Lateral Deviation Indicator vs Course Deviation Indicator

[tschuh00 1]

I have the GNS530 V2 running in FSX in the Carenado Seneca V.  It is interfaced to the f1 Aspen EFD1000 which has the Attitude Display on the top half of the instrument and the Navigational Display on the bottom half of the instrument.  The Attitude Display includes a "Lateral Deviation Indicator (LDI)" and the Navigation Display includes a "Course Deviation Indicator(CDI)".  And they both display a Glide Slope Indicator.  When flying an LPV approach, presumably the LDI and CDI should be displaying the same relative deviation.  However, the LDI is way more sensitive than the CDI.  In other words, when the CDI is barely indicating one dot of deflection, the LDI shows an off-scale deflection.  Is there a setting that I need be updating in the 530 v2 configuration so that the same data is being passed to these two indicators?  

   

 

 

Edited October 3, 2019 by RXP

[RXP 2,338]

Hi,

The problem is with the ASPEN. It is certainly using different simvars and/or different scales in order to 'simulate' what an ASPEN would display, and it gets it wrong in this case.

You can easily monitor what the GNS V2 is outputting to the simulator. In effect, each of our FltSim products installs a convenient monitoring gauge you can add to any panel! See the following in the v2.4.6 release notes:

Quote

New: rxpGpsDebug!variables (XML gauge) to monitor GNS V2 (simvars override and data out).

rxpGpsDebug!variables (XML gauge):
It is an xml gauge designed to help 3rd party aircraft vendors to monitor GNS V2 integration and the various simvar overrides.
It Installs to "Program Files (x86)\Reality XP\Gauges" and is pre-configured in RXP add-on.xml.

Just add this gauge to your panel.cfg file, preferably in its own popup window, then cross check the data output from the GNS V2 as you fly and compare this to the ASPEN readouts. Example of panel.cfg configuration:

[Window Titles]
...
Window##=RXP DEBUG

[Window##]
size_mm=128,256
background_color=2,2,2
position=0
visible=1
always_visible=1
ident=16000
gauge00=rxpGpsDebug!variables, 0, 0, 128, 256

 

Please note: in the real world, the GPS has a variable scale depending on the flight phase and/or user modifiable settings in the device itself (AUX pages). When connected to an EFIS, the scale and the deviation are both sent out in order for the EFIS to display the deviation needle correctly. However, there is no such 'scale' factor inherently managed within Flight Simulator (unlike X-Plane).

Third party EFIS gauges must therefore choose whether they just display the needle deviation verbatim from the value in the simvar, or whether they're trying to outsmart the system and risk failing. With a correct integration with he GNS V2 any third party EFIS gauge would be able to get such data needed to most appropriately scale the needle deviation.

In effect, third party EFIS gauge vendors can open and read the rxpGpsDebug gauge code (it is an unprotected XML gauge) to see what data is available, how to get it and make the most out of it.

[tschuh00 1]

Thank you for this additional information.  I added the gauge to my panel.cfg file.  When I bring up the new pop-up window all I get is a blank / black screen.  Should I be seeing the data being output from the GNS v2?  

[RXP 2,338]

Quote

It Installs to "Program Files (x86)\Reality XP\Gauges"

you might want to cross check the gauge is installed in the aforementioned folder to get started.

 

1 hour ago, RXP said:

and is pre-configured in RXP add-on.xml.

obviously this applies to P3D3/4. Otherwise for FSX you'd have to manually copy the gauge into the simulator "Gauges" folder.

[tschuh00 1]

Yes the gauge is in the Reality XP/Gauges folder. 

I am running on FSX.  So based on your reply I moved the Debug sub-folder (along with its contents) to the FSX/Gauges folder and retried.  

The pop-up window is still blank.  

In the mean time I also tried changing the HSI Lateral Sensitivity slider from 1 to 0.1 in the GNS v2 settings.  This had positive results.  The LDI needle now much more closely matches the CDI needle.  They are not identical (should be) but they are much closer.  It is also interesting that the LDI gets more sensitive as the airplane approaches the runway threshold (as it should) whereas the CDI maintains a consistent sensitivity throughout the approach (it should scale down the closer it gets to the threshold until it gets to maximum sensitivity at the threshold at which point a full-scale deflection should be 350' either side of center.  

