JPH09331515A - Level measurement system for catv transmission line - Google Patents
Level measurement system for catv transmission lineInfo
- Publication number
- JPH09331515A JPH09331515A JP8150830A JP15083096A JPH09331515A JP H09331515 A JPH09331515 A JP H09331515A JP 8150830 A JP8150830 A JP 8150830A JP 15083096 A JP15083096 A JP 15083096A JP H09331515 A JPH09331515 A JP H09331515A
- Authority
- JP
- Japan
- Prior art keywords
- level
- measurement
- band
- frequency
- transmission line
- 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
- Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
- Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明はＣＡＴＶ伝送路のレ
ベル測定方式に関し、特に双方向ＣＡＴＶ伝送路のレベ
ル測定方式に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CATV transmission line level measuring system, and more particularly to a bidirectional CATV transmission line level measuring system.
【０００２】[0002]
【従来の技術】従来の双方向ＣＡＴＶ伝送路のレベル測
定方式の第１の従来技術においては、下り伝送帯域の周
波数特性はセンタ局に信号発生器およびフィールド側に
レベル測定器を各各用意してセンタ局側から下り測定信
号を送出し、センタ局出力端と伝送路上の任意の測定ポ
イント、例えば同軸中継増幅器の下り出力端あるいはモ
ニタ端でその下り測定信号のレベルを測定し、かつ上り
伝送帯域の周波数特性は伝送路上の任意の測定ポイン
ト、例えば同軸中継増幅器の上り入力端あるいはモニタ
端からセンタ局とは別の信号発生器により上り測定信号
を入力して、センタ局にフィールド側とは別に用意され
るレベル測定器でその上り測定信号のレベルを測定する
というように、下り方向および上り方向別々に任意の区
間内の伝送レベル差を測定して周波数特性偏差を得る方
法を採っていた。2. Description of the Related Art In the first prior art of the conventional level measuring system of a bidirectional CATV transmission line, the frequency characteristic of the downlink transmission band is prepared by providing a signal generator at the center station and a level measuring device at the field side. Send the downlink measurement signal from the center station side, measure the level of the downlink measurement signal at the center station output end and any measurement point on the transmission path, for example, the downlink output end or monitor end of the coaxial repeater amplifier, and perform the uplink transmission. The frequency characteristic of the band is measured at any measurement point on the transmission line, for example, by inputting the upstream measurement signal from a signal generator other than the center station from the upstream input end or monitor end of the coaxial repeater amplifier, The level of the upstream measurement signal is measured by a separately prepared level measuring instrument, so that the transmission level difference in an arbitrary section in the downstream direction and the upstream direction separately. Measured and had adopted a method of obtaining a frequency characteristic deviation.
【０００３】しかし、この第１の従来技術による双方向
ＣＡＴＶ伝送路のレベル測定方式では、信号発生器およ
びレベル測定器がセンタ局側とフィールド側とに２組必
要となり、かつ測定人員もセンタ局側とフィールド側と
の両方に必要となって経済的ではなかった。However, in the level measuring system of the bidirectional CATV transmission line according to the first conventional technique, two sets of the signal generator and the level measuring device are required on the center station side and the field side, and the number of measuring personnel is also the center station. It was not economical because it was necessary for both the field side and the field side.
【０００４】この第１の従来技術の欠点を補うべく第２
の従来技術である特開平３−２８３８９１号公報の「Ｃ
ＡＴＶ伝送路レベル測定システム」は、図６を参照する
と、双方向の伝送路を監視する監視制御装置５１と、監
視制御装置５１の指令により複数の周波数を所定時間間
隔で順次１周波毎にテストパイロット信号を発生させる
信号発生器５０を有するセンタ装置と；監視制御装置５
１の指令によりセンタ装置の信号発生器５０から送出さ
れるテストパイロット信号のレベルを検出する復調部６
２と、テストパイロット信号を受信時間内に同期をとっ
て復調するよう復調部６２の局部発振器６２０を制御し
てそのレベル計測結果をセンタ装置へ転送する計測制御
部６３とを有する中継増幅器とから構成される。In order to make up for the drawbacks of the first prior art, the second
Japanese Patent Application Laid-Open No. 3-283891 "C"
Referring to FIG. 6, the "ATV transmission line level measuring system" includes a supervisory control device 51 for monitoring a bidirectional transmission line, and a plurality of frequencies are sequentially tested at predetermined time intervals for each frequency according to a command from the supervisory control device 51. A center device having a signal generator 50 for generating a pilot signal; a supervisory control device 5
Demodulation unit 6 for detecting the level of the test pilot signal transmitted from the signal generator 50 of the center device in response to the command 1
2 and a relay amplifier including a measurement control unit 63 that controls the local oscillator 620 of the demodulation unit 62 to demodulate the test pilot signal in synchronization within the reception time and transfers the level measurement result to the center device. Composed.
【０００５】次に動作について説明すると、監視制御装
置５１は、信号発生器５０へ所定周波数のパイロット信
号を出力するように指令を出し、同時に伝送路上の中継
増幅器の計測制御部６３内のＣＰＵ６３１に対して、局
部発振器６２０を制御してテストパイロット信号のレベ
ルを測定し、その測定データを監視制御装置５１へ送り
返すように指示を出す。監視制御装置５１は所定時間
後、上述の周波数とは別の周波数のテストパイロット信
号を出力するように再び信号発生器５０へ指示を出し、
同様の動作をシステムに行わせる。The operation will now be described. The supervisory controller 51 issues a command to the signal generator 50 to output a pilot signal of a predetermined frequency, and at the same time, the CPU 631 in the measurement controller 63 of the relay amplifier on the transmission path. On the other hand, the local oscillator 620 is controlled to measure the level of the test pilot signal, and an instruction is issued to send back the measured data to the supervisory control device 51. After a predetermined time, the supervisory controller 51 again instructs the signal generator 50 to output a test pilot signal of a frequency different from the above-mentioned frequency,
Causes the system to perform a similar operation.
