JPS5910623B2 - bus detection device - Google Patents

Description

【発明の詳細な説明】 本発明はバス検出装置に係わる。[Detailed description of the invention] The present invention relates to a bus detection device.

従来バス検知方式としては、ループ結合方式とアンテナ
結合方式力゛用いられてきた。ループ結合方式は路面に
導体ループコイルを埋設し、バスがループ上を通過した
時、そのループ電流によつて検知する方式であるが、ル
ープコイルを路面に埋設する埋設工事が困難であり、又
埋設されたループコイルが通過車輌の荷重、振動で切断
しやすいという問題があつた。Conventionally, the loop coupling method and the antenna coupling method have been used as bus detection methods. The loop coupling method is a method in which a conductor loop coil is buried in the road surface, and when a bus passes over the loop, it is detected by the loop current, but the burying work to bury the loop coil in the road surface is difficult, and There was a problem that the buried loop coil was easily broken by the load and vibration of passing vehicles.

又アンテナ結合方式はバス車輌の側壁に前方にのみ電波
を放射するような指向性をもつ円偏波放射アンテナを取
付け、路傍に円偏波受信アンテナを設置して、バスの車
上アンテナから出た電波を車上アンテナと同一方向回転
円偏波特性をもつ地上アンテナで受信するものであるが
、この方式は車上アンテナから発射された電波を直接地
上アンテナで受信する場合は円偏波の回転が同一方向で
あるため受信され、車上アンテナから他の物体にて反射
されて地上アンテナで受信する場合は円偏波の回転方向
がかわるため受信されにくく、直接受信電波のみを検出
しうるという利点をもつているが、実際には反射体であ
る他の物体の形状が球状でないため、反射波は完全な逆
方向回転の円偏波とはならず同一方向の円偏波成分も含
むため、他の物体にて反射された電波も受信点において
幾分受信されることになり問題はあつた。In addition, the antenna coupling method involves attaching a circularly polarized wave radiation antenna with a directivity that radiates radio waves only in the forward direction to the side wall of the bus, and installing a circularly polarized wave receiving antenna on the roadside. This method uses a ground antenna that rotates in the same direction as the on-board antenna and receives circularly polarized waves. The rotation of the circularly polarized wave is in the same direction, so it is received, but when it is reflected from the on-board antenna by another object and received by the ground antenna, it is difficult to receive it because the rotation direction of the circularly polarized wave changes, and only directly received radio waves are detected. However, since the shape of the other object that is the reflector is not spherical, the reflected wave is not a completely circularly polarized wave with opposite rotation, but also contains circularly polarized wave components in the same direction. Therefore, some radio waves reflected from other objects are also received at the receiving point, which poses a problem.

本発明は地上アンテナ及び車上アンテナを用いるアンテ
ナ検知方式のバス検出装置におけるアンテナの位置及び
指向性を特定することによつてその機能を改善したもの
である。The present invention improves the function of an antenna detection type bus detection device using a ground antenna and an on-vehicle antenna by specifying the position and directivity of the antenna.

本発明ではバス等の車輌の側壁のできるだけ高い位置に
車上アンテナを取付け、地上アンテナは路傍のできるだ
け低い位置に設置し、地上アンテナから車上アンテナ側
をみて一定範囲の仰角範囲のみ受信信号強度が大きく、
その他の仰角範囲では受信信号強度がｏに近くなるよう
にアンテナの指向性を選択する。In the present invention, the on-board antenna is installed as high as possible on the side wall of a vehicle such as a bus, and the ground antenna is installed as low as possible on the roadside, and the received signal strength is limited to a certain elevation angle range when looking from the ground antenna to the on-board antenna. is large,
In other elevation angle ranges, the directivity of the antenna is selected so that the received signal strength is close to o.

本発明の実施例を第１図によつて説明する。An embodiment of the present invention will be explained with reference to FIG.

