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jcomm

Navaids in XPX

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Has anyone noticed 2 limitations, sometimes very annoying, of VOR/DME modelling in XPX?

 

I believe they have to do with the fact that most scenery elements are tile-based, and if you happen to be in an adjacent tile to the one where your navaid belongs, then you will probably not be able to get any signal from it, even if well under reach, or even get weird DME readings:

 

To resume:

 

1) Even if your station has a range of, say, 130NM when you edit it, you wont be able to get coherent readings / signal from it until your aircraft enters the same area tile where that navaid is defined.

 

2) Altitude is no factor in VOR / DME reach. You can get a signal 90NM away from your aircraft being at sea level or at Angels-30...  This was one of the limitations ELITE had for quite a while until they accepted my complaints and changed it in v7.  Of course there are still problems with line of sight, but that's perfectly understandable to me because having to take into account such "clipping" effects under complex terrain areas would be heavy on the simulation....

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Not sure if its a feature or a bug but I usually can't pick up SLI when I'm traveling up the shore from San Diego until in within about 60 miles.

 

It may be a Low but I haven't checked.

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Not sure if its a feature or a bug but I usually can't pick up SLI when I'm traveling up the shore from San Diego until in within about 60 miles.

 

It may be a Low but I haven't checked.

 

I can't check it now, but I have a few examples of Low and High stations around here and, when coming from an adjacent tile of scenery, even if well withing their range you wont be able to "capture" it.

 

OTOH, the altitude problem is not a feature but rather a bug / limitation. You shouldn't be able to get signal from a VOR/DME at 90 NM from you when you're near sea level, even if there are no obstacles in the line of sight...

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I just recently bought the 727, so I've been doing a lot more VOR navigation.  I've noticed this behaviour too, and even instances where the VOR won't pickup until I'm 40 miles out. 

 

Strange though I haven't noticed it earlier - I've done plenty of VOR trips with the prop planes o

 

If you notice on the local map, only navaids appear for the loaded tiles.  I'm pretty sure I've seen navaids load up outside the loaded tile area in previous x-plane versions.

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anthony_d, on 26 Jun 2013 - 8:44 PM, said:

If you notice on the local map, only navaids appear for the loaded tiles. I'm pretty sure I've seen navaids load up outside the loaded tile area in previous x-plane versions.

Exactly!

 

Weird things happen when, for instance, you are tuned to & receiving a station with DME, and while well within it's reach you leave the tile where you were ( and the station too ). Your DME readings can look really strange, as well as your OBS readings...

 

Then, there's the altitude thingy... not really a show stopper since we could then argue that line of sight should also be modeled..., but it would be great to get at least some sort of "inverted top model" of coverage:

 

T (Terminal) - From 1,000 feet above ground level (AGL) up to and including 12,000 feet AGL at radial distances out to 25 NM.

L (Low Altitude) - From 1,000 feet AGL up to and including 18,000 feet AGL at radial distances out to 40 NM.

H (High Altitude) - From 1,000 feet AGL up to and including 14,500 feet AGL at radial distances out to 40 NM. From 14,500 AGL up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet AGL up to and including 45,000 feet AGL at radial distances out to 130 NM.

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It bugs me that the VOR will become active prior to the DME coming in.  It should be the other way around.  The VOR is VHF and the DME is UHF.

Maybe by the time XPX is 8 years old it will run better than FSX does at 8.

I still enjoy XPX.

 

Jerry

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I still enjoy XPX.

 

We do our best to....

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It bugs me that the VOR will become active prior to the DME coming in.  It should be the other way around.  The VOR is VHF and the DME is UHF.

Maybe by the time XPX is 8 years old it will run better than FSX does at 8.

I still enjoy XPX.

 

Jerry

 

 

Actually, VHF signals propagate farther than UHF signals at the exact same power. VHF has a wavelength on average of 2 meters vs. UHF of about 70 centimeters. This is why UHF radio signals work better in buildings vs. VHF working better in open areas.

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Actually, VHF signals propagate farther than UHF signals at the exact same power. VHF has a wavelength on average of 2 meters vs. UHF of about 70 centimeters. This is why UHF radio signals work better in buildings vs. VHF working better in open areas.

Thank you Mr. Bergman.  I did not know this.

I was making ref to years of flying when I thought I remembered (perhaps incorrectly) that the DME usually became active prior to the VOR.

Getting old.  I remember flying round engine equipment.

Thanks.

 

Jerry

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Thank you Mr. Bergman.  I did not know this.

I was making ref to years of flying when I thought I remembered (perhaps incorrectly) that the DME usually became active prior to the VOR.

Getting old.  I remember flying round engine equipment.

Thanks.

 

Jerry

 

What you are most likely noticing is a stronger UHF radio which makes it appear as if the signal comes in before the VOR, clouds can also upset a VHF signal when on the fringe of the coverage area, due to the propagation of both signals the UHF will come in first.

 

The lower the frequency the longer the wavelength, you although do reach a point where you will get interference from the atmosphere and other sources. This is why ADF's which use LF signals are horrific to use during thunderstorm activity nearby, today all they're good for in aircraft equipped with more modern navigation equipment is the baseball storm and a fancy lighting finder.

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