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bpcw001

Lear and RXP GTN 750 - losing VOR2

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Hi,

I am using the latest Lear 35 together with a single RXP GTN unit (version 2.5.16.0)

The GTN, as a single unit, is configured to COM1/NAV1, so my expectation is that it would only occupy the VOR1 channel via GPS.

I have put the frequency of a nearby VOR in both NAV1 and NAV2 and set both RMI needles to VOR.

Now, look at this:

In VLOC mode, both RMI needles indicate the selected VOR, as expected:

https://ibb.co/W0z9jMV

Now, the GTN is switched to GPS. Upon doing so, I lose the VOR1 indication on the RMI, since it is now coupled to the GPS. This works as expected:

https://ibb.co/187jKrp

Now, I add a waypoint to the flight plan in the GTN. Upon entering the waypoint, VOR2 indication on the RMI is lost:

https://ibb.co/XLSm0h8

However, the VOR2 channel should not be affected by the GTN at all, since it is configured to take COM1/NAV1. What is wrong here?

GTN config:

 

[GTN_750_1]
; comma separated list of read only settings.
locked = LinkOto,LinkCrs,LinkObs,LinkVor,AutoNavGps,AutoSelect,UseFailures,UseSimGpsCmds,LinkSimGps,AutoSavePln,UseAltMouse,UseLegacyVars
; is the master device if true.
MasterDevice = true 
ReduceRate = true 
LinkCrs = true 
LinkObs = true 
LinkVor = true 
UseSimGpsCmds = true 
LinkSimGps = true 
UseAltMouse = true 
VFRcode = #7000
OwnshipIcon = BUSINESS_JET
; aviation db: 0: nav_db2_grm, 1: nav_db2, 2: nav_heli_db2_grmn, 3: nav_heli_db2
NavDbType = 1
VFRmode = VFR_EUR
AFMS.rf_procedure_legs = 1
FuelType = JETA
PowerSource = BUS_AVIONICS
TawsSurface = HARD
Rheostat.Display = 67
AutoNavSource = 1
Rheostat.Buttons = 67
UseFailures = true 
MasterVolume = 50

[GTN_750_1.DEFAULT]
; show screen only gauge if true.
nobezel = false
; screen only border size (pixels).
border.size = 0
; screen only border color (#RGB or #RGBA).
border.rgba = #000000
; display mouse tooltips if true.
tooltips = false
; enable mouse clickspots if true, disable if false.
usemouse = true
; enable alternate click-spots (left CCW, right CW, middle Push) if true.
usealtmouse = false
; enable touch beyond screen bounds if true (2D only), clip if false (GTN native).
extendtouch = true
; auto-resize dimension (width,height)
refsize = 
; left mouse button on the screen toggles popup window by ident (ex: GPS_PANEL or 225) (requires SHIFT+left mouse button).
popleft = 
; right mouse button on the screen toggles popup window by ident (ex: GPS_PANEL or 225).
popright = 
; adjust brightness (0 to 100)
brightness.bezel = 100
; offset brightness (-100 to +100)
brightness.screen = 0

 

 

Thanks for looking into this.

 

 

 

 

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Posted (edited)
5 hours ago, bpcw001 said:

However, the VOR2 channel should not be affected by the GTN at all, since it is configured to take COM1/NAV1. What is wrong here?

Agree something is wrong somewhere. Unfortunately the applicable XML RMI code is in the interior model file which is compiled so I don't have access. However, try setting LinkVor = false in the RXP GTN ini file then save the file and reload the a/c. With that I think the RMI should only respond to VOR/ADF frequencies and be independent of whether the GTN is in the GPS or VLOC mode.

Al

Edited by ark

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Posted (edited)
1 hour ago, ark said:

Agree something is wrong somewhere. Unfortunately the applicable XML RMI code is in the interior model file which is compiled so I don't have access. However, try setting LinkVor = false in the RXP GTN ini file then save the file and reload the a/c. With that I think the RMI should only respond to VOR/ADF frequencies and be independent of whether the GTN is in the GPS or VLOC mode.

Al

Yes, that brings back both(!)  VOR needles on the RMI independent of GPS or VLOC mode.