第１図において１は路面、２，５はバス等の車輌でその
内２は図において前面から裏面方向に向う車線上を走行
し、５は裏面から前面に向う反対車線上を走行している
。３，６はバス等の車輌の側壁上部に取付けられた車上
アンテナ、４は路傍に設置された地上アンテナ、ｒはバ
ス等の車輌５と隣接車線を同方向に走行する他の車輌を
示す。In Figure 1, 1 is the road surface, 2 and 5 are vehicles such as buses, of which 2 is running on the lane that goes from the front to the back in the figure, and 5 is running on the opposite lane that goes from the back to the front. . 3 and 6 are on-board antennas attached to the upper side walls of vehicles such as buses, 4 is a ground antenna installed on the roadside, and r is another vehicle traveling in the same direction in the adjacent lane as vehicle 5 such as a bus. .

またＣは中央分離線、Ｈは車上アンテナの高さ、ｈは地
上アンテナの高さを示す。この実施例では車上アンテナ
はバス等車輌側壁のできるだけ高い位置即ち屋根に近い
位置に取付けられ、地上アンテナは少なくとも車上アン
テナより低い位置でできるだけ低いところ即ち地上に近
？して設置される。Further, C indicates the center separation line, H indicates the height of the on-board antenna, and h indicates the height of the ground antenna. In this embodiment, the on-board antenna is installed as high as possible on the side wall of a vehicle such as a bus, that is, close to the roof, and the ground antenna is installed as low as possible, that is, as close to the ground as possible and at least lower than the on-board antenna. will be installed.

このようにすると地上アンテナからは地上アンテナのそ
ばをバス等の車輌が通過する場合、車上アンテナを見上
げることになるがこの地上アンテナから車上アンテナを
見た仰角をθとすると、θはバス等の車輌が路傍の地上
アンテナからどの程度はなれた位置を通過するかによつ
て、又車上アンテナ、地上アンテナの高低差即ちＨ−ｈ
によつてもかわるが、車線の巾、車上アンテナ及び地上
アンテナの高さがきまればθはある範囲即ちθ１くθく
θ２の範囲に特定される。In this way, when a vehicle such as a bus passes by the ground antenna, the ground antenna will look up at the on-board antenna.If the elevation angle when looking at the on-board antenna from this ground antenna is θ, then θ is Depending on how far a vehicle passes from the roadside ground antenna, the height difference between the on-board antenna and the ground antenna, that is, H-h.
Although it depends on the vehicle, if the width of the lane and the height of the on-board antenna and the ground antenna are determined, θ can be specified within a certain range, that is, θ1, θ, and θ2.

この場合θ，はバス等の車輌が路傍から最もはなれた位
置を通過した場合の仰角、θ２はバス等の車輌が路傍の
ごく近くを通過した場合の仰角である。In this case, θ is the angle of elevation when the vehicle such as a bus passes the farthest position from the roadside, and θ2 is the angle of elevation when the vehicle such as the bus passes very close to the roadside.

片道２車線の往復路線の場合で考える。Consider the case of a round-trip route with two lanes each way.

地上アンテナを埠線の端より歩道側へ０．５ｍ引込んで
おり、高さｈは１．５ｍとする。又はバス等車輌の巾は
３．０ｍで車上アンテナの高さＨは３ｍとする。又車線
は巾がそれぞれ３．５ｍで片側に２車線あるものとする
。このような場合バス等の車輌が最も地上アンテナから
はなれた位置を通過するとして地上アンテナから車上ア
ンテナを見た仰角θｌを計算すると、となる。The ground antenna is retracted 0.5m from the edge of the wharf to the sidewalk side, and the height h is 1.5m. Alternatively, the width of a vehicle such as a bus is 3.0 m, and the height H of the on-board antenna is 3 m. The lanes are each 3.5 m wide and there are two lanes on each side. In such a case, assuming that the vehicle such as a bus passes through a position farthest from the ground antenna, the elevation angle θl when looking at the on-board antenna from the ground antenna is calculated as follows.

又バス等の車輌が地上アンテナに最も近いところを通過
するときの仰角θ２は、：０？．なる。Also, the elevation angle θ2 when a vehicle such as a bus passes closest to the ground antenna is: 0? ．． Become.

