NO833570L - MEASURING AND IDENTIFICATION SYSTEM - Google Patents

Description

important information

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i0T~l

Painting and identification system.

The present invention relates to a measurement and identification system, and more specifically a method for a\|-status measurement to and identification of living beings, e.g. animals, cg/or objects, as well as a transponder for use for the state measurement and identification, and calculated to ij k'ommunicate with an inquiry station.

From German Offenlegungsschrift No. 2,919,753 a stationary interrogation station and a transponder are known. The known interrogation station comprises an energy transmitter, a receiver and a assessment unit. The transponder consists of an energy receiver and energy converter, a characteristic memory, a clock generator and a coupling unit containing a characteristic transmitter, as well as at least one antenna. An opening code memory and an opening code transmitter are placed in the interrogation station, and the transponder comprises an opening code receiver, an opening code memory and an opening code comparator, which is connected together with the other modules i| jt<r>the transponder in such a way that a characteristic stored in the characteristic memory is only emitted from the transponder's energy transmitter: when the opening code emitted from the interrogation station and the opening code stored in the answering machine match. In the interrogation station, the energy transmitter and the opening code transmitter can be made up of one and the same transmitter. In a similar way, the energy receiver and the opening code receiver in the transponder can be made up of one and the same receiver: In addition, the interrogation station's energy transmitter can be equipped with a directional antenna. In the same way as the technique which is also discussed in the German Offen-legunsschrifter Nos. 2,736,217 and 2,508,201, the purpose is

in the interrogation station's energy transmitter to generate sufficient power supply for the transponder's switching unit. However, this represents an unnecessary complication of the system, even if a possibility of using a battery for the energy supply of the transponder is suggested. When using a battery in connection with the known system, there is the significant disadvantage that the battery will be constantly charged and thus discharged relatively quickly. _ Ved._ known, paging systems-v

bi li.a. used within hospital facilities and industrial enterprises, it is well known that the answering machines must be recharged regularly, usually during service hours, and there will thus often be a large number of machines that are occasionally inoperative.

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A significant disadvantage of the known solutions is that distance-b! Alignment is not possible, and position determination is in reality also very difficult to carry out, as the bearing possibilities are very limited, in that the Interrogator's energy emitter must necessarily have a wide radiation lobe to ensure that at least one answering machine answers. This in turn necessarily affects the applicability of the system. If the radiation lobe according to the known system is made narrow, one is largely dependent on being able to see the living being or object to be identified. One according to the the application indicated in the aforementioned publication will here be anti-theft protection where the answering device is located in a persistent radiation field from the interrogating device.

The present invention therefore aims to overcome the aforementioned disadvantages in a simple way, while at the same time providing a system with improved application possibilities than what has previously been possible.

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In animal breeding and cattle keeping, especially in outback, it has become an ever-increasing problem that animals disappear from the herd, either because they are exposed to accidents, e.g. falls off a cliff, dies from poisoning, foreign bodies etc., is killed by predators or for some other reason moves away from the herd. The problem is particularly large in connection with sheep farming, but also in connection with cattle that roam the open fields for large parts of the year. in

In what follows, the invention will therefore be particularly described in connection with the identification of sheep in the terrain, although the basic idea of the invention is of course not limited to this application.

The characteristic features of the invention will be apparent from the subsequent patent claims as well as from the subsequent description in I i h t ■ • • -^h— i with reference to the attached drawings. 1 '"s i i— — Fig. 1 shows, as an example, a polling station for carrying out the method according to the invention. Fig. 2 illustrates a transponder for carrying out the method according to the invention.

in Fig. 3 schematically shows the signal form for the signals which respectively i shows the interrogation station (fig. 3a) and the transponder (fig. 3b).

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Fig. 4 illustrates an application of the invention in connection with sheep searching.

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The present invention is based on that basic idea

that within a system all the transponders included in the system can operate on the same frequency, with only one transponder at a time responding to a coded call from a polling station. In practice, this means that the assignment of frequencies to a system of this kind is significantly simplified while at the same time "pollution"

of the ether becomes small. At the same time, "jamming" problems are largely avoided in this way.

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Within the aforementioned prior art, power consumption in particular has become a major problem, even with modern electronic equipment. This is because the transponders are set to listen continuously at the calling or questioning station. The present invention is thus based on the transponders to make use of intermittent listening and only j send answers back to the interrogation station by selective call.

