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April 25, 2017


Chris H

FYI..CDMA Cellular telephones never transmitted at (or anywhere near)a power level of +43 dBm (20 Watts). The power level is closer to +33 dBm (or less), or .2 Watts. This power level is nowhere near enough to cause an issue, such as the one you proposed above.

Chris H

Sorry for the Typo...+23 dBm (not +33), or 0.2 Watts is cell phone power level.

Dick Wall

A recently viewed Aircraft Investigation TV programme about TWA Flight 800 included a statement from the investigation findings that the fuel tank sensor operated at low voltage. No further explanation was given!! For a hazardous area such as a fuel tank, the circuitry for sensors used in the fuel tank must be of the NAMUR type (low voltage AND low current) with an intrinsic safety barrier between the sensor and power supply/control circuitry. This ensures that any arcing/sparking that might occur, for whatever reason, has insufficient energy to cause ignition. So, did the programme just skip over the full facts or are aircraft manufacturers just relying on low voltage for the safety of the sensor circuitry? Probably worth looking into further.

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