【０００６】このように、監視制御装置５１により信号
発生器５０と中継増幅器内の計測制御部６３とへ指令を
出して複数の周波数のレベルを測定することにより、伝
送路の帯域内の全体的なレベル特性を知ることができ、
また設定する周波数をＣＡＴＶシステムが運用するテレ
ビ信号伝送用の周波数を避けるように設定することによ
り、ＣＡＴＶシステム運用中でも支障なく伝送路のレベ
ルを測定できるようにしたものである。In this way, the supervisory control device 51 issues a command to the signal generator 50 and the measurement control unit 63 in the relay amplifier to measure the levels of a plurality of frequencies, so that the entire area within the band of the transmission path is measured. You can know the level characteristics,
Further, by setting the frequency to be set so as to avoid the frequency for transmitting the television signal operated by the CATV system, the level of the transmission line can be measured without any trouble even during the operation of the CATV system.
【０００７】[0007]
【発明が解決しようとする課題】この第２の従来技術で
ある特開平３−２８３８９１号公報の「ＣＡＴＶ伝送路
レベル測定システム」では、第１の従来技術に比較して
測定人員は削減できるが、中継増幅器が伝送路上に縦続
して複数台接続されるシステムでは、各各の中継増幅器
に復調部６２および計測制御部６３が個別に必要となる
ため、システム全体ではコスト高および消費電力の増加
となり、経済的ではなかった。The "CATV transmission line level measuring system" of Japanese Patent Laid-Open No. 3-283891, which is the second conventional technique, can reduce the number of measuring personnel as compared with the first conventional technique. In a system in which a plurality of relay amplifiers are connected in cascade on a transmission line, a demodulation unit 62 and a measurement control unit 63 are individually required for each relay amplifier, resulting in high cost and increased power consumption in the entire system. It wasn't economical.
【０００８】[0008]
【課題を解決するための手段】本発明によるＣＡＴＶ伝
送路のレベル測定方式は、ヘッドエンドを有するセンタ
側からフィールド側へ双方向ＣＡＴＶ伝送路上に中継増
幅器が複数接続される双方向ＣＡＴＶ伝送システムにお
いて、前記センタ側に前記双方向ＣＡＴＶ伝送路の下り
伝送帯域幅の第１の測定周波数信号をスイープ発生して
前記双方向ＣＡＴＶ伝送路の下り伝送帯域を通して前記
フィールド側へ送出する信号発生手段と、前記信号発生
手段出力の前記第１の測定周波数信号のレベルを測定し
て第１のレベル特性として記憶するとともに前記双方向
ＣＡＴＶ伝送路の下り伝送帯域を通して伝送された前記
センタ側信号発生手段送出の前記第１の測定周波信号の
レベルを前記フィールド側の所定の測定ポイントで測定
して第２のレベル特性として記憶するレベル測定記憶手
段と、前記レベル測定記憶手段における前記第１のレベ
ル特性と前記第２のレベル特性とから双方のレベル特性
差を算出して前記下り伝送帯域のレベル特性偏差を求め
るレベル偏差算出手段とを備える。A level measuring system of a CATV transmission line according to the present invention is a bidirectional CATV transmission system in which a plurality of relay amplifiers are connected on a bidirectional CATV transmission line from a center side having a head end to a field side. Signal generating means for sweeping and generating a first measurement frequency signal of the downlink transmission bandwidth of the bidirectional CATV transmission line on the center side and sending it to the field side through the downlink transmission band of the bidirectional CATV transmission line, The level of the first measurement frequency signal output from the signal generating means is measured and stored as a first level characteristic, and the center side signal generating means transmitted through the downlink transmission band of the bidirectional CATV transmission path is transmitted. The level of the first measurement frequency signal is measured at a predetermined measurement point on the field side to obtain a second level. The level characteristic storing means for storing the level characteristic difference between the first level characteristic and the second level characteristic stored in the level measuring storage means to obtain the level characteristic deviation of the downlink transmission band. And level deviation calculating means.