In this way, very small batteries can be used, which in turn brings both the weight and volume of the transponders down to a minimum. For certain embodiments, solar batteries can be advantageously used.

As a non-limiting example, it is proposed according to the invention

in the sense that the transponder has an active/inactive state ratio equal to i/lG00, i.e. that the transponder only listens approx. 1"'ms every second. An essential feature of the invention is thus ajt

In jdspeøt rreer shteas lt jonunf ørdekvevnednis g opå pdlyagtete s, kolnytttineus edrelt igi . caId. a 10r0 imkts ikgIon-

tively because in the questionnaire sent out by the polling station

nal to find an opening code that will cause activation of the transponder's transmitter part. A long code will provide maximum security, and can e.g. contain 32 bits. This is of particular importance when the system is used to call a large number of transponders in turn.

A further security in the present system lies

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i :that the transponder only answers a coded call.

The response time Atg detected at the polling station will be

a direct function of the shortest distance times two between the interrogating station and the answering transponder, i.e. approx. 6 'ns/ra or 6 ;.is/km. For practical applications, e.g.

at a mutual distance of approx. 5 km the response of the transpond<!->er takes place after approx. 15 us, and the response time detected at

The question mark will therefore be a total of approx. 30 ;us, which indicates a distance equal to 10/2 = 5 km. In the response time At

lij gger also a constant At. ■ - which represents, for example, ids-is 3 transp.

the delay that will be present in the transponder before it reacts. 3run filtering in the interrogation station, the time delay will be significantly greater, in the range of microseconds. The measurement accuracy depends on the signal/noise ratio and the measurement accuracy of the time delay. With modern microelectronics, it is possible to achieve circuits that operate without difficulty within nanoseconds, which means that the measuring accuracy can theoretically be of the order of 1-3 metres.

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A further main feature of the present system is that the transponder sends its response signals back with a carrier frequency that is an integer multiple of the interrogating station's frequency. In this way, any use of j oscillator is avoided in the transponder, which makes the system confident and prevents the unintended sending of signals from the transponder. Furthermore, a significant frequency stability is achieved in this way, as the transponder's carrier frequency will always be a predetermined whole multiple of the polling station's carrier frequency. in

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As the system is intended to be used with a relatively large number of transponders, while the number of interrogating stations will normally be a significantly smaller number, usually one or two, it is not obvious that it will be far less expensive for the system >to provide the equipment for frequency stability in the interrogation station.

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A further advantage of the transponder using a multiple of the interrogating station's transmitter frequency is that the same antenna can be used. In fig. 1 illustrates, by way of example, a jspier station for use in the present system.

However, it should immediately be understood that many individual adaptations of the questioning station are possible without thereby de-

depart from the idea and scope of the invention. The interrogation station comprises a combined transmitter and. receiving antenna as well as a diplexer 2 ! to isolate between transmitter part and receiver part. The interrogation station is provided with a transmitter 3 and an encoder 6 as well as a receiver 4 and a projector 7. The projector 7 can have any suitable design, but in a preferred embodiment will indicate e.g. . which transponder is interrogated, whether the transponder responds and the distance

to the transponder, calculated on the basis of the measured resppns-

r ; —— - i i In the time. The transmitter, encoder, receiver and display are preferably controlled by a central control unit containing a clock.

|A suitable carrier frequency for the polling station's transmitter part will lie within the UHF band. However, a narrow bandwidth is required, e.g. 15 kHz, which means that the transmitter must not have a frequency deviation greater than approx. 15 x 10 . This representation does not pose any significant problem, as the power supply, the technical equipment and the weight and volume of the interrogation stations

'can be made significantly larger than what is technically, practically and economically possible in connection with the transponders.

II<,>ifig. 2 shows a transponder intended for use in conjunction with the present system.

