JPH06138158A - Interference-wave discrimination system - Google Patents

Abstract

PURPOSE:To surely discriminate interference waves emitted from an object under test in a state that external waves exist. CONSTITUTION:A proximity receiving antenna 31 is arranged comparatively adjacent to an object 11 under test, and a regular receiving antenna 32 is arranged in a comparatively distant place. Frequency characteristics of electromagnetic waves received by the receiving antennas 31, 32 are displayed by using a plotter 16 so as to be overlapped on the same face. By using a displayed content, a frequency part received by the regular receiving antenna 32 at a reception level which is equal to, or larger than, the reception level of, e.g. the proximity receiving antenna 31 is discriminated to be external waves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference wave identification system for identifying an interference wave as an electromagnetic wave output from an electronic device such as an information processing device, and particularly to an external wave radiated from other than this electronic device. The present invention relates to an interference wave identification system that identifies interference waves without being affected.

[0002]

2. Description of the Related Art Electronic devices such as a television receiver and a word processor have various circuit elements such as an oscillator and a clock generator therein, and electromagnetic waves are often generated from these parts. If the electromagnetic waves are not properly shielded inside the device, such electromagnetic waves may cause malfunction in other electronic devices arranged outside, various devices using electronic components, transportation facilities, and the like. Therefore, it has become popular to measure the electromagnetic waves emitted to the outside, that is, the interference waves, to be useful for product development and design changes.

By the way, it is extremely difficult to accurately identify an interfering wave output from an object to be measured such as an electronic device. For example, since electromagnetic waves are emitted from various electronic devices in a normal room, it is difficult to distinguish an interfering wave output from the DUT and an external wave. Further, indoors exhibit complicated behaviors such as emitted electromagnetic waves hitting a wall or the like to be reflected, and electromagnetic waves are enhanced or extinguished due to a phase relationship, which makes their identification more difficult.

On the other hand, outside the room, it is possible to almost eliminate the influence on the discrimination caused by the electromagnetic waves emitted from one place being reflected by another object and returning, but various things such as airplanes and automobiles can be eliminated. Electromagnetic waves will come from here as foreign waves. Since such an extraneous wave is detected together with the interfering wave output from the DUT, there is a difficult problem that the two must be separated.

Of course, such an extraneous wave can be almost completely blocked by creating an anechoic chamber as a special facility. Further, by arranging a material that absorbs electromagnetic waves in the anechoic chamber, the problem due to the reflection can be solved. However, if an attempt is made to absorb electromagnetic waves favorably at all frequencies, especially in the low frequency band, the anechoic chamber becomes quite large and expensive, and cannot be easily constructed and used.

Therefore, conventionally, an object to be measured is placed in an appropriate place such as outdoors to measure an electromagnetic wave, and on the other hand, an external wave is identified and excluded from the result, and the measurement result of only the target interference wave is obtained. It is designed to get them.

FIG. 13 shows the structure of such an interference wave discrimination system which has been conventionally used. An electronic device (hereinafter referred to as an object to be measured) 11 for identifying an interference wave is placed on a turntable 12. The turntable 12 has a ground plane 13 made of an iron plate around the floor.
Is covered with. A receiving antenna 14 is vertically movably arranged at a position, for example, 10 m away from the DUT 11. The ground plane 13 reflects electromagnetic waves,
This is arranged in consideration of a state in which the DUT 11 is actually arranged and used in an office or the like.

In this state, (a) the object to be measured 11 is placed in an operating state and the turntable 12 is rotated. Then, the detection output obtained from the receiving antenna 14 is input to the spectrum analyzer 15. The turntable 12 is used to output the measurement result in the direction of the strongest electromagnetic wave when the electromagnetic wave output from the DUT 11 has directivity. The receiving antenna 14 is also moved up and down within a height range of 1 m to 4 m, for example, and the value at which the measurement result is the worst is used for each frequency. Spectrum analyzer 1 obtained in this way
The analysis result of No. 5 is output to the plotter 16, and the electromagnetic wave analysis chart 17 is printed out. Next, (b) the power of the DUT 11 is shut off, and the electromagnetic wave is measured by the antenna 14 in the same state as the above (a) except for this, and the analysis result is output as the analysis chart 17. .

