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Old 20th October 2010 | 06:59
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IO540
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From: EuroGA.org
I suggest notifying the relevant regulatory bodies if not already done so they can issue the appropriate safety advisories
The KN72 converter which does the stuff in this case is a 1970s design so has been around a while...

As BPF shows above, all kinds of failures are possible and some of these could kill you.

I just posted my illustration for those who have been taught that VORs are somehow superior to GPS

The way in which the three components of a VOR (CDI) receiver are generated (the deviation bar, the to/from flags, and the Invalid flag) is a disaster absolutely begging for a place to happen. They are generated by separate circuits, which can fail individually.

In contrast, a GPS usually has a single processor which either runs or doesn't. The LCD will have its own "processor" and this is how the LCD can freeze on a given indication when the main processor crashes, but it will not show anything meaningfully changing. The GPS satellite receiver is usually a separate module, with its own little processor, and if that fails, the main processor will put up a big "no satellite reception etc" message across the screen.

Whereas the VOR (and LOC/GS) system uses separate circuits which can fail individually. There lies the danger.

I don't know how e.g. a G1000 system does this. Does it use analog separation of these signals and then an A-D converter to get the LCD representations, or does it use a DSP to do a direct digital conversion receiver? The latter would be unlikely, on VHF.

I opened up the duff KN72 (there is no exchange option on it so it is basically worthless) and here is the inside.

Last edited by IO540; 20th October 2010 at 07:53.
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