The fansponders comprise an antenna unit 8 which can consist of a combined antenna or two antennas tuned respectively to the frequencies. fQ and the transponder's . sy ar frequency... n x f^ . IN

,The antenna unit 8 is followed by a first tuned amplifier 9 which can be brought into an inactive or active state by

a microprocessor 11. Said first amplifier 9 can optionally be made up of several individual amplifiers which are connected in a cascade. The first amplifier 9 is followed by a signal gate 10 which can be controlled from the aforementioned microprocessor

11 and communicates with the microprocessor 11 as it pleases

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be explained in what follows. The signal port 10 is followed by a frequency multiplier 12, which may possibly contain several frequency multiplication steps for frequency multiplication to an integer multiple of the interrogating station's carrier frequency fQ. At the output of the frequency multiplier 12, a signal with carrier frequency n x f is thereby produced, where n is an integer. The output signal from the frequency multiplier 12 is fed to the second tuned amplifier 15, which is controllable from the microprocessor 11. The aforementioned second amplifier 13,

can, like the aforementioned first amplifier 9, be made up of several I I tr! in interconnected in cascade. The amplifier 13 is followed by the antenna unit 8.

The antenna unit 8 can consist of a combined receiving and transmitting I 1 antenna, or two separate antennas for respectively receiving I free sequences f o and r of the response frequency n x f o.

The microprocessor 11 will include a clock which causes the M - i I amplifier 9 to be switched on intermittently, e.g. in an active/inactive state ratio equal to 1/1000 during the transponder's listening phase and further contains a detector which, upon detection, detects the interrogating station's carrier signal 17 with frequency fQ, see fig. 3a, causes the first amplifier 9 to be kept continuously open for detection of a possibly correct opening code 15 for the transponder, which is passed via the aforementioned signal port 10 to the detector 11 in the microprocessor, as operation of such opening code the end 16 of the received spy-jre signal with frequency fQmates via the signal port 10, via the frequency multiplier 12, the second amplifier 13, which i<1>oi Inå is kept open by the microprocessor 11, and out onto the antenna unit 81 as a acknowledgment signal 17 from the transponder. The questioner will now receive an indication if the transponder answers and

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i emits an activation signal 18 of the continuous wave type and with a limited duration, see fig. 3a. On receipt of this signal, the transponder will pass it through the amplifier 9 via the signal port 10 into the microprocessor 11 and back to the signal port 10, further to the frequency multiplier 1. 2, into the amplifier 13 and out onto the antenna 8, as part of the noted signal 18 is modulated with an information code 20 that is characteristic of the transponder in question. Thus, a composite response signal 19, 20, 21 Iay is sent from the transponder with a duration equal to the activation signal sent from the interrogating station; signal 18. The aforementioned signal which is emitted from the transponder in me! d the carrier frequency x O will consist of a first part I of the j type continuous wave, followed by a code-modulated part 20 and possibly followed by a last part 21 of the continuous wave type. However, the last part 21 can be included in part 20 if the information code is to be expanded.

I : The time that runs from the questioning station sending out its activation signal 17 to the transponder's response signal 19 - 21 occurs at the questioning station, is indicated as the time At s. This

•response time is a function of twice the distance between i i

the interrogating station and the transponder plus the natural reaction time for the transponder and the transponder. In this way: a very accurate measurement of the distance between the interrogating station and the transponder is achieved, which distance is indicated on the display 7.

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The information code 20 in the transponder's response signal can possibly be produced by one or more external information! transmitters 25 connected to the microprocessor 11. In connection with sheep searching, the information transmitter 25 can e.g. be a movement indicator to indicate whether the sheep is moving or not, or e.g. a device capable of; to measure the animal's pulse. As one will immediately understand, this information provider 25 can have any one for the purpose j

in appropriate design. If the informant 25

by repeated queries does not indicate any movement whatsoever

in 1 else, this may possibly cause one to seek out the j<1>sheep to see whether it is still alive or not.'

In the case of further development, it is conceivable that the microprocessor can control an external function device 26, e.g. as a result of the activation signal 18 from the interrogation station or a specially coded activation signal.

The application of the present system shall be further clarified with reference to fig. 4. In fig. 4, the questioning station is named with the reference number 22 and a number of sheep I n are located in the terrain. From the interrogation station 22 at a first location, designated as 22^, interrogation signals are emitted, primarily to the transponder 23^, and an acknowledgment signal, generally designated SA^, back from the transponder. The aforementioned activation signal is then emitted from the interrogation station

in 22^and a response signal, generally indicated under the designation , ;

back to the interrogation station from the transponder after a certain time corresponding to the distance between the interrogation station 22^

and the transponder 23-^. In cases where the terrain conditions are such that, for example, there is a ridge 24, the case may arise that the signals emitted from the transponder are also reflected by the ridge 24 and arrive at the interrogation station as reflected signals sAi_ref]_ However, these signals will arrive in time after the signal S^, and the interrogation station 2 2. A will therefore ignore the signal s^i_refi This is because: it will always be the signal that first arrives at the inquiry station, which indicates the shortest distance to

