JPS60227148A - Measuring method of wave motion transmission parameter - Google Patents

Abstract

PURPOSE:To simplify measurement procedure, and to perform data processing and to use a nonreflection type as a wave source and a detector by allowing a reflection coefficient measuring instrument to function as a detector for a transmitted wave. CONSTITUTION:The wave source 4 of a reflection coefficient measuring instrument 7 is turned on and the wave source 11 of a reflection coefficient measuring instrument 14 is turned off. The reflected wave indicator 6 of measuring instrument 7 indicates a reflection coefficient u1 when a component side is viewed from an input surface 1 through a directional coupler 5. Further, the measuring instrument 14 functions as the detector for a transmitted wave because the wave source 11 is off, and a reflected wave indicator 13 indicates a transmission coefficient I2. Then, the wave source 4 is turned off and the wave source 11 is turned on; the reflection coefficient measuring instrument 14 indicates a reflection coefficient u2 when a component 3 to be measured is viewed from the input surface 2 and the measuring instrument 7 indicates a reflection coefficient I1. Then the component 3 is removed and only the wave source 4 or 7 is turned on, and then the measuring instruments 6 and 14 indicate a reflection coefficient to the other measuring instrument and detection outputs to light from the wave sources 11 and 4. Those data are processed to measure the transmission parameter of wave motion.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention accurately measures the transmission characteristics of components that transmit waves such as magnetic waves and elastic waves by simultaneously using two reflection coefficient measuring instruments. The present invention relates to a method for measuring wave transmission parameters that enables the measurement of wave transmission parameters.

[Prior art]

The transmission characteristics of components that have one input and output surface (or input and output terminal), such as attenuators and transmission line connectors, are as shown in Figure 1 at surface (input surface in this case) 1. The wave p1 entering the part to be measured 3 and the wave coming out of the part to be measured 3 41% plane (output plane in this case) 2 of the part to be measured 3
There are four transmission parameters a11+al! representing the relationship between the wave p2 entering the component and the wave q exiting the component under test 3. +at
It is expressed as tl att as follows.

Q+ = act p+ + ass I)tQ! ”
act I)+ 10a2e I)tHowever, atzau
is a wave attenuator, and a11+at2 is a transmission parameter representing the amount of reflection.

Waves are coherently left (like microwaves and ultrasound waves)
In the case of a wave with one town interference), in general, p++q++pv+
Ch is expressed by amplitude and phase, and transmission parameter all+
aH+ a211 a21 is a complex number. On the other hand, waves are incoherent (non-coherent) like white light.
In the case of a wave, it is convenient to calculate pH+ q'+ + p2"+ Qt with the wave nokwa, and the above transmission parameter aII r 'I+t + at+ + "
22 f1 Positive Real 5 and Solving 0 A typical and important transmission of incoherent waves is optical transmission using a light emitting diode or a laser diode with a wide spectrum width as a light source.

Currently, methods for accurately measuring transmission parameters include:
Applicable only to network 7Nara for microwaves. A special method for accurately measuring the transmission parameters of incoherent transmission has not yet been developed, but the method shown in Figure 2 (a) to (f) is considered to be a suitable method at 0°C. In other words, as shown in Fig. 2(a), a non-reflection load 9 that does not reflect waves is placed on the output side of the component to be measured 3, and a wave source 4 is placed on the input side.
．． A reflection coefficient measuring device 7 consisting of a directional coupler 51 and a reflected wave indicator 6 is placed. At this time, the reflection coefficient measuring device 7 is ideal, and the reflected wave indicator 6 accurately measures the reflection coefficient q, /
If p, + are designated, the designated value Q+/p+ will be equal to the transmission parameter all.

Next, as shown in FIG. 2(b), a non-reflection wave source 4 is placed on the input side, and a non-reflection detector 10 for measuring the transmitted wave is placed on the output side.
put At this time, the non-reflection detector 100 and the reflected wave indicator 8
Suppose that indicates I.

Thereafter, as shown in FIG. 2(C), the part to be measured 3 is removed, and the waves from the non-reflection wave source 4 are directly input to the non-reflection detector 10. At this time, the reflected wave indicator 8 of the non-reflection detector 10
Suppose that the command indicates I+. If the non-reflection detector 10 is ideal and indicates a value proportional to the power q of the wave entering it, then the ratio between ■ and IL is I, /
I', becomes equal to the transmission parameter a2□.

By exchanging the input and output sides, the transmission parameter at2 can be measured as shown in FIG. 2(d), and the transmission parameter a12 can be measured as shown in FIGS. 2(c) and 2(f).

The drawbacks of the above measurement methods are as follows.

(11) It is difficult to realize a reflection-free wave source 4 and a reflection-free detector 10.

