RadiMation Application Note 154

How to perform a MIL-STD-461 CS114, Conducted susceptibility, bulk cable injection test

This application note explains how the MIL-STD-461 CS114, Conducted susceptibility, bulk cable injection test can be performed with RadiMation^®

CS114 is a test method used in military and aerospace environments to assess the susceptibility of electronic equipment to conducted RF (radio frequency) currents over a frequency range of 10 kHz to 200 MHz. The test uses pulse modulation to ensure that devices can withstand conducted interference without experiencing performance degradation or failure.

The exact requirements and test methods for the CS114 are specified in the MIL-STD-461.

Necessary equipment

The following devices are necessary to run the calibration, verification and EUT test:

• Signal generator
• Amplifier
• Coupler
• Forward power meter
• Current sensor
• Sensor power meter / Analyser
• 50 Ohm load
• 50 Ohm attenuator
• Current injection device
• Current injection calibration jig (Calibration fixture)
• Cable drivers with corrections

Tips

Note:

If the current unit is shown as μA, it can be changed to dBμA by clicking Units, select Current and click Edit to change this.

Define the test level

CS114 uses a limit that varies over the frequency range and therefor we have to configure a variable test level. These limits are configured with a correction file in RadiMation^®.

Create a correction file for the test level by selecting the menu:

    File

       New

          Correction

First create a correction file in RadiMation^® and specify the applicable test level (See 'TABLE IV CS114 limit curves.' and 'FIGURE CS114-1. CS114 calibration limits.' in MIL-STD-461.). In this example the limits for 'Aircraft (External or safety critical) / Curve 5 are configured.

Ensure that the correction file has a Frequency column and a Current column with the unit set to dBμA.

Store the correction file for the test level by selecting the menu:

    File

       Save correction

Store the test level as correction file on disk.

This correction file with the test level will be used during the calibration, verification and the EUT testing.

Calibration procedure

The calibration is performed to characterize the losses and determine the correct power level in the used measurement setup.

Calibration equipment

The configuration of the calibration test site should contain the following devices:

#	Device name	Tab in testsite configuration window	note
	Signal Generator	Devices 1	The signal generator to use
	Amplifier	Devices 1	The amplifier to use
	Coupler	Devices 1	The coupler to use
	Forward power meter	Devices 1	The forward power meter to use
	Sensor powermeter	Devices 2	The power meter or analyser to use for measuring the current
	Current Sensor	Devices 2	The current sensor to use with transfer factor attached to the driver
	Injection device	Devices 2	The injection clamp to use
	Jig	Devices 2	The jig to use
Cables
①	Cable current -> power meter	Cables	Cable with a correction file specified for the cable loss
②	Cable current -> power meter	Cables	Cable with the specified loss of the used attenuator
③	Cable current -> power meter	Cables	Cable with a correction file specified for the cable loss

Configure the calibration

There are three frequency ranges that have to be calibrated with the following settings (see TABLE III in MIL-STD-461.).

Band	Frequency range	Step size
Band 1	10 kHz - 1 MHz	5 %
Band 2	1 MHz - 30 MHz	1 %
Band 2	30 MHz - 200 MHz	0.5 %

These three bands can be configured and performed in three different calibrations. The calibration can be started from the menu by selecting:

    Calibration

       System calibration

          Conducted immunity

This example shows the settings for band 1.

Start

The start frequency of the test. For example 10 kHz.

End	The stop frequency of the test. For example 1 MHz.

Step	The frequency step, in this case 5%.

Test level

The test level, in this case current.

Variable

The variable test level, select the correction file created earlier.

Tolerance

The regulation tolerance.

Calibration method

Forward power.

Test equipment

Calibration test equipment.

Test engineer

The engineer that performed the calibration.

Calibration result

When the calibration is performed, the engineer is asked, to save the results of that calibration to a calibration (.CAL) file. It is possible to give the .CAL file any clear and distinct name. All three bands have to calibrated, and at the end, there should be three different calibration files that are generated.

Verification

Verification equipment

The configuration of the verification test site should contain the following devices:

#	Device name	Tab in testsite configuration window	note
	Signal Generator	Devices 1	The signal generator to use
	Amplifier	Devices 1	The amplifier to use
	Coupler	Devices 1	The coupler to use
	Forward power meter	Devices 1	The forward power meter to use
	Sensor powermeter	Devices 2	The power meter or analyser to use for measuring the current
	Current Sensor	Devices 2	The current sensor to use with transfer factor attached to the driver
	Injection device	Devices 2	The injection clamp to use
Cables
①	Cable current -> power meter	Cables	Cable (1) with a correction file specified for the cable loss
②	Cable current -> power meter	Cables	Cable (2) with the specified loss of the used attenuator
③	Cable current -> power meter	Cables	Cable (3) with a correction file specified for the cable loss

Configure the verification

CS114 requires to perform a verification of the setup with the probes in the calibration setup. With this verification it is important to verify that the forward power of the calibration is followed and that the generated current is within 3 dB tolerance of the current test limit. The verification can be performed in RadiMation^® by doing an actual conducted immunity test. This test can be started by selecting from the menu:

    Tests

       Conducted Immunity

          Multiband

Create a new multiband conducted immunity test and define three bands with the following settings:

Band	Frequency range	Step size
Band 1	10 kHz - 1 MHz	10 %
Band 2	1 MHz - 30 MHz	2 %
Band 2	30 MHz - 200 MHz	1 %

Start

The start frequency of the test. For example 10 kHz.

