Re: [Opengc-devel] NavTestGauge

[John W. <ca...@mm...>]

Hi,

The question is one of philosophy and division of labor...

IMO the FG side should do the flying (EOM), scenery, and systems modeling.
The glass displays should act like the flightdeck receiving data from the
aircraft systems. So in that world the display code gets a lat and lon from
the FG side and nav/radio data from the FG receivers. Given that setup, the
display side needs a panel to tune radios and send the frequencies to the FG
side receivers who search the nav world for in-range stations and return the
appropriate data. There should be NO panel displayed on the FG side except
perhaps for thr HUD

Having said that I then turned around and violated my own reasoning and
built a clone of the FG nav data base on the display side and modified the
FG nav/radio code to support situations present in glass displays like
multiple tuned in-range stations for MAP modes, auto-search/tuning when
flying in LNAV mode, etc.  The FG/OpenGC interface gets a bit complicated
with all the hand-shaking required to do this and somewhat
non-deterministic; i.e, the FMC auto-searches for in-range/tunable stations
and may select several to perform a nav calculation or use an INS (lat/lon)
as raw data or correlate with identified stations, especially when flying
great circle routes.

To mitigate the network traffic and the complexity inherent in a variable
length data packet I again felt the clone approach was a reasonable
compromise. So, yes one could allow the FG side to input VOR/Radio
frequencies by then you need to have some sort of signal/semaphore to
exchange to decide who has control.

One advantage of using OpenGC is to reduce the CPU and GPU workload on the
FG side. You can expect around a 15 to 20% inprovement in frame rate by
spreading out the work.

Again, I've not kept pace with the lastest CVS, there may be some legacy
code (circa 2001) that might still work with fgfs... Peraps Damion could
address that better than I.

Regards
John W.


----- Original Message -----
From: "Wendell Turner" <we...@ad...>
To: <ope...@li...>
Sent: Tuesday, September 16, 2003 2:02 PM
Subject: [Opengc-devel] NavTestGauge


> When using OpenGC with FlightGear, and displaying the
> NavTestGauge, I can't get the vor or adf needles to
> move.  Is that porting working with fgfs?  Are the
> needles on OpenGC supposed to track/mimic the ones on
> the fgfs panel?  I've tuned the radios in fgfs, but
> the needles on the NavTestGauge don't move.  (Maybe
> that is why it is called 'Test'?)
>
> Is there a better way to turn off the navaids
> and smaller airports other than to edit apt.dat?
>
> Wendell
>
>
>
>
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