JPH029715B2 - - Google Patents

Description

Detailed Description of the Invention The present invention includes a transmitter attached to a moving object, and when the moving object passes in front of a fixed point, radio waves sent from the transmitter are received by a receiver installed at the fixed point. In a passage determination method that detects the passage of the above-mentioned moving object in front of the above-mentioned fixed point, in particular, when multiple moving objects pass through multiple fixed points, it is possible to identify each moving object individually at each fixed point. The present invention relates to a method for determining the passage of a moving object.

When a moving object passes through a certain designated traffic zone,
Passage determination points (hereinafter referred to as fixed points) are established in the traffic zone,
To detect when a moving object passes through a fixed point, a transmitter is attached to the moving object, and the radio waves sent from the transmitter are received by a receiver installed at the fixed point, thereby detecting when the moving object passes through the fixed point. A method for determining the passage of moving objects is widely used.

Conventional methods are generally methods for determining whether a single moving object passes a fixed point or when multiple moving objects pass a fixed point in a predetermined order; In the case where a plurality of fixed points are passed in front of a plurality of fixed points in a disorderly manner, the conventional method cannot be used if it is necessary to judge the passage of each of the plurality of fixed points for each of the plurality of moving objects.

The present invention solves the above-mentioned conventional drawbacks and provides a method for determining the passage of a moving object, which can also determine in which fixed point area the moving object is present (that is, where the moving object is passing through). be.

Embodiments of the present invention will be described using the drawings.

As shown in the drawing, the fixed points are e.g. A, B and C.
They are set at three locations (generally at multiple locations) along the traffic zone 10, as shown in FIG. The distance between the fixed points A, B, and C is set to several times the width W of the traffic zone 10 (for example, if the width W of the traffic zone 10 is 50 m, the distance between the fixed points A, B, and B, C is set to be several times the width W of the traffic zone 10. is set at approximately 200m).

The fixed point passage determination of the moving object 11 or 12 is performed on the forward extension line of each fixed point A, B, and C, and the determination area of each fixed point A, B, and C is an area divided by the intermediate point between the adjacent fixed point. becomes. Further, a plurality of moving bodies, for example two moving bodies 11 and 12, move within the traffic zone 10, for example in the direction of the arrow.

The mobile bodies 11 and 12 have transmitters 13 equipped with omnidirectional transmitting antennas 15 and 16, respectively.
and 14 are attached, and unmodulated radio waves with different transmission frequencies (the transmission frequencies are Fa and Fb, respectively) are sent to the transmitters 11 and 12 via the transmission antennas 15 and 16. It is being sent from.

Fixed points A, B, and C are provided with receivers 100, 110, and 120, respectively, receiving antennas 101, 111, and 121, hybrid circuits 102, 112, and 122, mixer circuits 103,
113 and 123, modulation circuits 104, 114 and 124, local oscillation circuits 105, 115 and 12
5. Consists of low frequency oscillation circuits 106, 116 and 126.

In the receivers 100, 110 and 120, two receiving elements a and b are used as the receiving antennas 101, 111 and 121, but this is due to the directivity of the receiving antennas 101, 111 and 121,
This is to increase the receiving sensitivity, and the distance between the two receiving elements a and b is preferably a length equivalent to one wavelength of the radio wave used, and the transmitting frequency of the radio wave is, for example, 1680M.
When set to Hz, the distance between the two receiving elements a and b is approximately 20 cm, and each fixed point A, B, and C is placed at the midpoint.
It is arranged so that the Note that the configuration of the receiving antennas 101, 111, and 121 does not need to be a stack (configuration with two receiving elements), and depending on conditions, they may be configured with, for example, one receiving element.

Hybrid circuits 102, 112 and 122 are connected to respective receiving antennas 101, 111 and 12.
This circuit performs vector synthesis of the received signals from the two receiving elements a and b of 1 and extracts the sum signal. Note that, as described above, the receiving antenna 101,
If the configuration of 111 and 121 is one receiving element, the hybrid circuit 102, 112 and 12
2 is not required.

The local oscillation circuits 105, 115, and 125 are composed of oscillators having the same oscillation frequency (the oscillation frequency is F ₀ ).

The low frequency oscillation circuits 106, 116 and 126 are
Each has a different oscillation frequency (the oscillation frequency is
1, 2 and 3. ) consists of a low frequency oscillation circuit.

Modulation circuits 104, 114 and 124 convert the local oscillation signals of frequency F0 sent from local oscillation circuits 105, 115 and 125 into frequencies from low frequency oscillation circuits 106, 116 and 126, respectively.
This is a circuit that performs FM modulation using low frequency signals 1, 2, and 3.