the transponder. After the aforementioned measurement has been made and a first distance to the transponder has thus been determined, the interrogation station 22, which is preferably portable, is moved to a new location, here designated as 22 fi. As for 22 A, corresponding signal exchanges are made with the transponder 23 ^, where- '. after a second distance until the transponder is known. As the two locations 22^ and 22^ are known in the terrain, these can

is marked on a map and two circles with a radius equal to the respective measured distances can be drawn, whereby an exact position for the transponder 23^and thereby the associated sheep can be determined.\ If the antennas at the interrogation station 22 are directional,\e.g. has a radiation pattern less than 180 o , will<!>! two such measurements should be sufficient to be able to

determine the position of all the sheep to be identified

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are sighted and positioned. The measurement for the sheep with tran-; sponder 2 3_ takes place in a similar way as explained in connection with the transponder 2 3^, as the signals between transponder and interrogation station are generally designated as SA2 and SB2. It will also be immediately understood that measurements with regard to . - ■. in the transponders 23^, 2 3^, 2 35, 2 3g and 23^ can be carried out in a similar way. It will also be immediately understood that if: the position in the terrain for the transponders 2 3^ and 23^ were fixed, the position of the interrogation station 25 either at a place marked as 2?A or as 2 2^ could be easily determined.

The present system exhibits significant advantages compared to the known bearing systems, which are based on a directional antenna being directed towards the place with the highest signal strength. The listening device is then moved to a new location and a bearing is made towards the location which again has the greatest signal strength. However, in this case, reflections can cause significant measurement errors, while at the same time it can be very difficult to determine exactly in which direction the highest signal strength exists. With the present system, the distance to the signal generator (transponder) is instead measured from two locations, whereby a completely accurate coordinate determination can be made.

The present transponder could possibly be made in integrated circuit form and could thus be reduced in size and production cost. It is important to note that there is no frequency reference at the transponder, apart from the aforementioned bandpass filters, which further contributes

to reduce the costs of the transponder. By the fact that the transponder does not have its own local oscillator, it is completely avoided that the transponder starts transmitting automatically, as is often the case with the so-called emergency bearing transmitters. In the case of the known emergency direction finder transmitters, it is not possible to directly calculate the distance to them, as the present invention makes possible. J

If the polling station uses a special directive or phase-sensitive antenna, e.g. with an opening angle equal to 90°, will: that for certain applications, e.g. to find out whether the sheep is within a certain limited area, only a distance measurement is necessary. In this way, mani is told whether all or only some of the sheep are within a pre-determined quadrant of the circle. j ;

Claims (15)

