JPH0330831B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an interference noise testing device, and more specifically, it provides an interference noise testing device that has improved sensitivity and accuracy in measuring interference noise generated from electronic equipment. .

Now, interference noise generated by electronic equipment (hereinafter referred to as
EMI) is broadly classified into conductive EMI, which is transmitted through the signal lines and power lines of the electronic devices, and radioactive EMI, which is emitted from the electronic devices into space as radio waves and magnetic fields.

Since these EMIs cause malfunctions in the operation of electronic devices, it is required that their level be kept within a certain value. For this reason, it is necessary to measure the EMI of electronic equipment and test whether the intensity is within a certain value, which requires the EMI test equipment described above.

Note that for convenience of explanation, the measurement target will be limited to the radioactive EMI described above.

First, a conventional device of this type will be briefly explained using figures. FIG. 1 is a block diagram of a conventional device of this kind, and FIG. 2 is a diagram showing an example of EMI test standards.

In Fig. 1, 1 is the specimen, 2 is the specimen 1 mentioned above.
3 is a high frequency transmission line (hereinafter referred to as an RF transmission line) that transmits the radiated EMI; 4 is a radio frequency transmission line that is detected by the receiving antenna 2 and transmitted through the RF transmission line 3; a preselector comprising a bandpass filter for band-limiting the radioactive EMI that is transmitted, and having a function of sweeping the center frequency of the bandpass filter under the control of a central processing unit (hereinafter referred to as CPU) 8; 5 is an attenuator connected to the preselector 4 via the RF transmission line 3 and adjusts the intensity of the radiated EMI based on control of the CPU 8; 6 is connected to the attenuator 5 via the RF transmission line 3; , a receiver (such as a spectrum analyzer or an electric field measuring device) equipped with a function to measure the intensity of the radioactive EMI in the form of a frequency spectrum under the control of the CPU 8; 7 is a preselector 4, an attenuator 5, a receiver; machine 6, output display device 10, input device 1
1 and an input/output interface that relays with the CPU 8; 8 controls the preselector 4, attenuator 5, receiver 6, output display device 10, and input device 11 according to the processing program; A CPU 9 collects and processes the radioactive EMI measurement values, a storage device 9 stores the processing program, measurement values, test conditions, etc., and exchanges information with the CPU 8; An output display device (such as a plotter or a line printer) connected to the input/output interface and outputting and displaying the measured values, etc.; 11 is the input/output interface 7;
An input device (such as a keyboard) connected to the CPU 8 to input information such as test conditions to the CPU 8; This is an interface bus cable that connects the CPU 8 and the preselector 4, attenuator 5, receiver 6, output display device 10, and input device 11 to transmit digital signals.

In Figure 2, S is an example of the radioactive EMI standard,
S and S ₂ are an example of the above-mentioned radiated EMI standard s in which particularly low intensity is applied (for example, the radiated EMI standard applied to communication devices), and T is the above-mentioned receiving antenna 2, RF transmission line 3, preselector 4, This is the receiving sensitivity of the receiving system consisting of the attenuator 5 and the receiver 6, that is, the threshold level.

Next, the operation of a conventional device of this type will be explained.

The radioactive EMI generated from the specimen 1 is detected by the receiving antenna 2 and input to the preselector 4 through the RF transmission line 3.

The preselector 4 has its pass band controlled by the command of the CPU 8 and limits the band of the radioactive EMI, so the radioactive EMI that falls within the pass band
Only the signal passes through this and is input to the attenuator 5 through the RF transmission line 3.

The attenuator 5 adjusts the intensity of the radiated EMI to an appropriate value and transmits the excessive radiated EMI to the receiver 6.
It prevents EMI from being input, and its attenuation value is controlled by the CPU 8.

Then, the radioactivity that has passed through the attenuator 5 is
EMI is input to the receiver 6 through the RF transmission line 3.

The receiver 6 transmits the radioactive material according to the instructions of the CPU 8.
Measures the intensity of EMI in the form of a frequency spectrum. This measured value is sent via input/output interface 7.
It is taken into cpu8, and here the above receiving antenna 2
Processing is performed to correct the gain of the RF transmission line 3, the loss of the RF transmission line 3, etc., and the converted data is converted into engineering units and stored in the storage device 9. Then, it is displayed again on the output display device 10 in a predetermined format.

Because of this operation, the intensity of the radioactive EMI emitted by the specimen 1 can be automatically and quickly tested.

However, the standards applied in the above radioactive EMI test are as shown in Figure 2, and the radioactive EMI standard S is often set at a very low level such as S ₁ or S ₂ . .

The above S ₁ and S ₂ are set when the system in which the above specimen 1 is installed includes, for example, a highly sensitive receiving system.
This setting was made because it is necessary to keep the radiated EMI low near the receiving center frequency so as not to interfere with this.