(2) The part to be measured 3 and the measuring device are often attached and detached.

(3) Above +11. (21 also increases the sources of error.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the direct measurement method described above, and by making the reflection coefficient measuring device also function as a transmitted wave detector, it simplifies the measurement procedure and further improves the data It is processed so that the wave source and detector do not need to be non-reflective. This invention will be described below. ◎ [Embodiment of the invention] FIGS. 3(a) and 3(b) show an embodiment of the invention. Reference numerals 1 to 7 are the same as those shown in FIGS. 1 and 2, 11 is a wave source, 12 is a directional coupler, and 13 is a reflected wave indicator, and these constitute the reflection coefficient measuring device 14. has been done.

In this configuration, the reflection coefficient measuring devices 7 and 14 are simultaneously connected to the input and output sides of the component to be measured 3, as shown in FIG. 3(a). In this state, first, the wave source 4 of the reflection coefficient measuring instrument T is brought into an operating state (ON state), and the wave source 11 of the reflection coefficient measuring instrument 14 is brought into a non-operating state (OFF state). This way,
The reflection coefficient measuring device 70 reflected wave indicator 6 has a surface (input surface) 1
Specify the reflection coefficient u1 as viewed from the component side. In addition, since the wave source 11 of the reflection coefficient measuring device 14 is in the OFF state,
It simply functions as a detector of transmitted waves. In this state, the indicated value of the reflected wave indicator 13 is assumed to be I.

Next, when the wave source 4 is turned OFF and the wave source 11 is turned ON, the surface 2 becomes the human power surface and the surface 1 becomes the output surface, and the reflection coefficient measuring device 140 and the reflected wave indicator 13 become the (input surface) 2. The reflection coefficient U when looking at the part to be measured 3 is indicated. on the other hand,
Since the wave source 4 is in the OFF state, the reflection coefficient measuring device 1 functions as a detector. Indication ll of the reflected wave indicator 6 at this time
l! 1. shall be.

After recording each of the above indicated values I, , I, '&,
), remove the part to be measured 3 and set the wave source 4 as '1'.
: Functions, and the reflected wave indicator 6 indicates the reflection coefficient v2 when looking at the reflection coefficient measuring device 14 from the surface (manual surface) 2. The indicated value of the reflected wave indicator 13 in this state is assumed to be II.

Next, when the wave source 4 is turned OFF and the wave source 11 is turned ON, the reflected wave indicator 13 indicates the reflection coefficient v1 seen from the output surface 1 to the reflection coefficient measuring device 7. Calculate the indicated value of the reflected wave indicator 6 in this state.

shall be.

As a result of the above, the obtained 8 takes ui t 11+u
The following relationship exists between 2+I 21 Vtr I' and +Vll ll.

That is, for the part to be measured 3, since the wave sources 4, 11 and the reflection coefficient measuring devices 7, 14 which function as detectors are not reflection-free, ul l ul l It/I;, 1. /
I; is the direct transmission parameter a11+ at2r JI+
It is not equal to alt, and the relationships are as shown in equations (1) to (4).

However, the transmission parameter aIII a12+ 8211
322 can be obtained as follows by solving the equations +11 to (4) as simultaneous equations.

・・・・・・・・・(7) Since there is no noise, it can be applied to both coherent transmission and incoherent transmission. This is effective for transmission systems using multimode optical fibers for which there is no accurate measurement method. Therefore, we will specifically take up an optical attenuator for multimode optical fiber as provisional measurement component 3. Since the quantity A'' I Olog a2+ (in dB) is the most important, let us consider the case where we want to accurately measure A. .For multimode optical fiber transmission,
The source reflects about 10% of the light power, and the detector reflects about 4% of the light power. Furthermore, the attenuator itself often has a reflection of about 6%.

When these reflections cause spinal pressure, how much error will occur if attenuator A is installed using the 1α direct method shown in Figure 2?
) formula ~tp, Figure 4 shows the results of a theoretical evaluation based on formula (a). Here, the reason why the error shows a negative value is because the direct method shown in Figure 2 measures the attenuation smaller than the true value (i.e., so that the mounting is not large). This clearly shows the problems with the direct method shown in Figure 2.

In a graded optical fiber transmission system with a core diameter of 50 μm and a cladding diameter of 125 μm, the wave source is 4°11 and 0.
A reflection coefficient measuring device 7 consisting of an 85 μm laser diode, a directional coupler 5.12 using a semi-transparent mirror, and a reflected wave indicator 6.13 using a silicon PIN photodiode.
FIG. 5 shows the results of determining 6i11 using the method of this invention using two 14 units.