【０００９】また本発明によるＣＡＴＶ伝送路のレベル
測定方式は、前記センタ側における前記信号発生手段が
帯域制限を行う第１の制御信号に制御されて前記第１の
制御信号に制御される以前に出力していた前記第１の測
定周波信号の下り伝送帯域幅のスイープ幅を前記双方向
ＣＡＴＶ伝送路の上り伝送帯域幅に制限して第２の測定
周波数信号として前記下り伝送帯域内の所定の第１の周
波数帯を通して前記フィールド側へ送出し、前記フィー
ルド側の前記所定の測定ポイントにおいて、前記レベル
測定記憶手段が前記第２の測定周波信号のレベルを測定
して第３のレベル特性として記憶し、前記フィールド側
に、前記第２の測定周波数信号を前記双方向ＣＡＴＶ伝
送路の前記上り伝送帯域に周波数変換して第３の測定周
波数信号として出力し前記ＣＡＴＶ伝送路の前記上り伝
送帯域を通して前記センタ側へ返送するフィールド側周
波数変換手段を備え、前記センタ側に、前記ＣＡＴＶ伝
送路の前記上り伝送帯域を通して前記フィールド側周波
数変換手段から返送された前記第３の測定周波信号を前
記双方向ＣＡＴＶ伝送路の前記下り伝送帯域内の所定の
第２の周波数帯に周波数変換して第４の測定周波数信号
として出力し前記下り伝送帯域の前記第２の周波数帯を
通して再び前記フィールド側へ送出するセンタ側周波数
変換手段を備え、前記フィールド側の前記所定の測定ポ
イントにおいて、前記レベル測定手段が前記第４の測定
周波信号のレベルを測定して第４のレベル特性として記
憶し、前記レベル偏差算出手段が、前記レベル測定記憶
手段における前記第３のレベル特性と前記第４のレベル
特性とから双方のレベル特性差を算出して第５のレベル
特性を求めかつ前記レベル測定記憶手段における前記第
２のレベル特性の中の前記第４のレベル特性帯域に相当
するレベル特性と前記第５のレベル特性とから双方のレ
ベル特性差を算出することにより前記双方向ＣＡＴＶ伝
送路の前記上り伝送帯域のレベル特性偏差を求める。Further, in the level measuring system of the CATV transmission line according to the present invention, before the signal generating means on the center side is controlled by the first control signal for band limiting, it is controlled by the first control signal. The sweep width of the downlink transmission bandwidth of the first measurement frequency signal that has been output is limited to the uplink transmission bandwidth of the bidirectional CATV transmission line to obtain a predetermined measurement signal within the downlink transmission band as the second measurement frequency signal. It is transmitted to the field side through a first frequency band, and at the predetermined measurement point on the field side, the level measurement storage means measures the level of the second measurement frequency signal and stores it as a third level characteristic. Then, the second measurement frequency signal is frequency-converted to the upstream transmission band of the bidirectional CATV transmission line and output as the third measurement frequency signal to the field side. A field-side frequency conversion means for returning to the center side through the upstream transmission band of the CATV transmission path is provided, and the field-side frequency conversion means returned to the center side through the upstream transmission band of the CATV transmission path. The third measurement frequency signal is frequency-converted into a predetermined second frequency band in the downlink transmission band of the bidirectional CATV transmission line and output as a fourth measurement frequency signal, and the second measurement signal of the second transmission frequency band is output. Center frequency conversion means for transmitting the signal to the field side again through the frequency band of, and at the predetermined measurement point on the field side, the level measurement means measures the level of the fourth measurement frequency signal to obtain the fourth measurement frequency signal. As the level characteristic of the third level characteristic in the level measurement storage means. A difference between the two level characteristics is calculated from the fourth level characteristic to obtain a fifth level characteristic and corresponds to the fourth level characteristic band in the second level characteristic in the level measurement storage means. By calculating the level characteristic difference between the level characteristic and the fifth level characteristic, the level characteristic deviation of the upstream transmission band of the bidirectional CATV transmission line is obtained.
【００１０】さらに本発明によるＣＡＴＶ伝送路のレベ
ル測定方式は、前記レベル偏差算出手段が算出した前記
双方向ＣＡＴＶ伝送路の前記下り伝送帯域のレベル特性
偏差および前記上り伝送帯域のレベル特性偏差を表示あ
るいは記録する手段を有する。Further, in the level measuring method of the CATV transmission line according to the present invention, the level characteristic deviation of the downlink transmission band and the level characteristic deviation of the upstream transmission band of the bidirectional CATV transmission line calculated by the level deviation calculating means are displayed. Alternatively, it has a recording means.
【００１１】[0011]
【発明の実施の形態】次に、本発明について図面を参照
し説明する。本発明の一実施例である図１を参照すると
ＣＡＴＶ伝送路のレベル測定方式は、センタ局内にヘッ
ドエンド１を有し、このヘッドエンド１から同軸ケーブ
ルを通してＣＡＴＶ同軸中継増幅器３−１〜３−ｎに接
続される。そして、ＣＡＴＶ伝送路のレベル測定用とし
てセンタ側に測定送信部２が固定的に設けられ、またセ
ンタ局のモニタ端Ｘおよび同軸中継増幅器３−１〜３−
ｎの例えば同軸中継増幅器３−ｎのモニタ端Ｙにおいて
測定送信部２から送出される測定用信号レベルの測定を
行う移動可能な測定受信部４を備える。Next, the present invention will be described with reference to the drawings. Referring to FIG. 1 which is an embodiment of the present invention, a level measurement system for a CATV transmission line has a head end 1 in a center station, and a CATV coaxial relay amplifier 3-1 to 3-3 from this head end 1 through a coaxial cable. connected to n. A measurement transmitter 2 is fixedly provided on the center side for measuring the level of the CATV transmission line, and the monitor terminal X of the center station and the coaxial relay amplifiers 3-1 to 3-3-
For example, at the monitor end Y of the coaxial relay amplifier 3-n of n, a movable measurement receiving unit 4 for measuring the measurement signal level sent from the measurement transmitting unit 2 is provided.
【００１２】図２は、測定送信部２内部のブロック図で
ある。ここで信号発生部２１は、送信制御部２０により
制御されて所定周波数の下り測定用信号を出力し、その
下り測定用信号は方向性フィルタ２３を通して下位伝送
路方向に出力され、出入力端Ｗを介してＣＡＴＶ伝送路
の下方の同軸ケーブルへ送出される。そして、出入力端
Ｗから入力される所定周波数の上り測定用信号は方向性
フィルタ２３を通して送信制御部２０側に出力され、送
信制御部２０を制御するとともに周波数変換部２２で周
波数変換されて再び下り測定用信号として方向性フィル
タ２３を通して出入力端Ｗへ出力される。このように、
方向性フィルタ２３は上述した上り測定用信号と下り測
定用信号とを方向性分離するとともに上り帯域信号と下
り帯域信号とを方向性分離する。FIG. 2 is a block diagram of the inside of the measurement transmission unit 2. Here, the signal generator 21 is controlled by the transmission controller 20 to output a downlink measurement signal of a predetermined frequency, the downlink measurement signal is output to the lower transmission path direction through the directional filter 23, and the output / input terminal W is output. Via the cable to the coaxial cable below the CATV transmission line. Then, the upstream measurement signal having a predetermined frequency, which is input from the output / input terminal W, is output to the transmission control unit 20 side through the directional filter 23, controls the transmission control unit 20, and is frequency-converted by the frequency conversion unit 22 and is again converted. The downlink measurement signal is output to the input / output terminal W through the directional filter 23. in this way,
The directional filter 23 directionally separates the uplink measurement signal and the downlink measurement signal described above, and directionally separates the uplink band signal and the downlink band signal.
