JP2006129099A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device capable of quickly setting directivity suitable to communication media. <P>SOLUTION: This antenna device 1 is provided with receiving antennas 11 and 12 and a microcomputer 50. The respective receiving antennas 11 and 12 become a medium for receiving radio waves transmitted from the communication media. The microcomputer 50 changes the phase of the radio waves received by the receiving antennas 11 and 12 to set directivity in an aspect suitable to the communication media. The antenna device 1 is provided with a memory 50a. Phase contents for setting the directivity suitable to the communication media are associated with an identifier to be an index for specifying the communication media and stored in the memory 50a. The microcomputer 50 sets directivity on the basis of the phase contents associated with an identifier included in radio waves received by the receiving antennas 11 and 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antenna device. More specifically, the present invention relates to an antenna device having a feature in operation when setting directivity.

  In recent years, with the aim of improving road traffic safety, transportation efficiency, and comfort, etc., an advanced road traffic system (ITS: ITS: Intelligent Transport Systems) has been built. For example, to eliminate tollgate traffic on toll roads, improve convenience by making cashless, reduce management costs, etc. A non-stop automatic fee payment system (ETC: Electronic Toll Collection System) that makes payment is put into practical use. In addition, in order to support safe driving such as preventing accidents, information on the road is collected by sensors, etc., and warning warnings are given to drivers, and driving assistance such as steering wheel and brake control depending on the situation is provided. A system (AHS: Advanced Cruise-Assist Highway Systems) has been proposed. Furthermore, an inter-vehicle distance control system (ACC: Adaptive Cruise Control) that keeps the inter-vehicle distance from the preceding vehicle constant has also been proposed.

  And in order to implement | achieve all of these systems using one vehicle, it is necessary to make a vehicle respond | correspond to many communication media, such as vehicle-to-vehicle communication and road-to-vehicle communication. As a specific method, it is conceivable that a plurality of antennas are mounted on one vehicle, and each antenna is associated with each communication medium on a one-to-one basis. However, such a method is not preferable because the number of antennas mounted on one vehicle increases.

  Therefore, as another method for realizing the same, it is conceivable to reduce the number of in-vehicle antennas by switching the antenna directivity to a mode suitable for each communication medium. Such a method is realized by performing “adaptive processing” on the antenna. In addition, the technique regarding "adaptive processing" is disclosed by patent document 1-patent document 4, for example. Hereinafter, a conventional antenna device using adaptive processing will be described.

  As shown in FIG. 3, the antenna device 101 includes receiving antennas 111 and 112, phase shift circuits 121 and 122, a synthesis circuit 130, a demodulation circuit 140, and a microcomputer 150. Each of the receiving antennas 111 and 112 serves as a medium for receiving radio waves transmitted from each of a plurality of communication media. The phase shift circuit 121 is for changing the phase of the radio wave received by the receiving antenna 111. Similarly, the phase shift circuit 122 is for changing the phase of the radio wave received by the receiving antenna 112. The synthesizing circuit 130 is for synthesizing radio waves whose phases are changed by the phase shift circuits 121 and 122, respectively. The demodulation circuit 140 is for demodulating the radio wave synthesized by the synthesis circuit 130 to generate a reception signal.

The microcomputer 150 includes A / D conversion units 151 and 152 and an adaptive processing unit 153. The A / D converter 151 is for converting an analog radio wave whose phase has been changed by the phase shift circuit 121 into a digital format. Similarly, the A / D converter 152 is for converting an analog radio wave whose phase has been changed by the phase shift circuit 122 into a digital format. The adaptive processing unit 153 is for performing adaptive processing based on the radio wave converted into a digital format by each of the A / D conversion units 151 and 152. Here, the adaptive processing refers to feedback processing for changing the phase of radio waves received by the receiving antennas 111 and 112 to set the directivity in a mode suitable for each communication medium.
Japanese Patent Laid-Open No. 2000-22569 JP-A-9-326630 Japanese Patent Laid-Open No. 2002-261531 JP-A-10-209890

  Incidentally, when the antenna device 101 shown in FIG. 3 is used as an antenna device for a vehicle, the antenna device 101 is used in a radio wave environment that changes every moment as the vehicle travels. For this reason, when the antenna device 101 is preferably used as a vehicle antenna device, the antenna device 101 is required to perform feedback processing (adaptive processing) at a higher speed than the speed at which the radio wave environment changes. .

  However, there is a limit to the processing speed of feedback processing (adaptive processing). For this reason, it is conceivable that the feedback processing (adaptive processing) cannot follow the radio wave environment even if the antenna device 101 is adapted to correspond to dedicated short range communication (DSRC) such as ETC. That is, it is conceivable that the feedback process (adaptive process) is not converged in a very short time.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide an antenna apparatus capable of quickly setting directivity suitable for communication media.

