JPS5943015B2 - guided radio system - Google Patents

Description

[Detailed Description of the Invention] Recently, research has progressed on operation management systems that allow vehicles such as railways, urban transportation, monorails, etc. that move on fixed tracks to perform unmanned automatic operation by remote control from a central fixed device (central station). Adoption is progressing, but what is important here is that information transmission between central stations and moving objects such as vehicles must be highly reliable.

As is well known, improving the reliability of wireless communications requires increasing the signal-to-noise ratio (S/N), and for this purpose, there are two methods: increasing transmission power to increase signal strength, and reducing noise. In the case of a guided radio system, it is effective to increase the coupling between the guided wire and the antenna on the mobile body side. The present invention relates to an inductive radio system that can easily increase transmission power by eliminating the looping of radio waves between transmitting and receiving devices of a mobile body, and can increase the coupling between a guiding wire and an antenna compared to conventional systems. Conventional inductive radio circuits use parallel two-wire inductive wires and a loop antenna or one magnetic core rod-shaped (coil) antenna (hereinafter referred to as a magnetic core rod antenna) as a mobile antenna.
There are antennas that use parallel three-wire induction wires and intersecting loop antennas, but the coupling between these antennas and the magnetic flux generated in the induction wire requires only the component of magnetic flux perpendicular to the guiding wire plane. I'm trying to take this out by paying attention to it.

However, this causes the problem of so-called wrap-around between the transmitter and receiver, which limits the transmit power, and methods such as suppressing external noise by anti-phase synthesis are used. was insufficient. To explain more specifically, when guided radio is used for communication between a fixed station and a mobile object, if the mobile object is a train or vehicle of a railway or urban transportation system, the mobile object is equipped with a large number of powerful electrical devices due to its nature. Since it is loaded and operating, there is a lot of noise generated in the inductive radio band. The above-mentioned conventional noise cancellation method using anti-phase synthesis of noise is not very useful because the directionality of the noise magnetic flux distribution generated from heavy electrical equipment near the antenna is not determined. The present invention was developed to eliminate these drawbacks, and was developed from the viewpoint that in order to improve the S/N ratio, efforts should first be made to improve the signal S level. FIG. 1 is a basic configuration diagram of the present invention.

In this figure, 1 is a fixed station transmitter and receiver, 2, 3, and 4 are parallel three-wire guide wires, and the lines are laid out at equal intervals along the travel path of the moving body. 5 to 8 are devices placed on the moving body, 5 is a magnetic core (containing) rod-shaped antenna, 6
7 is a receiver, 7 is a crossed loop antenna formed into a figure 8 shape by intersecting loops at the center, and 8 is a transmitter.

As shown in the figure, the antennas 5 and 7 are centered on the ground of the central guide wire 3 and are placed parallel to the planes of the guide wires 2, 3, and 4, and move as the moving object moves. It shall be. Next, FIGS. 2 and 3 are layout diagrams of guide wires and antennas, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is a side view.

Note that FIG. 3 also shows the magnetic flux distribution due to the transmission current in the crossed loop antenna 7 used for transmission. FIG. 4 is a top view showing the arrangement of the guide wire and antenna, and is the same as FIG. 1, but also shows the magnetic flux when a high frequency current is supplied from the transmitter 8 to the loop antenna 7. Now, when a high frequency current is passed from the transmitter 8 of the mobile body to the cross-shaped loop antenna 7, horizontal and vertical components of magnetic flux are generated in the directions shown by vectors 11 and 12 in FIGS. 3 and 4, respectively.
The perpendicular magnetic flux component of is coupled to the guiding wire. However, this magnetic flux has an angular difference of 90 degrees from its axial direction with respect to the magnetic core rod-shaped antenna 5, and since the antenna 5 is in an equilibrium position with the center line aligned with the loop antenna 7, the antenna 5 due to this magnetic flux The induced voltage is zero and no magnetic flux is effectively coupled. In other words, the radio waves transmitted by the loop antenna 7 from the mobile body are well coupled to the guide wire, but are not coupled at all to the magnetic core rod antenna 5, which is the reception antenna of the mobile body, if the distance between the antennas 7 and 5 is appropriate. do not. Therefore, the mobile transmitting device composed of the antenna 7 and the transmitter 8 can increase the transmission power without considering the "circumvention" that causes the most interference to the mobile receiving device during transmission. Next, when a high frequency current is passed through the loop antenna 7 by transmission from the moving body side, the current induced in each guide wire is as clear from the direction of magnetic flux shown by the broken line arrow in FIG. The currents flowing in the guide wires 2 and 4 are in the same direction (in phase), and the current flowing in the central guide wire 3 is in the opposite direction (opposite phase).