【００１３】図３は、測定受信部４内部のブロック図で
ある。入出力端Ｚより入力された下り測定用信号は方向
性フィルタ４２を通してレベル測定部４３側に出力され
レベル測定部４３でレベル測定されて記憶部４４に記憶
される。一方、上り測定用信号は受信制御部４０に制御
されて周波数変換部４１において所定周波数の上り帯域
信号として出力され、方向性フィルタ４２を通して上位
伝送路方向に出力されて入出力端Ｚを介してＣＡＴＶ伝
送路の上方の同軸ケーブルへ送出される。FIG. 3 is a block diagram of the inside of the measurement receiving unit 4. The downlink measurement signal input from the input / output terminal Z is output to the level measuring unit 43 side through the directional filter 42, the level is measured by the level measuring unit 43, and stored in the storage unit 44. On the other hand, the upstream measurement signal is controlled by the reception control unit 40 and is output as an upstream band signal of a predetermined frequency by the frequency conversion unit 41, is output in the upper transmission path direction through the directional filter 42, and is output via the input / output terminal Z. It is sent to the coaxial cable above the CATV transmission line.
【００１４】図４は、ＣＡＴＶ伝送路のレベル測定に用
いる測定用信号の一例であり、（ａ）〜（ｃ）は下り伝
送帯域の周波数特性偏差を求める一例であり、（ｄ）〜
（ｉ）は上り伝送帯域の周波数特性偏差を測定する測定
用信号の周波数変換の一例である。図５は、図４におけ
る測定用信号の流れ図の一例であり、測定用信号の下り
方向の流れ、および測定用信号の上り方向の流れを図４
の（ａ）〜（ｉ）に対応して示したものである。FIG. 4 is an example of a measurement signal used for measuring the level of a CATV transmission line, (a) to (c) are examples of obtaining frequency characteristic deviations in the downlink transmission band, and (d) to (d).
(I) is an example of frequency conversion of the measurement signal for measuring the frequency characteristic deviation of the upstream transmission band. FIG. 5 is an example of a flow chart of the measurement signal in FIG. 4, showing the flow of the measurement signal in the downward direction and the flow of the measurement signal in the upward direction.
(A) to (i) of FIG.
【００１５】次に動作について説明する。まず、下り伝
送信号レベルおよびそのレベル偏差を測定する方法は、
以下のようにして実現する。双方向ＣＡＴＶ伝送路対応
のセンタ局内測定送信部２の送信制御部２０は、信号発
生部２１を制御して信号発生部２１から下り伝送帯域の
所望の測定周波数の信号を順次スイープ出力してヘッド
エンド１出力から双方向ＣＡＴＶ伝送路である同軸ケー
ブルへ送出する。この状態において、ヘッドエンド１出
力の測定用信号モニタ端Ｘに測定受信部４の入出力端Ｚ
を接続し、受信制御部４０内部の切替スイッチを「ＯＦ
Ｆ」の状態にしてレベル測定部１２において、受信した
下り伝送帯域の測定用信号レベルを測定し、記憶部４４
にその測定データを校正用データＡ（ｆ）（ｆ：周波
数）として格納する（図４のａ）。Next, the operation will be described. First, the method of measuring the downlink transmission signal level and its level deviation is
It is realized as follows. The transmission control unit 20 of the in-center measurement / transmission unit 2 for the two-way CATV transmission path controls the signal generation unit 21 to sequentially sweep out signals of a desired measurement frequency in the downlink transmission band from the signal generation unit 21 to output the head. The output from the end 1 is sent to the coaxial cable which is a bidirectional CATV transmission path. In this state, the measurement signal monitor end X of the head end 1 output is connected to the input / output end Z of the measurement receiving unit 4.
And connect the selector switch inside the reception control unit 40 to “OF
In the “F” state, the level measuring unit 12 measures the received measurement signal level of the downlink transmission band, and the storage unit 44
Then, the measured data is stored as calibration data A (f) (f: frequency) (a in FIG. 4).
【００１６】次に、測定受信部４の入出力端Ｚを測定し
ようとするレベル測定ポイントにおける指定の同軸中継
増幅器（ここでは３−ｎ）の入出力あるいはモニタ端Ｙ
に接続する（ここでは、モニタ端Ｙに接続する）。ヘッ
ドエンド１出力のモニタ端Ｘで測定したときと同様に、
受信制御部４０の切替スイッチを「ＯＦＦ」にしたまま
で、ヘッドエンド１からＣＡＴＶ伝送路である同軸ケー
ブルおよび同軸中継増幅器３−１，……を通して指定の
同軸中継増幅器３−ｎのモニタ端Ｙに出力される測定用
信号のレベルをレベル測定部４３で測定し、その結果を
記憶部４４に測定データＢ（ｆ）として格納する（図４
のｂ）。Next, the input / output or monitor end Y of the designated coaxial repeater amplifier (3-n in this case) at the level measuring point at which the input / output end Z of the measurement receiving unit 4 is to be measured.