  In order to achieve the above object, according to the first aspect of the present invention, a receiving antenna serving as a medium for receiving a radio wave transmitted from a communication medium and a phase of the radio wave received by the receiving antenna are changed. The phase content for setting the directivity suitable for the communication medium is used as an index for specifying the communication medium in the antenna device including the control unit that sets the directivity in a mode suitable for the communication medium. Storage means for storing in association with an identifier is provided, wherein the control means sets directivity based on phase content associated with an identifier included in a radio wave received by the receiving antenna. To do.

  According to a second aspect of the present invention, in the antenna device according to the first aspect, the storage means sets a phase content for setting directivity suitable for each of the plurality of communication media. It is characterized by being stored in association with an identifier serving as an index for specifying each.

  According to a third aspect of the present invention, in the antenna device according to the first or second aspect, the control means is a reception stage before a radio wave transmitted from a communication medium is received by the reception antenna. During standby, the widest directivity among the settable directivities is set.

  According to a fourth aspect of the present invention, in the antenna device according to the first or second aspect, the control means is a reception stage before a radio wave transmitted from a communication medium is received by the receiving antenna. At the time of standby, each of a plurality of directivities having different modes is switched and set.

The “action” of the present invention will be described below.
According to the first aspect of the present invention, the directivity is set based on the phase content associated with the identifier included in the radio wave received by the receiving antenna. That is, when the directivity suitable for the communication medium is set, unlike the conventional case, feedback processing (adaptive processing) is not performed. For this reason, it is not necessary to repeatedly perform a complicated operation associated with the feedback process.

According to the second aspect of the present invention, it is possible to quickly set the directivity suitable for each of the plurality of communication media. That is, the antenna device can be versatile.
According to the third aspect of the present invention, the widest directivity among the directivities that can be set is set during reception standby. For this reason, the radio wave transmitted from the communication medium can be quickly received.

  According to the fourth aspect of the present invention, at the time of reception standby, each of a plurality of directivities having different aspects is switched and set. Therefore, the direction in which the radio wave is transmitted can be specified based on the directivity when the radio wave is received by the receiving antenna.

Since this invention is comprised as mentioned above, there exist the following effects.
According to the invention described in any one of claims 1 to 4, directivity suitable for communication media can be quickly set.

Hereinafter, an embodiment in which the present invention is embodied in an automobile antenna device will be described.
An antenna device 1 according to this embodiment shown in FIG. 1 is an antenna device (multipurpose vehicle-mounted antenna device) that can handle a plurality of communication media. Specifically, the antenna device 1 is compatible with ETC (non-stop automatic fee payment system), AHS (driving support road system), and ACC (inter-vehicle distance control system). That is, the antenna device 1 can cope with vehicle-to-vehicle communication and road-to-vehicle communication.

  The antenna device 1 is built in an inner rear view mirror (not shown). The antenna device 1 includes receiving antennas 11 and 12, phase shift circuits 21 and 22, a synthesis circuit 30, a demodulation circuit 40, and a microcomputer 50.

  Each of the receiving antennas 11 and 12 serves as a medium for receiving radio waves transmitted from communication media. In the present embodiment, each of the reception antennas 11 and 12 serves as a medium for receiving radio waves transmitted from each of a plurality of communication media. The phase shift circuit 21 is for changing the phase of the radio wave received by the receiving antenna 11. Similarly, the phase shift circuit 22 is for changing the phase of the radio wave received by the receiving antenna 12. The synthesizing circuit 30 is for synthesizing radio waves whose phases have been changed by the phase shift circuits 21 and 22, respectively. The demodulation circuit 40 is for demodulating the radio wave synthesized by the synthesis circuit 30 to generate a reception signal. Then, the demodulation circuit 40 outputs the received signal to a signal processing circuit (not shown). The demodulation circuit 40 also outputs the received signal to the microcomputer 50.

  The microcomputer 50 is a CPU unit including a CPU, ROM, RAM, and the like (not shown). The microcomputer 50 includes a nonvolatile memory 50a. In the memory 50a, the phase content is stored in association with the identifier (see FIG. 2). Specifically, in the memory 50a, each of a plurality (three types in this embodiment) of phase contents is stored in association with each of a plurality (three types in this embodiment) of identifiers in a one-to-one correspondence. ing. Specifically, the first phase content is associated with the first identifier. On the other hand, the second phase content is associated with the second identifier. On the other hand, the third phase content is associated with the third identifier.