従つてこのような実施例では地上アンテナから車上アン
テナを見た仰角は常Ｋ２Ｏ．６ナくθく７１．６.の範
囲にあることになる。Therefore, in such an embodiment, the elevation angle when looking at the on-vehicle antenna from the ground antenna is always K2O. This means that it is in the range of 6 × θ × 71.6.

つぎに車上アンテナから発射された電波がどのような経
路をとおつて地上アンテナに受信されるかを考える。第
１図に電波の経路をＴｌ，ｔ２，ｔ３にて示したが、経
路ｔｌは車上アンテナから出た電波を直接地上アンテナ
にて受信する場合を、経路Ｔ２は車上アンテナから出た
電波が路面１で反射して受信される場合を、経路Ｔ３は
反対車線を逆方向に走行するバス等の車輌５の車上アン
テナ６から出た電波が反対車線を走行する別の車輌等で
反射され地上アンテナにて受信される場合を示している
。Next, consider what route the radio waves emitted from the on-board antenna take to be received by the ground antenna. In Fig. 1, the radio wave paths are shown as Tl, t2, and t3. Route tl represents the case where the radio waves emitted from the on-board antenna are directly received by the ground antenna, and route T2 represents the case where the radio waves emitted from the on-board antenna are received directly. is reflected on the road surface 1 and received, route T3 is the radio wave emitted from the on-board antenna 6 of a vehicle 5 such as a bus traveling in the opposite direction in the opposite lane and reflected by another vehicle traveling in the opposite lane. This shows the case where the signal is received by a ground antenna.

この場合経路Ｔ３の信号受信は必要のない信号の受信で
あり誤動作につながるので好ましくない。又経路Ｔ２の
信号受信も直接誤動作につながるものではないが必要の
ないものであり、経路ｔ１の信号のみを受信しうるよう
にすれば十分である。前述の地上アンテナから車上アン
テナを見た仰角とこの電波経路を合わせて考えると仰角
がθ１くθくθ２の範囲において受信信号強度が大きく
なり、その他の仰角範囲特にθくθ，の範囲で受信信号
強度が０に近くなるよう地上アンテナの指向性を選択す
れば電波の経路Ｔ２あるいはＴ３の信号を遮断すること
ができるということがわかる。次にある仰角範囲におい
て受信強度が大で他の仰角範囲では受信強度が０に近く
なるようにするための具体的手段について述べる。この
ようなアンテナの理想的指向性Ｄ（θ）は下記（１）式
で与えられる。In this case, signal reception on path T3 is undesirable because it is unnecessary signal reception and may lead to malfunction. Further, reception of the signal on the path T2 does not directly lead to malfunction, but is unnecessary, and it is sufficient to receive only the signal on the path t1. Considering the above-mentioned elevation angle as seen from the on-board antenna from the ground antenna and this radio wave path, the received signal strength becomes large in the elevation angle range of θ1 to θ2, and in other elevation angle ranges, especially in the range of θ to θ. It can be seen that by selecting the directivity of the ground antenna so that the received signal strength is close to 0, it is possible to block the signal on the radio wave path T2 or T3. Next, specific means for making the reception strength large in a certain elevation angle range and close to 0 in other elevation angle ranges will be described. The ideal directivity D(θ) of such an antenna is given by the following equation (1).

一一 ゛ ８゛ − −６ ′ このような指向性特性を有するアンテナを完全なものと
して実現することは不可能なので実際のアンテナで近似
する特性を有するものを選ぶことになるが、第２図に示
す垂直アレイアンテナを用いてかなり近く近似できる。11 ゛ 8゛ - -6' Since it is impossible to realize a perfect antenna with such directional characteristics, we will choose one with characteristics that approximate those of the actual antenna. A fairly close approximation can be made using the vertical array antenna shown in .

第２図においてＡ。A in Figure 2.

