JPH0583161A - Line changeover system - Google Patents
Line changeover systemInfo
- Publication number
- JPH0583161A JPH0583161A JP26701291A JP26701291A JPH0583161A JP H0583161 A JPH0583161 A JP H0583161A JP 26701291 A JP26701291 A JP 26701291A JP 26701291 A JP26701291 A JP 26701291A JP H0583161 A JPH0583161 A JP H0583161A
- Authority
- JP
- Japan
- Prior art keywords
- line
- signal
- transmission
- working
- switching
- 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
Landscapes
- Time-Division Multiplex Systems (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は無線デジタル伝送におけ
る回線切替システムに関し、更に詳しくは、従属する複
数の変調区間で異なった変調処理を行う無線伝送におけ
る回線切替システムに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching system in wireless digital transmission, and more particularly to a line switching system in wireless transmission which performs different modulation processing in a plurality of subordinate modulation sections.
【０００２】[0002]
【従来の技術】一般に、無線デジタル伝送用の回線切替
システムにおいては、例えば、帯域の異なった複数の変
調区間で異なった信号変調を行う。この場合には、図２
に示されているように、例えば２つの変調区間３０，３
２を直列に接続しており、各変調区間で無線ディジタル
伝送が行われる現用回線Ａと予備回線Ｂの切替が行われ
る。2. Description of the Related Art Generally, in a line switching system for wireless digital transmission, for example, different signal modulation is performed in a plurality of modulation sections having different bands. In this case,
, Two modulation intervals 30, 3
2 are connected in series, and the working line A and the protection line B for wireless digital transmission are switched in each modulation section.
【０００３】図３には、従来の回線切替システムを構成
する回線切替回路（図２の３０又は３２に対応）の構成
が示されている。この回線切替回路は、図の左側の送信
部と右側の受信部とから構成されている。送信部は、入
力インターフェース信号の送信回線の切替を行う送端切
替回路１０と、この送端切替回路１０を制御する送端切
替制御回路１２と、パイロット信号（模擬試験信号）を
発生するパイロット信号発生回路１４と、送端切替回路
１０から出力された現用信号及び予備信号を各々無線伝
送用に多重化する多重化回路１６及び１８とから構成さ
れている。多重化回路１６，１８では、入力信号に無線
伝送に必要なオーバヘッドビットを付加する信号処理を
行い、当該回路１６，１８から出力された信号は各々現
用回線Ｓ１，予備回線Ｓ２に載せら、無線周波数への変
換及び所定の変調処理が行われる。送端切替制御回路１
２は、後述する受端切替制御回路２８からの送端切替指
示信号を受信する。FIG. 3 shows the configuration of a line switching circuit (corresponding to 30 or 32 in FIG. 2) which constitutes a conventional line switching system. The line switching circuit is composed of a transmitter on the left side and a receiver on the right side of the figure. The transmitter includes a transmission end switching circuit 10 that switches the transmission line of the input interface signal, a transmission end switching control circuit 12 that controls the transmission end switching circuit 10, and a pilot signal that generates a pilot signal (simulated test signal). It comprises a generation circuit 14 and multiplexing circuits 16 and 18 for respectively multiplexing the working signal and the backup signal output from the sending end switching circuit 10 for wireless transmission. The multiplexing circuits 16 and 18 perform signal processing for adding an overhead bit necessary for wireless transmission to the input signal, and the signals output from the circuits 16 and 18 are placed on the working line S1 and the protection line S2, respectively. Conversion to a frequency and predetermined modulation processing are performed. Sending end switching control circuit 1
2 receives a sending end switching instruction signal from a receiving end switching control circuit 28 described later.
