JPS63267028A - Premises radio signal transmission equipment - Google Patents
Premises radio signal transmission equipmentInfo
- Publication number
- JPS63267028A JPS63267028A JP62101417A JP10141787A JPS63267028A JP S63267028 A JPS63267028 A JP S63267028A JP 62101417 A JP62101417 A JP 62101417A JP 10141787 A JP10141787 A JP 10141787A JP S63267028 A JPS63267028 A JP S63267028A
- Authority
- JP
- Japan
- Prior art keywords
- radio signal
- parallel line
- premises
- line
- wireless
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000008054 signal transmission Effects 0.000 title claims description 9
- 230000005672 electromagnetic field Effects 0.000 claims abstract description 14
- 238000004891 communication Methods 0.000 abstract description 11
- 230000005540 biological transmission Effects 0.000 abstract description 6
- 238000005562 fading Methods 0.000 abstract description 6
- 230000008878 coupling Effects 0.000 abstract description 3
- 238000010168 coupling process Methods 0.000 abstract description 3
- 238000005859 coupling reaction Methods 0.000 abstract description 3
- 238000006243 chemical reaction Methods 0.000 abstract 1
- 230000005684 electric field Effects 0.000 description 12
- 230000005855 radiation Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 238000010295 mobile communication Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000012778 molding material Substances 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Near-Field Transmission Systems (AREA)
Abstract
Description
［発明の技術分野］
この発明は、移動通信方式において、特にビル構内等に
おける可搬型無線端末間の構内無線信号伝送設備に関す
る。[Technical Field of the Invention] The present invention relates to a mobile communication system, and particularly to in-premise wireless signal transmission equipment between portable wireless terminals in a building or the like.
従来、移動無線は、主として屋外で使用されていたが、
工場製造設備の制御やオフィス端末機器のネットワーク
化、無線端末化のニーズから、今後、構内での無線通信
の利用が盛んになると考えられる。
しかしながら、一般に構内又は室内では、周囲が壁面や
スチールキャビネット等で囲まれており、電波を遠方の
部屋まで伝搬させることが難しく、同一室内においても
、無線機のアンテナから放射された電波は、周囲で反射
され、それによる定在波で電界強度が場所によって著し
く変化し、移動通信等の場合フェージングによるレベル
変動が屋外に比較して３０ｄＢ以上も増加し、通信を困
難にすることが知られている。上記の現象は、半固定の
端末においても現れ、設置場所の選定を厄介にしたり、
周囲の配置物の変化によっても電界が変化するなど、通
信を不安定にする決定があった。
また、構内無線の別の問題点として、電波伝搬の減衰も
大きく、微細な多数の無線ゾーンを配置する方法が一般
に考えられている。この場合、接近した無線ゾーンで同
一周波数を使用すると、定在波が生じ、特に境界領域で
は、電界が零になるところが生じる。さらに、無線によ
る双方向通信を前提として、無線ゾーン相互間の干渉を
避けるには、非常に多くの無線周波チャネルを用い、そ
の組合せによって、通信の制御を行わなければならない
。その結果、周波数資源が有限であるため、利用者数が
制限され、かつ回線の制御が複雑で、経済性も悪くなる
という欠点があった。
また、これらの問題を解決する方法の一つに、誘導無線
が低周波で用いられているが、高周波では伝送損失が増
えるなどのために、余り広範囲に用いることかできなか
った。
［発明の目的］
この発明は、上記のような点に鑑みなされたもので、ビ
ル構内全域での双方向通信を容易にすると共に、室内で
のフェージングを解消し、構内無線の有効利用ができる
構内無線信号伝送設備を提供することを目的とする。
［発明の要点］
すなわち、この発明に係わる構内無線信号伝送設備は、
各室内において、無線信号を同軸ケーブルから分岐して
平行線路に加え、この平行線路の他端に無反射終端を接
続しておき、進行波による誘導電磁界を励振し、室内に
おける電磁界分布の均一化を図るようにしたものである
。
［発明の実施例］
以下、図面を参照して、この発明の一実施例を説明する
。第１図は、一実施例に係わる構内無線信号伝送設備の
全体構成を示す図であり、アンテナ１は、構内無線を外
部の通信・放送システムネットワークに接続させるため
のもので、同軸ケーブル２によって、無線周波信号（以
下、単に無線信号と称す）が分波器３に接続される。分
波器３は、必要により片方向又は双方向増幅器機能を付
与して、同信号をヘッドエンド装ｗｔ４に伝送する。
ヘッドエンド装置４は、同軸ケーブル６を通じて伝送さ
れる構内無線の上りの無線信号を下りの無線信号に周波
数変換して送出する機能および外部からの無線信号を直
接または同無線信号を下りの無線信号に周波数変換して
送出する機能を有する。
監視制御装置５は、各移動端末からの送信周波数と送信
出力レベルを監視したり、特定の無線チャンネルで全体
のチャンネル割当を制御するものである。但し、簡単化
したシステムでは、この監視制御装置５を省略してもよ
い。
同軸方向性結合器７は、建物の廊下領域りに無線信号を
分岐するためのもので、結合度としては、１Ｏ−２０ｄ
Ｂのものを使用する。方向性結合器８の分岐出力側には
、天井に沿わせて配置した平行線路９を接続し、同線路
９の他端は、平行線路９の特性インピーダンスに等しい
抵抗からなる無反射終端１０を接続する。
また、壁で隔てられた室内領域Ｂに対しても、同様に、
方向性結合器１４、平行線路１５、無反射終端１６を接
続したものを配置する。さらに、隣の室内領域Ｃに対し
ても順次同様の配役を行う。
また、廊下領域りに対しては、同軸−平行線路変換器１
１を介して無線信号を分岐し、上記室内領域Ａ乃至Ｃに
配設された平行線路（９，１５）との相互干渉を避ける
ために、平行線路１２．無反射終端１３を上記室内領域
Ａ乃至Ｃの平行線路（９，１５）とは直交して配設する
