USB Charge Ports: Difference between revisions

USB Charge Ports (view source)

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-What to look for:
-RF Emissions
-* RF noise emitted by a USB charger can disturb or even knock out for example: your GPS receivers, your VHF radio reception, your NAV/ILS/GS reception, your ADS-B traffic / weather reception, etc
-* Almost all USB chargers will emit some RF noise because internally they need to convert 12V or 24V down to 5V and they do that using a switching power supply (because a conventional power supply would have to burn off the difference as heat (13.2V - 5V = 8.2V; times the current 2.4A = 20W; cooling surface area needed to burn that off is more than 100 square inch, not possible in a small form factor). Good USB chargers will use shielding methods and electronic measures such as spread spectrum technology to avoid emissions or at least lower the emissions in the frequency bands relevant for aviation.
-* The center frequency of the RF noise will depend on the load, which is mostly influenced by the fluctuating charging or operating power of the devices attached. It could also be that you never had a problem for years, then you buy a new iPad or phone which charges at a different rate and only now it creates an issue. It can also be that only a specific VHF frequency is affected which may foil a handoff to the next controller or it may be that only a specific ILS approach is affected. Therefore you cannot deduct that a certain cheap, non-aviation model, which works for someone else, will also work for you. But it may.
-* There is no known remedy for receivers to overcome RF noise. If the RF noise is exactly on the receiver's frequency, and much stronger than the far away signal, you lose reception, even with a $10,000 certified receiver. Unfortunately, aviation still uses amplitude modulation on VHF where RF noise cannot be distinguished from the signal.
 Supported Charging Protocols
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 * [[USB_Charge_Ports2|USB Charge Ports Part 2]]
-[[Category:XOptional]]
+[[Category:Optional]]