuit 15") are provided to control the impedance as viewed from the responder antenna 5. Thq modulation circuit 14 changes the impedance, as viewed from the responder antenna 5, of the matching circuit 15 when receiving a pulse of a coded pulse train from the output line 13, and maintains the impedance of the matching circuit 15 when not receiving a pulse.
When the impedance, as viewed from the responder antenna 5, of the matching circuit 15 is changed, the reflectance of an electromagnetic wave being received by the responder antenna 5 is changed accordingly. In the interrogator 1, the interrogator antenna 3 receives a reflected wave, and the interrogator controller 2 demodulates a temporal variation of the reflected wave to thereby detect a variation of the impedance of the matching circuit 15 of the code responder 4, i.e., the code generated by the coder 11.
Fig. 2 shows a specific example of the code responding system of Fig. 1 which example deals with 5-bit codes, and Fig.
- 7 3 3 is a timing chart showing an operation of the system of Fig. 2. In the system of Fig. 2, as shown in part (a) of Fig. 3, the interrogator antenna 3 normally outputs a carrier wave 19 of a predetermined frequency, and the transmi- ssion of the carrier wave 19 is temporarily suspended by performing, at time tl, 100% amplitude modulation by use of a rectangular pulse, for instance. A time interval to of suspending the carrier wave 19 is set shorter than the delay in each of the delay elements 9a-9e to avoid overlap of pulses output from the delayed pulse generator 8 (described later) of the code responder 4.
The matching circuits 6 and 15 of the code responder 4 are composed of passive elements, which do not require any power supply, and are usually set so as to maintain a certain impedance.
Fig. 4 is a Smith chart showing impedance characteristics of the matching circuits 6 and 15 as viewed from the responder antenna 5. Normally, the impedance of the matching circuit 6 is so adjusted as to be located at point A (impedance -matched state). On the other hand, the impedance of the matching circuit 15 is set at point B (infinite value). As a result, an electromagnetic wave received by the responder antenna 5 is absorbed, with no reflection, by the matching circuit 6 that is in a matched state; that is, all of the electromagnetic wave is input to the demodulation circuit 7.
Being a lowpass filter composed of a diode 7a and a high-impedance line 7b, the demodulation circuit 7 removes a is high-frequency component of the carrier wave received by the responder antenna 5, and generates a single rectangular pulse p, at time t, in response to the above-described suspension of the carrier wave (see part (b) of Fig. 3). The single rectangular pulse thus generated is input to the delayed pulse generator 8.
Composed of a microstrip line or the like, the highimpedance line 7b can be made sufficiently small.
The five delay elements 9a-9e of the delayed pulse generator 8 produces single pulses P2-p6 at the output taps 10a10e at times t2-t6, respectively (see parts (c)-(g) of Fig. 3).
The five switching terminals 12a-12e of the coder 11 generate an ID code corresponding to the code responder 4. In the example of Fig. 2, the terminals 12a, 12d and 12e are closed while the terminals 12b and 12c are open. Therefore, as shown in part (h) of Fig. 3, the pulses P2f P5 and P6 that were given to the switching terminals 12a, 12d and 12e also appear on the output line 13.
In this embodiment, a state in which a switching terminal is closed and a pulse is transferred from the delayed pulse generator 8 to the output line 13 is represented by data "l," and a state in which a switching terminal is open and a pulse is not transferred from the delayed pulse generator 8 to - 9 the output line 13 is represented by data "0. coder 11 generates an ID code "10011."
The modulation circuit 14 is composed of a diode 14a and a high-impedance line 14b. When the modulation circuit 14 receives each pulse of a coded pulse train from the output line 13, the diode 14a provides a bias to change the impedance characteristic of the modulation circuit 14. The impedance of the matching circuit 15 as viewed from the responder antenna 5 is changed accordingly. In this embodiment, the impedance of the matching circuit 15 is so set as to be located at point C (zero impedance) on the Smith chart of Fig. 4 when the biasing by the diode 14a is effected.
