RTCA DO-160: “Environmental Conditions and Test Procedures for Airborne Equipment”
RTCA DO-160 is key for getting electronics modules tested in order to ensure proper operation and support certification of aircraft. The current Rev is G and can be purchased here. Its history traces back to 1958, about the same time the precursors to MIL-STD-461 were coming into existence. It follows the same general principles as many MIL-STD-461-derived standards: test individual units very thoroughly, and when you integrate them into a larger system you have a good chance that will operate together successfully. In DO-160, EMC-related topics are a subset of a larger realm of environmental testing, including thermal, humidity, shock & vibe, sand & dust, salt spray, etc. Sections 16 - 23, plus 25, are the ones with the most EMC/E3 impact.
Section 16 specifies “Power Input” and can be thought of as a power quality spec. It controls things like normal operating voltages, both AC and DC, normal transients, ripple voltages, phase imbalance for AC power, and abnormal conditions as well. It has more in common with MIL-STD-704 than 461 or 464. This section assumes the equipment under test (EUT) is getting power in one of the following forms: 14, 28, or 270 Vdc, or 115 or 230 Vrms AC at 400 Hz.
Section 17 is for “Voltage Spike” testing. This is most similar to MIL-STD-461 CS06/CS106 testing, which was removed from the latest 461 Rev G. It can be found in the older versions of 461, as well as in GSFC-STD-7000.
Section 18, “Audio Frequency Conducted Susceptibility”. This is closely related to MIL-STD-461 CS101, which can be a tricky test to execute.
TIP:
Figure 18-1 of DO-160G shows an optional current monitor as part of the test setup. Always use this if you have the equipment–it gives you a lot of additional information for not a lot of extra effort. In particular it gives you the ability to calculate how the input impedance of the EUT is changing over frequency.
Section 19 covers “Induced Signal Susceptibility”. This doesn’t have a direct MIL-STD-461 analogue, but in general it is looking for susceptibility to low frequency stimulus induced in signal lines, as opposed to Section 18 focusing on power lines.
Section 20, “RF Susceptibility (Radiated and Conducted)” covers similar test methods to MIL-STD-461 CS114 and RS103. The radiated test includes both semi-anechoic and reverb methods.
Section 21, “Emission of RF Energy”, covers similar test methods to MIL-STD-461 CE102 and RE102. As in Section 20, the radiated test includes both ALSE and reverb methods.
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Use reverb testing whenever possible to save time. DO-160G Section 20 has excellent information about the mathematical and statistical techniques needed to ensure a chamber is set up correctly. The math is scarier, but there’s a significant savings in terms of testing time-in-chamber.
Sections 22 and 23 cover lightning testing (“Lightning Induced Transient Susceptibility” and “Lightning Direct Effects”). These share a lot of heritage with MIL-STD-464 as electromagnetic environmental effects tests. Section 25 covers ESD, and like most ESD specs basically follows IEC 61000-4-2.
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One of the things that separates DO-160 from other standards is the use of alphanumeric codes to describe the EUT and the applicable tests. Whenever you pin down a letter/number designation that applies to your EUT, write it down somewhere. Otherwise you’ll spend a lot of time flipping back and forth across many pages trying to find the right code again.