Here, the attenuation of the component under test 3 can be varied continuously from OdB to 10dB, and the large loss at OdB is approximately 1
．． It is a 5dB optical attenuator. This variable optical attenuator emits light into space from the end face of an optical fiber, and attenuates the transmitted light by reflecting the light in different directions at an angle to a semi-transparent mirror. +4 optical fiber
Light inside 41. <It is of structure.

Therefore, when the amount of attenuation is small, the reflected light from the output side tends to return to the input side, and the transmission parameter aIII
a22 becomes large' (small in dB display). on the other hand,
As the amount of summer attenuation increases, it becomes difficult for the reflected light from the output side to return to the input side, so the transmission parameter all 812 becomes smaller, but since the amount of light reflected by the translucent vision itself increases, when the amount of attenuation increases to a certain extent. The transmission parameter aII+a2□ remains flat or slightly thick (dB
The displayed value is expected to be slightly smaller). This is supported by the experimental results shown in FIG.

According to FIG. 6, the results measured by the direct method of FIG. 2 are smaller in dB by about 0.02 dB to 0.035 dB. This also agrees with the theoretical prediction shown in FIG.

The above explanation is based on the assumption that the human power side is 1 threshold and the output side is 1 threshold.
Although this was done for parts with two or more input/output surfaces, it is also possible to apply a non-reflective load to any surface other than one input surface and one output surface. It is possible to determine the transmission parameters by sequentially measuring the transmission parameters of the parts made in this way while changing the input and output surfaces.

〔Effect of the invention〕

As explained in detail above, this invention is based on a wave source.

A reflection coefficient measuring device consisting of a directional coupler and a reflected wave indicator is connected to the input side and the output side of the component under test, respectively, and one wave source and the other wave source are alternately KONL, and both reflected wave indicators are measured at that time. Obtain 4 pieces of data, 2 pieces each from the instrument only, then remove the part to be measured and do the same, alternately ONL one wave source and the other wave source, then 2 pieces each from both reflected wave indicators only. Obtain 4 pieces of data and measure the transmission parameters of the part under test from a total of 8 pieces of data. Accurately determine the transmission parameters of the part under test for both coherent waves and incoherent waves. be able to. Therefore, there are the following advantages.

(1) There is no need for a non-probe wave source or a non-reflection detector.

(2) There is less need to attach and detach parts to be measured and measuring instruments.

(3) According to the above (t+, f21), accurate measurement with small error is 1 north.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of wave transmission parameters, Figure 2 (a) ~
(f) is a diagram showing a conventional measurement procedure for wave transmission parameters, FIG. 3 (aL < b) is a diagram showing a measuring element JIB for wave transmission parameters according to an embodiment of the present invention, and FIG. 4 is a conventional method. expected in ii! Figure 5 is a diagram showing the results of measuring transmission parameters according to the present invention, and Figure m6 is a diagram showing the difference between the measurement results of the conventional method and the method according to the present invention. In the figure, 1.2 is a surface, 3 is a part to be measured, 4, 11 is a wave source,
5.12 is a directional coupler, 6 and 13 are reflected wave indicators, 7
, 14 is a reflection coefficient measuring device. Designated representative: Todoroki, director of the Research Institute for Electronic Technology (Fig. 1, Fig. 2, Fig. 3 (a) V211 (b) v+1; Table i! (4 + X dB) - Fig. 6 Bon name relative table (dB) - Hand, continuation amendment (self-produced) Showa 2 I 1? Month/511 Display of 1 case 1964 patent application No. 13! ;! ；Otsu No. 2 Name of Invention Method for Measuring Wave Transmission Parameters Higashi Prefectural Capital T Dai III V, M Shikaseki 111J 3 No. 1 ++ 4 I Industrial Technology ((・For Director Xia [], 1 Yu ii 1 U 4 Designated Agent As shown in the attached sheet, 0's U] is Vl, u2 is v2.(b)'s ul
Correct v1+u2 to v2. Figure 3 (a) V211 (b) 112

Claims (1)

[Claims] A reflection coefficient measuring device consisting of a wave source, a directional coupler, and a reflected wave indicator is connected to the input side and the output side of the component to be measured that transmits waves, respectively, and only the wave source of one of the reflection coefficient measuring devices is turned on. Then, turn on only the wave source of the other reflection coefficient measuring device to obtain two data using both reflected wave indicators, and then remove the part to be measured and With the bidirectional coupler connected, only one of the wave sources is turned on to obtain two data from both of the reflected wave indicators, and then only the other wave source is turned on.
A method for measuring a wave transmission parameter, characterized in that two pieces of data are obtained from both of the reflected wave indicators, and the transmission parameter of the part to be measured is measured based on these eight pieces of data.