End	The stop frequency of the test. For example 1 MHz.

Frequency Step

The frequency step, see 5.12.3.4.c.3.

Dwell Time

The dwell time specified see TABLE II.

Frequency Change Mode

Constant.

Modulation

Modulation is optional during the verification.

Test equipment

The equipment needed for the verification.

Location Type

Injection clamp.

Test Level

Specify the current substitution method.

Inputs

Add the current sensor as an input.

Each band needs a test level defined with the test level Current substitution method and the appropriate calibration file attached.

Description

The description of the test level.

Calibration file

Select the calibration file to use.

Test level

Variable current, and specify the correction file for the applicable test level.

Calibration method

Select Forward Power.

Tolerance

Specify the tolerance to use.

Next to the test level add an input Current sensor, this will ensure that the current is measured during the test.

Run the verification test

When all settings are configured press Start Test to run the verification test.

Verification result

With the result of the verification it should be possible to determine if the measured current is within the 3 dB tolerance of the current test limit as specified in clause 5.12.3.4.c of the MIL-STD-461.

EUT Testing

EUT Testing equipment

The configuration of the eut test site should contain the following devices:

#	Device name	Tab in testsite configuration window	note
	Signal Generator	Devices 1	The signal generator to use
	Amplifier	Devices 1	The amplifier to use
	Coupler	Devices 1	The coupler to use
	Forward power meter	Devices 1	The forward power meter to use
	Sensor powermeter	Devices 2	The power meter or analyser to use for measuring the current
	Current Sensor	Devices 2	The current sensor to use with transfer factor attached to the driver
	Injection device	Devices 2	The injection clamp to use
Cables
①	Cable current -> power meter	Cables	Cable (1) with a correction file specified for the cable loss
②	Cable current -> power meter	Cables	Cable (2) with the specified loss of the used attenuator
③	Cable current -> power meter	Cables	Cable (3) with a correction file specified for the cable loss

Configure the EUT test

To perform the actual test on the EUT, create a conducted immunity multiband test with 3 bands. The conducted immunity multiband test, can be started by selecting from the menu:

    Tests

       Conducted Immunity

          Multiband

The following bands should be configured.

Band	Frequency range	Step size
Band 1	10 kHz - 1 MHz	5 %
Band 2	1 MHz - 30 MHz	1 %
Band 2	30 MHz - 200 MHz	0.5 %

Start

The start frequency of the test. For example 10 kHz.

End	The stop frequency of the test. For example 1 MHz.

Frequency Step

The frequency step, see Table III.

Dwell Time

The dwell time.

Frequency Change Mode

Constant.

Modulation

Configure Pulse Modulation with 1 kHz and 50% duty cycle.

Test equipment

The equipment needed for the conducted immunity test.

Location Type

Injection clamp.

Test Level

Specify the current substitution method. Also add a "Measured Current Limit"

Inputs

No inputs are needed.

To configure the pulse modulation settings click Config next to the modulation settings, click the PM tab, and enter the pulse modulation settings as defined in 5.12.3.4.d.1.

Activate modulation

Check this checkbox to enable the pulse modulation.

Frequency

The PM frequency 1 kHz.

Duty Cycle

A duty cycle of 50%.

Also apply modulation out of the dwell-time period

Check this checkbox to enable modulation outside the dwell-time.

At TestLevel click Add to add a new Test level and select TestLevel - Current substitution method

Description

The description of the test level.

Calibration file

Select the calibration file to use for this band.

Test level

Variable current, and specify the correction file for the applicable test level.

Calibration method

Select Forward Power.

Tolerance

Specify the tolerance to use.

Next to the test level add a limit, At TestLevel click Add to add a new Limit and select Limit - Measured Current Limit

With this limit the level will not be regulated higher than the measured current in the cable even if the forward power is not reached yet.

Description

The description of the limit

Constant current

The current to limit on.

When all bands are configured press Start Test to run the EUT test.

EUT Test Result

Once the test is finished, the results of this test are stored in the EUT file and available as one of the performed Tests in the EUT file. Selecting the corresponding test result and pressing on Info will show the test results again.

Conclusion

The RadiMation^® Conducted Immunity multiband test can be used to perform the CS114 verification and the EUT test with a calibration file and the current sensor used as a limit in the EUT test.

The sensitivity of an EUT to incoming electromagnetic interference. This is equivalent to the term Immunity. RadiMation® always uses the term Immunity.

Radio Frequency

Equipment Under Test

The ability of an EUT to be immune to incoming electromagnetic interference. This is equivalent to the term susceptibility that is used by some standards.

CALibration

Decibel

The ability of an EUT to be immune to incoming electromagnetic interference. This is equivalent to the term susceptibility that is used by some standards.