DME for skyview

[ploucandco]

Hello, when I look in the skyview manuals, I see that the DME functionality when using VOR as HSI source was initially foreseen (place for distance on the small window right to the HSI with VOR infos). Also, the table on HSI requirements in the installation manual shows a line with DME.

I understand that not many people are willing to use a DME in the US as you can use GPS instead of DME. But that's not the case everywhere in the world (e.g. Europe).

There is no DME analog entry on the skyview like in the HS34 and the 2 ARINC inputs are typically used by the GPS and by the VOR/ILS system.

The SL30 protocol that is pretty well implemented in Dynon products also supports DME information to be displayed on the SL30 display: the message $PMRRV41 (see SL30 installation manual) is used for this purpose. It is clear that this is an input message to the SL30 and not an output message from the SL30 to Skyview as the VOR information.

But as it uses exactly the same format that all the other SL30 output, it would be pretty straightforward to use the same convention to input DME information via the same serial port to Skyview. Just a small microcontroller that gets information from the DME and the SL30 stream and creates a new stream with both information combined (we are in the experimental world). Even Garmin/Apollo had a box (DB30 now defunct) that delivers this $PMRRV41 sentence to an SL30 when associated with a King DME KN63.

Are there any plans to support DME information on skyview? What I just proposed seems, from my perspective at least, very easy to implement. Or is it already supported as an undisclosed feature
Well, I understand that any changes could have impact...

Thanks, Jacques

 

[Edwardoc]

I like your idea Hope it is possible.

 

[mmarien]

Ok. I have to ask. Why would you want a DME if you have GPS? Both supply a distance, except the GPS is horizontal ground distance while the DME is slope distance. The benefit of GPS is that it can compute a distance to any coordinated point (waypoint) while the DME is restricted to working ground stations.

 

[Edwardoc]

I have a single VOR/ILS without DME and a non approach certified GPS in the Skyview.  Lets say I want to fly an ILS that uses an ARC off of a VOR/DME to intercept the final approach course.  I can put the VOR in the GPS and get pretty accurate DME but I don't think that is totally legal since the GPS is not approach certified and not slant range.  If I had a VOR/DME available I could keep the VOR selected for the ARC until about the lead radial and then select ILS & Tune & Identify and intercept the final.  I can put the GPS on the airport for Situation awareness and all is legal.  Just one use of DME.  For us with non approach certified GPS's, it would be nice to have.   

 

[dynonsupport]

Using any IFR certified GPS (even just enroute certified) has been legal as a replacement for a DME since 1998 in the USA:

http://www.aopa.org/Advocacy/Air-Tr...-Services-Brief-Use-of-GPS-in-lieu-of-DME-ADF

 

[dynonsupport]

Jacques,
DME was never planned for SkyView. I glanced at the user manual and don't see where we indicate that. We do show distances when the source is a GPS, but not when it's a VLOC.

In any case, having DME is not a request we've really had before. The whole reason we didn't do it in SkyView is that we did it in the D10/D100 series and nobody used it. It is of course technically possible via a variety of methods. I don't think the demand exists enough for us to design a whole product to mix DME info with an SL-30 radio stream, but if someone else really wants to do that, we may be able to add the display of the data in $PMRRV41 pretty easily.

It's a bit of a chicken and egg problem though. There isn't much demand, and no product exists today for us to test against, and nobody can design a product to work with us yet since we don't support it. If you send us a working device that does this we'll be pretty motivated to help you out

 

[ploucandco]

Hello, many thanks for this very positive answer.

The Skyview installation manual version O table 7 mentions the DME concerning the HSI requirements. But the line is empty

In fact, I was planning to make an interface between a DME receiver and the analog interface of the HS34. But when I saw the capabilities of Skyview with the new autopilot and a potential future 8.33 radio (I am based in Europe) with the same kind of interface that what you have, I decided to invest in a skyview system.

So I'll work out this box to interface with an SL30 stream and a DME (will be or a KN63 or a NARCO 890) to output this $PMRRV41 string.

You will hear from me again in the next few weeks

Jacques

 

[TRCsmith]

Ok, I second it for DME. All I have is the SL-30 and no IFR GPS. I could use the DME. 

 

[purlee]

A lot of Regional Airport approaches in New Zealand are still Arc/DME and a lot of reporting points are still Radial/DME and frankly Radial/DME position reporting is easy and efficient.

I vote for Jacques DME solution!

 

[jgills240]

I also have only an sl30, with no ifr legal gps. Luckily, southern California doesn't have many approaches with dme, but they are out there, and it would be nice to be able to use the equipment on board!  Especially since any GPS box worth anything is still over $10k, before subscription costs (I hate subscription costs).

 

[johnsteichen]

maybe I should request an ADF/NDB  function because I used to love it so much.......   Nah...

 

[ploucandco]

DME is still in use everywhere and GPS is not a legal replacement of DME during approach phase of a flight even in the US. On top of that, DME-DME is considered as the backup when GPS is not available.

A Garmin DB30 (http://static.garmin.com/pumac/DB30_InstallationManual.pdf) connected to a King 62-63-64 is the way to go as it provides a serial output with $PMRRV41 string that is similar to the SL30 strings. You can find second hand boxes on ebay from time to time. I had no opportunity till now to make a small box to combine the serial output of a DB30 with the serial output of a SL30. That would allow to have Skyview displaying the real distance to a VOR/DME (green) instead of the GPS derived distance (magenta) like today.
Anyway, I would expect that adding a DB30 in the list of serial devices that Skyview can support should not be a big effort for Dynon.

 

[dynonsupport]

Jaques,
In the USA, an IFR certified GPS has been a legal replacement as a DME on all approaches since 1998, before WAAS even existed. If you have a IFR GPS on board, a DME is completely unneeded, which is why we so little interest in them in the USA.

 

[swatson999]

DME is still in use everywhere and GPS is not a legal replacement of DME during approach phase of a flight even in the US. On top of that, DME-DME is considered as the backup when GPS is not available.

http://www.aopa.org/Advocacy/Air-Traffic-Services-,-a-,-Technology/Air-Traffic-Services-Brief-Use-of-GPS-in-lieu-of-DME-ADF

and event *that* is 17 years old.

 

[jgills240]

I'd like to add my name to the small list of peeps wanting DME. I don't have a certified GPS, but even if I did, having a backup distance source in the event of hardware failure or GPS blackout (which is becoming the norm here in socal with all this military GPS interference testing). I'm willing to bet a "lot" of people have this problem, but are just using the Skyview's "distance to fix" display, which is i'm assuming is technically not legal. IFR GPS is still very expensive, maybe the 2020 mandate will lower that, but the backup part is really what i'm interested in....

 

[swatson999]

...in the event of hardware failure or GPS blackout (which is becoming the norm here in socal with all this military GPS interference testing).

Oh, come on...it is not "becoming the norm". In fact, I've been flying in SoCal for 23 years and I don't think I've *ever* seen any "military GPS interference testing" in the area.

Maybe in some locations, like White Sands NM or the like, where it is sometimes NOTAM'd, but not here (in one of the busiest airspaces in the world).

Seriously?

 

[TRCsmith]

Ok, I second it for DME. All I have is the SL-30 and no IFR GPS. I could use the DME. 

Never mind. I have a cert IFR GPS Grmin 480. ;D