JPH0122894B2 - - Google Patents
Info
- Publication number
- JPH0122894B2 JPH0122894B2 JP10755680A JP10755680A JPH0122894B2 JP H0122894 B2 JPH0122894 B2 JP H0122894B2 JP 10755680 A JP10755680 A JP 10755680A JP 10755680 A JP10755680 A JP 10755680A JP H0122894 B2 JPH0122894 B2 JP H0122894B2
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- output
- optical cable
- measured
- converter
- 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.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 claims description 30
- 230000005540 biological transmission Effects 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 3
- 238000012360 testing method Methods 0.000 description 9
- 238000005259 measurement Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 5
- 238000009434 installation Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000004393 prognosis Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Description
【発明の詳細な説明】
本発明は通信用光ケーブルのベースバンド伝送
特性の測定を行う装置に関する。特に、光ケーブ
ルを布設した後に、遠く分離された両端の間で試
験を行うために適する測定装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring baseband transmission characteristics of optical communication cables. In particular, the present invention relates to a measuring device suitable for performing tests between far separated ends of an optical cable after it has been installed.
光ケーブルの布設前に、光ケーブルの両端が極
く近傍にあり、測定装置の送信側装置と受信側装
置が抵抗減衰器等の安定な測定基準で直結できる
ときには、その光ケーブルの伝送特性をその測定
基準と比較することにより、高精度に測定するこ
とができる。しかし、光ケーブルが布設され、両
端が数Kmないし数＋Km離れた場合には、比較基準
を設定することができないので、送信側装置の信
号レベルおよび受信側装置の信号レベルの絶対値
を正しく設定あるいは測定しなければならない。 Before installing an optical cable, if both ends of the optical cable are in close proximity and the transmitting and receiving devices of the measurement device can be directly connected using a stable measurement standard such as a resistive attenuator, the transmission characteristics of the optical cable should be determined by that measurement standard. By comparing with , it is possible to measure with high accuracy. However, when an optical cable is installed and both ends are separated by several kilometers or several + kilometers, it is not possible to set a comparison standard, so the absolute values of the signal level of the transmitting side device and the signal level of the receiving side device must be set correctly or Must be measured.
さらに、両端が離れている場合には、送信側装
置から送られている周波数を受信側装置が知るた
めに、同期信号等の送受が必要であり、このため
に被測定光ケーブルに並行して何らかの電気信号
を伝送するためのケーブルが必要になる。 Furthermore, if the two ends are far apart, it is necessary to send and receive synchronization signals, etc. in order for the receiving device to know the frequency being sent from the transmitting device, and for this reason, it is necessary to send and receive a synchronization signal etc. in parallel to the optical cable under test. A cable is required to transmit electrical signals.
このため従来装置は、絶対精度を備えた大がか
りなものであり、また同期信号の送受のために介
在線等を利用するように構成されている。さら
に、従来装置では測定の間に両端の操作者が相互
に電話連絡が可能であることが必要とされてい
る。 For this reason, conventional devices are large-scale devices that require absolute accuracy, and are configured to utilize intervening lines or the like for transmitting and receiving synchronization signals. Additionally, conventional devices require that operators at both ends be able to communicate by telephone between measurements.
本発明はこれを改良するもので、布設後の光ケ
ーブルの特性を簡便に精度よく測定することがで
き、同期信号等の別信号の送受が不要であり、原
則的に両端の操作者の電話連絡を必要としない装
置を提供することを目的とする。 The present invention improves on this by making it possible to easily and accurately measure the characteristics of an optical cable after it has been laid, eliminating the need for transmitting and receiving separate signals such as synchronization signals, and basically allowing operators at both ends to contact each other by telephone. The purpose is to provide a device that does not require
光ケーブルのベースバンド周波数特性は、原則
的にベースバンド周波数（変調周波数）の定数乗
に比例する特性であり、この単位長さ当りの特性
はケーブルの種類、光信号波長等によりほぼ定ま
つている。このような光ケーブルは布設によつて
そのベースバンド特性が大きく変化することがな
い。布設により切断または接続等が行われ、長さ
が変化することは考えられるが、基本的な特性に
は変化がない。 The baseband frequency characteristics of optical cables are, in principle, proportional to the baseband frequency (modulation frequency) raised to the power of a constant, and these characteristics per unit length are approximately determined by the cable type, optical signal wavelength, etc. . The baseband characteristics of such optical cables do not change significantly due to installation. Although it is conceivable that the length may change due to cutting or connection during installation, the basic characteristics remain unchanged.