(Here, it is connected to the monitor end Y). Similar to when measured at the monitor end X of the headend 1 output,
The monitor end Y of the designated coaxial relay amplifier 3-n is passed from the head end 1 through the coaxial cable and the coaxial relay amplifier 3-1, ... The level of the measurement signal output to the measurement unit 43 is measured by the level measurement unit 43, and the result is stored in the storage unit 44 as measurement data B (f) (FIG. 4).
B).
【００１７】そして、記憶部４４から演算部４５へ校正
用データＡ（ｆ）および測定データＢ（ｆ）を送出し、
演算部４５において同軸中継増幅器３−ｎとヘッドエン
ド１出力との信号レベル偏差Ｔ（ｆ）をＴ（ｆ）＝Ｂ
（ｆ）−Ａ（ｆ）の式により算出し、その算出結果を記
憶部４４に出力して格納するとともに表示部４６に出力
して表示する（図４のｃ）。Then, calibration data A (f) and measurement data B (f) are sent from the storage unit 44 to the calculation unit 45,
In the calculation unit 45, the signal level deviation T (f) between the coaxial relay amplifier 3-n and the output of the head end 1 is calculated as T (f) = B.
It is calculated by the formula (f) -A (f), and the calculation result is output to and stored in the storage unit 44 and also displayed and output to the display unit 46 (c in FIG. 4).
【００１８】このようにして、下り伝送信号レベルＢ
（ｆ）およびそのレベル偏差Ｔ（ｆ）を測定することが
できるが、ここにおけるレベル偏差Ｔ（ｆ）とは、同軸
ケーブルの√ｆ損失特性にもとづく√ｆ偏差を意味す
る。In this way, the downlink transmission signal level B
Although (f) and its level deviation T (f) can be measured, the level deviation T (f) here means the √f deviation based on the √f loss characteristics of the coaxial cable.
【００１９】続いて、上り伝送信号レベルおよび上り伝
送帯域のレベル偏差を測定する方法は、以下のようにし
て実現する。測定受信部４の入出力端Ｚは同軸中継増幅
器３−ｎの入出力あるいはモニタ端Ｙに接続された状態
とする。測定受信部４の受信制御部４０内の切替スイッ
チを「ＯＮ」の状態にして周波数変換部４１を制御し、
周波数変換部４１からセンタ局への制御信号を出力し
て、その制御信号を方向性フィルタ４２を介して入出力
端Ｚから双方向ＣＡＴＶ伝送路の上り伝送帯域を通して
センタ局の測定送信部２へ送出して、その制御信号を測
定送信部２内の出入力端Ｗおよび方向性フィルタ２３を
介して送信制御部２０に入力する。この制御信号によっ
て送信制御部２０は、信号発生部２１を制御して信号発
生部２１が出力する信号発生帯域、つまり測定周波数信
号のスイープ幅をＡ（ｆ）から上り伝送帯域幅のＡ（ｆ
1 ）に制限する（図４のｄ）。このスイープ幅の制限に
よりＡ（ｆ1 ）の帯域に帯域制限された測定周波数信号
は、ＣＡＴＶ伝送路の下り伝送帯域および同軸中継増幅
器３−ｎのモニタ端Ｙと測定受信部４の入出力端Ｚおよ
び方向性フィルタ４２とを通してレベル測定部４３およ
び受信制御部４０にＢ（ｆ1 ）として入力される（図４
のｅ）。受信制御部４０は、内部の切替スイッチを「Ｏ
Ｎ」の状態でＢ（ｆ1 ）帯域の測定周波数信号を周波数
変換部４１へ出力し、周波数変換部４１において上り伝
送帯域の本来のＣＡＴＶ信号と同じレベルで上り伝送帯
域のＣ（ｆ0 ）に変換される（図４のｆ）。そして、Ｂ
（ｆ1 ）からＣ（ｆ0 ）に周波数変換された測定周波数
信号は、ＣＡＴＶ伝送路の上り伝送帯域を通してセンタ
局の測定送信部２にＤ（ｆ0 ）として入力され（図４の
ｇ）、測定送信部２の周波数変換部２２において下り伝
送帯域の本来のＣＡＴＶ信号と同じレベルで再び周波数
変換され（図４のｈ）て、ヘッドエンド１出力からＣＡ
ＴＶ伝送路の下り伝送帯域および同軸中継増幅器３−ｎ
を通して再び測定受信部４の入出力端Ｚおよび方向性フ
ィルタ４２を介してＥ（ｆ2 ）として入力され（図４の
ｈ）、受信制御部４０により再び制御されてレベル測定
部４３で測定され（図４のｉ）、測定データＦ（ｆ2 ）
として記憶部４４に格納される（図４のｉ）。そして、
記憶部４４から演算部４５に対して前回求めた偏差デー
タＴ（ｆ）と今回求めた測定データＦ（ｆ2 ）とを送出
して、演算部４５において所望の上り伝送帯域の信号レ
ベル偏差Ｒ（ｆ0 ）を、Ｒ（ｆ0 ）＝Ｆ（ｆ2 ）−Ｂ
（ｆ2 ）−Ｂ（ｆ1 ）−Ｔ（ｆ2 ）の式によって求め
る。ここで、ｆ0 は所望の上り伝送帯域の測定周波数、
およびｆ1 （ｆ2 ）は周波数変換前（後）の下り伝送帯
域の測定周波数である。そして、この式により算出した
Ｒ（ｆ0 ）の算出結果を演算部４５から表示部４６へ再
び送出して画面表示するとともに、記憶部４５へ上り帯
域偏差データＲ（ｆ0 ）として格納する。Subsequently, the method for measuring the level deviation of the upstream transmission signal level and the upstream transmission band is realized as follows. It is assumed that the input / output terminal Z of the measurement receiving section 4 is connected to the input / output of the coaxial relay amplifier 3-n or the monitor terminal Y. The changeover switch in the reception control unit 40 of the measurement reception unit 4 is set to the “ON” state to control the frequency conversion unit 41,
The frequency converter 41 outputs a control signal to the center station, and the control signal is transmitted from the input / output terminal Z through the directional filter 42 to the measurement transmitter 2 of the center station through the upstream transmission band of the bidirectional CATV transmission path. The signal is sent out and the control signal is input to the transmission controller 20 via the input / output terminal W in the measurement transmitter 2 and the directional filter 23. With this control signal, the transmission controller 20 controls the signal generator 21 to output the signal generation band output by the signal generator 21, that is, the sweep width of the measurement frequency signal from A (f) to the upstream transmission bandwidth A (f).
