 | <inter-signal-con-lab-test>
The requirements to capacitively coupled-in interferences are described in an analogue way to the requirements to interferences by conduction in power supply conductions ( <inter-supply-con>). The pulses used within that correspond, concerning their characteristics, to the pulses used in Interferences by conduction in power supply conductions ( <inter-supply-con>). Although, because of the origin of these pulses, they are not the same pulses. In order to realize a capacitive coupling of an interference into the interference sink, the coupling clamp is used.
Apart from the test pulses defined by standards, it is possible to define further test pulses (e.g. company-specific test pulses).
The requirements to interferences which can be coupled into signal input conductions, data conductions, and control conductions, as well as into output conductions, are described to one or various corresponding vehicle network voltage(s) by means of interference strength tests. During an interference strength test, the behaviour of a DUT is tested by exposing the sample to a test pulse. For an interference strength test, following specifications can be made.
| | Test pulse
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| | Severity level and corresponding peak voltage for the test pulse
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| | Test voltage
Vehicle network voltage applied during the test. It will only be defined if it deviates from the standard test voltage.
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| | Internal resistance of the generator Ri
Internal resistance of the interference source
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| | Minimum test amount
The minimum test amount is defined by the number of test pulses or by the duration of the test.
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| | Interference source
The known component which generates the test pulse.
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| | Operating state
The operating state defines the state of the system at which the test is performed. If the test is to be performed with various operating states, these can be grouped.
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| | Function state
The assignment of a function state to the test is accomplished by a code letter (A...E).
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| | Fault description
The failure mode of the system will be described in textual form, in addition to the function state (if it is not equal to A).
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| | Additional specifications
Apart from the a.m. specifications, it is always possible to give additional specifications for a test. These include, e.g., a test temperature which differs from general specifications, the test set-up, the description of the coupling clamp and further specifications which have not been defined yet.
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Figure 34: Structure of laboratory testing
Example for content:
Definition of the test pulse:
Representation example for test pulses for coupled-in interferences on transmission and sensor conductions and a 12 volts vehicle network
Test pulse
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t1
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t2
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t3
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tr
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td
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Unit
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s
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ms
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ms
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µs
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ms
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1
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0,5
-5
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1
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2
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2
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0,5
-5
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1
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3a
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0,0001
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10
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90
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0,005
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0,0001
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3b
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0,0001
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10
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90
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0,005
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0,0001
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new
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Determination of severity levels for coupled-in interferences on transmission and sensor conductions according to DIN 40839 part 3.
Test pulse
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Pulse amplitude U s in volts
at severity level
(for 12/24V vehicle network voltage)
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I
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II
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III
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IV
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1
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-7.5/-15
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-15/-30
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-22.5/-45
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-30/-60
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2
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7.5/15
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15/30
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22.5/45
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30/60
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3a
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-15/-14
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-30/-28
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-45/-56
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-60/-80
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3b
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10/14
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20/28
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30/56
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40/80
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The peak voltage depends on the severity level and on the vehicle network voltage. Further user-defined or in-house standard specific severity levels with corresponding voltages U s can be defined to given test pulses.
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