  Here, in ETC (non-stop automatic fee payment system), bidirectional communication is performed between the ETC roadside device and the ETC in-vehicle device. Then, when radio waves are transmitted from the ETC roadside unit, an identifier serving as an index for specifying the ETC is added. In the present embodiment, an identifier serving as an index for specifying the ETC corresponds to the first identifier.

  On the other hand, in AHS (driving support road system), two-way communication is performed between an AHS roadside device and an AHS in-vehicle device. Then, when radio waves are transmitted from the AHS roadside unit, an identifier serving as an index for specifying AHS is added. In the present embodiment, an identifier serving as an index for specifying AHS corresponds to the second identifier.

  On the other hand, in ACC (inter-vehicle distance control system), two-way communication is performed between the ACC on-vehicle device of the own vehicle and the ACC on-vehicle device of the preceding vehicle (other vehicle). Then, when a radio wave is transmitted from the ACC on-vehicle device of another vehicle, an identifier serving as an index for specifying ACC is added. In the present embodiment, an identifier serving as an index for specifying ACC corresponds to the third identifier.

In short, the identifier serves as an index for specifying the communication medium.
By the way, in order to make the single antenna device 1 compatible with any of ETC (non-stop automatic fee payment system), AHS (driving support road system), and ACC (inter-vehicle distance control system), directivity must be set for each. It is necessary to switch to a mode suitable for each communication medium. In the present embodiment, the directivity in a mode suitable for ETC corresponds to the first directivity. On the other hand, the directivity in a mode suitable for AHS corresponds to the second directivity. On the other hand, the directivity in a mode suitable for ACC corresponds to the third directivity.

  Here, the microcomputer 50 changes the phase of the radio wave received by the receiving antennas 11 and 12 to set the directivity to a mode suitable for the communication medium. Specifically, the microcomputer 50 sets the directivity to a mode suitable for communication media by setting predetermined phase contents for the phase shift circuits 21 and 22. Specifically, the microcomputer 50 sets the first phase content for the phase shift circuits 21 and 22 when setting the directivity to an aspect suitable for ETC (first directivity). On the other hand, the microcomputer 50 sets the second phase content for the phase shift circuits 21 and 22 when setting the directivity to a mode suitable for AHS (second directivity). On the other hand, the microcomputer 50 sets the third phase content for the phase shift circuits 21 and 22 when setting the directivity to an aspect suitable for ACC (third directivity).

In short, the phase content is for setting directivity suitable for communication media.
Next, the operation of the antenna device 1 will be described.
Now, the antenna device 1 is compatible with any of ETC (non-stop automatic toll payment system), AHS (driving support road system), and ACC (inter-vehicle distance control system). However, the travel route of the automobile equipped with the antenna device 1 is indefinite. For this reason, at the time of reception standby, which is the stage before the radio waves transmitted from the communication media are received by the receiving antennas 11 and 12, it is specified whether the radio wave is transmitted first from ETC, AHS, or ACC. Can not. Therefore, the directivity suitable for any one of ETC, AHS, and ACC (for example, ETC) should not be set in advance during reception standby. The reason for this is that when radio waves are transmitted first from a communication medium other than ETC (for example, AHS) even though the directivity suitable for ETC is set in advance during reception standby, the radio waves from the AHS are received. This is because there is a risk that it will not be possible. Incidentally, directivity suitable for ETC, directivity suitable for AHS, and directivity suitable for ACC are different.

  Therefore, in the present embodiment, the microcomputer 50 sets the widest directivity among the directivities that can be set during reception standby. In other words, the microcomputer 50 provides the phase shift circuits 21 and 22 with a phase content that can reliably receive the radio wave even if the radio wave is transmitted first from any of ETC, AHS, and ACC during reception standby. Set for In other words, the microcomputer 50 sets directivity that covers all of the communication media that can be handled during reception standby.

  In such a reception standby state, when a radio wave is transmitted first from the ETC, the radio wave (including a modulated first identifier that is an index for identifying the ETC) Are received by the receiving antennas 11 and 12. Then, the phase of the radio wave received by the receiving antenna 11 is changed by the phase shift circuit 21. On the other hand, the phase of the radio wave received by the receiving antenna 12 is changed by the phase shift circuit 22. The radio waves whose phases have been changed by the phase shift circuits 21 and 22 are synthesized by the synthesis circuit 30. The radio wave synthesized by the synthesis circuit 30 is demodulated by the demodulation circuit 40 to generate a reception signal. A received signal is input from the demodulating circuit 40 to a signal processing circuit (not shown), and the demodulated circuit 40 also includes a received signal (a first identifier which is an identifier serving as an index for specifying the ETC). ) Is entered.