，Ａｌ．Ａ２・・・・・・Ａｎ，Ａ］′，Ａ２５・・・
・・・Ａｎ′はアレイアンテナ素子、ｄは素子間隔を示
す。又素子Ａ。の励振振巾をＡ。，素子Ａｉｌ．Ａｉの
複素励振振巾をＡｉ＋Ｊｂｉとすると指向性Ｄψは次の
ようになる。但しψ Ｋｄｓｉｎθ この垂直アレイアンテナの合成指向性Ｄ１ψを用いて（
１）式の理想的指向性に最小自乗誤差の意味で近似する
には、を満足するように励振振巾をきめればよい。, Al. A2...An, A]', A25...
. . . An' is an array antenna element, and d is an element spacing. Motoko A. The excitation width is A. , Element Ail. If the complex excitation width of Ai is Ai+Jbi, the directivity Dψ is as follows. However, ψ Kdsinθ Using the composite directivity D1ψ of this vertical array antenna, (
In order to approximate the ideal directivity in formula 1) in the sense of least square error, the excitation amplitude should be determined so as to satisfy the following.

ここでＤ（θ）おり式で与えられる理想指向性であつて
θとψの間にはψ＝Ｋｄｓｉｎθの関係がある。一つの
実施例を第３図を使つて説明する。λ ｄ＝−として３素子で考えると励振強度及び位相は（３
）（４）式から次のようになる。Here, the ideal directivity is given by the equation D(θ), and there is a relationship between θ and ψ of ψ=Kdsinθ. One embodiment will be explained using FIG. 3. Considering three elements with λ d=-, the excitation intensity and phase are (3
) (4) gives the following.

この場合の地上アンテナの結合度を前記した車上アンテ
ナ、地上アンテナの高さ等の位置の例及び片側２車線の
寸法例に対し電波経路Ｔ，だけでなくＴ２及びＴ３も考
慮して計算したものが第３図に示すグラフである。The degree of coupling of the ground antenna in this case was calculated by considering not only the radio wave path T, but also T2 and T3 for the above-mentioned example of the location of the on-board antenna and ground antenna such as height, and the dimension example of two lanes on each side. This is the graph shown in FIG.

この実施例によれば〔Ｄ〕として示されている仰角の範
囲は２０．６Ｄ〜Ｎ．６示の範囲であるが、これは本実
施例での順方向に走行するバス等の車輌に取りつけられ
た車上アンテナを地上アンテナから見た仰角の存在範囲
であり、この範囲では結合度は、−１０ｄｂ以上あり実
用的に十分な受信がなｊされる。According to this example, the range of elevation angles indicated as [D] is 20.6D to N. 6, this is the range of the elevation angle of the on-board antenna attached to a vehicle such as a bus traveling in the forward direction when viewed from the ground antenna, and in this range, the degree of coupling is , -10 db or more, and sufficient reception is achieved for practical purposes.

又反対車線を逆方向に走行するバス等に取付けられた車
上アンテナを順方向の地上アンテナから見た仰角範囲は
、０となり、第 ３図では〔Ｕ〕の範囲として示しているが、この範囲で
は結合度は−１７ｄｂ以下であり、結合度が低いため誤
つた信号として受信されることはない。Also, the elevation angle range of an on-board antenna installed on a bus, etc. that is traveling in the opposite direction when viewed from the ground antenna in the forward direction is 0, and is shown as the range [U] in Figure 3. The degree of coupling is -17 db or less within the range, and because the degree of coupling is low, it will not be received as an erroneous signal.

又第３図からもわかるように車上アンテナと地上アンテ
ナの高低差を大きくとり、θ，を大きくすると１〕の範
囲と田〕の範囲の結合レベル差が拡がるので、できるだ
け車上アンテナに対し地上アンテナは低い方がよい。又
本発明を実用する場合円偏波の電波を使用ずれば反射波
の影響が減少され、その特性が更に改善されることは当
然である。Also, as can be seen from Figure 3, if the difference in height between the on-board antenna and the ground antenna is increased and θ is increased, the difference in coupling level between the range 1) and the range 2) will increase, so the on-board antenna should be adjusted as much as possible. The lower the ground antenna, the better. Further, when the present invention is put into practice, it is natural that if circularly polarized radio waves are used, the influence of reflected waves will be reduced and the characteristics will be further improved.