【０００４】一方、受信部は、無線周波数から復調され
た受信信号のオーバヘッドビットを除去するとともに、
回線品質監視情報信号を出力する分離化回路２０，２２
と、分離化回路２０，２２から各々供給された信号（現
用信号と予備信号）の何れを出力するかの切替を無瞬断
で行う無瞬断切替回路２４と、分離化回路２２から供給
された信号からパイロット信号を検出するパイロット信
号検出回路２６と、分離化回路２０，２２からの回線品
質監視情報信号とパイロット信号検出回路２６からの出
力信号に基づいて無瞬断切替回路２４及び送端切替制御
回路１２を制御する受端切替制御回路２８とから構成さ
れている。On the other hand, the receiving section removes overhead bits of the received signal demodulated from the radio frequency, and
Separation circuits 20 and 22 for outputting line quality monitoring information signals
And a non-instantaneous interruption switching circuit 24 for switching which of the signals (current signal and standby signal) respectively supplied from the demultiplexing circuits 20 and 22 to be output without interruption. Based on the line quality monitoring information signal from the demultiplexing circuits 20 and 22 and the output signal from the pilot signal detection circuit 26 It is composed of a receiving end switching control circuit 28 for controlling the switching control circuit 12.
【０００５】以上のように構成された回線切替回路にお
いて、送信部で送端切替回路１２は入力インターフェイ
ス信号ａを現用信号ｂと予備信号ｃとに分岐し、送端切
替制御回路１２からの制御信号ｄによりパイロット信号
発生回路１４の出力信号ｅと現用信号ｂを分岐した信号
との一方を予備信号ｃとして出力する。多重化回路１
６，１８は入力信号ｂ，ｃに無線伝送に必要なオーバヘ
ッドビットを負荷する信号処理を行い、多重化信号ｆ，
ｇを出力する。送端切替制御回路１２は、受端切替制御
回路２８からの送端切替指示信号ｈに基づき制御信号ｉ
を出力する。多重化信号ｆ，ｇは変調及び無線周波数へ
変換され出力される。In the line switching circuit configured as described above, the sending end switching circuit 12 branches the input interface signal a into the working signal b and the backup signal c in the transmitting section, and the control from the sending end switching control circuit 12 is performed. One of the output signal e of the pilot signal generation circuit 14 and the signal obtained by branching the working signal b by the signal d is output as the spare signal c. Multiplexing circuit 1
Reference numerals 6 and 18 perform signal processing for loading overhead bits required for wireless transmission on the input signals b and c, and a multiplexed signal f,
Output g. The sending end switching control circuit 12 controls the control signal i based on the sending end switching instruction signal h from the receiving end switching control circuit 28.
Is output. The multiplexed signals f and g are modulated and converted to a radio frequency and output.
【０００６】受信部では、無線周波数からの変換及び復
調された信号ｊ，ｋが分離化回路２０，２２へ入力され
る。分離化回路２０，２２は復調信号ｊ，ｋより、送信
側で付加したオーバヘッドビットを除去し、出力信号
ｌ，ｍを出力するとともに、回線品質監視情報信号ｎ，
ｑを受端切替制御回路２８へ出力する。無瞬断切替回路
２４は、現用信号ｌと予備信号ｍとを入力し、受端切替
制御回路２８の制御信号ｐにより、現用信号ｌと予備信
号ｍとを無瞬断で切替、切替後の信号ｑを出力する。パ
イロット信号検出回路２６は入力信号ｍがパイロット信
号かどうかの判定を行い、パイロット信号の場合には、
検出信号ｒを出力する。In the receiving section, the signals j and k converted and demodulated from the radio frequency are input to the demultiplexing circuits 20 and 22. The demultiplexing circuits 20 and 22 remove the overhead bits added on the transmitting side from the demodulated signals j and k, and output the output signals 1 and m, and the line quality monitoring information signals n and n.
q is output to the receiving end switching control circuit 28. The hitless switching circuit 24 inputs the working signal 1 and the standby signal m, and switches the working signal 1 and the standby signal m by the control signal p of the receiving end switching control circuit 28 without hitting, and after switching. Output signal q. The pilot signal detection circuit 26 determines whether the input signal m is a pilot signal, and when the input signal m is a pilot signal,
The detection signal r is output.