Depending on the disturbing wave identification system, (c) the object to be measured 11 is measured in a non-operating state using the receiving antenna 14, and then (d) the object to be measured 11 is turned on to receive. The receiving operation may be performed by the antenna 14.

FIGS. 14 and 15 show the respective analysis charts in the cases (a) and (b). In the analysis chart 24 of FIG.
As shown in, the interference wave 21 output from the DUT 11
And the external wave 22 output from another electronic device or the like reaches the reception antenna 14 and is received. On the other hand,
In the analysis chart 25 shown in FIG. 5, the power of the device under test 11 is off, so that only the external wave 22 reaches the receiving antenna 14.

Conventionally, these two types of analysis charts 2
Peaks 4 and 25 are overlapped, and peaks 26 are present at the same frequency position in common (only a part of them is indicated in the figure)
Was regarded as an extraneous wave, and these were excluded from the measurement target. On the contrary, in FIG. 15, the part 27 where no external wave is generated and the part where the waveform peak 28 exists in FIG. 14 is regarded as an interfering wave.

In order to easily identify the disturbing wave, for example, the chart created by the plotter 16 for two-color recording is drawn in black while the power of the DUT 11 is off, and the DUT 11 is measured. Draw the chart in red with the power turned on. By doing so, the peaks 26 that commonly exist at the same frequency position become black, and only the portion corresponding to the peak 28 of the waveform in FIG. 14 becomes red. Therefore, it was possible to easily distinguish only the red waveform from the interference wave.

[0013]

As described above, in the conventional interference wave discrimination system, measurement is performed in two states, that is, a state in which both an extraneous wave and an interfering wave exist and a state in which only an extraneous wave exists. The obtained spectrum analysis results were compared, and the commonly existing waveform portion was determined to be due to the foreign wave. Then, the peak 28 which does not exist in FIG. 15 but exists only in FIG. 14 is found and identified as an interfering wave, or both are displayed by being overlapped with two colors and the interfering wave is identified by the color difference. I was doing.

However, in the disturbing wave identification system shown in FIG. 13, the time when the power source of the DUT 11 is turned on to detect both the disturbing wave and the foreign wave, and the power source of the DUT 11 is turned off. This is naturally different from the time when only the extraneous wave is detected. Therefore, the analysis chart 2 shown in FIG.
4 and the analysis chart 25 shown in FIG. 15 differ in the reception state of the external wave. For example, when an airplane flies at one measurement or when a commercial radio is used, the printout of the external wave itself in the two analysis charts 24 and 25 is greatly different. Therefore, even if there is a new peak only in the portion of FIG. 14 in the frequency region where the peak value does not exist as shown in FIG. 15, it is surely due to the interference wave. I couldn't say for sure.

Further, it is necessary to have a considerable amount of knowledge and experience to accurately discriminate between the interference wave and the foreign wave.
It wasn't easy for anyone. Further, in order to distinguish between the interfering wave and the foreign wave, the power of the DUT 11 is turned on.
There is a problem in that it needs to be turned off, and depending on the device, this requires a considerable amount of time. Further, since the exogenous wave changes every moment, it is necessary to make full use of the identification method corresponding to this in order to increase the reliability of the identification, which also requires a lot of time.

Therefore, an object of the present invention is to provide an interference wave identification system capable of reliably identifying an interference wave emitted from an object under measurement in the presence of an external wave.

Another object of the present invention is to provide an interference wave identifying system capable of identifying an interference wave in a short time.

[0018]

According to a first aspect of the present invention, (a) a first antenna which is arranged relatively close to an object to be measured which generates an interfering wave as an electromagnetic wave and which measures the electromagnetic wave; (B) A second antenna which is located relatively far from the object to be measured and which measures electromagnetic waves, and (c) a frequency at which the frequency characteristics of the electromagnetic waves received by these first and second antennas are superimposed and displayed on the same plane. The characteristic display means is provided in the interference wave identification system.