On the contrary, when a transmission (signal) current is passed from the fixed transceiver 1 to the guide wires 2, 3, and 4 as shown in Figure 5, the magnetic flux generated by the guide wire 3 is a current with the opposite phase to this. Guide wire 2 that flows
, 4, the horizontal component 13 of the magnetic flux that extends in the direction of the center and intersects with the magnetic core rod-shaped receiving antenna 5 becomes stronger as shown in FIG.
The signal level S can be increased because it is strongly coupled with the . Next, in order to clarify the effects of the above-mentioned present invention, numerical examples will be explained. The distance between the three-wire guide wires is, for example, about 150 mm, the external dimensions of the loop antenna 7 are about 150 mm in width and 300 mm in length, and the minimum distance between the loop antenna 7 and the magnetic core antenna 5 is 100 mm in the arrangement shown in FIG. In this case, as an example, the amount of attenuation of the power induced in the guide wire from the transmitting antenna 7 is about 40 dB, and the amount of attenuation of the power sent from the fixed side to the guide wire and the power induced in the receiving antenna 5 is about 40 dB.

It is conceivable that the current induced in the induction wire by the transmission from the mobile body will also generate an induced voltage in the receiving antenna 5, but this is more than 80 dB lower than the transmitting level and depends on the selection of the receiving threshold level. can be easily ignored. Note that it has been confirmed that the voltage directly induced from the transmitting antenna 7 to the receiving antenna 5 is smaller than that using the above-mentioned guide wire as an intermediate, and can be ignored even by actual measurements. Furthermore, as shown in Fig. 5, the effect of configuring the guide wire in a three-wire configuration and effectively interlinking the magnetic flux generated by the guide wire 3 to the antenna 5 is that the transmission power of the fixed station is constant and the distance between the antenna 5 and the guide wire 3 is It has been proven that, when is constant, the reception strength of the antenna 5 is, for example, 40 dB when the guide wire 3 is alone (ground return wire), whereas it increases by 6 to 7 dB in the case of a three-wire system.

As described above, according to the present invention, even if the transmitting antenna and the receiving antenna on the mobile side are provided very close to each other, the transmitting power of the mobile device can be increased compared to conventional devices, and the received signal strength can be increased. This can be improved by increasing the coupling between the receiving antenna and the guiding wire, resulting in significant practical effects such as improved communication quality and high reliability.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIGS. 2 to 4 are layout diagrams of a guide wire and a mobile antenna, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is a side view. Figure 4 is a soil surface map. FIG. 5 is a diagram of the magnetic flux distribution of the guiding wire in the case of transmission from the fixed side. 1... Fixed side transceiver, 2, 3, 4...
... Parallel three-wire induction wire, 5 ... Rod-shaped coil antenna with magnetic core, 6 ... Mobile object side receiver, 7 ...
. . . Cross-shaped loop antenna, 8 .
14...Horizontal and vertical components of magnetic flux due to induced wire current.

Claims (1)

[Claims] 1 Parallel line 3 installed along the travel path of the moving body and with the central line as a common return line and the stationary transceiver connected to one end.
Fixed side equipment consisting of a wire type guide wire and a fixed side equipment placed on a movable body and crossed on the guide line in the approximate center so as to form a figure 8 in a direction parallel to the guide line plane and perpendicular to the guide line. A cross-shaped loop antenna for transmission, a transmitter that outputs a transmission signal to it, and a certain distance from the above-mentioned cross-shaped loop antenna, aligning its axis in a direction parallel to the loop antenna surface and perpendicular to the guide line, and centering the center of the antenna. An inductive radio system characterized in that it is equipped with a moving object side equipment consisting of a rod-shaped coil antenna with a receiving magnetic core that matches the guiding wire of the antenna, and a receiver that receives the output of the receiving rod-shaped coil antenna.