【０００７】ここで、切替回路１０，２４の切替シーケ
ンスを簡単に説明すると、現用回線Ｓ１の回線品質監視
情報信号ｎの出力により、送端切替回路１２が制御さ
れ、予備回線Ｓ２にも現用信号と同一信号が分岐され
る。受端側のパイロット信号検出信号ｒにより、送端側
での送並が確認され、無瞬断切替回路では制御信号ｐに
より切替が行われる。The switching sequence of the switching circuits 10 and 24 will be briefly described. The output terminal switching circuit 12 is controlled by the output of the line quality monitoring information signal n of the working line S1 and the working signal is also supplied to the protection line S2. And the same signal is branched. The parallel transmission on the transmission end side is confirmed by the pilot signal detection signal r on the reception end side, and switching is performed by the control signal p in the non-instantaneous interruption switching circuit.
【０００８】[0008]
【発明が解決しようとする課題】しかしながら、上記の
ような従来の回線切替システムにおいては、複数の切替
回路を直列に接続する構成であるため、システムが大規
模で複雑になるという欠点があった。However, in the conventional line switching system as described above, there is a drawback that the system becomes large-scale and complicated because it is configured to connect a plurality of switching circuits in series. ..
【０００９】[0009]
【発明の目的】本発明の目的は、コンパクト且つ簡素な
構成の回線切替システムを提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide a line switching system having a compact and simple structure.
【００１０】[0010]
【課題を解決するための手段】本発明は上記目的を達成
するために、入力インターフェース信号を送信する送信
部と、当該送信部から出力され、縦属する複数の変調区
間で異なった変調処理を施された伝送信号を受信する受
信部との間に位置する変調区間の境界部に回路品質を表
す信号を伝送信号から分離する手段と、この分離信号を
伝送信号に再び多重化する手段を有した回線切替システ
ムを提供する。In order to achieve the above-mentioned object, the present invention performs a different transmission process for transmitting an input interface signal and different modulation processes output from the transmission unit in a plurality of vertically belonging modulation intervals. And a means for separating the signal indicating the circuit quality from the transmission signal at the boundary of the modulation section located between the reception section for receiving the transmission signal and the means for re-multiplexing the separation signal into the transmission signal. Provide a line switching system.
【００１１】[0011]
【作用】隣接する２つの変調区間の境界部における回線
切替操作を省いた信号伝送が実行される。第１の変調区
間の受端で現用及び予備の各回線の復調信号から伝送品
質信号が分離される。次に、第２の変調区間の送端で現
用及び予備の各回線の伝送信号に先に分離した伝送品質
信号を多重化して第２の変調区間に無線伝送される。こ
の作用に基づいて前記境界部における回線切替回路の装
置が不要になる。The signal transmission is executed without the line switching operation at the boundary between two adjacent modulation sections. At the receiving end of the first modulation section, the transmission quality signal is separated from the demodulated signals of the working and protection lines. Next, at the transmission end of the second modulation section, the transmission signals of the working and protection lines are multiplexed with the previously separated transmission quality signal and wirelessly transmitted to the second modulation section. On the basis of this action, the device of the line switching circuit at the boundary portion becomes unnecessary.
【００１２】[0012]
【実施例】以下、本発明の一実施例を添付図面を参照し
つつ詳細に説明する。図１に示された本実施例の回線切
替システムは、２つの変調区間で異なった変調を採用し
たものであり、図２に示された従来のシステムに対応す
る。この回線切替システムは、図の左側の送信部と、右
側の受信部と、これらの間に配置された変調区間境界部
４０とから構成されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The line switching system of the present embodiment shown in FIG. 1 employs different modulation in two modulation sections, and corresponds to the conventional system shown in FIG. This line switching system includes a transmitter on the left side of the figure, a receiver on the right side, and a modulation section boundary section 40 arranged between them.
【００１３】送信部は従来と同様に、入力インターフェ
ース信号の送信回線の切替を行う送端切替回路１０と、
この送端切替回路１０を制御する送端切替制御回路１２
と、パイロット信号を発生するパイロット信号発生回路
１４と、送端切替回路１０から出力された現用信号及び
予備信号を各々無線伝送用に多重化する多重化回路１６
及び１８とから構成されている。多重化回路１６，１８
では、入力信号に無線伝送に必要なオーバヘッドビット
を付加する信号処理を行い、当該回路１６，１８から出
力された信号は各々現用回線Ｓ１，予備回線Ｓ２に載せ
ら、無線周波数への変換及び所定の変調処理が行われた
後、変調区間境界部４０に送信される。送端切替制御回
路１２は、後述する受端切替制御回路２８からの送端切
替指示信号を受信する。As in the conventional case, the transmission section includes a transmission end switching circuit 10 for switching the transmission line of the input interface signal,
A sending end switching control circuit 12 for controlling the sending end switching circuit 10
, A pilot signal generation circuit 14 for generating a pilot signal, and a multiplexing circuit 16 for respectively multiplexing the working signal and the backup signal output from the sending end switching circuit 10 for wireless transmission.