従つて、布設完予後の試験に際しては、ベース
バンド周波数の広範囲にわたつて、多数の周波数
点について測定することは必ずしも必要でなく、
ごく少数の周波数について測定すれば十分にその
特性を知ることができる。特に、特定のケーブル
の種類、光信号波長が定められているときには、
２点の周波数について伝送特性を測定すれば、こ
れにより全体の特性を正しく推測することがで
き、実用上何ら問題がない。 Therefore, when testing the prognosis of installation completion, it is not necessarily necessary to measure at many frequency points over a wide range of baseband frequencies;
Measuring a very small number of frequencies is sufficient to understand its characteristics. Especially when a specific cable type and optical signal wavelength are specified,
If the transmission characteristics are measured at two frequencies, the overall characteristics can be estimated correctly, and there is no problem in practical use.
発明者らは、布設された多数の光ケーブルにつ
いて試験を行い、２点の周波数のみにより伝送特
性を測定しても、布設後のケーブル試験として十
分であることを確めた。 The inventors conducted tests on a large number of installed optical cables and confirmed that measuring the transmission characteristics using only two frequencies is sufficient for cable testing after installation.
本発明はこのような原理に基づくものであつ
て、送信側装置には、あらかじめ定められた２個
の被測定ベースバンド周波数を自動的に交互に切
替えて送出する発振器と、この発振器の出力を変
調入力とし出力光が被測定光ケーブルに接続され
る電気光変換器とを備え、受信側装置には、被測
定光ケーブルの出力光を入力としその出力光を復
調して上記２個の被測定ベースバンド周波数の出
力信号を得る光電気変換器と、この出力信号を１
個の中間周波数に変換する周波数変換器と、この
周波数変換器の出力に得られる前記中間周波数信
号のレベルを検出する検波器と、この検波器出力
を取込み演算処理する演算器とを備えた構成を特
徴とする。 The present invention is based on such a principle, and the transmitting side device includes an oscillator that automatically switches and transmits two predetermined baseband frequencies to be measured, and an output of this oscillator. It is equipped with an electro-optic converter whose output light is connected to the optical cable under test as a modulation input, and the receiving side device receives the output light of the optical cable under test as input, demodulates the output light, and transmits the output light to the two bases under test. A photoelectric converter that obtains an output signal of a band frequency, and a
A configuration comprising: a frequency converter that converts the intermediate frequency into a frequency converter; a detector that detects the level of the intermediate frequency signal obtained at the output of the frequency converter; and a calculator that receives and processes the output of the detector. It is characterized by
実施例図面により詳しく説明する。 This will be explained in detail with reference to the drawings.
第１図は本発明実施例装置構成図である。この
図で、１は送信側装置、２は被測定光ケーブル、
３は受信側装置である。送信側装置１には、ベー
スバンド周波数内にあらかじめ定められた周波数
f1、f2を発生する発振器１１，１２と、この出力
を切替えて送出する切替器１３と、この出力を変
調入力とする電気光変換器１４と、上記切替器を
駆動する切替信号発生器１５とを含む。また、受
信側装置３には、光ケーブル２の出力光を入力と
しこれを復調する光電気変換器３１と、（f1＋
f2）／２なる周波数を発生する局部発振器３２
と、光電気変換器３１の出力と局部発振器３２の
出力とを混合して周波数変換を行う混合器３３
と、この出力を検波する検波器３４と、この出力
を演算処理する演算器３５と、この出力を表示す
る表示器３６とを含む。 FIG. 1 is a diagram showing the configuration of an apparatus according to an embodiment of the present invention. In this figure, 1 is the transmitting side device, 2 is the optical cable to be measured,
3 is a receiving side device. The transmitting device 1 has a predetermined frequency within the baseband frequency.
Oscillators 11 and 12 that generate f 1 and f 2 , a switch 13 that switches and sends out the output, an electro-optical converter 14 that uses this output as a modulation input, and a switching signal generator that drives the switch. 15. The receiving device 3 also includes a photoelectric converter 31 that inputs the output light of the optical cable 2 and demodulates it, and (f 1 +
A local oscillator 32 that generates a frequency of f 2 )/2
and a mixer 33 that performs frequency conversion by mixing the output of the opto-electrical converter 31 and the output of the local oscillator 32.
, a detector 34 that detects this output, an arithmetic unit 35 that processes this output, and a display 36 that displays this output.
このように構成された装置の動作を説明する。
第２図は第１図に×印で示す点の信号波形図であ
る。すなわち、切替信号発生器１５は、第２図ａ
に示すように、一定周期の繰返し方形波を送出
し、これにより切替器１３が動作して、切替器１
３の出力には第２図ｂに示すように、周波数f1と
f2が交互に等しい間隔で現われる。これが電気光
変換器１４で光信号に変調されて、被測定光ケー
ブル２に送出される。 The operation of the device configured in this way will be explained.