That is, according to the first aspect of the invention, the first antenna is arranged relatively close to the object to be measured, and the second antenna is arranged relatively far away. Then, the frequency characteristics of the electromagnetic waves received by the first and second antennas are displayed in an overlapping manner on the same surface, and by using this display content,
For example, by discriminating that the frequency portion received by the second antenna at a reception level equal to or higher than the reception level of the first antenna is an external wave, it is possible to distinguish the interfering wave from the external wave. It will be possible.

According to the second aspect of the present invention, (a) a first antenna arranged to be relatively close to an object to be measured which generates an interfering wave as an electromagnetic wave and measuring the electromagnetic wave; and (b) an object to be measured. A second antenna, which is located relatively far away and which measures electromagnetic waves, and (c) the measurement results of the first and second antennas are compared for each frequency, and an external wave as an electromagnetic wave other than the measured object is output. Foreign wave removing means for removing
(D) The interference wave identifying system is provided with an interference wave identifying means for identifying the electromagnetic wave removed by the extraneous wave removing means as an interference wave.

That is, according to the second aspect of the present invention, the first antenna is arranged relatively close to the object to be measured, and the second antenna is arranged relatively far away. Then, the measurement results of the first and second antennas are compared for each frequency to remove an external wave as an electromagnetic wave to be output other than the object to be measured, and the remaining electromagnetic wave is an interfering wave emitted from the object to be measured. Will be identified as

According to the third aspect of the present invention, (a) a first antenna arranged relatively close to the object to be measured which generates an interfering wave as an electromagnetic wave and measuring the electromagnetic wave; and (b) an object to be measured. The second antenna, which is located relatively far away and which measures electromagnetic waves, and (c) the value obtained by subtracting the reception level of the second antenna from the reception level of these first antennas is less than the predetermined first positive value. Corresponding to a frequency determined to belong to the above-mentioned range by the comparing means, and comparing means for each frequency to determine whether or not it belongs to a range smaller than a predetermined second positive value. First or second
And an interfering wave identifying means for identifying the reception result of the antenna as an interfering wave obtained from the object to be measured.

That is, according to the third aspect of the invention, the first antenna is arranged relatively close to the object to be measured, and the second antenna is arranged relatively far away. Whether or not the value obtained by subtracting the reception level of the second antenna from the reception level of these first antennas belongs to a range larger than the predetermined first positive value and smaller than the predetermined second positive value. These are compared for each frequency, and the reception result of the first or second antenna corresponding to the frequency that is considered to belong to the above-described range is identified as the interfering wave obtained from the DUT.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples.

First embodiment

FIG. 1 shows an outline of the configuration of an interference wave identifying system according to the first embodiment of the present invention. The same parts as those in FIG. 13 are designated by the same reference numerals, and the description thereof will be appropriately omitted. In the device shown in FIG. 1, a proximity receiving antenna 31 is vertically movable by an antenna support mechanism (not shown) at a position 1 m away from a rotatable turntable 12 on which an object to be measured 11 is placed.
Further, the regular reception antenna 32 is vertically movable by a supporting mechanism (not shown) at a position 10 m away from the turntable 12 as in the conventional case.

The A channel signal 33 obtained from the regular receiving antenna 32 is input to the spectrum analyzer 15. The B channel signal 34 obtained from the proximity receiving antenna 31 is input to the spectrum analyzer 15 at a different time from the A channel signal 33. Spectrum analyzer 1
The respective analysis results of 5 are output to the plotter 16, and the electromagnetic wave analysis chart 35 is printed out. In the disturbance wave identification system of the present embodiment, the operation of turning on / off the power of the device under test 11 is not particularly required.

FIG. 2 is a plan view of this interference wave discrimination system. In this example, the straight line connecting the proximity receiving antenna 31 and the center of the turntable 12 is the regular receiving antenna 3
It intersects with a straight line connecting 2 and the center of the turntable 12 at a substantially right angle. However, it is free for both to be arranged in an angular relationship other than this.

