RU2426148C1 - Telemetry system for identification of objects - Google Patents

Abstract

FIELD: physics. ^ SUBSTANCE: proposed system comprises readout unit and two transducers arranged on different objects to be identified. Readout unit comprises unmodulated oscillation generator, three multipliers, transceiving antenna, low-pass filter, adder, power amplifier, duplexer, HF amplifier, four bandpass filters, two mixers, local oscillator, two intermediate frequency amplifiers, two phase detectors, registration unit, all said components being interconnected in a certain way. Every transducer incorporates piezo crystal with aluminium thin-film double-finger transducer and set of reflectors. Said double-finger transducer comprises electrodes and buses connected with micro strip transceiving antenna. ^ EFFECT: efficient identification of two close objects by using radio-frequency marks and complex phase-modulated signals. ^ 2 dwg

Description

The proposed system relates to telemetry systems for identifying objects using the microwave range of electromagnetic waves and can be used to identify nearby small-tonnage containers, baggage at airports, customs points for identification at checkpoints, in agriculture for the identification and selection of animals and etc.

Telemetry systems for identifying objects are known (autoswitch. USSR No. 1054887, 1627832, 1769217; RF patents No. 2054694, 2057334, 2105993, 2183033, 2267158, 2292587, 2326404, 2378661; US patents No. 4075632, 4096477, 4739328, 4739328, 4739328, 4739328, 4739328, 4739328, 4739328, 47907648, 6639509; UK patent No. 2164424; French patent No. 2630236; German patents No. 4231800, 4336898; patents EP No. 0242906, 0469769; Review of automatic identification. Conference reports. M: Sovincenter, September 20-21, 1988; Goth J. SAW device - The basis of a vehicle identification system.Electronics, 1990, issue 3, etc.

Of the known systems closest to the proposed is the "Telemetric system for identifying objects" (RF patent No. 2054694, G01S 13/78, 1992), which is selected as a prototype.

The known system includes a reading unit 1, sensors 2, 3, transceiver antennas 6, 12, 12 ', an unmodulated oscillation generator 4, a transmission line 5, n couplers 7, n mixers 8, n low-pass filters 9, n / 2 amplifiers 10, demodulator-adder 11, modulators 21, 21 ', power supply unit 22, code generators 18, 18', switches 19, 19 ', switching pulse generators 20, 20', which makes it possible to identify signals of two closely spaced sensors.

In the known system for resolving sensors located at the same or different ranges within the main lobe of the antenna pattern of the reading unit 1, the mode of dividing the operation of the sensor modulators in time is used.

The reading unit 1 contains two pairs of directional couplers included in the transmission line and located in it at a distance of λ / 4 between the couplers of one pair and at a distance not equal to λ / 4 between the pairs, λ is the operating wavelength of the unmodulated oscillator.

All this reduces the efficiency of identification of two closely located objects.

An object of the invention is to increase the identification efficiency of two closely spaced objects by using radio frequency tags on surface acoustic waves and complex signals with phase shift keying.

The problem is solved in that a telemetric identification system of objects, containing, in accordance with the closest analogue, a reading unit and at least two sensors with transceiver antennas mounted on different identifiable objects, remote from the reading unit and located in the main lobe of the antenna pattern of the reading unit wherein the reading unit contains an unmodulated oscillation generator, a transceiver antenna and two mixers, differs from the closest analogue in that the it is equipped with three multipliers, a narrow-band filter, an adder, a power amplifier, a duplexer, a high-frequency amplifier, four bandpass filters, a local oscillator, two intermediate-frequency amplifiers, two phase detectors and a recording unit, and the first multiplier, the second input are connected in series to the output of the unmodulated oscillator which is connected to the output of the generator of unmodulated oscillations, a narrow-band filter, an adder, the second input of which is connected to the output of the generator unmodulated oscillations, a power amplifier, a duplexer, the input-output of which is connected to a transceiver antenna, a high-frequency amplifier and two processing channels, each of which consists of a first bandpass filter, a mixer, the second input of which is connected to the local oscillator output, and is connected in series to the output of the high-frequency amplifier , an intermediate frequency amplifier, a multiplier, a second band-pass filter of a phase detector, the second input of which is connected to the output of the local oscillator, and a recording unit, while the second input a multiplier of the first processing channel is connected to the output of the unmodulated oscillator, and the second input of the multiplier of the second processing channel is connected to the output of a narrow-band filter, each sensor is made in the form of a piezocrystal with an aluminum thin-film interdigital transducer deposited on its surface and a set of reflectors, while the interdigital the converter contains two comb systems of electrodes, the electrodes of each of the combs are connected to each other by buses, the transceiver antenna is made also in microstrip on the surface of the piezoelectric crystal and is associated with the tires, the sensors have different distances between the electrodes and are tuned to different frequencies.

