SC-226 MEETING MINUTES Working Group JANUARY 14 ... - RTCA

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RTCA Paper No. 021-13/SC226-010 February 6, 2013 Christian Grone – Sennheiser Anthony Mangiameli – Bose Gregory Laborde – Cobham (not in attendance) Francesco Orsino – Gables Engineering Don Nault – Boeing Mark Goldberg - Honeywell Todd Blackstock – AEM Steven Parker – Bosch Security System Marchus Schmitz – Becker Avionics (not in attendance) Greg Sherwood – Garmin (not in attendance) Greg Frye – FAA (on the phone) First item of discussion: Pink Noise. Paul Menard - Avtech Suggestion to add reference to IEC60065 in the definitions section of the standard as a “recommended definition of pink noise” As part of the General Test Conditions for audio, IEC60065 section 4.1.6 states “Where relevant, a standard signal consisting of PINK NOISE, band-limited by a filter whose response conforms to that given in figure C.1 in annex C.” IEC60065 Figure C.1 from annex C is shown below. Second item of discussion: RF Susceptibility, Rick Robles - Gables Gables offered language addressing for Section 20 allowance for special instances where “in-band” RF threat signals can cause noise beyond the required threshold for the equipment performance similar to the allowance in Section 2.5.10 and 2.5.11 of the current DO-214 standard. Honeywell mentioned that they test the threat level to determine that there are no operational failures or system state changes as a result of the full threat level being applied. DO-214 allows the threat signal to be lowered to 2V/M when the threat signal generates too much audio noise. Example: The Category S definition is the ambient RF environment in the aircraft. There already has been a precedence set by DO160 to use Category S to pass RF MOPS. This should also be the Category used to pass the signal to noise audio MOPS. Airbus mentioned that they had an instance where a CAM was made non-functional by a GSM RF signal installed on the aircraft. ED112 now requires a minimum threat level of 20V/M as a minimum allowance. Boeing will discuss a possible solution with Gables and get back to us. Completed discussion of Gables paper. Proposed language was provided to Boeing to review. Page 2 of 20
RTCA Paper No. 021-13/SC226-010 February 6, 2013 Third item of discussion: RF Susceptibility test levels and parasitic oscillation definition, Scott Moore - Jupiter Avionics The DO-214 Sec 2.5.11.2 Sustained Ambient RF Test (Radiated and Conducted) requires changes to the frequencies and levels used during the audio noise without signal test. However there is no clear instruction regarding which modulation to apply during the exposure. My other suggestion is for 2.8.2.2.1 Audio Frequency Response. It would be beneficial to have a definition of what a "parasitic oscillation" is, or change the requirement such that a standard and measurable audio attribute is referred to. Committee discussion identified that DO-160 includes the specified modulation frequency and level as well as the RF threat signal levels and frequencies. 20.4 paragraph (e) and 20.5 paragraph (e) both define the modulation frequency and level. The committee also agreed that it is true that parasitic oscillation was not well defined. The definitions section was revised to change Spurious Signals to Spurious/Parasitic Signals. Committee review of the definitions section found that the existing definition adequately covers the definition of “parasitic”. Other sections that referred ambiguously to oscillations in the form of “unwanted” oscillations were revised to include “parasitic” where applicable. Fourth item of discussion: ANR performance testing requirements, Anthony Mangiamelli and Dan Gauger - Bose Bose offered a paper regarding performance testing of headsets, relative to problems with characterizing performance around the 1KHz center as is currently done. Using the 1KHz center is found not effective or consistent and does not reflect human speech perception. A graph offered by Bose illustrates the actual performance. Bose proposes requiring a wide band performance test rather than a discrete 1KHz test. Todd Blackstock – AEM inquired about a concern over cert authorities’ possible perception that the headset and audio system might be perceived not consistent with one another. A note can be added to address the equivalency of the 1KHz specified headset to the 1KHz center frequency use to characterize performance of the audio system. Page 3 of 20
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SC-226 MEETING MINUTES Working Group JANUARY 14 ... - RTCA

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