RU2095821C1 - System for detection of position of mobile object - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: device has equipment which is installed on mobile object, n base stations and main station. Marker decoder, receiver and decoupling unit are introduced to equipment of each mobile unit to accomplish the goal of invention. Each base station in addition has marker decoder, address decoder and time interval meter. Main radio station has synchronization unit, transmitter and decoupling unit. This results in possibility to measure traveling time for radio waves from base station to mobile object. EFFECT: increased precision of object position detection. 3 dwg

Description

 The invention relates to radar technology, and in particular to secondary radar systems.

 Known [1] systems for determining the location of a moving object, containing (Fig. 1) equipment 1 of a moving object (software) including an antenna (Ant) 2, a transmitter 3, a power key 4, a grating apparatus of N radio receivers (base stations) 5 comprising an antenna 6, an isolation unit (RB) 7, a transmitter (Rx) 8, a receiver (Rx) 9, a signal level meter (IMS) 10, the equipment of the main radio receiving station 11, consisting of an antenna 12, a receiver 13, and a location computer 14.

 If it is necessary to transmit an alarm, the key 4 of equipment 1 is closed and the transmitter 3 begins to generate signals that are emitted by antenna 2, are received by antennas 6 of the base stations (BS) 5, through RB 7 they are fed to PFP 9, amplified by it and fed to ICS 10, calculated by the level of the received signal, the distance between the BS and the software and the encoded signal of the ICS 10 containing information about the measured distance modulates the PRD 8, the oscillations of which through RB 7 are supplied to the antenna 6, emitted, received by the antenna 12 of the main radio station 11, amplified by by the receiver 13 and fed to the calculator 14, which according to the information received from a number of BS that received the software signal, calculates the location of the object.

 The disadvantage of this system is the low accuracy of positioning.

где L длина волны;
σ₁,σ₂ коэффициенты усиления антенн подвижного средства и БС соответственно;
P_пр принимаемая мощность.When radio waves propagate in free space, the distance R between a moving object can be determined by the formula

where L is the wavelength;
σ ₁ , σ ₂ the gains of the antennas of the vehicle and BS, respectively;
P _pr received power.

где n показатель степени.Consequently, defining P _ave and knowing L, σ ₁ and σ ₂ may calculate R. However, as shown in [2] in an urban average value of received power signal depending on the location of streets on which transmitter and receiver are mounted may vary 10-20 dB. This will lead to the fact that the measured values of R may differ by 3.10 times with a quadratic law of variation in the power of the received signal. In the conditions of the city, a change in capacity occurs according to the law

where n is an exponent.

 As shown in [3], n depends on the elevation height of the receiver antenna h PRM and the transmitter h PRD.

 For example, with h Rx = 1.5 m and h Rx = 70 m, n = 3.3.

 Under these conditions, the change in the power of the reflected signal described in [2] will lead to a spread of R by a factor of 2.4.

 That is, at a nominal value of R = 1 km, R '= 0.5 km or R "= 4 km can be calculated, which makes it difficult to detect software that has given an alarm.

 The aim of the invention is to increase the accuracy of determining the coordinates of a moving object.

 This goal is achieved by the fact that in the system for determining the location of a moving object, containing the equipment of a moving object, including an antenna and serially connected key and a transmitter, equipment of base stations, consisting of serially connected antennas, an isolation unit, to the second input of which a transmitter is connected, and the receiver, the equipment of the main radio receiving station, consisting of an antenna and series-connected receiver and calculator, are introduced into the equipment of the moving object the decoupling unit, the receiver and the decoder of the marker are connected in series, the first input of the decoupling unit is connected to the output of the antenna, and the second to the output of the transmitter, the output of the marker decoder is connected to the second input of the transmitter, the second inputs of the receiver and decoder of the marker are connected to the key output, as part of the base station a time interval meter is introduced, serially connected marker decoder and address decoder, the inputs of the time interval meter are connected to the outputs of the transmitter and receiver, and the output to the first input is not the transmitter, the first input of the marker decoder and the second input of the address decoder are connected to the output of the receiver, and the output of the address decoder is connected to the second input of the transmitter, and the main radio receiving station has serially connected synchronizer, transmitter and decoupling unit, the input-output of which is connected to the antenna, and output to the input of the receiver.

 The output of the system is the location computer of the main radio receiving station (RPS).

 The essence of the claimed system is that the RPS generates microwave pulses containing a marker and a BS code, having received a BS whose address matches the code of the emitted signal, generates marker pulses and simultaneously launches a range finder. If the mobile vehicle needs to give an alarm, its transceiver is turned on, receiving BS marker pulses, which are amplified by the receiver, decoded and triggering a transmitter emitting an alarm signal, which is received by the BS, which measures the time T between its emitted pulse and received from the software. From the measured time T, the distance R = c • T / 2 is calculated, where c is the speed of light, the time interval meter (range finder) generates a code containing a marker and a range code. This signal is modulated by the BS transmitter, the microwave oscillations of which are emitted by the BS antenna, are received by the RPS base and fed to the computer.