Mixer circuits 103, 113 and 123 mix the received signals from the hybrid circuits 102, 112 and 122 with the modulation circuits 104, 114 and 12.
This circuit mixes the modulated local oscillation signal from 4 and creates an intermediate frequency signal having a frequency that is the difference between the two signals.

To explain the operation of the receiver 100, the frequency transmitted from the local oscillation circuit 105 is
The local oscillator signal of F0 is transmitted to any other receiver 110.
and a low frequency oscillation circuit 1 that oscillates at a different frequency from the low frequency oscillation circuits 116 and 126 of 112.
The modulation circuit 104 performs FM modulation with the low frequency oscillation signal (oscillation frequency 1) from 06, and the modulation signal and the received signal sent out from the hybrid circuit 102 when the moving object 11 or 12 passes in front of the fixed point A. The signal is input to the mixer circuit 103, where it is converted into an intermediate frequency signal having a frequency equal to the difference between the two signals.

The frequency of the intermediate frequency signal when the moving body 11 passes the fixed point A is F1, and the frequency of the intermediate frequency signal when the moving body 12 passes the fixed point A is F1.
Assuming F2, the respective frequencies F1 and F2 are F1=|Fa−F0| F2=|Fb−F0|.

The intermediate frequency signal having a frequency of F1 and/or the intermediate frequency signal having a frequency of F2 is sent to the signal synthesis circuit 20.
1 and 202 to the signal processing section 300.

Regarding the other receivers 110 and 120, the areas of fixed points B and C are respectively
The same operation as above is performed by passing.

Further, the signal combining circuits 201 and 202 are connected to the receiver 1.
This circuit is provided to transmit signals sent from 00, 110, and 120 to the signal processing section 300 through the same route.

The signal processing section 300 includes an IF/AMP circuit 301, an IF
Discrimination circuit 302, FM detection circuit 303, low frequency discrimination circuits 304 and 305, AM detection circuit 306,
It is composed of a display circuit 307.

The IF/AMP circuit 301 connects each receiver 100, 11
This is a circuit that amplifies intermediate frequency signals output from 0 and 120.

The IF discrimination circuit 302 includes a number of IF filters 3 equal to the maximum number of movable objects that can be discriminated (two in this case).
02F1 and 302F2 are built in, and the center frequency of each is the frequency of the intermediate frequency signal mentioned above.
If set to F1 and F2, moving object 11 or 1
2 passes through fixed points A, B, or C, intermediate frequency signals sent from receivers 100, 110, or 120 are discriminated for each of the frequencies F1 and F2.

The FM detection circuit 303 converts the above intermediate frequency signal into FM
The detection circuit includes FM detection sections 303F1 and 303F2 for each of the frequencies F1 and F2.

The low frequency discrimination circuits 304 and 305 each include a number of filters 30 equal to the number of fixed points (three in this case).
41, 3042, 3043 and 3051, 305
2, 3053, the center frequencies of which are set to the oscillation frequencies 1, 2, and 3 of the low frequency oscillation circuits 106, 116, and 126 in the receivers 100, 110, and 120, and the FM detection circuit The signal detected by 303 is set to the above frequency 1,
Discriminate every 2 or 3.

The AM detection circuit 306 is a circuit that performs AM detection on the intermediate frequency signals of the frequencies F1 and F2.
It consists of

The display circuit 307 is a low frequency discrimination circuit 304, 30
5 and the AM detection circuit 306, the signal is processed, and fixed points A, B, and C of the moving object 11 or 12 are detected.
(The movement status within the area of each fixed point A, B, C, the passing time in front of each fixed point A, B, C, the time required to pass between adjacent fixed points, etc.) is displayed or recorded.

Next, the operation of the signal processing section 300 will be explained using an example in which the moving object 11 passes through the fixed point A.

An intermediate frequency signal (frequency
F1) is amplified by the IF/AMP circuit 301, and then
Selected by IF filter 302F1 of IF discrimination circuit 302, and then selected by FM detection section 3 of FM detection circuit 303.
FM detection is performed at 03F1.

In this case, the demodulated signal detected by the FM detection section 303F1 is a signal having frequency 1 related to the receiver 100, and this demodulated signal is detected by the low frequency discrimination circuit 304.
The signal is selected by filter 304 1 and input to display section 307 . The display unit 307 determines that the moving object 11 is present in the area of the fixed point A based on the fact that the demodulated signal has a frequency of 1 and that it is input from the low frequency discrimination circuit 304.

In addition, the IF filter 302 of the IF discrimination circuit 302
The output signal of F1 is also input to AM detection section 306F1 of AM detection circuit 306 and subjected to AM detection.