And 18. Multiplexing circuit 16, 18
Then, signal processing for adding an overhead bit necessary for wireless transmission to the input signal is performed, and the signals output from the circuits 16 and 18 are placed on the working line S1 and the protection line S2, respectively, and converted to a radio frequency and predetermined. Is transmitted to the modulation section boundary section 40. The sending end switching control circuit 12 receives a sending end switching instruction signal from a receiving end switching control circuit 28 described later.
【００１４】変調区間境界部４０は、復調された受信信
号のオーバヘッドビットを除去するとともに、回線品質
監視情報（回線品質劣化情報と回線断あるいは機器障害
情報）を分離する分離化回路４２，４４と、再び無線伝
送に必要なオーバヘッドビットを付加するとともに、回
線品質監視情報の多重化を行う多重化回路４６，４８と
から構成されている。The modulation section boundary section 40 removes overhead bits of the demodulated received signal, and separate circuits 42 and 44 for separating line quality monitoring information (line quality deterioration information and line disconnection or equipment failure information). Further, it is composed of multiplexing circuits 46 and 48 which again add overhead bits required for wireless transmission and multiplex the line quality monitoring information.
【００１５】また、受信部は、無線周波数から復調され
た受信信号のオーバヘッドビットを除去するとともに、
回線品質監視情報信号を出力する分離化回路２０，２２
と、分離化回路２０，２２から各々供給された信号（現
用信号と予備信号）の何れを出力するかの切替を無瞬断
で行う無瞬断切替回路２４と、分離化回路２２から供給
された信号からパイロット信号を検出するパイロット信
号検出回路２６と、分離化回路２０，２２からの回線品
質監視情報信号とパイロット信号検出回路２６からの出
力信号に基づいて無瞬断切替回路２４及び送端切替制御
回路１２を制御する受端切替制御回路２８とから構成さ
れている。The receiving unit removes overhead bits of the received signal demodulated from the radio frequency, and
Separation circuits 20 and 22 for outputting line quality monitoring information signals
And a non-instantaneous interruption switching circuit 24 for switching which of the signals (current signal and standby signal) respectively supplied from the demultiplexing circuits 20 and 22 to be output without interruption. Based on the line quality monitoring information signal from the demultiplexing circuits 20 and 22 and the output signal from the pilot signal detection circuit 26 It is composed of a receiving end switching control circuit 28 for controlling the switching control circuit 12.
【００１６】次に、以上のように構成された回線切替シ
ステムの動作及び作用について説明する。この説明につ
いて、図３の各信号と同一の信号には同一の引用符号が
使用されている。従って、重複する説明は省略されてい
る。送信部の多重化回路１６，１８から出力された信号
ｇ，ｆは、第１の変調処理を施された後に変調区間境界
部４０に信号ｋ' ，ｉ' として供給される。そして、変
調区間境界部４０の多重化回路４４，４６から出力され
た信号ｇ' ，ｆ' は、第２の変調処理が施された後に受
信部に信号k ' ，ｊ' として供給される。Next, the operation and action of the line switching system configured as described above will be described. In this description, the same reference numerals are used for the same signals as those in FIG. Therefore, redundant description is omitted. The signals g and f output from the multiplexing circuits 16 and 18 of the transmitter are subjected to the first modulation processing and then supplied to the modulation section boundary section 40 as signals k ′ and i ′ . Then, the signals g ′ and f ′ output from the multiplexing circuits 44 and 46 of the modulation section boundary section 40 are supplied to the receiving section as signals k ′ and j ′ after being subjected to the second modulation processing.