So it would be very helpful to use the aforementioned debug tool to see what is being passed. 

[RXP 2,338]

39 minutes ago, tschuh00 said:

I moved the Debug sub-folder (along with its contents) to the FSX/Gauges folder and retried.  

This is the correct folder to copy:

"C:\Program Files (x86)\Reality XP\Gauges\debug\rxpGpsDebug"

copy to:

"[path_to_fsx]\Gauges\rxpGpsDebug"

 

[RXP 2,338]

42 minutes ago, tschuh00 said:

whereas the CDI maintains a consistent sensitivity throughout the approach

IIRC this is normal and expected. This should be explained in the Garmin Pilot's Guide too.

[tschuh00 1]

56 minutes ago, RXP said:

This is the correct folder to copy:

"C:\Program Files (x86)\Reality XP\Gauges\debug\rxpGpsDebug"

copy to:

"[path_to_fsx]\Gauges\rxpGpsDebug"

 

Thanks that did the trick, debugger is working now, thank you!  

I am going to review the data being passed now and see what's going on with the LDI and CDI/HSI discrepancies.  

[tschuh00 1]

On 10/3/2019 at 9:56 AM, RXP said:

Hi,

The problem is with the ASPEN. It is certainly using different simvars and/or different scales in order to 'simulate' what an ASPEN would display, and it gets it wrong in this case.

You can easily monitor what the GNS V2 is outputting to the simulator. In effect, each of our FltSim products installs a convenient monitoring gauge you can add to any panel! See the following in the v2.4.6 release notes:

Just add this gauge to your panel.cfg file, preferably in its own popup window, then cross check the data output from the GNS V2 as you fly and compare this to the ASPEN readouts. Example of panel.cfg configuration:

[Window Titles]
...
Window##=RXP DEBUG

[Window##]
size_mm=128,256
background_color=2,2,2
position=0
visible=1
always_visible=1
ident=16000
gauge00=rxpGpsDebug!variables, 0, 0, 128, 256

 

Please note: in the real world, the GPS has a variable scale depending on the flight phase and/or user modifiable settings in the device itself (AUX pages). When connected to an EFIS, the scale and the deviation are both sent out in order for the EFIS to display the deviation needle correctly. However, there is no such 'scale' factor inherently managed within Flight Simulator (unlike X-Plane).

Third party EFIS gauges must therefore choose whether they just display the needle deviation verbatim from the value in the simvar, or whether they're trying to outsmart the system and risk failing. With a correct integration with he GNS V2 any third party EFIS gauge would be able to get such data needed to most appropriately scale the needle deviation.

In effect, third party EFIS gauge vendors can open and read the rxpGpsDebug gauge code (it is an unprotected XML gauge) to see what data is available, how to get it and make the most out of it.

Your comment about the problem being with the Aspen is almost certainly correct.  Unfortunately the author of that tool seems to have gotten out of the business, and the gauge is no longer supported.  Furthermore, it's the only such gauge that I've been able to find in the marketplace that I can add to my Carenado Seneca.  And so I am trying to get the best emulation possible until a new and improved version comes from another author.  

With that in mind, do you happen to have any further information regarding the fields that your debug tools is passing back.  Of particular interest is the "HSI CDI Needle (Percenet)" field on page 3. HSI Data.  I am typically seeing numbers like 12700.00.  How to I interpret these numbers?  Do they have any relationship to HSI deflection?  Being a percentage field, I would expect them to be something like 0 - 100, correlating to centered needle through full-scale deflection at 100%.  

 

 

[RXP 2,338]

These are standard FltSim variables documented in the SDK:

http://www.prepar3d.com/SDKv3/LearningCenter/utilities/variables/simulation_variables.html

As for the ASPEN, if this is an XML gauge, you may be able to change the code directly, Otherwise, there isn't much room available.

[tschuh00 1]

That helps thanks.  I'll research the Aspen gauge some more.  In the meantime, according to the SDK, the HSI CDI Needle value ranges from +/- 127.  I'm seeing values more like 12700.00 which is 100 times the SDK specified range.  Any thoughts on why that is?  

[RXP 2,338]

yes, you can ask FltSim to use different units for each simvar, and our XML 'debug' gauge is just using a percent unit which in the end *100 the value.