The strength of the radio waves from the transmitter 13 received by the receiver 100 changes in accordance with the distance of the moving object 11 from the fixed point A, and this change is caused by a change in the amplitude of the intermediate frequency signal output from the receiver 100. It appears. Therefore, the demodulated signal detected and output by the AM detection section 306F1 has an amplitude (level) that corresponds to the distance of the moving object 11 from the fixed point A, and the amplitude is such that the moving object 11 is in front of the fixed point A. It reaches its maximum when it passes through . Therefore, based on the amplitude value of the demodulated signal, the distance of the moving object 11 to the fixed point A can be determined from time to time, and based on the fact that the amplitude has reached a maximum, it is possible to determine whether the moving object 11 is passing in front of the fixed point A. These data are displayed on the display circuit 307.

The above explanation is an example in which the moving object 11 is passing through the area of fixed point A, but as can be easily understood from this explanation, the frequencies F1 and F2 of the intermediate frequency signal are
correspond to moving objects 11 and 12, respectively, and frequencies 1, 2, and 3 of the low frequency signal correspond to fixed points A and 12, respectively.
Since it corresponds to B and C, no matter which moving object exists in which fixed point area, the passage of the moving object can be grasped for each moving object and for each fixed point.

Furthermore, the above embodiment is an embodiment in which the signals (intermediate frequency signals) output from the respective mixer circuits of a plurality of receivers are mixed using a signal synthesis circuit and connected to the signal processing section 300 via a coaxial cable. However, when the distance between the receiver and the signal processing unit 300 becomes large, the wireless method is advantageous, and when the carrier wave is modulated with a composite signal from mixer circuits of several receivers, or when the distance between each fixed point is long. A carrier wave may be provided in each receiver, and in this case, signal processing in the signal processing section may be performed by adding a receiving function and a demodulation function to the signal processing section.

As described above in detail, the present invention provides many effects as follows.

(1) It is possible to accurately determine when a moving object passes in front of a fixed point, and even if there are multiple moving objects and the multiple moving objects pass through multiple fixed points in a disorderly manner, it is possible to accurately determine when a moving object passes in front of a fixed point. can be determined with high accuracy.

(2) Since the transmitter mounted on the mobile object only needs to transmit unmodulated radio waves, the configuration of the transmitter is extremely simple, compact, and lightweight. In addition, since the transmitter can be constructed at low cost, especially when there are a large number of moving objects, the system can be constructed at low cost.

(3) The receivers installed at multiple passage determination points have the same local oscillation circuit, except that the oscillation frequencies of the low-frequency oscillation circuits that modulate the local oscillation signal are set to be different. Since they can all be configured in the same way, the receiver can be adjusted at extremely low cost, and the equipment can be adjusted easily.

(4) Even if the number of passing judgment points increases, the types of frequencies of the signals sent from the receiver will not increase due to this (the types of frequencies of the signals are equal to the number of moving objects, (It is unrelated to the number of passing judgment points.), it is easy to transmit the signal to the signal processing section.

[Brief explanation of drawings]

The drawing is a block diagram showing an embodiment of the invention. 11, 12... Mobile object, 13, 14... Transmitter, 100, 110, 120... Receiver, 300
... Signal processing section, 101, 111, 121 ... Receiving antenna, 102, 112, 122 ... Hybrid circuit, 103, 113, 123 ... Mixer circuit, 104, 114, 124 ... Modulation circuit, 1
05, 115, 125...Local oscillation circuit, 10
6,116,126...Low frequency oscillation circuit, 20
1,202...Signal synthesis circuit, 302...IF discrimination circuit, 303...FM detection circuit, 304,30
5...Low frequency discrimination circuit, 306...AM detection circuit, 307...Display circuit.

Claims (1)

[Scope of Claims] 1. A transmitter is mounted on a moving body, a receiver is installed at each of a plurality of passage determination points, and the radio waves transmitted from the transmitter are received by the receiver, thereby achieving the above-mentioned movement. In a passage determination method in which the passage of a body is determined at each of the plurality of passage determination points, the transmitter of the mobile object transmits unmodulated radio waves, and the reception at each of the passage determination points is performed. The machine mixes local oscillation signals of the same frequency modulated with mutually different low frequency signals and unmodulated radio waves from the transmitter of the mobile object, and generates an intermediate frequency signal having a frequency that is the difference between the two frequencies. is created and sent from both receivers to the signal processing section through the same route, and the signal processing section identifies the passing judgment point through which the moving object has passed by the low frequency signal included in the above intermediate frequency signal, and A mobile object passage determination method that detects the passage of a mobile object in front of the relevant passage determination point by detecting the maximum level of a frequency signal. 2. When there are multiple moving objects, the transmitters mounted on the moving objects transmit unmodulated radio waves with different frequencies, and the receivers at the passing judgment points transmit intermediate frequency signals corresponding to the frequency of the transmitters. 2. A method for determining passage of a moving object according to claim 1, wherein the passage determination method for a moving object is performed for each moving object and for each passing determination point by sending the information to the signal processing section.