Therefore, the intensity of S ₁ and S ₂ is extremely low, and is often even lower than the threshold level T of the receiving system.

In such a case, there was a drawback that the radioactive EMI could not be measured in the frequency range indicated by _S1 or _S2 .

Furthermore, the intensity of the radioactive EMI is low and the T
There is also a drawback that when the radiated EMI is in the vicinity, noise in the measurement system such as internal noise of the receiver 6 causes a large error in the measured value of the radiated EMI.

These drawbacks are a fatal problem in radioactive EMI measurement, and an EMI test device that solves this problem has been desired.

This invention was made to solve such problems, and will be described in detail below with reference to the drawings.

FIG. 3 is a block diagram of the configuration of an embodiment of the present invention, and FIG. 4 is a flowchart showing the flow of processing. In the figure, 1 to 12 are the same as in Figure 1, 13, 14,
15 is a switching device having a function of switching the connection of the RF transmission line 3 according to a command from the CPU 8; 16 is a calibration device that is connected to the switching device 13 and generates known drifting noise under the control of the CPU 8; 17 is an amplifier inserted between the switching devices 14 and 15 to amplify the radioactive EMI; 18 is a power supply control device connected to the amplifier 17 to turn on and off the power to the amplifier 17 under control of the CPU 8; It is.

Next, the operation of the present invention will be explained using FIGS. 3 and 4.

A processing program is stored in advance in the storage device 9, and before the CPU 8 starts operating according to the processing program, the specimen 1 and the receiving antenna 2 are set up at predetermined positions as shown in FIG. 4A. then cpu
8 begins to move, in FIG. 4B, test conditions such as the test frequency band, the type of receiving antenna 2, the type of standard, and the necessity of initial calibration are input from the input device 11, and the CPU 8 and stored in the storage device 9.

Next, in FIG.
and performs initial settings of the power supply control device 18. That is, each of the above components, the preselector 4, the attenuator 5,
Receiver 6, switching devices 13, 14, 15, calibration device 1
The CPU 8 performs operations such as setting the CPU 6 and the power supply control device 18 to a standby state for commands from the CPU 8, and setting the attenuator 5 to provide maximum attenuation.

Next, in FIG. 4D, the CPU 8 determines whether or not a calibration operation is necessary. The judgment here is made according to the input information regarding the necessity of initial calibration as described above. If initial calibration is required, proceed to E immediately; if the above-mentioned initial calibration is not required, proceed immediately to H of Figure 4. .

Next, in FIG. 4E, a calibration setup is performed by the CPU 8. Here, the switching device 13 is driven by a command from the CPU 8, and connection is made so that the standard noise generated by the calibration device 16 is input to the preselector 4, and the standard noise of the frequency band to be calibrated is output from the calibration device 16. Output.

Next, in FIG. 4F, after the standard noise is amplified by the amplifier 17, it is input to the receiver 6 through the attenuator 5, and the standard noise is measured. Since the standard noise used here is calibrated in advance, the reception accuracy of the receiver 6 can be grasped by measuring the standard noise. Furthermore, in the measurement of the standard noise, the CPU 8 reads the reception strength of the receiver 6 when the strength of the standard noise is switched to two levels, and performs a predetermined calculation, so that the preselector 4 amplifier 17 and the receiver 6 Obtain the internal noise strength value of Then, the measured value of the standard noise and the internal noise intensity value are stored in a storage device 9.
to be memorized.

Next, in FIG. 4G, the CPU 8 determines whether the calibration operation has ended, and if it has not ended, the process returns to F to continue the calibration operation, and if it has ended, the process advances to FIG. 4H.

In H, a predetermined receiving antenna 2 is connected to the preselector 4 via the switch 13 according to a command from the CPU 8,
Connected to a predetermined amplifier 17 via a switch 14, connected to an attenuator 5 via a switch 15, and
The above components are connected so that the receiver 6 can measure them.

Next, in Figure 4 I, the radioactivity emitted from specimen 1
Measure EMI. Here, the CPU 8 gives a command to the receiver 6 to continuously sweep the reception frequency of the receiver 6 within a predetermined frequency range with a predetermined resolution. As a result, the measured value of the intensity frequency spectrum of the radioactive EMI is obtained and stored in the storage device 9. While the receiver 6 is measuring the above-mentioned intensity frequency spectrum, the CPU 8 is
monitors the timing to enter the calibration operation, and if an event occurs such as when a predetermined time has elapsed after the start of measurement or when switching the receiving antenna 2, an interrupt is generated to I and the process returns to E. Fly,
Here, the above-mentioned calibration operation is performed. Furthermore, while measuring the above intensity spectrum, cpu 8
In Figure K, the threshold level T is calculated from the above internal noise measurement value, and when it is determined that the sensitivity of the receiver 6 is insufficient, for example in the area _S1 or _S2 in Figure 2, the amplifier 17 is driven. Power supply control device 1
8 is driven by instructions from the CPU 8, and power is supplied to the amplifier 17 to operate it. At the same time, cpu8
gives a command to the switchers 14 and 15, inserts the amplifier 17 between the preselector 4 and the attenuator 5, and
Amplify EMI.