Figure 1 presents the main parts of the system and their relative position in space. Figure 2 shows the structural diagrams of the reading unit and sensors.

Sensors 2 and 3 are located on adjacent identifiable objects so as not to obscure each other in the main lobe of the radiation pattern of the antenna 6 of the reader 1. The width of the main lobe 2 of the antenna 6 is defined as the ratio λ / D, where D is the diameter of the aperture of the antenna. Sensors 2 and 3 are located at a distance from the reading unit 1.

The reader 1 contains a series-connected oscillator 4 of unmodulated oscillations, a first multiplier 5, the second input of which is connected to the output of the generator 4 of unmodulated oscillations, a narrow-band filter 7, an adder 8, the second input of which is connected to the output of the generator 4 of unmodulated oscillations, a power amplifier 9, a duplexer 10, the input-output of which is connected to the transceiver antenna 6, a high-frequency amplifier 11 and two processing channels, each of which consists of a series of high-frequency amplifier 11 the frequencies of the first band-pass filter 13.1 (13.2), mixer 8.1 (8.2), the second input of which is connected to the output of the local oscillator 14, the amplifier 15.1 (15.2) of the intermediate frequency, the multiplier 16.1 (16.2), the second input of which is connected to the output of the generator 4 of unmodulated oscillations (narrow-band) filter 7), a second band-pass filter 17.1 (17.2), a phase detector 18.1 (18.2), the second input of which is connected to the output of the local oscillator 14, and the registration unit 19.

Each sensor 2 (3) is made in the form of a piezocrystal with an aluminum thin-film interdigital transducer (IDT) deposited on its surface and a set of reflectors 24.1 (24.2). In this case, the IDT contains two comb systems of electrodes 20.1 (20.2), the electrodes of each of the combs are connected to each other by buses 21.1 (21.2) and 22.1 (22.2). The transceiver antenna 12.1 (12.2.) Is made in the form of a microstrip also on the surface of the piezocrystal and is connected to the buses 21.1 (21.2) and 22.1 (22.2). Sensors 2 and 3 have different distances between the electrodes 20.1 and 20.2, are tuned to different frequencies and are radio frequency tags.

The transceiver antenna 6 can be made in the form of a horn, half-wave vibrator or spiral antenna.

Telemetric identification system of objects works as follows.

A generator of 4 unmodulated oscillations generates a high-frequency oscillation

u ₁ (t) = U ₁ · Cos (w ₁ t + φ ₁ ), 0≤t≤T ₁ ,

where U ₁ , w ₁ , φ ₁ , T ₁ - amplitude, carrier frequency, initial phase and duration of high-frequency oscillations.

which goes to the first input of the adder 8 and to the two inputs of the multiplier 5. At the output of the last, a high-frequency oscillation is formed

u ₂ (t) = U ₂ · Cos (w ₂ t + φ ₂ ), 0≤t≤T ₁ ,

where U ₂ = _^1/2 U ^{₂ January;}

w ₂ = 2w ₁ ; φ ₂ = 2φ ₁ ,

which is allocated by a narrow-band filter 7 and fed to the second input of the adder 8. The total voltage is generated at the output of the adder 8

