JPH02124489A - Moving-body identifying apparatus - Google Patents

Abstract

PURPOSE:To make an apparatus compact and light in a simple constitution by providing the constitution wherein a phase shifter is inserted between any parts of a branching means, a mixer and a transmitting and receiving antenna. CONSTITUTION:This apparatus is composed of a non-modulating carrier oscillator 101, a halving device 102, a circulator 103, an antenna 104, a phase shifter 105, mixer 106 and a signal processor 107. The phase shifter 105 is inserted between the having device 102 and the mixer 106. In an interrogator 1, the modulated wave of a responder 2 which is received with the antenna 104 is inputted into the mixer 106 through the circulator 103. The output of the oscillator 101 which is distributed to the phase shifter 105 through the halving device 102 is inputted into the mixer 106. The shifter 105 is controlled with the processor 107. The phase of the locally oscillated wave is continuously changed in a specified period, e.g. from 0 deg. to 108 deg. at e.g. from 1ms to 2ms. The output is received in the mixer 106. The processor 107 demodulates the output of the mixer 106 by the odd number of times at the period of the phase change. Thus the received data are obtained. Therefore, a point where the output of the demodulated signal becomes 0 and disappears is shifted, and the intrinsic data of the responder 2 can be demodulated.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention transmits and receives data over a relatively short distance between an interrogator having a transmitting and receiving function and a transponder that is mainly attached to a moving object and used. This invention relates to an interrogator for a mobile object identification device.

<Conventional technology> In recent years, we have been managing the entry and exit of nine production managers within the factory.

Mobile object identification devices are now in the spotlight for gate management in parking lots, logistics management, and the like.

For example, when used for production control in a factory, a transponder with various data such as part codes, processing procedures, destinations, etc. for the products on the production line inputted in advance to the storage unit is used to respond to the products on the line. Meanwhile, interrogators are installed at each point on the production fin. The interrogator transmits an interrogation radio wave to the responsive device attached to the products flowing on the production line, reads the unique information inside the transponder based on the signal returned from the transponder, and uses that information to control production. This is what we do. The demodulation method of such an interrogator reception section is to use a part of the unmodulated carrier that is sent to the transponder as an interrogation signal as a local oscillation source of the mixer, and mix it with the received signal re-radiated from the transponder in the mixer. , homodyne detection with demodulation is used. However, this method has a peculiar phenomenon in that the demodulated signal output becomes 0 and disappears depending on the relative distance between the interrogator and the transponder.

In order to prevent this phenomenon, conventionally two systems of mixers were provided.

FIG. 4 shows a conventional example.

In the interrogator 3, the signal generated by the non-modulated carrier oscillator 301 is divided into two by a divider 302, one of which is divided by the circulator 3.
03. The interrogation signal is radiated to the transponder 4 via the antenna 304. The transponder 4 modulates the received unmodulated carrier with internally stored unique data and re-radiates it toward the interrogator 3. In the interrogator 8, the modulated signal is received by the antenna 304 and input to the in-phase distributor 306 via the circulator 30a. In the common mode distributor 306,
The modulated signal is divided into two in phase and input to mixers 807 and 308, respectively.

On the other hand, the signal of the unmodulated carrier oscillator 801 distributed by the two-way divider 302 is inputted to the 90° distributor 305 as a local oscillation source, and after being distributed into two signals having a phase difference of 90°, each The signal is input to mixer BOY 808. The mixing outputs of the mixers 807 and 08 are input to the signal processor 309. By the way, as mentioned above, in homodyne detection, the signal disappears due to the relative distance between the interrogator 8 and the responder 4. , 0 occurs.

Expressing this mathematically, the output of mixer 307 is K−c
os(*i-*1) The output of the mixer 308 is K-cos(silk-(*1+90°))=K・5in(#
i −111). However, K is a constant, and yi is the phase e '1+l' of the input signal to the mixers 307 and 308.
1 +9Q are local oscillation signal mixers 807 and 8, respectively.
This is the input phase to 08.

If these are shown in a graph, it will be as shown in FIG.

From FIG. 5, when the output of one mixer is 0, the output of the other mixer is the maximum output, and both outputs never become 0 at the same time. Therefore, if the signal processor 309 performs processing with this point in mind, the received signal can be demodulated regardless of the relative distance between the interrogator 3 and the transponder 4.

<Problems to be solved by the invention> However, as mentioned above, the conventional system uses two systems of mixers, making the circuit complicated, making it difficult to adjust the circuit, and having a large size and high cost. Was.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mobile object identification device that does not require two mixer circuits in the demodulation section of the interrogator and is equipped with a simple, compact, lightweight, and inexpensive interrogator.

Means for Solving the Problems> To achieve the above object, the present invention provides an interrogator having a demodulator that emits an interrogation signal, receives a response signal, and demodulates data; A signal is output from the second and third terminals, and a signal input to the third terminal is output from the fourth terminal. There is a microwave branching means configured to output the microwave from a terminal, a first terminal of the branching means is connected to the output of the oscillating means, and an eighth terminal of the branching means is connected. a transmitting/receiving antenna, a mixing means for mixing signals from the second and fourth terminals of the branching means, and a signal processing means for processing signals from the output of the mixing means, and the phase of the input signal is kept constant. There is a phase shifter that changes the output signal continuously or stepwise with a period of The present invention provides a mobile object identification device configured to achieve the above object.