。
以下、第１図の構内無線信号伝送設備の動作について説
明する。室内領域Ａの可搬型無線端末１８からの送信無
線信号は、平行線路９で受信されて上り無線信号となっ
てヘッドエンド装置４に進み、ここで周波数変換された
下り無線信号が全 ・構内に放送され、室内領域Ｂの相
手の可搬型無線端末１９に、平行線路１５からの誘導電
磁界を介して受信される。この際、送受信周波数配置を
一般の移動無線と同様にガートバンドを設けて分離して
おくと、同時の双方向通信つまり全二重通信が容易にで
きる。
一般に、アンテナ近傍の電磁界分布は、電解又は磁界の
強度が距離の２乗に反比例して減少する誘導電磁界成分
と、距離に反比例して減少する放射電磁界からなり、通
常のアンテナは後者を利用する。しかしながら、放射体
として平行線路を用いると、一様空間においては、電磁
放射は平行線路の長さには無関係で、進行方向に線路幅
に関係した強度で生じる。直線的に配設した平行線路の
周囲は、主として非放射の誘導電磁界のみとなる。
その誘導電磁界強度は、平行線路の間隔の２乗にに比例
し、観測点までの距離の２乗に反比例する。
なお、実際には平行線路に比較的接舵した構造物の不均
一による２次的放射が発生する。
そこで、平行線路９．１５の各線路間隔を伝送無線信号
の波長に比例して適当な値を用い、天井、壁面又は床上
の平坦な場所に直線的に配置すれば、過大な放射成分の
発生を抑圧することができる。
すなわち、平行線路９，１５による無線サービス領域を
適当に設定すれば、距離に対し２乗に反比例する電磁界
、したがって４乗に反比例して減衰する電力分布を利用
して、隣接平行線路相互の干渉や、屋外の他の無線機器
への妨害を大幅に軽減させることができる。また、平行
線路９，１５の終端部や折れ曲がり部には進行波放射を
吸収させるための吸収板等を設けてもよい。このように
して、室内の壁面等に於ける反射波と、その定住波によ
るフェージングを最小にすることができる。
この結果、本方法によれば比較的高い周波数まで少ない
相互干渉で構内無線を利用することが可能となった。
ここで、平行線路９．１５のような平行線路が自由空間
に置かれ、その終端が特性インピーダンスで終端され、
進行波のみを励振したときの放射電力の割合は、平行線
路の長さには無関係で、次式で与えられる。
Ｐ ｒ ／ Ｐ ＝ １６０ ／ Ｚ Ｏ（ｙｒ Ｄ
／ λ）ここで、ｚＯは平行線路の特性インピーダンス
、Ｄは平行線路の線路間隔、λは波長である。線路間隔
りを大きくすると、誘導電磁界を大きくすることができ
るが、その上限は上記放射損によって制限される。今、
放射損（Ｐｒ／Ｐ）を０．１におさえると、Ｚ Ｏ＝
３００−６００ ｏｈｍのとき最大の線路間隔は、Ｄｉ
ａｘ−０，１４λ−０，２λとなり、これを最大伝送無
線信号の波長に対する線路間隔の上限として線路を配設
すればよい。その最大間隔は４０ＭＨｚで１．５ ｍ、
８００ＭＨｚで７．５０であり、サービスエリアを局限
したり、放射を抑える必要があるときや、平行線路に受
信される雑音を少なくしたいときは、上記の値からさら
に縮小すればよい。
第２図は、平行線路の線路間隔を６０とし、そこから２
．５ｍ下の平面内電界強度を計算したものであり、水平
、垂直方向の電界Ｅｘ、Ｅｙおよびそれらを合成した電
界の絶対値ＩＥＩを曲線として示す。
第２図に示すように、水平偏波、垂直偏波共に、平行線
路の直下近傍に電界が零になる位置があるのに対し、電
界の絶対値は変化が滑らかである。
従って、移動機である可搬型無線端末１８．１９では、
水平垂直両方向の電界を送受信できるよう、角度を可変
にした棒状のホイップアンテナが、一般のフェライトバ
ーアンテナに似た、高い周波数用として、コアを省略し
た長い円筒状のコイルからなるループアンテナを使用す
ればよい。後者のアンテナは、円筒の長さ方向の電界と
、これと直交し、位相が９０”遅れた電界を作り、円偏
波又は楕円偏波の特性を持つので、任意偏波の無線信号
に結合でき、向きに制限を与えない可搬型無線端末用に
適する。
なお本実施例では２条の電線からなる平行線路を用いた
が、これを更に多条にして無線信号の伝達領域を加減し
たり、平行線路の素材として線路間隔を一定に保つよう
誘電体材料でモールドしたものを使用してもよい。また
、コンクリートや金属面が露出するなど不連続部を有す
る床面や壁面に配線する場合に平行線路上に生じる反射
波を低減するため、誘電体モールド材料の厚さを導体の
直径以上にしたり、平行線路の導体と、平行線路取り付
は面との間隔を一定距離にするよう整形した誘電体モー
ルド材を使用たちのを使用することもできる。
さらに本発明は、従来の平行線路だけでなく、横方向へ
の電波の放射の少ないものであれば、広義の平行線路と
考えてよく、前記の変形した線路のほか、同軸線路にス
ロットを設けたようなものを使用してもよい。
［発明の効果］
以上のように本発明によれば、構内分配用の同軸線路の
末端を平行線路とし、その誘導電磁界で可搬型無線端末
との間に結合を取るようにした結果、不必要な放射によ
る相互干渉を抑えることができ、音声やデータなどの無
線伝送に適した設備が実現され、ビル構内全域での双方
向通信を容易によると共に、室内でのフェージングを解
消し、構内無線の有効利用が可能となる。Traditionally, mobile radio was mainly used outdoors, but
The use of wireless communications within workplaces is expected to become more popular in the future due to the need for controlling factory manufacturing equipment, networking office terminal equipment, and wireless terminals. However, in a campus or room, it is generally surrounded by walls, steel cabinets, etc., making it difficult for radio waves to propagate to distant rooms. Even within the same room, the radio waves radiated from the radio antenna are It is known that the electric field strength changes significantly depending on the location due to the standing wave caused by it, and in the case of mobile communications, the level fluctuation due to fading increases by more than 30 dB compared to outdoors, making communication difficult. There is. The above phenomenon also appears in semi-fixed terminals, making it difficult to select the installation location,