U _∑ (t) = U ₁ (t) + U ₂ (t),

which is amplified in the power amplifier 9 and through the duplexer 10 enters the transceiver antenna 6, is radiated by it, is received by the microstrip transceiver antennas 12.1 and 12.2 of the sensors 2 and 3, respectively. The latter are a piezocrystal with an aluminum thin-film interdigital transducer of surface acoustic waves (SAW) deposited on its surface, which consists of two comb systems of electrodes 20.1 (20.2) deposited on the surface of the piezocrystal. The electrodes of each of the combs are connected to each other by buses 21.1 (21.2) and 22.1 (22.2). The tires, in turn, are connected to the microstrip transceiver antenna 12.1 (12.2). Sensor 2 is tuned to the carrier frequency w ₁ , and sensor 3 is tuned to the carrier frequency w ₂ .

The received harmonic oscillation u ₁ (t) [u ₂ (t)] is converted by an interdigital transducer into an acoustic wave that propagates along the surface of the piezocrystal, is reflected from a set of reflectors 24.1 (24.2), and again converted into an electromagnetic signal with phase shift keying (FMN) :

u ₃ (t) = U ₃ · Cos [w ₁ t + φ _к1 (t) + φ ₁ ],

u ₄ (t) = U ₄ -Cos [w ₂ t + φ _к2 (t) + φ ₂ ], 0≤t≤T ₁ ,

where φ _к1 (t) = {0, π}, φ _к2 (t) = {0, π} are the manipulated phase components that display the phase manipulation law in accordance with the modulating codes M ₁ (t) and M ₂ (t), wherein φ _k1 (t) = const, φ _k2 (1) = const at Kτ _e <1 <(K + 1) τ _e and can change abruptly at t = _e Kτ, i.e. at the borders between elementary premises (K = 1, 2, ..., N ₁ -1);

τ _e , N ₁ - the duration and number of chips that make up a signal of duration T ₁ (T ₁ = N · τ _e );

In this case, the internal structure of the generated QPSK signals is determined by the IDT topology, has an individual character and contains all unique information about identifiable objects, for example, number, type of container, baggage, its color and other characteristic features.

The generated PSK signals u ₃ (t) and u ₄ (t) are emitted by microstrip antennas 12.1 and 12.2, respectively, on the air, received by the transceiver antenna 6 of the reader 1 and through the duplexer 10, the high-frequency amplifier 11 and the bandpass filters 13.1 and 13.2 arrive at the first inputs mixers 8.1 and 8.2 respectively. In this case, the tuning frequencies w _n1 and w _{n2 of the} bandpass filters 13.1 and 13.2 are selected equal to w _n1 = w ₁ , w _n2 = w ₂ .

The voltage of the local oscillator 14 is supplied to the second inputs of the mixers 8.1 and 8.2

u _g (t) = U _g Cos (w _g t + φ _g ).

At the output of the mixers 8.1 and 8.2, a voltage of combination frequencies is generated. Amplifiers 15.1 and 15.2 are allocated voltage intermediate frequencies:

u _up1 (t) = U _pr1 · Cos [w _up1 t + φ _к1 (t) + φ _up1 ],

u _up2 (t) = U _pr2 · Cos [w _up2 t + φ _к2 (t) + φ _up2 ], 0≤t≤T ₁ ,

where U _pr1 = _^1/2 · U ₃ U _{g; Np2} U = _^1/2 · U U _{4 g;}

w _up1 = w ₁ -w _g is the first intermediate frequency;

w _up2 = w ₂ -w _g is the second intermediate frequency;

φ _up1 = φ ₁ -φ _g ; φ _up2 = φ ₂ -φ _g ,

which go to the first inputs of the multipliers 16.1 and 16.2, respectively.