FIG. 3 shows the measurement results obtained by the plotter of the interference wave discrimination system of this embodiment. In this figure, the horizontal axis represents the frequency of electromagnetic waves. The vertical axis represents the peak value of the electromagnetic wave for each frequency in units of decibel (dB). The measurement result 41 indicated by the dotted line on the lower side represents the measurement result on the B channel received by the proximity receiving antenna 31, and the measurement result 42 indicated by the solid line on the upper side is the measurement result on the A channel received by the regular receiving antenna 32. It shows the result. These are plotted on a plotter 16 having a two-color printing function, for example, in two colors of yellow and red on the same coordinate axis. In Fig. 3, since the drawing is made in one color, both measurement results 4
In order not to be indistinguishable from each other by overlapping 1 and 42, they are displayed vertically shifted. Next, using the waveforms A _{1 to} A ₄ and B _{1 to} B ₄ surrounded by ellipses in this figure, a method of identifying an interference wave will be considered.

FIG. 4 is for explaining a method of discriminating between an external wave and an interfering wave. Regarding the waveform A ₁ and the waveform B ₁ shown in FIG. 9A, the peak value of the waveform A ₁ is the waveform B ₁
Is larger than the peak value of. Since the regular reception antenna 32 is present at a position farther from the DUT 11 than the proximity reception antenna 31, if the interference wave is an electromagnetic wave output from the DUT 11, the waveform received by the proximity reception antenna 31 will always be received. Since the above becomes larger, the above size relation will never hold. Therefore, the identification result in this case is “external wave”. Waveform A ₄ shown in FIG.
The same result is obtained for the waveform B ₄ and the waveform B ₄ .

Regarding the waveforms A ₂ and B ₂ shown in FIG. 9B, the peak value of the waveform A ₂ is smaller than the peak value of the waveform B ₂ . Therefore, the identification result in this case is “interfering wave” from the above. That is, the peak value of the interfering wave output from the DUT 11 at a predetermined frequency can be measured using this portion.

The peak values of the waveform A ₃ and the waveform B ₃ shown in FIG. 3C are substantially equal to each other. The proximity receiving antenna 31 and the regular receiving antenna 32 differ greatly in distance from the DUT 11, but in many cases there is no great difference in distance from the viewpoint of an airplane or broadcast wave source that outputs an external wave.
Therefore, if these external wave generation sources are in the same electromagnetic wave generation state, the reception levels of both reception antennas 31 and 32 are substantially equal. Therefore, the discrimination result in the example shown in FIG.

As described above, in the interference wave identification system of the first embodiment, the plotter 16 draws the measurement results of the electromagnetic waves received by the near field reception antenna 31 and the regular reception antenna 32 in two colors as peak values for each frequency. Therefore, it is possible to easily distinguish the interfering wave from the extraneous wave by comparing the peak value for each frequency, and to identify the one caused by the interfering wave without the need for a special analyzer. You can know the intensity distribution.

Further, since it is possible to distinguish between an external wave and an interfering wave without having to turn on / off the power of the device under test 11, it is possible to easily turn on / off the power as in a large computer. There is also an advantage that even if the device cannot be used, the electromagnetic waves emitted from the device can be easily identified.

Second embodiment

FIG. 5 shows the structure of an interference wave identifying system according to the second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be appropriately omitted. In the second embodiment, the proximity receiving antenna 31 and the regular receiving antenna 32 are used as in the first embodiment. The A channel signal 33 obtained from the regular reception antenna 32 and the B channel signal 34 obtained from the close reception antenna 31 are separately input to the spectrum analyzer 15 as signals in different time zones,
The worst value at each frequency in combination with the height of each antenna 31, 32 and the rotational position of the turntable 12 is obtained.

The computer 51 inputs the measurement result 52 thus obtained from the spectrum analyzer 15 and determines whether the peak value of each frequency is due to an interfering wave or an external wave. The state of this determination will be described later in detail. The determination result 53 is output to the plotter 16, and the electromagnetic wave analysis chart 55 is printed out. Even in the disturbance wave identifying system of the present embodiment, the operation of turning on / off the power of the device under test 11 is not particularly required.