The decision was made to make communications unstable, such as by changing the electric field due to changes in surrounding objects. Another problem with local wireless is that the attenuation of radio wave propagation is large, and a method of arranging a large number of fine wireless zones is generally considered. In this case, the use of the same frequency in close radio zones results in standing waves and points where the electric field is zero, especially in boundary areas. Furthermore, assuming two-way wireless communication, in order to avoid interference between wireless zones, communication must be controlled by using a very large number of radio frequency channels and by combining them. As a result, since frequency resources are limited, the number of users is limited, line control is complicated, and economic efficiency is poor. In addition, one method to solve these problems is to use guided radio at low frequencies, but transmission loss increases at high frequencies, so it has not been possible to use it over a wide range of areas. [Purpose of the Invention] This invention was made in view of the above points, and it facilitates two-way communication throughout the building premises, eliminates fading indoors, and makes effective use of premises wireless. The purpose is to provide on-premises wireless signal transmission equipment. [Summary of the invention] In other words, the in-plant wireless signal transmission equipment according to the present invention has the following features:
In each room, the wireless signal is branched from the coaxial cable and added to a parallel line, and a non-reflection termination is connected to the other end of this parallel line to excite the induced electromagnetic field due to the traveling wave, which changes the electromagnetic field distribution in the room. This is to ensure uniformity. [Embodiment of the Invention] An embodiment of the invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of a premises wireless signal transmission facility according to an embodiment. , a radio frequency signal (hereinafter simply referred to as a radio signal) is connected to the duplexer 3. The duplexer 3 is provided with a unidirectional or bidirectional amplifier function if necessary, and transmits the same signal to the headend equipment wt4. The headend device 4 has a function of converting the frequency of an uplink radio signal of the premises radio transmitted through the coaxial cable 6 into a downlink radio signal and transmitting the same, and a function of converting the frequency of an uplink wireless signal transmitted through the coaxial cable 6 into a downlink radio signal, and converting the radio signal directly from the outside or converting the same radio signal into a downlink radio signal. It has the function of frequency converting and transmitting. The monitoring and control device 5 monitors the transmission frequency and transmission output level from each mobile terminal, and controls overall channel allocation for a specific wireless channel. However, in a simplified system, this monitoring and control device 5 may be omitted. The coaxial directional coupler 7 is for branching the wireless signal to the corridor area of the building, and has a coupling degree of 1O-20d.
Use B. A parallel line 9 arranged along the ceiling is connected to the branch output side of the directional coupler 8, and the other end of the line 9 is connected to a non-reflection termination 10 consisting of a resistance equal to the characteristic impedance of the parallel line 9. Connecting. Similarly, for indoor area B separated by a wall,
A directional coupler 14, a parallel line 15, and a non-reflection termination 16 are connected. Furthermore, similar casts are sequentially performed for the adjacent indoor area C as well. In addition, for the corridor area, a coaxial-parallel line converter 1