FIG. 2 is a signal waveform diagram at the points indicated by x marks in FIG. 1. That is, the switching signal generator 15 operates as shown in FIG.
As shown in FIG.
As shown in Figure 2b, the output of 3 has frequencies f 1 and
f 2 appear alternately at equal intervals. This is modulated into an optical signal by the electro-optic converter 14 and sent to the optical cable 2 to be measured.
受信側装置では、光電気変換器３１の出力に現
われる周波数f1、f2を混合器３３で１個の中間周
波数に変換する。すなわち、周波数f1に対しては
f1＋f2／２−f1＝f2−f1／２
であり、また周波数f2に対しては
f2−f1＋f2／２＝f2−f1／２
であつて、いずれも等しい中間周波数
f2−f1／２
が得られる。この中間周波数の信号は検波器３４
で検波され、第２図ｃに示す信号を得る。すなわ
ち、周波数f1の受信レベルはL1であり、周波数f2
の受信レベルはL2である。この第２図ｃに示す
信号は演算器３５に取込まれ演算される。 In the receiving side device, the frequencies f 1 and f 2 appearing in the output of the opto-electrical converter 31 are converted into one intermediate frequency by a mixer 33 . That is, for frequency f 1 , f 1 + f 2 /2 − f 1 = f 2 − f 1 /2, and for frequency f 2 , f 2 − f 1 + f 2 /2 = f 2 − f 1 /2 and an equal intermediate frequency f 2 −f 1 /2 is obtained. This intermediate frequency signal is transmitted to the detector 34.
The signal shown in FIG. 2c is obtained. That is, the reception level at frequency f 1 is L 1 , and at frequency f 2
The reception level of is L2 . The signal shown in FIG. 2c is taken into the computing unit 35 and computed.
第３図に光ケーブルのベースバンド損失周波数
特性の一例を示す。いま、一例として被測定光ケ
ーブルがこのケーブルであつて、周波数f1が
175MHz、f2が300MHzであるとする。この光ケー
ブルの基本的な損失特性が周波数ｆに対して
Ｌ＝f〓 但しαは定数
であることがわかつていれば、２つの特定の周波
数f1、f2を測定しそのときの損失を知れば、ほぼ
この全特性を相当程度正確に知ることができる。
演算器３５はこの演算処理を行う。 FIG. 3 shows an example of the baseband loss frequency characteristics of an optical cable. As an example, if the optical cable to be measured is this cable, and the frequency f 1 is
Suppose it is 175MHz and f2 is 300MHz. The basic loss characteristics of this optical cable are as follows for frequency f: L=f〓 However, if we know that α is a constant, we can measure two specific frequencies f 1 and f 2 and find out the loss at that time. If so, almost all of these characteristics can be known with considerable accuracy.
The arithmetic unit 35 performs this arithmetic processing.
最も簡単な一例として、演算器３５は単に
L1−L2
を演算するのみであり、これによつて第３図のよ
うな曲線を標定することができる。このとき表示
器３６にはこの差の値を表示する。 In the simplest example, the calculator 35 simply calculates L 1 -L 2 , and thereby a curve as shown in FIG. 3 can be located. At this time, the value of this difference is displayed on the display 36.
この２つのレベル差を演算する場合には、送信
側装置１および受信側装置３で、それぞれ絶対レ
ベル較正を厳しく行う必要がない。すなわち、実
際に伝送された２つの信号の差を求めるのである
から、その回路が同一であればその絶対レベルを
知らなくとも、差を精度よく求めることは可能で
ある。 When calculating the difference between these two levels, it is not necessary to strictly perform absolute level calibration in the transmitting side device 1 and the receiving side device 3, respectively. That is, since the difference between two actually transmitted signals is determined, if the circuits are the same, it is possible to accurately determine the difference without knowing their absolute levels.
演算器３５の構成は、その目的によりさまざま
に構成することができる。マイクロプロセツサに
よりこれを構成し、いくつかの光ケーブルの基本
的特性を記憶させ、測定結果から全体の特性を演
算推定させることができる。 The configuration of the computing unit 35 can be variously configured depending on its purpose. It can be configured with a microprocessor, store some basic characteristics of the optical cable, and calculate and estimate the overall characteristics from the measurement results.