  Then, when the first identifier is included in the received signal, the microcomputer 50 selects the phase content (first phase content) associated with the first identifier and stored in the memory 50a. Then, the microcomputer 50 sets the first phase content for the phase shift circuits 21 and 22. As a result, the directivity (first directivity) in a mode suitable for ETC is set. In the state where the first directivity is set, the radio wave transmitted from the ETC roadside device is reliably received, and bidirectional communication between the ETC roadside device and the ETC on-board device is suitably performed. .

  After that, when the identifier (first identifier) serving as an index for specifying the ETC is no longer included in the received signal, the microcomputer 50, as in reception standby, has the widest directivity among the settable directivities. Set. That is, at this time, the microcomputer 50 gives the phase content to the phase shift circuits 21 and 22 so that the radio wave can be reliably received even when the radio wave is transmitted next from any of ETC, AHS, and ACC. Set. In other words, at this time, the microcomputer 50 sets the directivity covering all of the compatible communication media.

  Then, when a radio wave is transmitted next from any one of ETC, AHS, and ACC, the microcomputer 50 receives signals from the receiving antennas 11 and 12 in the same manner as when the first radio wave is transmitted from the ETC. The directivity is set based on the phase content associated with the identifier included in the received radio wave.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) Directivity is set based on the phase content associated with the identifier included in the radio waves received by the receiving antennas 11 and 12. That is, when the directivity suitable for the communication medium is set, unlike the conventional case, feedback processing (adaptive processing) is not performed. For this reason, it is not necessary to repeatedly perform a complicated operation associated with the feedback process. Therefore, directivity suitable for communication media can be set quickly.

  (2) In the memory 50a, phase contents for setting directivity suitable for each of the plurality of communication media are stored in association with an identifier serving as an index for specifying each of the plurality of communication media. ing. Therefore, directivity suitable for each of the plurality of communication media can be quickly set. That is, the antenna device 1 can be versatile.

(3) During reception standby, the widest directivity among the settable directivities is set. For this reason, the radio wave transmitted from the communication medium can be quickly received.
In addition, the said embodiment can also be changed and actualized as follows.

  A configuration may be employed in which each of a plurality of directivities having different modes is switched and set by the microcomputer 50 during reception standby. If comprised in this way, the direction from which the electromagnetic wave was transmitted can be specified based on the directivity when the electromagnetic waves are received by the receiving antennas 11 and 12.

  Specifically, the directivity covering all of the compatible communication media is divided into a plurality of regions (first region, second region, third region,..., N region). The microcomputer 50 switches and sets the directivity in the order of the first area, the second area, the third area,..., The Nth area, the first area, the second area,. .

  Alternatively, the order of the Nth region, the (N-1) region, the (N-2) region, ..., the first region, the Nth region, the (N-1) region, ... (reverse order). ) May be configured to switch the directivity.

  Alternatively, the directivity may be switched and set in the order from the high reception frequency region to the low reception frequency region using the history of radio waves received in the past by the reception antennas 11 and 12.

The number of communication media that can be handled by the antenna device 1 is not limited to three. That is, it may be any one, two, four or more.
The type of communication media that the antenna device 1 can handle is not limited to ETC, AHS, and ACC.

-The number of receiving antennas is not limited to two. That is, it may be three or more.
-An antenna apparatus is not limited to the thing for motor vehicles.

The block diagram which shows the structure of the antenna apparatus of this embodiment. The conceptual diagram which shows the memory content of a memory. The block diagram which shows the structure of the conventional antenna apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Antenna apparatus, 11 ... Reception antenna, 12 ... Reception antenna, 50 ... Microcomputer (control means), 50a ... Memory (storage means).

Claims (4)

A receiving antenna serving as a medium for receiving radio waves transmitted from a communication medium, and control means for changing the phase of the radio wave received by the receiving antenna to set the directivity to a mode suitable for the communication medium. In the antenna device provided,
A storage means for storing the phase content for setting the directivity suitable for the communication medium in association with an identifier serving as an index for specifying the communication medium is provided,
The antenna device according to claim 1, wherein the control unit sets directivity based on a phase content associated with an identifier included in a radio wave received by the receiving antenna. The antenna device according to claim 1,
The storage means stores phase contents for setting directivity suitable for each of a plurality of communication media in association with an identifier serving as an index for specifying each of the plurality of communication media. An antenna device characterized by that. In the antenna device according to claim 1 or 2,
The control means sets the widest directivity among the settable directivities during reception standby, which is a stage before the radio wave transmitted from the communication medium is received by the receiving antenna. Antenna device. In the antenna device according to claim 1 or 2,
The control means switches and sets each of a plurality of directivities having different aspects at the time of reception standby, which is a stage before a radio wave transmitted from a communication medium is received by the reception antenna. apparatus.

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