 Having received information about the distances between the software and at least 3 BS, the main RPM calculator determines the location of the software.

 Thus, the main difference between the claimed system and the prototype is that the location of the software is carried out not by the level of the received BS signal, but by the distances between the software and three BS, which improves the accuracy of determining the location of the software.

 Comparison of the claimed device with the prototype shows the presence of newly introduced blocks: decoupling unit, receiver, marker decoder in the equipment of a moving object; marker decoder, address decoder and range finder in the BS; decoupling unit, transmitter and synchronizer in the main RPS, and the location is calculated according to the measured BS ranges.

 The introduction of such blocks to increase the accuracy of determining software that sends a distress signal from public sources is unknown, which allows us to conclude that the proposed solution meets the criterion of "novelty."

 The newly introduced blocks are widely known [4, 5] However, their use in accordance with the described relationships makes it possible to significantly increase the accuracy of determining the PO field.

 This solution does not explicitly follow from the prior art, which meets the criterion of "inventive step".

 The system can be used to send distress signals to collectors, drivers of mobile vehicles, law enforcement officials and individuals.

 In FIG. 1 presents a functional diagram of a prototype; figure 2 is a functional diagram of the proposed system; figure 3 diagrams of stresses explaining the principle of operation of the proposed system.

 The system contains equipment 1 of a moving object, which includes an antenna (Ant) 2, an isolation unit (RB) 3, a transmitter (Rx) 4, a receiver (Rx) 5, a marker decoder 6, a transmitter key 7, an equipment 8 of several receiving devices (BS base stations), each of which includes an antenna 9, an isolation block 10, a transmitter 11, a receiver 12, a marker decoder (Dec M) 15, an address decoder (Dec A) 14, a time interval meter, equipment of the main radio receiving station 16 , which includes the antenna 17, the decoupling unit 18, the transmitter to 19, synchronizer 20, a receiver 21, a calculator 22.

 The system operates as follows. If it is necessary to transmit an alarm, a key 7 is turned on, which supplies power to the equipment of the moving object. The synchronizer 20 generates pulses "a", following with a period T and containing a marker and an information part containing the address of the BS, moreover, the address code of the BS varies from pulse to pulse from the 1st BS to the last (Nth). These pulses trigger the transmitter 19, the oscillations of which through the decoupling unit 18 are fed to the antenna 17. The oscillations "b" emitted by the antenna 17 are received by the antennas 9 of the base stations 8, amplified by them through the RB 10 to the receiver 11 and fed to the marker decoder 13, which selects the marker and starts the address decoder 14.

 If the code transmitted by the main RPS 16 coincides with the address of the BS, then at the output of the decoder of address 14 there is a pulse "in", which starts the transmitter 11, the oscillations of which through RB 10 are supplied to the antenna 9, are emitted, and after a time ti are received by the antenna 2 of the vehicle 1 and through RB 3 they arrive at receiver 5, are amplified by it and fed to marker decoder 6, at the output of which a pulse "d" arises, transmitter 4 starts to generate oscillations that are fed through antenna 3 to antenna 2, radiated and received by antenna 9 of the base station 8, reinforced reception minikom 12, enter the input of the time interval meter 15, which measures the time between the emitted pulse and the received pulse "e" and converts this time into a code that is transmitted to the transmitter 11, which generates pulses "g", containing a marker and a code corresponding to the distance from the first base station to the object that gave the alarm. These oscillations "h" are received by the antenna 17 of the main RPS 16, amplified by the receiver 21 and fed to the computer 22.

 In the next period, the synchronizer 20 generates a code containing the number of the 2nd BS, which, having adopted this code, emits a polling pulse of moving objects. If a moving object is in the coverage area of the 2nd BS, then it generates a response signal, which is received by the 2nd BS, which measures the delay time from its antenna to the object and transmits this time in the form of a main RPS code, which, after receiving this signal, transmits it to calculator 22, etc.

 Based on the measured distances from the object to the first, second and third stations, the computer 22 determines the location of the object. To reduce the fluctuation error of the range measurement in the computer, averaging over n measurements takes place.

где σ_ПРДn,σ_ПРМm σ_g ошибки, вызываемые изменением времени задержки в цепях передатчика, приемника и декодера аппаратуры подвижного объекта;
σ_ПРМБС нестабильность времени задержки в цепях приемника БС.The advantage of the claimed system compared to the prototype is the greater accuracy of calculating the location of a moving object, which is determined only by errors in measuring the distance between the moving object and the BS and can be calculated by the formula

where σ _PRDn , σ _PRPm σ _g errors caused by a change in the delay time in the chains of the transmitter, receiver and decoder of the equipment of a moving object;
σ _{PRBS is the} delay time instability in the BS receiver circuits.

Errors related to the possibility of zooming were not taken into account, because In the time interval meter, a crystal oscillator having a frequency instability of 10 ^-4 can be used, which leads to a 1 m error when measuring R <10 km.