1, and to avoid mutual interference with the parallel lines (9, 15) arranged in the indoor areas A to C, the parallel lines 12. The non-reflection termination 13 is disposed perpendicular to the parallel lines (9, 15) in the indoor areas A to C. The operation of the in-plant wireless signal transmission equipment shown in FIG. 1 will be described below. The transmitted radio signal from the portable radio terminal 18 in the indoor area A is received by the parallel line 9, becomes an uplink radio signal, and proceeds to the headend device 4, where the frequency-converted downlink radio signal is transmitted throughout the premises. It is broadcast and received by the other party's portable wireless terminal 19 in the indoor area B via the induced electromagnetic field from the parallel line 15. At this time, if the transmitting and receiving frequency arrangement is separated by providing a guard band like in general mobile radio, simultaneous two-way communication, that is, full-duplex communication can be easily performed. In general, the electromagnetic field distribution near an antenna consists of an induced electromagnetic field component whose electrolytic or magnetic field strength decreases in inverse proportion to the square of the distance, and a radiated electromagnetic field whose intensity decreases in inverse proportion to the distance. Use. However, when parallel lines are used as radiators, electromagnetic radiation occurs in a uniform space with an intensity that is independent of the length of the parallel lines and is related to the line width in the direction of travel. The surroundings of the parallel lines arranged linearly are mainly only non-radiated induced electromagnetic fields. The intensity of the induced electromagnetic field is proportional to the square of the distance between the parallel lines and inversely proportional to the square of the distance to the observation point. Note that, in reality, secondary radiation occurs due to the non-uniformity of structures that are relatively close to the parallel track. Therefore, by using an appropriate value for the line spacing of the parallel lines 9.15 in proportion to the wavelength of the transmitted wireless signal and placing them linearly on a flat place on the ceiling, wall, or floor, excessive radiation components can be prevented. can be suppressed. In other words, if the wireless service area of the parallel lines 9 and 15 is set appropriately, the electromagnetic field that is inversely proportional to the square of the distance, and therefore the power distribution that is attenuated inversely proportional to the fourth power, can be used to connect adjacent parallel lines to each other. Interference and interference with other wireless devices outdoors can be significantly reduced. Further, an absorbing plate or the like may be provided at the end portions or bent portions of the parallel lines 9, 15 to absorb traveling wave radiation. In this way, it is possible to minimize fading caused by reflected waves on the walls of the room and the resulting waves. As a result, according to this method, it has become possible to use a local wireless system with little mutual interference up to relatively high frequencies. Here, a parallel line such as parallel line 9.15 is placed in free space, and its end is terminated with a characteristic impedance,
The ratio of radiated power when only traveling waves are excited is independent of the length of the parallel line and is given by the following equation. P r / P = 160 / Z O(yr D