【００１７】そして、受端切替制御回路２８において回
線品質監視情報信号ｎにより現用信号の異常を検出した
場合には、送端切替制御回路１２に対して送信変換信号
ｈを送信する。送端切替制御回路１２が当該信号ｈに基
づき、送端切替回路１０を制御し、予備回線Ｓ２にも現
用回線Ｓ１と同一信号ｃを分岐する。前述した変調区間
境界部４０では、分離化回路４２，４４は復調信号k
' ，ｊ' より送信部で付加されたオーバーヘッドビッ
トを除去して出力信号ｕ，ｓを出力するとともに、回線
品質監視情報ｎ' ，ｑ' を多重化回路４６，４８へ出力
する。ここで、無線伝送に必要なオーバヘッドビットを
入力信号ｓ，ｕに再び付加するとともに、回線品質監視
情報ｎ' ，ｑ' を多重化し、多重化信号ｇ' ，ｆ' が出
力される。この多重化信号ｇ' ，ｆ' は変調と無線周波
数への変換処理を受けた後、無線伝送される。受信部で
は、図３で説明した作用と同じ作用が行われる。When the receiving end switching control circuit 28 detects an abnormality in the working signal by the line quality monitoring information signal n, it transmits the transmission conversion signal h to the sending end switching control circuit 12. The sending end switching control circuit 12 controls the sending end switching circuit 10 based on the signal h, and branches the same signal c as the working line S1 to the protection line S2. In the above-mentioned modulation section boundary portion 40, the demultiplexing circuits 42 and 44 have the demodulated signal k
', J' output signal u to remove overhead bits added by the transmitting unit than outputs a s, and outputs the line quality monitoring information n ', q' the to the multiplexing circuit 46. Here, the overhead bits necessary for wireless transmission are added again to the input signals s and u, the line quality monitoring information n ′ and q ′ are multiplexed, and multiplexed signals g ′ and f ′ are output. The multiplexed signal g ', f' after receiving a conversion process to the modulation and radio frequency, and wirelessly transmitted. The receiving unit performs the same operation as the operation described in FIG.
【００１８】[0018]
【発明の効果】以上説明したように本発明は、入力信号
を送信する送信部と、縦属する複数の変調区間で異なっ
た変調処理を施された伝送信号を受信する受信部との間
に位置する隣接する変調区間の境界部に回線品質を表す
信号を伝送信号から分離する手段と、分離した信号を伝
送信号に再び多重化する手段を設けたため、システムを
コンパクト且つ簡素な構成にすることができるという効
果がある。As described above, according to the present invention, the position between the transmission unit for transmitting the input signal and the reception unit for receiving the transmission signal subjected to the different modulation processing in the plurality of vertically belonging modulation sections is provided. Since the means for separating the signal indicating the line quality from the transmission signal and the means for re-multiplexing the separated signal to the transmission signal are provided at the boundary between adjacent modulation sections, the system can be made compact and simple. There is an effect that you can.
【図１】本発明の一実施例に係る回線切替システムの構
成を示すブロック図。FIG. 1 is a block diagram showing a configuration of a line switching system according to an embodiment of the present invention.
【図２】従来の回線切替システムの構成を示す概念図。FIG. 2 is a conceptual diagram showing a configuration of a conventional line switching system.
【図３】従来の回線切替システムを構成する回線切替回
路の構成を示すブロック図。FIG. 3 is a block diagram showing a configuration of a line switching circuit that constitutes a conventional line switching system.