When the impedance of the matching circuit 15 becomes 0, the combined impedance of the parallel connection of the matching circuits 6 and 15 also becomes 0. As a result, the carrier wave non-reflecting condition which is established by the above-described impedance matching is lost, and the responder antenna 5 reflects the carrier wave transmitted from the interrogator antenna 3.
On the other hand, when the modulation circuit 14 does not receive a pulse from the coder 11, the diode 14a does not provide a bias. Therefore, the matching circuit 15 maintains the impedance of the normal state, and the carrier wave nonreflecting condition continues to be established by the impedance matching.
at Therefore, the - Part (i) of Fig. 3 shows outputs of reflected waves from the responder antenna 5. The carrier wave is ref lected at times t2, t5 and t6, which correspond to appearances of the pulses p2, p5 and P6 The reflected wave are received by the interrogator antenna 3, and demodulated by the interrogator controller 2. Thus, the code generated in the coder 11 is decoded.
Fig. 5 shows the total configuration of a code responding system according to another embodiment ofthe invention. An interrogator 11 transmits to a code responder 41 modulated wave that has been produced by modulation by use of particular code.
In the code responder 41, the modulated wave transmitted from the responder antenna 5 is received by the responder antenna 3, and supplied to a correlator 16 via the matching circuit 6. The correlator 16 has an ID code that coincides with the code of the modulated wave that is transmitted from the interrogator 1 1. When receiving the modulated wave, the correlator 16 generates a pulse, which is supplied to the delayed pulse generator 8.
In the delayed pulse generator 8, the delay elements 9a-9z sequentially delay the pulse supplied from the correlator 16 and produce, at the output taps lOa-10z, a plurality of pulses deviated in time from one another, in the same manner as in the first embodiment. In the coder 11, the coding operation is performed on the time axis using the pulses supplied from 11 the output taps 10a-10 in accordance with the switching states of the switching terminals 12a-12z.
A pulse train generated on the output line 13 is input to a signal conversion circuit 17, which converts the pulse train into a shaped pulse by removing a high-frequency component. The modulation circuit 14 and the matching circuit 15 have the same configurations as those in the first embodiment. When a pulse is supplied from the signal conversion circuit 17 to the modulation circuit 14, the impedance of the matching circuit 15 as viewed from the responder antenna 5 is changed. The reflectance of the electromagnetic wave being received by the responder antenna 5 changes in accordance with the impedance change of the matching circuit 15. The interrogator controller 2' of the interrogator 11 detects the code generated in the coder 11 by demodulating a temporal variation of the reflected wave.
Fig. 6 shows a specific example of the code responding system of Fig. 5 which example deals with 5-bit codes, and Fig. 7 is a timing chart showing an operation of the system of Fig.
6. Impedance characteristics of the matching circuits 6 and 15, which are set the same as those of the example shown in Fig. 2, are represented by the points indicated on the Smith chart of Fig. 4.
As shown in part (a) of Fig. 7, after outputting a PSK wave 20 that has been produced by modulation by use of a particular ID code, the interrogator antenria 3 of the 1 interrogator 1 1 transmits a carrier wave 21 during a period corresponding to the response period of the code responder 41.
The code responder 4' has a SAW correlator 16' serving as the correlator 16. An ID code that corresponds to the characteristic of the PSK wave 20 output from the interrogator antenna 3 is set in the SAW correlator 161. As shown in parts (a) and (b) of Fig. 7, the SAW correlator 161 outputs a pulse modulated wave P, including a high-frequency burst signal at time T, that is delayed f rom time To (the time point when transmission of all bits of the PSK wave 20 has been completed) by a predetermined time..
The pulse-modulated wave P, is supplied to the delayed pulse generator 8. As shown in parts (c)-(g) of Fig. 7, the delay elements 9a-9e of the delayed pulse generator 9 sequentially delay the pulse-modulated wave P, by a predetermined time, so that pulse-modulated waves P2_P6 are generated on the output taps lOa-10e at times T2-T61 respectively.