/λ) Here, zO is the characteristic impedance of the parallel lines, D is the line spacing of the parallel lines, and λ is the wavelength. Increasing the line spacing can increase the induced electromagnetic field, but its upper limit is limited by the radiation loss. now,
If the radiation loss (Pr/P) is kept to 0.1, Z O=
At 300-600 ohm, the maximum line spacing is Di
ax-0, 14λ-0, 2λ, and the lines may be arranged with this as the upper limit of the line spacing for the wavelength of the maximum transmitted radio signal. The maximum spacing is 1.5 m at 40MHz,
It is 7.50 at 800 MHz, and when it is necessary to localize the service area, suppress radiation, or when it is desired to reduce noise received on parallel lines, the above value can be further reduced. In Figure 2, the line spacing of parallel lines is 60, and 2
．． The in-plane electric field strength 5 m below is calculated, and the electric fields Ex and Ey in the horizontal and vertical directions and the absolute value IEI of the combined electric field are shown as a curve. As shown in FIG. 2, for both horizontally polarized waves and vertically polarized waves, there is a position where the electric field becomes zero immediately below the parallel line, whereas the absolute value of the electric field changes smoothly. Therefore, in the portable wireless terminal 18.19, which is a mobile device,
A rod-shaped whip antenna with a variable angle that can transmit and receive electric fields in both horizontal and vertical directions uses a loop antenna consisting of a long cylindrical coil without a core for high frequencies, similar to a general ferrite bar antenna. do it. The latter antenna creates an electric field in the length direction of the cylinder and an electric field that is perpendicular to this and whose phase is delayed by 90'', and has the characteristics of circularly or elliptically polarized waves, so it can be coupled to radio signals of arbitrary polarization. This makes it suitable for portable wireless terminals that do not impose restrictions on orientation.Although a parallel line consisting of two wires was used in this example, it is also possible to increase or decrease the transmission area of wireless signals by increasing the number of parallel wires. , you may use a dielectric material molded to keep the line spacing constant as the material for parallel lines.Also, when wiring on floors or walls that have discontinuities such as exposed concrete or metal surfaces. In order to reduce reflected waves that occur on parallel lines, the thickness of the dielectric molding material is made equal to or greater than the diameter of the conductor, and the distance between the conductor of the parallel line and the surface of the parallel line mounting is adjusted to a certain distance. Furthermore, the present invention is applicable not only to conventional parallel lines, but also to parallel lines in a broad sense as long as they emit less radio waves in the lateral direction. In addition to the above-mentioned modified line, a coaxial line with slots may also be used. [Effects of the Invention] As described above, according to the present invention, the end of the coaxial line for on-site distribution As a result of using parallel lines and coupling between them and portable wireless terminals using the induced electromagnetic field, it is possible to suppress mutual interference due to unnecessary radiation, making the equipment suitable for wireless transmission of voice and data. This enables easy two-way communication throughout the building premises, eliminates fading indoors, and makes effective use of premises wireless.