FIG. 6 shows the configuration of a computer used in the interference wave discrimination system of the second embodiment. CPU (Central Processing Unit) 61 of computer
Is a working memory 6 through a bus 62 such as a data bus.
3, a magnetic disk control circuit 64, a display control circuit 65, an input circuit 66 and an output circuit 67. Here, a magnetic disk 69 is connected to the magnetic disk control circuit 64, and a program and other data for analyzing electromagnetic waves using this computer are stored therein. The working memory 63 reads this program when analyzing electromagnetic waves, and temporarily stores data necessary for various controls.

The display control circuit 65 is connected to the CRT 71, and is adapted to display various instructions regarding the identification of the interference wave and the identification result. The input circuit 66 outputs the measurement result 52 output from the spectrum analyzer 15 shown in FIG.
On the other hand, while being input, the keyboard 72 is connected to input data associated with various key operations. The output circuit 67 is connected to the plotter 16 shown in FIG. 5, and outputs the discrimination result 53 to this for visualization.

FIG. 7 shows the flow of the electromagnetic wave discrimination processing of the computer in this embodiment. This process is started when the input circuit 66 shown in FIG. 6 inputs the measurement result 52 from the spectrum analyzer 15 and an instruction for starting the identification is given from the keyboard 72. At this point, the CPU 61 (FIG. 6) initially sets the frequency number n stored in the working memory 63 to “1” (step S
101). Here, the frequency number n is a number in which the frequencies at which the peak values are detected by the spectrum analyzer 15 are sequentially assigned from the lower side to the higher side, and the initial value is "1".

The CPU 61 then determines whether or not the current frequency number n exceeds its maximum value MAX (step S102), and if not (N), the frequency f
Peak value f of both A channel and B channel at _n
na and f _nb are read from the working memory 63 (step S
103). The measurement result 52 obtained from the spectrum analyzer 15 is stored in the working memory 63 in advance.

The CPU 61 first compares whether the two read peak values f _na and f _nb are equal (step S104). If these are equal (Y), it means that the external wave is received by the two receiving antennas 31 and 32 as already described in the first embodiment.
The waveform of the frequency f _n is an extraneous wave (step S105). Therefore, the identification result is stored in the working memory 63 in association with the corresponding frequency (step S1).
06), the frequency number n is incremented by +1 (step S107). Then, returning to step S102, the operation for the next frequency number is started.

Process of repeating work in this way
Then, in step S104, the two peak values f_na, F_nbIs different
(N). In this case, the CPU 61
Value f _naOther peak values f_nbIs larger than
Is determined (step S108). If this relationship is
If it does not stand (N), that is, in the regular reception antenna 32
Peak value f_naIs the peak of the proximity receiving antenna 31
Value f_nbIf it is larger than that, it is explained in the first embodiment.
Frequency f for the same reason as_nWaveform is judged as an extraneous wave
(Step S105). The subsequent processing is already explained
This is exactly what was done (steps S106 and S107).

When it is determined in step S108 that the other peak values f _nb are larger than the peak value f _na , the difference between them is larger than the predetermined positive value X ₁ , and this value X n When it is smaller than another predetermined value X ₂ which is larger than ₁ (step S109; Y), the frequency f _n
Of the waveform is identified as being caused by the interfering wave (step S11).
0).

First, it is necessary that the value obtained by subtracting the peak value f _na from the peak value f _nb is larger than the predetermined positive value X ₁ is because the difference between the two sizes is small. This is because it can be considered that this is due to the level fluctuation when the two receiving antennas 31 and 32 receive the external wave. Therefore, when the value obtained by subtracting the peak value f _na from the peak value f _nb is less than or equal to the predetermined positive value X ₁ , (step S
109; N), the waveform of the frequency f _n is determined to be an external wave (step S105).

Next, the value obtained by subtracting the peak value f _na from the peak value f _nb is larger than the positive value X ₁ by a predetermined value X ₂
It is required that the proximity receiving antenna 31 be smaller than the regular receiving antenna 32.
Even if it is arranged near 1, even if the reception level of the proximity receiving antenna 31 is abnormally high, it cannot be understood that it is due to the occurrence of an interfering wave. For example, when an external wave is generated only when the proximity receiving antenna 31 is receiving, such a situation may occur. Therefore, also in this case, it is determined that the extraneous wave is generated (step S105), and is excluded from the measurement target.