以上説明したように本発明によれば、測定周波
数を２周波のみとして、装置を極めて簡単化する
ことができる。送信側装置で自動的に周波数を切
替えて送信し、これに受信側で同期をとる必要が
ないので、同期信号の伝送が不要である。上記２
周波の差をとる場合には、装置の絶対較正が不要
であり、さらに装置の構成および取扱いを簡略化
することができる。また、送信側装置は被測定光
ケーブルにその出力を単に接続しておけば十分で
あり、両端の操作者の間で原則的に電話による打
合せを必要としないで測定を行うことができる。
本発明の装置により得られた測定結果は、実際の
光ケーブルの試験に十分な程度の精度を備えてい
る。 As explained above, according to the present invention, the measurement frequency can be set to only two frequencies, and the apparatus can be extremely simplified. Since there is no need for the transmitting side device to automatically switch the frequency and transmit, and for the receiving side to synchronize with this, there is no need to transmit a synchronization signal. Above 2
When taking the frequency difference, absolute calibration of the device is not required, and furthermore, the configuration and handling of the device can be simplified. Furthermore, it is sufficient for the transmitting side device to simply connect its output to the optical cable to be measured, and measurements can be carried out without the need for a telephone discussion between operators at both ends in principle.
The measurement results obtained by the apparatus of the present invention have sufficient accuracy for testing actual optical cables.
第１図は本発明実施例装置の構成図。第２図は
その動作説明用波形図。第３図は光ケーブルのベ
ースバンド損失周波数特性の一例を示す図。
１……送信側装置、２……被測定光ケーブル、
３……受信側装置、１１，１２……発振器、１３
……切替器、１４……電気光変換器、１５……切
替信号発生器、３１……光電気変換器、３２……
局部発振器、３３……混合器、３４……検波器、
３５……演算器、３６……表示器。
FIG. 1 is a configuration diagram of an apparatus according to an embodiment of the present invention. FIG. 2 is a waveform diagram for explaining the operation. FIG. 3 is a diagram showing an example of baseband loss frequency characteristics of an optical cable. 1... Sending side device, 2... Optical cable to be measured,
3... Receiving side device, 11, 12... Oscillator, 13
...Switcher, 14...Electro-optical converter, 15...Switching signal generator, 31...Opto-electrical converter, 32...
Local oscillator, 33... mixer, 34... detector,
35...Arithmetic unit, 36...Display unit.
Claims (1)
ンド周波数を自動的に交互に切替えて送出する発
振器と、この発振器の出力を変調入力とし出力光
が被測定光ケーブルに接続される電気光変換器と
を送信側装置に備え、被測定光ケーブルの出力光
を入力としその出力光を復調して上記２個の被測
定ベースバンド周波数の出力信号を得る光電気変
換器と、この出力信号を１個の中間周波数に変換
する周波数変換器と、この周波数変換器の出力に
得られる前記中間周波数信号のレベルを検出する
検波器と、この検波器出力を取込み演算処理する
演算器とを受信側装置に備えた光ケーブル伝送特
性測定装置。1. An oscillator that automatically switches and transmits two predetermined baseband frequencies to be measured, and an electro-optic converter whose output light is connected to the optical cable to be measured using the output of this oscillator as a modulation input. The transmitting side device is equipped with an opto-electrical converter that inputs the output light of the optical cable to be measured and demodulates the output light to obtain output signals of the two baseband frequencies to be measured, and converts this output signal into one intermediate The receiving side device is equipped with a frequency converter that converts the frequency into a frequency, a detector that detects the level of the intermediate frequency signal obtained as the output of the frequency converter, and an arithmetic unit that receives and processes the output of the detector. Optical cable transmission characteristics measuring device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10755680A JPS5730925A (en) | 1980-08-04 | 1980-08-04 | Device for measuring optical cable transmission characteristics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10755680A JPS5730925A (en) | 1980-08-04 | 1980-08-04 | Device for measuring optical cable transmission characteristics |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5730925A JPS5730925A (en) | 1982-02-19 |
| JPH0122894B2 true JPH0122894B2 (en) | 1989-04-28 |
Family
ID=14462170
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10755680A Granted JPS5730925A (en) | 1980-08-04 | 1980-08-04 | Device for measuring optical cable transmission characteristics |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5730925A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60115818A (en) * | 1983-10-31 | 1985-06-22 | Fujitsu Ltd | Measuring device of wavelength dispersion coefficient |
| JP2002541474A (en) * | 1999-04-09 | 2002-12-03 | コーニング・インコーポレーテッド | Optical fiber characteristics measurement device |
-
1980
- 1980-08-04 JP JP10755680A patent/JPS5730925A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5730925A (en) | 1982-02-19 |
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