On 01/03/2009 08:34 AM, James Turner wrote:
<snip> Lots of stuff we agree on.... </snip>
> No, the *deflection* properties really are broken, because they're in
> ambiguous units, I think (especially the magic factor-of-5 multiple
> that started this thread).
As always, I look at things primarily from the _user_ point
of view. We should do what's best for the _users_.
They don't care what local units are used to communicate
between the tuner and the CDI head. It could be "gallons"
as Torsten mentioned.
The existing code uses [0 ± 10] gallons for the left/right
needle and [0 ± 3.5] gallons for the up/down needle. The
xml instrument designers have come to terms with this.
Some comments here and there, documenting this convention,
wouldn't hurt. IMHO nothing more than comments is worth
bothering with.
On the scale of things, this is not "broken". There are
dozens upon dozens of things far more broken than this.
> I am going to add 'deviation-degrees' for
> both the LOC and GS, and I think that's what should be preferred going
> forwards, especially once the full-sector is defined - which it seems
> to be, now.
Not a great idea, for reasons discussed below, including
the fact that it fails miserably for RNAV units.
> I'd still be inclined to include deviation-norm alongside deviation-
> deg, i.e just do the divide by full-sector deviation inside the
> navradio code, since I am sure this would make panel designers much
> happier.
That would make instrument designers much happier, because
VOR sensitivity is different from LOC sensitivity, and LOC
sensitivity varies from place to place. Real World LOC
sensitivity is *not* half a degree per dot, no matter how
many non-experts say it is.
Also RNAV units drive the left/right needle in units that
have nothing to do with degrees.
In the Real World, there is an industry standard that is
used to communicate from the tuner to the CDI head,
namely
CDI Left/Right 150 mV into 1K load
CDI Up/Down 150 mV into 1K load
CDI Glide Slope Flag 300 mV into 1K load
CDI VOR/LOC Flag 300 mV into 1K load
which has never been and cannot be denominated in
degrees. Sending "degrees" to the CDI head is a waste
of time. Why do things the hard way when the easy
(and almost realistic) way is already implemented?
The existing scheme, which puts out a normalized
full-scale deflection, is almost realistic and has
proven perfectly adequate over the years. The
choice of what the normalization constant should
be is a private matter between the tuner-designers
and the CDI-designers. Fussing over private
matters doesn't do the users much good.
There are dozens and dozens of bugs that *do* adversely
affect real users who really fly the sim ... and IMHO
those should get priority. After the real bugs are
fixed we can fuss over things users don't see.
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