As described above, the peak value for each measured frequency is discriminated as to whether it is caused by an external wave or an interfering wave, and the discrimination result is stored in the working memory 63 in association with the frequency. Will be done. Then, when the measured maximum frequency is exceeded (step S102; Y), all the operations are completed (END).

8 to 11 show an example of the discrimination result of the interference wave output from the plotter. Of these, in FIG. 8, the frequency is 30 MHz (megahertz) to 80 MH
z up to 80 MHz to 100 MHz in FIG.
FIG. 10 shows 100 MHz to 150 MHz, and the last FIG. 11 shows 150 MHz to 200 MHz. In these figures, the vertical axis represents the emission level of the interfering wave. Further, in the figure, the straight lines indicated by the levels “BL” at both ends represent the “0” level of the interfering wave. The fact that these fluctuate at each frequency is based on the difference in the characteristics of the receiving antenna 31 (32) with respect to the frequency.

Similarly, both ends are indicated by level "LL" in the figure.
The straight lines show the upper limit of the allowable range of disturbance waves.
It Therefore, for example, the five disturbing waves extracted in FIG.
Peak value of 81₁~ 81_FourOf the first, third and
And the fourth peak value 81₁, 81 ₃, 81_FourIs the tolerance
I know that it is over and some kind of countermeasure is necessary
It In this example, the second peak value 81₂Is within the allowable range
It is barely.

FIG. 12 shows another example of the discrimination result of the interference wave output from the plotter. In this example, the reception result of the A channel by the regular reception antenna 32 is shown by a solid line, and the reception result of the B channel by the close reception antenna 31 is shown by an X mark. Then, a circle mark is added to the peak position of the waveform identified as the interfering wave, as in FIGS. 8 to 11. Further, in this figure, the straight line indicated by the level "LL" at both ends indicates the upper limit of the allowable range of the interfering wave.

For the convenience of drawing, the solid line and × are shown in this figure.
The mark indicates the measurement result by the two receiving antennas 31 and 32. When the plotter 16 can record in two colors,
These are, for example, the red solid line and the yellow solid line.
As a matter of course, it is possible to display the images in different colors.

In the second embodiment described above, the output of the spectrum analyzer 15 to which the A chart signal 33 or the B channel signal 34 is input is used as it is in the computer 5.
However, the output of the spectrum analyzer 15 may be compared with a predetermined threshold value by a comparator, and only the value exceeding this may be input to the computer 51. Alternatively, in a computer that does not have an A / D conversion function, the output of the comparator may be supplied with a signal after A / D conversion by the A / D converter. By thus cutting the signal level that does not reach the threshold value with the comparator, it becomes possible to remove noise, and it is possible to prevent the peak wave of the noise level from being erroneously identified as an interfering wave.

Further, in the embodiment described above, the regular receiving antenna 32 is explained as the second antenna arranged relatively far from the object to be measured, but it is used as the first antenna arranged relatively close to it. You may handle it. In this case, the second antenna will be installed further away.

[0054]

As described above, according to the first aspect of the present invention, the first and second distances with respect to the object to be measured are different.
We decided to measure the electromagnetic wave with the antenna and display the frequency characteristics of the received electromagnetic waves on the same paper or the same display screen, so by comparing the contents, which is the interference wave? It is possible to easily identify whether or not the wave is an external wave. Moreover, at this time, since it is not necessary to turn on / off the power of the device under test, there is a case where it takes time for the power supply to rise and fall as in the case where the device under test is a relatively sophisticated computer. Also, there is an effect that the interference wave can be measured without turning off the power.

According to the second aspect of the invention, the electromagnetic waves are measured by the first and second antennas having different distances to the object to be measured, and the reception levels of these antennas are compared for each frequency. Since the extrinsic wave is decided to be removed by this, there is an effect that the interference wave can be automatically identified without requiring special knowledge or experience in measuring the interference wave.