Limit to 1 ) (d in Fig. 4). The measurement frequency signal band-limited to the band A (f 1 ) due to the limitation of the sweep width is used for the downlink transmission band of the CATV transmission line, the monitor end Y of the coaxial relay amplifier 3-n, and the input / output end of the measurement receiving unit 4. It is input as B (f 1 ) to the level measurement unit 43 and the reception control unit 40 through the Z and the directional filter 42 (FIG. 4).
E). The reception control unit 40 sets the internal changeover switch to “O”.
In the state of “N”, the measured frequency signal in the B (f 1 ) band is output to the frequency conversion unit 41, and in the frequency conversion unit 41, C (f 0 ) in the upstream transmission band is at the same level as the original CATV signal in the upstream transmission band. Is converted to (f in FIG. 4). And B
The measurement frequency signal frequency-converted from (f 1 ) to C (f 0 ) is input as D (f 0 ) to the measurement transmission unit 2 of the center station through the upstream transmission band of the CATV transmission line (g in FIG. 4). The frequency conversion unit 22 of the measurement transmission unit 2 performs frequency conversion again at the same level as the original CATV signal in the downlink transmission band (h in FIG. 4), and outputs from the headend 1 output to CA.
Downstream transmission band of TV transmission path and coaxial relay amplifier 3-n
Is again input as E (f 2 ) via the input / output terminal Z of the measurement receiving unit 4 and the directional filter 42 (h in FIG. 4), is controlled again by the reception control unit 40, and is measured by the level measuring unit 43. (I in FIG. 4), measurement data F (f 2 )
Is stored in the storage unit 44 (i in FIG. 4). And
The deviation data T (f) obtained last time and the measurement data F (f 2 ) obtained this time are sent from the storage unit 44 to the calculation unit 45, and the calculation unit 45 outputs the signal level deviation R of the desired upstream transmission band. (F 0 ), R (f 0 ) = F (f 2 ) −B
It is calculated by the formula of (f 2 ) -B (f 1 ) -T (f 2 ). Here, f 0 is the measurement frequency of the desired upstream transmission band,
And f 1 (f 2 ) are measured frequencies in the downlink transmission band before (after) frequency conversion. Then, the calculation result of R (f 0 ) calculated by this equation is sent again from the calculation unit 45 to the display unit 46 to be displayed on the screen and stored in the storage unit 45 as the upstream band deviation data R (f 0 ).
【００２０】以上説明したように、最初に下り伝送帯域
の帯域内区間レベル偏差を測定し、次にセンタ局出力の
測定周波数信号を測定受信部４で周波数変換すること
と、下り伝送帯域の周波数特性偏差算出結果を利用する
ことにより、上り伝送帯域の周波数特性偏差をも自動的
に１つの同一測定系で得られるので、省力化を図ること
が出来る。また、本来テレビ信号レベルを読み取るのみ
のレベル測定と異なり、測定用信号の測定周波数間隔を
細かく設定することにより、よりきめ細かい伝送路のレ
ベルチェックが行える。さらに、記憶部４４への記憶デ
ータに種々の加工を施すことにより、伝送路品質の維持
および向上に有効に活用可能となる。尚、本発明は、同
軸中継増幅器により構成される双方向ＣＡＴＶ伝送路の
みならず、光同軸ハイブリッドシステムのような光系伝
送路を含む双方向ＣＡＴＶ伝送路等にも容易に適用可能
なことは改めて説明するまでもなく明らかである。ま
た、本発明を一実施例によってのみ説明したが、本発明
は本実施例のみに限定されず、本発明の趣旨を逸脱しな
い範囲内で種々の変更／変形が可能であるのは勿論であ
る。As described above, first, the in-band section level deviation of the downlink transmission band is measured, then the measurement frequency signal output from the center station is frequency-converted by the measurement receiving unit 4, and the frequency of the downlink transmission band is changed. By using the characteristic deviation calculation result, the frequency characteristic deviation in the upstream transmission band can be automatically obtained in one and the same measurement system, so that labor can be saved. Further, unlike the level measurement in which only the TV signal level is read, the level of the transmission line can be more finely checked by setting the measurement frequency interval of the measurement signal finely. Further, by applying various processing to the data stored in the storage unit 44, it becomes possible to effectively utilize the maintenance and improvement of the transmission path quality. The present invention can be easily applied not only to the bidirectional CATV transmission line configured by the coaxial relay amplifier, but also to the bidirectional CATV transmission line including the optical system transmission line such as the optical coaxial hybrid system. It is obvious without explaining again. Further, although the present invention has been described with reference to only one embodiment, the present invention is not limited to this embodiment, and it is needless to say that various modifications / variations can be made without departing from the spirit of the present invention. .