1. Procedure for distance measurement to and identification of living beings, e.g. sheep, and/or objects, characterized in that a time-limited interrogation signal (14,15,16) with a first carrier frequency (fQ) is sent from an interrogation station (1-7) to a transponder (8-13), which interrogation signal contains an opening code (15) for the transponder (8-13), that the transponder upon detection of the interrogation signal's carrier frequency (f ) and said opening code (15) sends back an identifying acknowledgment signal (17) of duration equal to a final part (16) of the interrogation signal, the acknowledgment signal having a second carrier frequency (n x f ) which is equal to an integer multiple of the first carrier frequency (fQ), | that the interrogating station (1-7) upon receipt of the acknowledgment signal in (17) transmits a time-limited activation signal (18) with said first carrier frequency (fQ)/ that the transponder (8-13) upon receipt of the activation signal in (18) sends back a response signal ( 19-21) with a frequency equal to said second carrier frequency, which response signal has a duration equal to the activation signal and possibly contains an information code (20), and that the time (At ) between the sending of the activation signal (18) and the reception of the response signal (19-21) is measured and used to calculate the distance between the interrogating station and the transponder. 2. Method as stated in claim 1, characterized in that the acknowledgment signal and the activation signal are of the pure continuous wave (CW) type. 3. Method as specified in claims 1 and 2, characterized in that the inquiry signal (14-16) and the response signal (19-21) over part of their duration (14,16;19,21) i are of a pure continuous wave, said opening code (15) and said information code (20) appear by pulse modulation of respective carrier frequencies. ir-~*^ ■ ■' ' ' 1; 4. Method as stated in claim 3, character i-* characterized in that the interrogation signal (14-16) with the first j carrier frequency (f ) is composed of a continuous wave ;(14) in the opening code (15) and a continuous wave ( 16). in 5. Procedure as stated in claim 3, character - characterized in that the response signal (19-21) with the second carrier frequency (n x f ) is composed of a continuous wave (19) which is followed by the information code (20), and possibly terminated by a continuous wave (21). 6. Method as stated in one or more of the preceding claims, characterized in that the transponder (8-13) listens intermittently prior to receiving the interrogation signal (14-16), e.g. with an active/inactive state s--ratio equal to 1/100 0. 7. Method as specified in one or more of the preceding claims, characterized in that the transponder (8-13) upon receiving the correct interrogation signal frequency ;(fQ ) listens continuously over a period of time related to the duration of the interrogation signal in order to detect any correct opening code (15 ) in the interrogation signal. j 8. Method as stated in one or more of the preceding claims, characterized in that the transponder uses part or all of the signal emitted from the interrogating station to generate a carrier wave output signal (17; 19-21), in which frequency appears by frequency multiplication of ask-| the rest carrier frequency (fQ )• j 9. Method as specified in any of the preceding claims, where the position of the living being and/or the objects is to be determined, characterized in that the interrogation station (1-7) performs identification and distance measurement repeatedly from different relative positions the transponder, and that the transponder's position is determined by distance cross-reflection (fig. 4) . ■- —— I I 10. Transponder for use in measuring the distance to and identifying living beings, e.g. sheep, and/or objects and intended to communicate with an interrogation station (1-7), characterized in that transponclere:i includes: a) a receiver and transmitter antenna unit (8), b) first controllable signal amplifier means (9) connected to the antenna unit (8)., c) a controllable signal gate (10) connected to said first sig- nalf ors térkermidler's (9) output, and which has a two-way connection with a detector and control unit (11), e.g., a microprocessor, and also connected to a frequency-i: multiplier 1 (13), which multiplies the interrogator signal's carrier frequency (f ) by an integral multiple of the frequency, d) other controllable amplifier means (13) connected with fre- — the output of the frequency multiplier (12) for amplifying the output signal of the transponder, the output of said second: iI controllable amplifier means (15) is connected to the antenna unit (8). t 11. Transponder as stated in claim 10, character!-; cert by said amplifier means (9, M3) being controlled i from the detector and control unit (11). 12. Transponder as specified in claim 10 or 11, characterized in that the detector and control unit (11) contains a clock which causes the first-mentioned amplifier means (9) to be switched on intermittently, e.g. in an active/inactive state ratio equal to M/1000, during the transponder's listening phase, and contains a detector which, upon detection of the interrogating station's carrier wave (14) with the first carrier frequency (f )' ; causes the first amplifier means (9) to be kept continuously operative for the detection of a possible correct opening, s-ji code, as upon detection of such an opening code (15) the <I> end (16) of the received inquiry signal is fed via the signal port I !(1i 0) to the antenna unit (8) via the frequency multiplier I(12) o<p mentioned other amplifier means (13) .. 13. Transponder as specified in claim 12, characterized in that the detector and control unit (11) at tran the sponder's reception of an activation signal (18) of the type kél ntinuerli <g> wave, controls this signal via the signal gate and on to the frequency multiplier (12) and from there to the antenna unit (8) as a response signal with said second carrier frequency (n x fQ ) via said other amplifier means (13). in 14. Transponder as specified in claims 12 and 13, characterized in that the detector and control unit [ 1. 1) is provided with cf. at least one external, connectable information provider (25) . j 15. Transponder as specified in one or more of the claims 12 - 1 41, characterized in that the detector and control unit (11) is connected to one of these activatable •external functional organ (26) . jl6- Transponder as specified in any of the krays ;10 -15, characterized in that detector- , • The part in the detector and control unit (11) contains a memory I I foIr the opening code identifying the transponder number. ,17. Transponder as specified in claim 15, character i - sle r t in that said function device (26) is activated on and off in a coded activation signal from the interrogation station. i 118 - Transponder as stated in any of the preceding claims, characterized in that the antenna unit consists of a combined receiver and transmitter antenna, i.e. an antenna tuned to the receiving frequency and an antenna tuned to the transponder's response frequency n x fQ. in