The second inputs of the multipliers 16.1 and 16.2 are supplied with voltage u ₁ (t) and u ₂ (t) from the outputs of the generator 4 of unmodulated oscillations and a narrow-band filter 7, respectively. The output of the multipliers 16.1 and 16.2 are formed voltage:

u ₅ (t) = U ₅ · Cos [w _g t-φ _к1 (t) + φ _g ],

u ₆ (t) = U ₆ · Cos [w _g t-φ _к2 (t) + φ _g ], 0≤t≤T ₁ ,

where U ₅ = ^l / ₂ U _up1 · U ₁ ;

U ₆ = _^1/2 · U U _{up2 2;}

which are allocated by bandpass filters 17.1 and 17.2 respectively and are supplied to the first inputs of the phase detectors 18.1 and 18.2 respectively, the second outputs of which are supplied with the voltage u _g (t) of the local oscillator 14. At the output of the phase detectors 18.1 and 18.2 low-frequency voltages are generated:

u _н1 (t) = U _н1 · _{Cosφ к1} (t),

u _n2 (t) = U _n2 · _{Cosφ k2} (t), 0≤t≤T ₁ ,

where U _H1 = _^1/2 · U U _{5 g;}

U _H2 = _^1/2 · U U _{6 g;}

proportional to the modulating codes M1 (t) and M2 (t), carrying information about identifiable objects.

Low-frequency voltages u _н1 (t) and u _н2 (1) are recorded by the recording unit 19.

Thus, the proposed telemetric system for identifying objects in comparison with the prototype and other technical solutions of a similar purpose provides increased identification efficiency of two closely spaced objects. This is achieved using radio frequency tags on surface acoustic waves and complex signals with phase shift keying.

The main features of radio-frequency tags on surface acoustic waves are small dimensions and the absence of power sources, which significantly increases the efficiency and reliability of identification of closely located objects.

Complex QPSK signals have high energy and structural secrecy.

The energy secrecy of complex QPSK signals is due to their high reducibility in time or spectrum with optimal processing, which reduces the instantaneous radiated power. As a result, a complex QPSK signal at the receiving point may be masked by noise and interference. Moreover, the energy of a complex QPSK signal is by no means small; it is simply distributed over the time-frequency domain so that at each point of this region the signal power is less than the power of noise and interference.

The structural secrecy of a complex QPSK signal is caused by a wide variety of their forms and significant ranges of parameter values, which makes it difficult to optimize or at least quasi-optimal processing of complex QPSK signals of an a priori unknown structure in order to increase the sensitivity of the receiving device.

Claims (1)

A telemetry identification system for objects, comprising a readout unit and at least two sensors with transceiver antennas mounted on different identifiable objects, remote from the readout unit and located in the main lobe of the antenna pattern of the readout unit, wherein the readout unit contains an unmodulated oscillator, a transmit-receive antenna, and two mixers, characterized in that the reading unit is equipped with three multipliers, a narrow-band filter, an adder, a power amplifier a duplexer, a high-frequency amplifier, four bandpass filters, a local oscillator, two intermediate-frequency amplifiers, two phase detectors and a recording unit, and the first multiplier is connected in series to the output of the unmodulated oscillation generator, the second input of which is connected to the output of the unmodulated oscillation generator, narrow-band filter, adder the second input of which is connected to the output of the generator of unmodulated oscillations, a power amplifier, a duplexer, the input-output of which is connected to the receiver a transmitting antenna, a high-frequency amplifier and two processing channels, each of which consists of a first bandpass filter, a mixer, the second input of which is connected to the output of a local oscillator, an intermediate-frequency amplifier, a multiplier, a second band-pass filter, a phase detector, each connected in series to the output of the high-frequency amplifier the second input of which is connected to the output of the local oscillator and the registration unit, while the second input of the multiplier of the first processing channel is connected to the output of the generator of unmodulated oscillations and the second input of the multiplier of the second processing channel is connected to the output of the narrow-band filter, each sensor is made in the form of a piezocrystal with an aluminum thin-film interdigital transducer deposited on its surface and a set of reflectors, while the interdigital transducer contains two comb electrode systems, the electrodes of each of the combs are connected to each other by tires, the transceiver antenna is made of a microstrip also on the surface of the piezocrystal and is connected to the tires, the sensors have different distance e between the electrodes and are tuned to different frequencies.

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