But you lose RNAV/LPV vertical guidance 😞. That seems to require VOR linking to be set to true, I just tried it with LPV approaches into LFSB. No glide slope on Lear HSI with VOR linking in GTN disabled.

Other ideas?

Edited by bpcw001

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if it wasn‘t for the LPV vertical guidance it would be perfect. VOR1 and 2 completely separated from GPS.

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24 minutes ago, bpcw001 said:

if it wasn‘t for the LPV vertical guidance it would be perfect. VOR1 and 2 completely separated from GPS.

Yes, that was the idea.  I don't understand why a VOR setting would impact a vertical mode -- surprises me.

Al

 

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19 minutes ago, ark said:

Yes, that was the idea.  I don't understand why a VOR setting would impact a vertical mode -- surprises me.

Al

 

I‘ll tinker with it some more.

Let‘s see what I can come up with. 

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Posted (edited)

Now, as far as I can see, when LinkVor = false, the glide slope *is* there for LPV approaches.

The problem is that the red vertical GS flags across the sides of ADI and HSI do not clear away. Next to the red flags, on the right side, you can see a tiny yellow arrow tip that moves with vertical guidance in case an LPV approach is active. It appears that the flags obstruct the yellow vertical guidance pointers. You can even see more of the yellow vertical guidance if the deviation is big so the yellow arrows go above or below the red flags.

See here: https://ibb.co/G7X91FV

 

However, on arming the GS on the autopilot system, GS will not be captured (presumably because the signal is flagged as invalid).

Unless there is a setting in the RXP GTN.ini file other than LinkVor=true which kills the VOR indications on the RMI (please share!), I think the Lear ADI/HSI should take away the GS flags and make the autopilot accept the vertical signal as soon as there is any GS input and work properly with LinkVor = false

 

Edited by bpcw001

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Posted (edited)

Having read a bit around on the RXP GTN forums it appears that LinkVor = true is a requirement for vertical guidance autopilot approach coupling to work. 

So it appears that the Lear 35 RMI must learn to deal with this and keep both VOR channels open independent of GPS mode or ILS coupling ( the latter only using VOR1 and not blocking VOR2 as well).

Edited by bpcw001

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Posted (edited)
On 5/23/2019 at 12:20 PM, bpcw001 said:

Having read a bit around on the RXP GTN forums it appears that LinkVor = true is a requirement for vertical guidance autopilot approach coupling to work. 

So it appears that the Lear 35 RMI must learn to deal with this and keep both VOR channels open independent of GPS mode or ILS coupling ( the latter only using VOR1 and not blocking VOR2 as well).

Dave,

I have found a bug in the Lear interior model file that was causing the problem with the RMI VOR needle 2. If you PM me an email address I'll send you a copy to try ( I think it will 'fit' through the email system). 

As for VOR needle 1, I don't think there is anything that can be done at this point to "free it up" as long as the RXP GTN750 has LinkVOR= true because in GPS mode, the GPS drives NAV1 -- that is just how the sim works. However, it may be possible to get the RXP GTN to work in the Lear with LinkVOR= false and then both RMI needles will be available when in GPS mode. A WIP.

Al

Edited by ark

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Posted (edited)
On 5/23/2019 at 12:20 PM, bpcw001 said:

Having read a bit around on the RXP GTN forums it appears that LinkVor = true is a requirement for vertical guidance autopilot approach coupling to work. 

Not so. I have been able to modify the Lear AP code so you can set LinkVor=false and the RXP GTN 750 will work as intended in GPS mode. This in turn frees up both RMI needles to be used independently of the GTN 750.

As I mentioned above, PM me an email address if you would like to try the modified code.

Al

Edited by ark

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Posted (edited)
On 5/27/2019 at 1:10 AM, ark said:

Not so. I have been able to modify the Lear AP code so you can set LinkVor=false and the RXP GTN 750 will work as intended in GPS mode. This in turn frees up both RMI needles to be used independently of the GTN 750.

As I mentioned above, PM me an email address if you would like to try the modified code.

Al

Sorry for the late reply. Been quite busy recently. Definitely interested. Will send email through PM.

Edited by bpcw001

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