In the interrogator of the mobile object identification device configured as described above, the demodulated signal output becomes 0 by controlling the phase shifter at a speed sufficiently slower than the modulation speed of the transponder. By shifting the vanishing point, the unique data from the transponder can be demodulated.

<Example> Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

FIG. 1 is a block diagram showing an embodiment of an interrogator l of a mobile object identification device according to the present invention, in which a non-modulated carrier oscillator 1
01.2 distributor 102. Circulator 103. Antenna I04. Phase shifter 105° mixer 106. Signal processor!
07, and in this embodiment, the branching means is 2.
The transfer device 105 is composed of a distributor 102 and a circulator 103;
inserted between.

In FIG. 1, the output of the unmodulated carrier oscillator 101 is distributed to the circulator +03 and the phase shifter 105 by a 2-way divider, and the one that passes through the circulator +03 is radiated as an interrogation signal from the antenna +04 to the transponder 2. be done. The unmodulated carrier received by the transponder 2 is modulated with data specific to the transponder 2, and then re-radiated to the interrogator l. 1, the modulator received by the antenna 104 passes through the circulator 103 to the mixer 10.
6. On the other hand, the phase shifter 105 in the two-way divider 102
The output of the unmodulated carrier oscillator 101 is inputted to the mixer 106 as a local oscillation source via a phase shifter +05 controlled by the signal processor 107.

At this time, the mixing output level of the mixer 106 changes as shown in FIG. 2 depending on the phase j1 of the phase shifter 105.

There is a point where the mixer output level becomes O depending on the relative distance between the interrogator 1 and the transponder 2, but even at that point, the signal processor 107 controls the phase shifter 105 and the oscillator 1
If the phase of the local oscillation wave from 01 is changed at a constant cycle, for example from Oo to 180°t, an amplitude component will always occur. Therefore, if this component is processed by the signal processor 107, demodulation is always possible regardless of the relative distance between the interrogator 1 and the transponder 2.

However, the temporal change in the phase control of the locally oscillated wave by the phase shifter +05 needs to be sufficiently slower than the modulation speed of the modulated wave re-radiated from the transponder 2. In this embodiment, the modulated wave is set to 100 kHz, and the phase shifter +05 changes the phase of the local oscillation wave continuously or stepwise from 00 to 180 degrees at a period of Imms to 2 ms, and outputs the modulated wave to the mixer 106. input. Signal processor 1
At 07, the output of the mixer 106 is demodulated an odd number of times, for example, 5 times, during the period in which the phase shifter +05 is changing the phase, and reception data is obtained. Since the modulated wave emitted from the transponder 2 also includes various reflected waves, it is not always possible to receive correct data in the above period. Therefore, there is no problem with the received data if all five back-tone results are the same, but if some of the data is different,
Data is determined by majority decision. Depending on the situation, the number of demodulations can be set to 7 or 9 times.

In the above embodiment, the phase shifter 105 is combined with the two-way divider 102 and the mixer! 06, the phase shifter 105 is inserted between the antenna 104 and the circulator +03.
Similar effects can be obtained regardless of the location between the circulator 103 and the mixer 106, or between the two-way divider 102 and the circulator +03. Also,
A directional coupler may be used as the branching means instead of the distributor 102 and the circulator 103. An example in this case is shown in FIG.

Also in Figure 3, the phase shifter! 05 is directional coupler 1
If it is inserted between 0B and the mixer 106 (A or B) or between the antenna 104 and the directional coupler 108 (C), the same effect as the first embodiment can be obtained.

<Effects of the Invention> As described above, according to the present invention, the configuration is simplified because only one mixer system is required instead of two mixers in the past.
A mobile object identification device equipped with a small, lightweight, and inexpensive interrogator can be obtained, and the effects of the present invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment according to the present invention, and FIG.
The figure is an explanatory diagram showing changes in the output level of the mixer when the phase of the phase shifter changes, FIG. 3 is a block diagram showing the second embodiment, and FIG. 4 is a block diagram showing a conventional moving object identification device. , FIG. 5 is an explanatory diagram showing a change in mixer output level depending on the relative distance between an interrogator and a transponder in a conventional device. 1.3: Interrogator, 2,4: Responder, 101
゜301: Unmodulated carrier oscillator, 102,30
2=2 distributor, toa, aoa: circulator. 104.304: Antenna, 105: Phase shifter. 106°307°: Mixer. 07°: Signal processor. Bidirectional coupler. 305: 90° 2 splitter. 306 two-in-phase two-distributor.

Claims (1)

[Claims] 1. An interrogator having a demodulator that emits an interrogation signal, receives a response signal, and demodulates data; and an interrogator that receives the interrogation signal with an antenna, modulates it with built-in data, and regenerates it as the response signal. In the mobile object identification device, the interrogator includes an oscillating means for oscillating microwaves, and a signal input to the first terminal is output from the second and third terminals. , microwave branching means configured such that the signal input to the third terminal is output from the fourth terminal, and the output of the oscillation means is connected to the first terminal of the branching means. a transmitting/receiving antenna connected to a third terminal of the branching means, a mixing means for mixing signals from the second and fourth terminals of the branching means, and processing a signal from the output of the mixing means. There is a phase shifter comprising a signal processing means, which changes the phase of an input signal continuously or in a stepwise manner at a constant period to produce an output signal, and the phase shifter is connected to the branching means and the branching means. A mobile object identification device configured to be inserted between a mixer and the transmitting/receiving antenna.