Further, according to the invention described in claim 3, the electromagnetic waves are measured by the first and second antennas having different distances to the object to be measured, and the reception levels of these antennas are compared for each frequency. First when removing foreign waves by
Whether or not the value obtained by subtracting the reception level of the second antenna from the reception level of the antenna of is within a range larger than the predetermined first positive value and smaller than the predetermined second positive value for each frequency. I decided to compare each. Therefore, if the reception level of the first antenna is higher than the reception level of the second antenna due to mere noise, or if the level difference between the two is not a large value, it is erroneously disturbed. There is an effect that the reliability for identification is improved without being identified as a wave.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire system showing a side view of a part of the configuration of an interference wave identifying system according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the entire system in which a part of the configuration of the interference wave measuring system of the first embodiment is shown as a plan view.

FIG. 3 is a characteristic diagram in which the measurement results in the first embodiment are separately shown for description on the A channel and the B channel.

FIG. 4 is an explanatory diagram showing a method of discriminating between an external wave and an interfering wave in the first embodiment.

FIG. 5 is a schematic configuration diagram of an interference wave identification system according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing the configuration of a computer used in the interference wave identification system according to the second embodiment.

FIG. 7 is a flowchart showing a flow of electromagnetic wave identification processing of a computer in the second embodiment.

FIG. 8 is a plan view showing an example of an identification result of an interference wave output from a plotter for frequencies from 30 MHz to 80 MHz.

FIG. 9 is a plan view showing an example of an identification result of an interference wave output from a plotter for frequencies of 80 MHz to 100 MHz.

FIG. 10 is a plan view showing an example of an identification result of an interference wave output from a plotter for frequencies of 100 MHz to 150 MHz.

FIG. 11 is a plan view showing an example of an identification result of an interference wave output from a plotter for frequencies of 150 MHz to 200 MHz.

FIG. 12 is a plan view showing another example of the discrimination result of the interfering wave output from the plotter.

FIG. 13 is a schematic configuration diagram showing a configuration of a conventionally used interference wave identification system.

FIG. 14 is a characteristic diagram showing a measurement result in a state where the power of the device under test is turned on in the conventionally used interference wave identification system.

FIG. 15 is a characteristic diagram showing a measurement result in a state where the power of the object to be measured is turned off in the conventionally used interference wave identification system.

[Explanation of symbols]

11 ... Object to be measured, 12 ... Turntable, 15 ... Spectre analyzer, 16 ... Plotter, 21 ... Interfering wave, 22 ...
External wave, 31 ... Proximity reception antenna (first antenna),
32 ... Regular receiving antenna (second antenna), 33 ... A
Channel signal, 34 ... B channel signal, 51 ... Computer, 55 ... Analysis chart, 61 ... CPU, 63 ... Working memory, 69 ... Magnetic disk, 71 ... CRT

Claims (3)

[Claims] 1. A first antenna, which is arranged relatively close to an object to be measured and which generates an interference wave as an electromagnetic wave, and which measures the electromagnetic wave; and an electromagnetic wave, which is arranged relatively far from the object to be measured. An interference wave identification system comprising a second antenna and frequency characteristic display means for displaying the frequency characteristics of electromagnetic waves received by the first and second antennas on the same surface. 2. A first antenna, which is arranged relatively close to an object to be measured which generates an interfering wave as an electromagnetic wave, and which measures the electromagnetic wave, and an electromagnetic wave which is arranged relatively far from the object to be measured. A second antenna, an external wave removing unit that compares the measurement results of the first and second antennas for each frequency, and removes an external wave as an electromagnetic wave that is output other than the DUT, and removes the external wave. An interference wave identifying means for identifying the electromagnetic wave after being removed by the means as an interference wave. 3. A first antenna, which is arranged relatively close to an object to be measured and which generates an interfering wave as an electromagnetic wave, and which measures the electromagnetic wave; and an electromagnetic wave which is arranged relatively far from the object to be measured. A range in which the value obtained by subtracting the reception level of the second antenna from the reception levels of the second antenna and the first antenna is larger than the predetermined first positive value and smaller than the predetermined second positive value. And a reception result of the first or second antenna corresponding to the frequency determined to belong to the range by the comparison means for comparing whether or not it belongs to each frequency. An interference wave identifying system, comprising: an interference wave identifying means for identifying an interference wave.