As in the case of the example of Fig. 2, the switching terminals 12a-12e of the coder 11 are so set as to generate an ID code inherent in the code responder 4'. As shown in part (h) of Fig. 7, only the pulse-modulated waves P2. P5 and P6 that were supplied to the closed terminals 12a, 12d and 12e appear on the output line 13, to produce a pulse train representing an ID code "10011."
- 13 Fig. 8 shows a configuration of the signal conversion circuit 17. Composed of a diode 17a and a high-impedance line 17b, the signal conversion circuit 17 removes the highfrequency burst signal from each pulse P appearing on the output line 13, to produce a positive-voltage pulse P,. As a result, as shown in part (i) of Fig. 7, the pulsemodulated waves P2r P_5 and P6 are converted to positive-voltage pulses P21, Ps' and P6' while the temporal relationship between the pulsemodulated waves P2. P5 and P6 are maintained. The positive- voltage pulses P2', P_5' and P6' are input to the modulation circuit 14.
The modulation circuit 14 has the same configuration as that of Fig. 2. When each of the pulses P2' r P5, and P6' is input to the modulation circuit 14, the diode 14a provides a bias and the impedance characteristic of the modulation circuit 14 is changed. As a result, the impedance of the matching circuit 15 as viewed from the responder antenna 5 becomes 0. Since the carrier wave non- reflecting condition is lost, the responder antenna 5 reflects the carrier wave 21 being transmitted from the interrogator 11. The interrogator controller 2' detects the code generated in the code responder 4' by demodulating the temporal variation of the reflected wave.
The polarity of the diode 17a in the signal conversion circuit 17 may be reversed to convert a pulse-niodulated wave that is supplied from the output line 13 to a negative-voltage - 14 pulse, in which case the polarity of the diode 14a in the conversion circuit 14 should also be reversed to maintain the above-described operation.
In this embodiment, the SAW correlator 16 of the code responder 41 is so set as to respond to only the PSK wave that has been produced by modulation by use of a particular code. Therefore, even where code responders 41 of a plurality of systems exist in a mixed manner, a response can be obtained from only a code responder 41 of a desired system by properly controlling the code of the PSK wave transmitted from the interrogator 11, if codes of PSK waves are allocated to the respective systems in advance. In this manner, the code responders 41 can be identified individually for the respective systems, to thereby enable CDMA (code series multiple access). Further, since the system call code can be determined by the structure of the SAW correlator 16, the invention enables construction of a system that is hard to counterfeit and superior in secrecy.
While in the above embodiments response is made with generation of a fixed, inherent code, the invention is not limited to such a case. Response may be made with generation of a variable code, as in a further embodiment shown in Fig. 9.
A code responding system of Fig. 9 has basically the same configuration as that of Fig. 1, and is different therefrom in that switching terminals 12a'-12z' of a coder 11' are bimetallic contacts 24a-24z that open or close in accordance with the temperature.
The bimetallic contacts 24a-24z open or close at different temperatures, for instance, such that the first bimetallic contact 24a opens or closes at OOC, the second bimetallic contact 24b at 50C, the third bimetallic contact 24c at 100C, and so forth. Since the switching states of the respective switching terminals 12al-12zt change in accordance with the temperature, the generated code also varies with the temperature.
The bimetallic contacts 24a-24z can also be used in the second embodiment shown in Fig. 5.
Semiconductors which are different in, for instance, impurity concentration, and whose conductivities vary with the temperature can also be used as the switching terminals 12a' 12z'. in the same manner as the bimetallic contacts 24a-24z.
In addition to the means that respond to a temperature variation, there can be used, as the switching terminals 12a' M', means that respond to a variation of a receiving light quantity such as phototransis tors and CdS cells, and means that respond to external force such as thin-platelike vibration sensors.
As described above, according to the invention, response to a transmitted electromagnetic wave is made upon its reception such that the reflectance of the electromagnetic wave is changed in accordance with an inherent or variable code 16 - generated in the code responder. Since the code is sent to the interrogator in the form of a temporal variation of a reflected wave, the code detection accuracy in the interrogator can be improved.