第１図は本発明の一実施例に係わる全体構成を示す図、
第２図は同実施例における平行線路直下の電界を示す図
である。
１・・・アンテナ、２．６・・・同軸ケーブル、３・・
・分波器、４・・・ヘッドエンド装置、５・・・監視制
御装置、７・・・同軸方向性結合器、８．１４・・・方
向性結合器、９．１２．１５・・・平行線路、１０，１
３，１６゜１７・・・無反射終端、１１・・・同軸−平
行線路変換器、１８．１９・・・可搬型無線端末。FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention;
FIG. 2 is a diagram showing the electric field directly under the parallel line in the same embodiment. 1...Antenna, 2.6...Coaxial cable, 3...
- Branching filter, 4... Head end device, 5... Supervisory control device, 7... Coaxial directional coupler, 8.14... Directional coupler, 9.12.15... parallel lines, 10,1
3,16°17... Non-reflection termination, 11... Coaxial-parallel line converter, 18.19... Portable wireless terminal.
Claims (3)
ブルに接続され上記同軸ケーブルを通じて伝送された構
内無線の上り無線信号を下り無線信号に周波数変換して
送出する機能および外部からの無線信号を直接または同
無線信号を下り無線信号に周波数変換して送出する機能
を有したヘッドエンド装置とを備えた構内無線信号伝送
設備において、上記同軸ケーブルの途中から無線信号を
分岐する分岐手段と、この分岐手段の分岐出力側に接続
され他端に無反射終端を接続してなる平行線路と、この
平行線路上の無線信号による誘導電磁界を介して結合さ
れる可搬型無線端末とを具備したことを特徴とする構内
無線信号伝送設備。(1) A coaxial cable installed within the premises, a function that converts the frequency of the uplink radio signal of the premises wireless connected to this coaxial cable and transmitted through the coaxial cable to a downlink radio signal, and sends out the radio signal, and the external radio signal. branching means for branching the radio signal from the middle of the coaxial cable; A parallel line connected to the branch output side of the branching means and a non-reflection termination connected to the other end, and a portable wireless terminal coupled via an induced electromagnetic field generated by a radio signal on the parallel line. A premises wireless signal transmission facility characterized by:
長の０．１−０．２倍にしたことを特徴とする特許請求
の範囲第１項記載の構内無線信号伝送設備。(2) The in-plant radio signal transmission equipment according to claim 1, wherein the line spacing of the parallel lines is set to 0.1 to 0.2 times the wavelength of the maximum transmitted radio signal.
を具備したことを特徴とする特許請求の範囲第１項記載
の構内無線信号伝送設備。(3) The in-plant wireless signal transmission equipment according to claim 1, further comprising another parallel line disposed perpendicular to the parallel line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62101417A JPS63267028A (en) | 1987-04-24 | 1987-04-24 | Premises radio signal transmission equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62101417A JPS63267028A (en) | 1987-04-24 | 1987-04-24 | Premises radio signal transmission equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63267028A true JPS63267028A (en) | 1988-11-04 |
| JPH0479489B2 JPH0479489B2 (en) | 1992-12-16 |
Family
ID=14300129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62101417A Granted JPS63267028A (en) | 1987-04-24 | 1987-04-24 | Premises radio signal transmission equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63267028A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5115463A (en) * | 1990-06-25 | 1992-05-19 | David Moldavsky | Extended cordless telephone system |
| JP2002228698A (en) * | 2001-02-02 | 2002-08-14 | Melco Inc | Electric field probe |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61220532A (en) * | 1985-03-26 | 1986-09-30 | Tokyo Electric Power Co Inc:The | Laying method for communication line in tunnel or the like |
-
1987
- 1987-04-24 JP JP62101417A patent/JPS63267028A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61220532A (en) * | 1985-03-26 | 1986-09-30 | Tokyo Electric Power Co Inc:The | Laying method for communication line in tunnel or the like |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5115463A (en) * | 1990-06-25 | 1992-05-19 | David Moldavsky | Extended cordless telephone system |
| JP2002228698A (en) * | 2001-02-02 | 2002-08-14 | Melco Inc | Electric field probe |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0479489B2 (en) | 1992-12-16 |
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