【００２１】[0021]
【発明の効果】以上説明したように本発明によれば、最
初に下り伝送帯域の区間レベル偏差を測定し、次にセン
タ局出力の測定周波数信号を測定受信部で周波数変換す
ることと、下り伝送帯域の周波数特性偏差算出結果を利
用することにより、上り伝送帯域の周波数特性偏差をも
自動的に１つの同一測定系で得られるので、設備および
測定人員の両方で省力化を図ることが可能となり、経済
的に非常に有利となる。As described above, according to the present invention, the section level deviation of the downlink transmission band is first measured, and then the measurement frequency signal output from the center station is frequency-converted by the measurement receiving section. By using the calculation result of the frequency characteristic deviation of the transmission band, the frequency characteristic deviation of the upstream transmission band can be automatically obtained with one and the same measurement system, so that both equipment and personnel can save labor. It becomes very economically advantageous.
【００２２】また本来のＣＡＴＶ信号のレベルを読みと
るだけのレベル測定と異なり、測定用信号の測定周波数
間隔を細かく設定することにより、より細かく伝送路の
レベルチェックが行える。さらに記憶データに種々の加
工を施すことにより、伝送路品質の維持，向上に有効に
活用可能となる。Further, unlike the level measurement in which the level of the original CATV signal is simply read, the level of the transmission line can be checked more finely by setting the measurement frequency interval of the measurement signal finely. Further, by applying various processing to the stored data, it becomes possible to effectively utilize for maintaining and improving the transmission line quality.
【図１】本発明の一実施例を示すＣＡＴＶ伝送路のレベ
ル測定方式を示す系統図である。FIG. 1 is a system diagram showing a level measurement system of a CATV transmission line showing an embodiment of the present invention.
【図２】同実施例の測定送信部を示すブロック図であ
る。FIG. 2 is a block diagram showing a measurement transmission unit of the same embodiment.
【図３】同実施例の測定受信部を示すブロック図であ
る。FIG. 3 is a block diagram showing a measurement receiving unit of the embodiment.
【図４】同実施例のＣＡＴＶ伝送路のレベル測定に用い
る測定用信号の一例である。FIG. 4 is an example of a measurement signal used for measuring the level of the CATV transmission line of the embodiment.
【図５】同実施例のＣＡＴＶ伝送路のレベル測定に用い
る測定用信号の流れ図の一例である。FIG. 5 is an example of a flow chart of a measurement signal used for measuring the level of the CATV transmission line of the embodiment.
【図６】第２の従来例を示すブロック図である。FIG. 6 is a block diagram showing a second conventional example.
１ ヘッドエンド ２ 測定送信部 ３−１〜３−ｎ 同軸中継増幅器 ４ 測定受信部 ２０ 送信制御部 ２１ 信号発生部 ２２ 周波数変換部 ２３ 方向性フィルタ ４０ 受信制御部 ４１ 周波数変換部 ４２ 方向性フィルタ ４３ レベル測定部 ４４ 記憶部 ４５ 演算部 ４６ 表示部 Ｗ 出入力端 Ｘ，Ｙ モニタ端 Ｚ 入出力端 1 Headend 2 Measurement transmission part 3-1 to 3-n Coaxial relay amplifier 4 Measurement reception part 20 Transmission control part 21 Signal generation part 22 Frequency conversion part 23 Directional filter 40 Reception control part 41 Frequency conversion part 42 Directional filter 43 Level measurement unit 44 Storage unit 45 Calculation unit 46 Display unit W I / O terminal X, Y monitor terminal Z I / O terminal
Claims (3)
ールド側へ双方向ＣＡＴＶ伝送路上に中継増幅器が複数
接続される双方向ＣＡＴＶ伝送システムにおいて、 前記センタ側に前記双方向ＣＡＴＶ伝送路の下り伝送帯
域幅の第１の測定周波数信号をスイープ発生して前記双
方向ＣＡＴＶ伝送路の下り伝送帯域を通して前記フィー
ルド側へ送出する信号発生手段と、 前記信号発生手段出力の前記第１の測定周波数信号のレ
ベルを測定して第１のレベル特性として記憶するととも
に前記双方向ＣＡＴＶ伝送路の下り伝送帯域を通して伝
送された前記センタ側信号発生手段送出の前記第１の測
定周波信号のレベルを前記フィールド側の所定の測定ポ
イントで測定して第２のレベル特性として記憶するレベ
ル測定記憶手段と、 前記レベル測定記憶手段における前記第１のレベル特性
と前記第２のレベル特性とから双方のレベル特性差を算
出して前記下り伝送帯域のレベル特性偏差を求めるレベ
ル偏差算出手段と、 を備えることを特徴とするＣＡＴＶ伝送路のレベル測定
方式。1. A bidirectional CATV transmission system in which a plurality of relay amplifiers are connected on a bidirectional CATV transmission line from a center side having a head end to a field side, wherein a downlink transmission bandwidth of the bidirectional CATV transmission line is provided on the center side. The signal generating means for sweep-generating the first measured frequency signal and sending it to the field side through the downlink transmission band of the bidirectional CATV transmission line; and the level of the first measured frequency signal output from the signal generating means. The level of the first measured frequency signal sent from the center side signal generating means, which is measured and stored as the first level characteristic and transmitted through the downlink transmission band of the bidirectional CATV transmission line, is set to a predetermined value on the field side. Level measurement storage means for measuring at a measurement point and storing it as a second level characteristic; A level deviation calculating means for calculating a level characteristic difference between the first level characteristic and the second level characteristic in the stage to obtain a level characteristic deviation of the downlink transmission band, and a CATV. Transmission line level measurement method.