As shown in [6], when using receivers with a bandwidth of 4–5 MHz and constructing a transmitter and decoder on RF transistors, σ _PRDn ≈ σ _PR ≈ σ _g ≈ σ _PRMBS = 15 m, i.e. σ _g 30 m, which is less than an order of magnitude less than in the prototype.

 If it is necessary to increase accuracy, solutions for decreasing σ can be used.

 The system can be implemented. If we assume that the antenna installation height of the software is 1-3 m, the antenna installation height of the BS is approximately 50 m, the carrier frequency lies in the 900 MHz range, then according to [3] the exponent n lies between 2.4 and 3.3.

или 10•lg N_рл 127 дБ.Having taken n 3, the distance R 2000 m, the gain of the antenna 2 of the software equal to 1, and the gain s ₂ , the antenna of the BS equal to 3, we get that the loss in the radio line BS-software

or 10 • log N _rl 127 dB.

При построении гетеродинов и задающих генераторов на поверхностных акустических волнах относительная нестабильность их частот

При f 8•10⁸, Δf 40 •10³ Гц, т.е. полоса пропускания приемника определяется только спектром сигнала. Тогда при коэффициенте шума K_ш 2 коэффициенте различимости Д=10 чувствительность приемника

или 10•lg N_пр≈ 130 дБ/Вт.With a bit duration of t _b 2 μs and a bit front duration of τ _f 0.5 μs, the necessary bandwidth of the receiver

When constructing local oscillators and master oscillators on surface acoustic waves, the relative instability of their frequencies

When f 8 • 10 ⁸ , Δf 40 • 10 ³ Hz, i.e. The receiver bandwidth is determined only by the spectrum of the signal. Then when the noise factor K _W 2 the distinguishability coefficient D = 10 the sensitivity of the receiver

or 10 • log N _pr ≈ 130 dB / W.

 Therefore, to ensure a range of 2 km, it is enough to have a pulsed transmitter power of 1 W, which can be obtained using a small-sized semiconductor generator.

 The system provides a short time for receiving alarm information.

As follows from FIG. 3, repetition period
T _p 2 R _BS / c + n _a • t _b + 2 R _PO / c + t ₃ + p _d • t _bd ,
where n _a , n _{d the} number of bits of addresses and ranges;
R _BS , R _PO distance between the base and base station and the base station and the mobile means;
t _ba , t _{bd the} duration of the address bit and range, respectively.

It was believed that the bit duration t _ba = 2 μs, the number of base stations N _b 64 is sufficient to cover a city with an area of 100 km ² , so n _a = 6.

Discrete chosen range 25 m _to 2000 when R m n _d 7 necessary.

If we assume that the maximum distance between the BS and the RPS is 15 km, then
T _n 100 μs + 6 • 2 + 13 + 7 • 2 ≈140 μs.

 About 20 μs is needed to receive a signal from the software.

Therefore, with a large margin, the repetition period T _{p of the} synchronizer pulses can be selected equal to 500 μs. If we assume that the number of BS N _b is 64 and averaging over K 8 measurements occurs, then the update time of the information
T _oi T _p • N _b • K 500 • 64 • 8 0.128 s,
those. less than 0.2 s is required to receive an alarm.

Literature
1. A system for determining the location of a moving object. US patent N 5055851. RZHS, Inventions of the world, issue 85, MKI σ 01 K • S, N 10, M. 1993, p. 36.

 2. Edited by UK Jakes. Communication with moving objects in the microwave range. M. Communication, 1979, p. 81.101.

 3. Trubin B. M. Shevtsov V. P. Trepakhin O.A. Digital radiotelephone systems for rural areas. Foreign Radio Electronics, N 9, 1991.

 4. M.V. Vambersky, V.P. Abramov, V.I. Kazantsev. Design of decoupling devices NI Microwave Radio and communications, 1982.

 5. W. Titze, C. Schenck. Semiconductor circuitry. M. World, 1982.

 6. Radio system for the protection of premises. UPKB Detail, 1993.

Claims (1)

 A system for determining the location of a moving object, comprising equipment of a moving object, including an antenna and a series-connected key and a transmitter, equipment N of base stations, consisting of a series-connected antenna, an isolation unit, to the second input of which a transmitter is connected, and a receiver, equipment of the main radio receiving station , consisting of an antenna and series-connected receiver and calculator, characterized in that sequentially introduced into the composition of the equipment of the moving object connected decoupling unit, receiver and decoder of the marker, the first input of the decoupling unit is connected to the output of the antenna, and the second to the output of the transmitter, the output of the decoder of the marker is connected to the second input of the transmitter, the second inputs of the receiver and decoder of the marker are connected to the output of the key, the base station time interval meter, serially connected marker decoder and address decoder, inputs of the time interval meter are connected to the outputs of the transmitter and receiver, and the output is to the first input of the transmitter, the first the marker decoder stroke and the second input of the address decoder are connected to the output of the receiver, and the output of the address decoder is connected to the second input of the transmitter, and a series-connected synchronizer, transmitter and decoupling unit, the input-output of which is connected to the antenna, and the output to the input, are introduced into the main radio receiving station receiver.

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