１０ 送端切替回路 １２ 送端切替制御回路 １４ パイロット信号発生回路 １６，１８，４４，４６ 多重化回路 ２０，２２，４０，４２ 分離化回路 ２４ 無瞬断切替回路 ２６ パイロット信号検出回路 ２８ 受端切替制御回路 ４０ 変調区間境界部 10 Sending end switching circuit 12 Sending end switching control circuit 14 Pilot signal generating circuit 16, 18, 44, 46 Multiplexing circuit 20, 22, 40, 42 Separation circuit 24 Non-interruption switching circuit 26 Pilot signal detecting circuit 28 Receiving end Switching control circuit 40 Modulation section boundary
Claims (2)
に応じて現用回線から予備回線に分岐し、少なくとも２
つの変調区間で前記各回線縦属する第１及び第２の信号
に異なった変調を与えて無線伝送し、前記伝送品質に応
じて前記各回線の１つに切り替えることにより、受端に
おける出力信号を出力する回線切替システムにおいて、 前記第１の変調区間の受端に設けられ、受信信号から前
記伝送品質を示す伝送品質信号を前記各回線毎に分離す
る手段と、 前記第２の変調区間の送端に設けられ、送信信号に前記
伝送品質信号を前記各回線毎に多重化する手段を備えた
ことを特徴とする回線切替システム。1. An input signal at a transmitting end is branched from a working line to a protection line according to the transmission quality of the signal, and at least 2
Different modulations are given to the first and second signals vertically belonging to each line in one modulation section and wireless transmission is performed, and the output signal at the receiving end is changed by switching to one of the lines according to the transmission quality. In the line switching system for outputting, a means provided at a receiving end of the first modulation section for separating a transmission quality signal indicating the transmission quality from a received signal for each of the lines, and a transmission section for transmitting the second modulation section. A line switching system provided at an end, comprising means for multiplexing the transmission quality signal into a transmission signal for each line.
備回線の切り替えによって縦属する第１及び第２の少な
くとも２つの変調区間を経て無線ディジタル伝送を行う
回線切替システムにおいて、 前記送信部が、 現用回線にて入力インターフェース信号を予備回線へ出
力する信号と現用回線へ出力する信号とに分配する手段
と、 現用回線及び予備回線にて前記分配信号に無線伝送に必
要な信号処理を行う手段と、 現用回線及び予備回線にて回線品質劣化情報，回線断情
報，機器障害情報等の２つの回線切替情報を前記信号処
理後の主信号に多重化する手段を備え、 前記受信部が、 現用回線及び予備回線にて前記２つの回線切替情報を分
離，判定する手段と、 現用回線及び予備回線にて回線品質劣化及び機器障害を
検出する手段と、 現用回線にて前記分離，判定結果及び前記検出結果に基
づき、予備回線からの信号と現用回線の信号とを無瞬断
切替する手段を備えた構成を有することを特徴とする回
線切替システム。2. A line switching system for performing wireless digital transmission between at least two first and second modulation sections vertically belonging to each other by switching between a working line and a protection line between a transmitting unit and a receiving unit, wherein the transmitting unit comprises: Means for distributing the input interface signal on the working line into a signal to be output to the protection line and a signal to be output to the working line; and means for performing signal processing necessary for wireless transmission on the distribution signal on the working line and the protection line. , A means for multiplexing two pieces of line switching information, such as line quality deterioration information, line disconnection information, and equipment failure information on the working line and the protection line, into the main signal after the signal processing, wherein the receiving unit is a working line. And a means for separating and determining the two pieces of line switching information on the protection line, a means for detecting line quality deterioration and equipment failure on the working line and the protection line, and a working circuit. The separation, determination results and based on the detection result, line switching system characterized in that it has a structure having means for signal hitless switching the signal of the working line from the protection line at.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3267012A JP3061909B2 (en) | 1991-09-18 | 1991-09-18 | Line switching system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3267012A JP3061909B2 (en) | 1991-09-18 | 1991-09-18 | Line switching system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0583161A true JPH0583161A (en) | 1993-04-02 |
| JP3061909B2 JP3061909B2 (en) | 2000-07-10 |
Family
ID=17438836
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3267012A Expired - Lifetime JP3061909B2 (en) | 1991-09-18 | 1991-09-18 | Line switching system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3061909B2 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61189037A (en) * | 1985-02-15 | 1986-08-22 | Fujitsu Ltd | Optical terminal station device |
| JPS62253231A (en) * | 1986-01-07 | 1987-11-05 | Fujitsu Ltd | Active/standby changeover system |
-
1991
- 1991-09-18 JP JP3267012A patent/JP3061909B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61189037A (en) * | 1985-02-15 | 1986-08-22 | Fujitsu Ltd | Optical terminal station device |
| JPS62253231A (en) * | 1986-01-07 | 1987-11-05 | Fujitsu Ltd | Active/standby changeover system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3061909B2 (en) | 2000-07-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 19980903 |