以上述べたように本発明においては地上アンテナを車土
アンテナよりもできるだけ低い位置に設置し、地上アン
テナの指向性を地上アンテナから順方向に走行するバス
等の車輌の車上アンテナを見た仰角の存在範囲において
受信信号強度が大きくなるよう又その他の仰角範囲で受
信信号強度が０に近くなるよう選択したものであるので
、反対車線を走行するバス等の車輌の車上アンテナから
の電波の影響は受けることがなく優れたバス検出をする
ことができる。As described above, in the present invention, the ground antenna is installed as low as possible than the vehicle soil antenna, and the directivity of the ground antenna is adjusted to the elevation angle when looking at the vehicle antenna of a vehicle such as a bus traveling in the forward direction from the ground antenna. The received signal strength is selected so that the received signal strength is large in the range where the angle exists, and the received signal strength is close to 0 in other elevation angle ranges, so that the radio waves from the on-board antenna of a vehicle such as a bus traveling in the opposite lane are Excellent bus detection can be performed without being affected.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の実施例説明図、第２図は本発明の地上
アンテナの一実施例、第３図は本発明実施例の結合度を
示す図である。 図中１は路面、２，５はバス等の車輌、３，６は車上ア
ンテナ、４は地上アンテナ、７は他の車輌、Ｔ，，ｔ２
，ｔ３は電波経路、Ｃは中央分離線を示す。FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is an embodiment of the terrestrial antenna of the present invention, and FIG. 3 is a diagram showing the degree of coupling of the embodiment of the present invention. In the figure, 1 is the road surface, 2 and 5 are vehicles such as buses, 3 and 6 are on-board antennas, 4 is ground antenna, 7 is another vehicle, T,, t2
, t3 indicate the radio wave path, and C indicates the center separation line.

Claims (1)

【特許請求の範囲】 １ バス等の車両の側壁部に車上アンテナを取付け、路
傍に設置した地上アンテナで車上アンテナから出された
電波を受信することにより順方向車線にそつて走行する
バス等の車輌の地上アンテナ際の通過を検知するバス検
出装置において、地上アンテナは少なくとも上記車上ア
ンテナより低い位置に設置し、該地上アンテナの指向性
を地上アンテナから該地上アンテナの際を順方向に通過
するバス等の車輌の車上アンテナを見た時の仰角の存在
範囲において受信信号強度が大きくかつ少なくとも上記
仰角の存在範囲以下の仰角範囲では受信信号強度が０に
近くなるように選択し、反対車線を逆方向に通過するバ
ス等の車輌の車上アンテナから出された電波は検知しな
いようにしたことを特徴とするバス検出装置。 ２ 地上アンテナを垂直アレイアンテナで構成したこと
を特徴とする特許請求の範囲第１項記載のバス検出装置
。[Claims] 1. A bus that travels along the forward lane by installing an on-board antenna on the side wall of a vehicle such as a bus, and receiving radio waves emitted from the on-board antenna with a ground antenna installed on the roadside. In a bus detection device that detects passage of a vehicle near the ground antenna, the ground antenna is installed at least at a lower position than the above-mentioned on-board antenna, and the directivity of the ground antenna is changed from the ground antenna to the ground antenna in the forward direction. The received signal strength is selected so that the received signal strength is large in the range of elevation angles when looking at the on-board antenna of a vehicle such as a bus passing by, and the received signal strength is close to 0 at least in the range of elevation angles below the above range of elevation angles. A bus detection device characterized in that it does not detect radio waves emitted from an on-board antenna of a vehicle such as a bus passing in the opposite direction in the opposite lane. 2. The bus detection device according to claim 1, wherein the terrestrial antenna is constituted by a vertical array antenna.