The reflectance of a transmitted electromagnetic wave is changed by generating a coded pulse train that corresponds to the code, and then changing the impedance as viewed from the receiving means in accordance with the coded pulse train.
Therefore, the reflected wave varies greatly even with pulses of very small amplitudes.
Where the code responder responds by generating a code that varies with the state of an external factor, the interrogator side can obtain information relating to a variation of the external factor. For example, where the code responder responds by generating a variable code that is set by a combination of on/off states of a plurality of bimetallic contacts, the interrogator side can obtain information relating to the temperature.
17
Claims (19)
1 1
2 1 2 4 1 2 2. The code responding method of claim 1, wherein the code is a fixed code that is inherent in the code responder.
3. The code responding method of claim 1, wherein the code is a variable code.
4. The code responding method of claim 1, wherein in the single pulse generating step the single pulse is generated only when the received electromagnetic wave is coded by a particular code.
5. A code responder comprising:
nteans f(-:)r ari f--1c-ctroniagrietic ,, C-; 3 means for generating a single pulse when the receiving 4 means receives the electromagnetic wave; means for generating time-series pulses by sequentially 6 7 8 9 10 11 12 13 1 2 1 1 2 1 2 3 4 5 delaying the single pulse; coding means for generating a coded pulse train based on the time-series pulses in accordance with a code associated with the code responder; and means for changing a reflectance of the electromagnetic wave by changing an impedance, as viewed f rom the receiving means, of the code responder in accordance with the coded pulse train.
6. The code responder of claim 5, wherein the code is a fixed code that is inherent in the code responder.
The code responder of claim 5, wherein the code is a variable code.
8. The code responder of claim 7, wherein the code is set in accordance with a state of an external factor.
9. The code responder of claim 7, wherein the coding means includes a plurality of bimetallic contacts that open or close in accordance with a temperature, and wherein the code is set by a combination of on/off states of the respective bimetallic contacts.
- 19 1
10. The code responder of claim 5, wherein the single 2 pulse generating means generates the single pulse only when the 3 received electromagnetic wave is coded by a particular code.
1 2 3 4 6 7 8 9 10
11
12
13
14 16 18 19 11. A code responding system comprising:
at least one code responder comprising:
means for receiving an electromagnetic wave; means for generating a single pulse when the receiving means receives the electromagnetic wave; means for generating time-series pulses by sequentially delaying the single pulse; coding means for generating a coded pulse train based on the time-series pulses in accordance with a code associated with the code responder; and means for changing a reflectance of the electromagnetic wave by changing an impedance, as viewed from the receiving means, of the code responder in accordance with the coded pulse train; and an interrogator comprising:
means for transmitting the electromagnetic wave; means for receiving a reflection wave that is reflected from the code responder; and means for detecting the code by demodulating a temporal variation of the received reflection wave.
1 12. The code responding system. of claim 11, wherein the code is a fixed code that is inherent in the code responder.
2 3 1 13. The code responding system of claim 11, wherein 2 the code is a variable code.
2 3 1 2 3 4 1 14. The code responding system of claim 13, wherein the code is set in accordance with a state of an external factor.
15. The code responding system of claim 13, wherein the coding means includes a plurality of bimetallic contacts that open or close in accordance with a temperature, and wherein the code is set by a combination of on/off states of the respective bimetallic contacts.
16. The code responder of claim 11, wherein the single pulse generating means generates the single pulse only when the 3 received electromagnetic wave is coded by a particular code.
- 21
17. A code responding method substantially as any one herein described with reference to the accompanying drawings.
18. A code responder substantially as herein described with reference to and as illustrated in Figs. 1 to 4, or Figs. 5 to 8, or Fig. 9 of the accompanying drawings.