In addition, if the intensity of the radioactive EMI is so strong that it exceeds the linear operating region of the amplifier 17, the power supply control device 18 controls the power supply of the amplifier 17 according to a command from the CPU 8.
is cut off, switchers 14 and 15 operate, and amplifier 17
Remove it and insert RF transmission line 3 in its place. In this way, it is possible to measure the intensity frequency spectrum with the required receiving sensitivity and to prevent the generation of unnecessary waves due to the nonlinear operation of the amplifier 17.

Next, at L, cpu8 determines whether the measurement of the above intensity spectrum has been completed, and if it has been completed, M
Now, the measured value of the above intensity spectrum,
The internal noise intensity value and the measured value of the standard noise are retrieved from the storage device 9 and subjected to correction processing prescribed by the processing program.

Next, output the result of the above correction processing with N to the display device 1.
Output and display on 0.

As explained above, according to the present invention, the amplifier 1
7 is inserted before the receiver 6, and the amplifier 1
7, corrects internal noise of the amplifier 17, etc., and performs a calibration operation as necessary, so the reception system threshold level T
The advantage arises that not only is it possible to measure lower level radiated interference noise, but also that the accuracy of said measurement can be significantly increased.

Furthermore, since the above-mentioned calibration operation and the above-mentioned amplifier connection/disconnection operation are automatically performed, there is an advantage that the EMI test is labor-saving and speedy.

Note that although only radioactive EMI has been described here, the same applies to conductive positive EMI.

In addition, in the above embodiment, each component was shown as being separated one by one, but it is possible to combine several components into one and provide the functions of each of the components described above. Various modifications may be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional interference noise test device, Fig. 2 is a diagram showing an example of an interference noise test standard, Fig. 3 is a block diagram of an embodiment of the present invention, and Fig. 4 is a block diagram of the present invention. 2 is a flowchart showing the flow of processing by. In the figure, 1 is a specimen, 2 is a receiving antenna, 3 is a high-frequency transmission line, 4 is a preselector, 5 is an attenuator, 6 is a receiver, 7 is an input/output interface, 8 is a central processing unit, and 9 is a storage device , 10 is an output display device, 1
1 is an input device, 12 is an interface bus cable, 13 is a switch, 14 is a switch, 15 is a switch, 16 is a calibration device, 17 is an amplifier, and 18 is a power supply control device. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Claims] 1. A detector that detects interference noise generated from electronic equipment, a preselector that band-limits the interference noise detected by the detector, and measures the intensity of the interference noise band-limited by the preselector. An interference noise test device for measuring the intensity of the interference noise, comprising: a switch connected between the detector and the preselector; a calibration device that generates standard noise input to the preselector; an amplifier connected between the preselector and the receiver to amplify the band-limited interference noise; and a calibration device connected to the amplifier to supply power to the amplifier. A power supply control device to be controlled is connected to the input side and output side of the amplifier, and the amplifier is connected between the preselector and the receiver, or the amplifier is disconnected and a high frequency between a switching device for inserting a transmission line, a storage device for storing programs necessary for processing the interference noise, test conditions, and measurement values of the interference noise measured by the receiver; and the storage device; In addition to exchanging information, it also controls the switching device, the preselector, the receiver, the calibration device, and the power supply control device, collects the measured value of the interference noise obtained from the receiver, and performs the measurement. A central processing unit that performs predetermined processing based on the values, an output display device that outputs and displays the processing results of the measured values, and an input device that inputs the test conditions, and operates the detector according to the test conditions. inputting the standard noise sent from the calibration device to the receiver via the preselector and the amplifier each time the switch switches;
The above standard noise is measured, and the internal noise of the receiving system consisting of the above detector, the above preselector, and the above amplifier is measured. Furthermore, the measurement accuracy value of the above receiving system is determined, and the measured value of these internal noises and the measured value are measured. The measurement value of the interference noise intensity is corrected using the accuracy value, and when the amplifier performs nonlinear operation due to the interference noise input to the amplifier, the amplifier is adjusted between the preselector and the receiver. An interference noise testing device characterized in that the central processing unit switches the connection between the two and inserts the high frequency transmission line.