が第１の制御信号に制御されて前記第１の制御信号に制
御される以前に出力していた前記第１の測定周波信号の
下り伝送帯域幅のスイープ幅を前記双方向ＣＡＴＶ伝送
路の上り伝送帯域幅に制限して第２の測定周波数信号と
して前記下り伝送帯域内の所定の第１の周波数帯を通し
て前記フィールド側へ送出し、 前記フィールド側の前記所定の測定ポイントにおいて、
前記レベル測定記憶手段が前記第２の測定周波信号のレ
ベルを測定して第３のレベル特性として記憶し、 前記フィールド側に、前記第２の測定周波数信号を前記
双方向ＣＡＴＶ伝送路の前記上り伝送帯域に周波数変換
して第３の測定周波数信号として出力し前記ＣＡＴＶ伝
送路の前記上り伝送帯域を通して前記センタ側へ返送す
るフィールド側周波数変換手段を備え、 前記センタ側に、前記ＣＡＴＶ伝送路の前記上り伝送帯
域を通して前記フィールド側周波数変換手段から返送さ
れた前記第３の測定周波信号を前記双方向ＣＡＴＶ伝送
路の前記下り伝送帯域内の所定の第２の周波数帯に周波
数変換して第４の測定周波数信号として出力し前記下り
伝送帯域の前記第２の周波数帯を通して再び前記フィー
ルド側へ送出するセンタ側周波数変換手段を備え、 前記フィールド側の前記所定の測定ポイントにおいて、
前記レベル測定手段が前記第４の測定周波信号のレベル
を測定して第４のレベル特性として記憶し、 前記レベル偏差算出手段が、前記レベル測定記憶手段に
おける前記第３のレベル特性と前記第４のレベル特性と
から双方のレベル特性差を算出して第５のレベル特性を
求めかつ前記レベル測定記憶手段における前記第２のレ
ベル特性の中の前記第４のレベル特性帯域に相当するレ
ベル特性と前記第５のレベル特性とから双方のレベル特
性差を算出することにより前記双方向ＣＡＴＶ伝送路の
前記上り伝送帯域のレベル特性偏差を求めることを特徴
とする請求項１記載のＣＡＴＶ伝送路のレベル測定方
式。2. The downlink transmission band of the first measurement frequency signal output before the signal generating means on the center side is controlled by the first control signal and controlled by the first control signal. The sweep width of the width is limited to the upstream transmission bandwidth of the bidirectional CATV transmission line, and the second measurement frequency signal is transmitted to the field side through a predetermined first frequency band within the downstream transmission band, At the predetermined measurement point on the side,
The level measurement storage means measures the level of the second measurement frequency signal and stores it as a third level characteristic, and the second measurement frequency signal is provided on the field side to the upstream of the bidirectional CATV transmission line. Field side frequency conversion means for frequency-converting to a transmission band and outputting as a third measurement frequency signal and returning to the center side through the upstream transmission band of the CATV transmission line is provided, and the center side of the CATV transmission line is provided. The third measurement frequency signal returned from the field-side frequency conversion means through the upstream transmission band is frequency-converted into a predetermined second frequency band within the downstream transmission band of the bidirectional CATV transmission line, and a fourth frequency band is obtained. Center side frequency conversion for outputting as the measured frequency signal of and transmitting again to the field side through the second frequency band of the downlink transmission band. It comprises a stage, at the predetermined measurement point of the field side,
The level measuring means measures the level of the fourth measured frequency signal and stores it as a fourth level characteristic, and the level deviation calculating means stores the third level characteristic and the fourth level characteristic in the level measurement storing means. And the level characteristic corresponding to the fourth level characteristic band in the second level characteristic in the level measurement storage means. The level characteristic deviation of the CATV transmission line according to claim 1, wherein a level characteristic deviation of the upstream transmission band of the bidirectional CATV transmission line is obtained by calculating a level characteristic difference between the fifth level characteristic and the fifth level characteristic. Measurement method.
双方向ＣＡＴＶ伝送路の前記下り伝送帯域のレベル特性
偏差および前記上り伝送帯域のレベル特性偏差を表示あ
るいは記録する手段を有することを特徴とする請求項１
または２記載のＣＡＴＶ伝送路のレベル測定方式。3. A means for displaying or recording the level characteristic deviation of the downlink transmission band and the level characteristic deviation of the upstream transmission band of the bidirectional CATV transmission path calculated by the level deviation calculating means. Claim 1
Alternatively, the CATV transmission line level measurement method described in 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8150830A JP2944514B2 (en) | 1996-06-12 | 1996-06-12 | CATV transmission line level measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8150830A JP2944514B2 (en) | 1996-06-12 | 1996-06-12 | CATV transmission line level measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09331515A true JPH09331515A (en) | 1997-12-22 |
| JP2944514B2 JP2944514B2 (en) | 1999-09-06 |
Family
ID=15505329
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8150830A Expired - Lifetime JP2944514B2 (en) | 1996-06-12 | 1996-06-12 | CATV transmission line level measurement method |
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| Country | Link |
|---|---|
| JP (1) | JP2944514B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007201584A (en) * | 2006-01-24 | 2007-08-09 | Dx Antenna Co Ltd | Amplifier for community receiving system |
-
1996
- 1996-06-12 JP JP8150830A patent/JP2944514B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007201584A (en) * | 2006-01-24 | 2007-08-09 | Dx Antenna Co Ltd | Amplifier for community receiving system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2944514B2 (en) | 1999-09-06 |
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