19. A code responding system having a code responder according to claim 18.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34423593A JPH07174845A (en) | 1993-12-17 | 1993-12-17 | Code responding method, core responder, and code responding system using the code responder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9425459D0 GB9425459D0 (en) | 1995-02-15 |
| GB2285557A true GB2285557A (en) | 1995-07-12 |
Family
ID=18367679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9425459A Withdrawn GB2285557A (en) | 1993-12-17 | 1994-12-16 | Code responding system utilizing a variation of reflectance of a transmitted electromagnetic wave |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH07174845A (en) |
| DE (1) | DE4445285A1 (en) |
| GB (1) | GB2285557A (en) |
| NO (1) | NO944864L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2363498A (en) * | 2000-06-16 | 2001-12-19 | Marconi Caswell Ltd | Memory device receiving an input and generating a corresponding data bearing output signal in response |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3299885B2 (en) * | 1996-03-22 | 2002-07-08 | 和夫 坪内 | Wireless data transceiver |
| DE19641022A1 (en) * | 1996-10-07 | 1998-04-09 | Abb Patent Gmbh | Danger detector activation unit |
| DE19957557A1 (en) * | 1999-11-30 | 2001-06-07 | Siemens Ag | Identification system, esp. for vehicle |
| JP4757713B2 (en) * | 2006-06-01 | 2011-08-24 | 三菱電機株式会社 | Intruder identification device |
| JP5046092B2 (en) * | 2006-12-15 | 2012-10-10 | 独立行政法人産業技術総合研究所 | Temperature sensor, living body health management system |
| FR2946152B1 (en) * | 2009-05-27 | 2016-07-08 | Commissariat A L'energie Atomique | HIGH-PRECISION ABSOLUTE HYPERFREQUENCY TELEMETER WITH MULTI-STATE REFLECTION DEVICE. |
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| US5247305A (en) * | 1990-10-10 | 1993-09-21 | Nippondenso Co., Ltd. | Responder in movable-object identification system |
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- 1993-12-17 JP JP34423593A patent/JPH07174845A/en active Pending
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- 1994-12-15 NO NO944864A patent/NO944864L/en unknown
- 1994-12-16 GB GB9425459A patent/GB2285557A/en not_active Withdrawn
- 1994-12-19 DE DE19944445285 patent/DE4445285A1/en not_active Ceased
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| GB958313A (en) * | 1961-03-24 | 1964-05-21 | Gen Electric | Improvements in communication system |
| GB1067320A (en) * | 1964-08-07 | 1967-05-03 | Gen Electric | Object identifying apparatus |
| US4263595A (en) * | 1978-05-16 | 1981-04-21 | Siemens Aktiengesellschaft | Apparatus for identifying objects and persons |
| GB2165424A (en) * | 1984-10-09 | 1986-04-09 | X Cyte Inc | Surface acoustic wave passive transponder having acoustic reflectors |
| EP0324564B1 (en) * | 1988-01-14 | 1995-07-12 | Sony Corporation | System for communicating identification information and the like |
| WO1990009707A1 (en) * | 1989-02-17 | 1990-08-23 | Integrated Silicon Design Pty. Ltd. | Transponder system |
| EP0420180A1 (en) * | 1989-09-27 | 1991-04-03 | Nippon Soken, Inc. | Transponder for vehicle identification device |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2363498A (en) * | 2000-06-16 | 2001-12-19 | Marconi Caswell Ltd | Memory device receiving an input and generating a corresponding data bearing output signal in response |
| GB2363498B (en) * | 2000-06-16 | 2005-06-01 | Marconi Caswell Ltd | Transponder device for generating a data bearing output |
| US7234642B2 (en) | 2000-06-16 | 2007-06-26 | Mineral Lassen Llc | Memory device |
| US7793844B2 (en) | 2000-06-16 | 2010-09-14 | Ian J Forster | Memory device |
| US8113433B2 (en) | 2000-06-16 | 2012-02-14 | Mineral Lassen Llc | Memory device |
Also Published As
| Publication number | Publication date |
|---|---|
| NO944864L (en) | 1995-06-19 |
| JPH07174845A (en) | 1995-07-14 |
| GB9425459D0 (en) | 1995-02-15 |
| DE4445285A1 (en) | 1995-06-22 |
| NO944864D0 (en) | 1994-12-15 |
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| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |