HSI questions/comments

[khorton]

Now that I know that I will be able to feed an HSI with GNS 430 VOR/ILS data, I'm starting to study the details of the HSI implementation.  I have a few questions/comments:

1. If the GPS is providing data to the HSI, there is a text field for "ALT".  What is the source of this altitude?  GPS?  If it is GPS altitude, what useful information does it provide the pilot given that ATC expects us to fly barometric altitude, which may differ by several hundred feet from GPS altitude?  If it is barometric altitude, why do we need it on the HSI?  I think this field is just useless clutter.

2. Would it be possible in a future update to display the TO waypoint ID?  This is very useful information.

3. Why display "DTW" next to the distance to the GPS waypoint?  This seems like clutter.  The "NM" after the number makes it clear that it is a distance.

4. Why not use more standard abbreviations?  Most EHSIs on type-certificated aircraft would use "BRG" instead of "BTW", "DTK" (desired track) instead of "CRS" (course).  Course is quite ambiguous without an adjective, as it could mean current course, or desired course.

5. Why display 5 dots on each side of the CDI?  Generally speaking, HSIs on type-certificated aircraft would display two dots, with the first dot at half-scale deflection, and the second dot at full-scale deflection.

6. Time to go ("TTG") to the next waypoint is also useful info, so it would be nice to be able to display it.

7. The wording in the manual is a bit confusing in the section about Course Indicator.  It talks about the "course heading" that the GPS is reporting.  Actually, that is the desired track.  The GPS has no idea what heading you will need to fly to achieve that track, as it has no idea what the winds are.

Thanks for making the HSI mode.

 

[Thomas_Schaad]

Thanks Kevin for summing it up. I absolutely agree with you in all points.

Kind regards

Thomas

 

[dynonsupport]

Now that I know that I will be able to feed an HSI with GNS 430 VOR/ILS data, I'm starting to study the details of the HSI implementation. I have a few questions/comments:

1. If the GPS is providing data to the HSI, there is a text field for "ALT". What is the source of this altitude? GPS? If it is GPS altitude, what useful information does it provide the pilot given that ATC expects us to fly barometric altitude, which may differ by several hundred feet from GPS altitude? If it is barometric altitude, why do we need it on the HSI? I think this field is just useless clutter.

It's GPS altitude - anything in the magenta color on that screen is GPS-sourced. We've displayed it because it is available, but in the next firmware release it's likely going away to make room for display improvements.

2. Would it be possible in a future update to display the TO waypoint ID? This is very useful information.

Not sure if this is in the NMEA stream, but if it is, we'll consider it.

3. Why display "DTW" next to the distance to the GPS waypoint? This seems like clutter. The "NM" after the number makes it clear that it is a distance.

4. Why not use more standard abbreviations? Most EHSIs on type-certificated aircraft would use "BRG" instead of "BTW", "DTK" (desired track) instead of "CRS" (course). Course is quite ambiguous without an adjective, as it could mean current course, or desired course.

5. Why display 5 dots on each side of the CDI? Generally speaking, HSIs on type-certificated aircraft would display two dots, with the first dot at half-scale deflection, and the second dot at full-scale deflection.

6. Time to go ("TTG") to the next waypoint is also useful info, so it would be nice to be able to display it.

All interesting points that are worth taking another look at.

7. The wording in the manual is a bit confusing in the section about Course Indicator. It talks about the "course heading" that the GPS is reporting. Actually, that is the desired track. The GPS has no idea what heading you will need to fly to achieve that track, as it has no idea what the winds are.

What we are trying to say is that "this is the direction that the current course points, from origin to destination. Note that course can mean lots of things depending on the context that it's given in. We actually spent a lot of time arguing over what course means.

That said, it's probably worth thinking about again if it's confusing customers though.

Thanks for making the HSI mode.

 

[khorton]

I asked about displaying the To Waypoint, and Dynon said:

Not sure if this is in the NMEA stream, but if it is, we'll consider it.

My somewhat aging GNS 430 outputs the To Waypoint in sentence K in the Type 1 Aviation Format stuff.  The December 2002 Installation Manual describes that as "Destination Waypoint", but my testing showed that it is actually the To Waypoint, at least on my GNS 430, which is quite old.

A couple more comments:

1. The label "SPD" on the GPS ground speed field is a bit ambiguous, and probably not needed.  It obviously means speed, but which one?  IAS, CAS, TAS, or ground speed?  The data has units of "KT", so it is clear that it is a speed.  The colour says that it is from the GPS.  The label could probably be removed, but if it is retained it would make sense to change it to "GS" (i.e. Ground Speed).

2. It would be easier to quickly pick out the stuff in the text block if it wasn't all jammed on one place.  On HSIs and EHSI on type-certificated aircraft, important data items go in the corners, with a bit of space between them and anything else.  The GPS ground speed item would benefit from a promotion to a corner, perhaps the top right corner.

3. The OBS item on the VOR page and the CRS item on the GPS page are really similar items from a piloting point of view.  They tell you the track you need to fly to stay on course.  They really should be in the exact same place on the two pages.

4. It would be useful to put the Track item directly below the Course (desired track) item on the GPS page (or rather, move the Course item to be above the Track).  That type of presentation helps the pilot compare the current track to the desired track, and adjust the track as required to either stay on course, or regain course.

Please don't take these comments as negative criticism.  Your current HSI is a very nice start.  I am simply trying to help you make it even better.

 

[dynonsupport]

1. GS was specifically avoided because it is also used for glide slope.

3. The OBS on an SL30 setup is specifically controlled by a button labeled OBS on the SL30. So it makes sense to call this OBS on our screen as well. Some HSIs do call this course (CRS), but they are typially using that nomencalture for the knob you spin as well. On GPS, there's no OBS to speak of, so CRS makes more sense.

We definitely appreciate your feedback! Keep it coming!

 

[khorton]

Good point on GS for the ground speed label.  I still believe that label is not needed, as the "KTS" units make it clear that this is a speed.  Less stuff on the screen is better.

What label do you use for ground speed if the user has specified mph or kilometre/hour for his speed units?

What unit labels do you use for distance to waypoint if the user has selected mph or kilometre/hour as the speed units?  I think it is logical to stick with nm, as that is the standard for aviation distances (except maybe in Russia or  China).  Or, should there be a specific Setup menu item for HSI distance units?  That may be the safest answer.

I do believe that no matter what you call the VOR OBS value or the GPS CRS value, they should be in the exact same place on the screen.  This will help the pilot's eye find them quickly.  Both values are used the same way once they are set.

 

[funflying]

I have just got my D100 running and have done some initial set-up. I used the output data line from my Garmin 196 to pin 22 (#3 on the serial port) to display the information to the HSI. To see if it is working I thought I would run the GPS on simulator mode in the hangar to see the data on the HSI of the Dynon. Well nothing popped up in corners of the HSI screen so I was unsure whether it would see anything in this mode. I had an opportunity to roll the plane outside, and while the engine was running I dialed in a go-to destination, and still the data did not appear on the HSI screen.

One guy told me that I really need to be moving to get the GPS streaming data, which made some sense to me in my simple mind. My hope against hope is that it is a little thing, because so far the firmware set-up, lists download, and other set-up have gone so well I want to think everthing is going to work like a charm.

Let me know what you think. Thanks, Pat

 

[dynonsupport]

Did you press "navsrc" to bring up the HSI? You can switch between just a DG and the HSI, so maybe you were in the DG mode, where no HSI data is displayed. If you don't have a NAVSRC button, then the unit isn't seeing the GPS data.

You don't have to be moving for it to work, or even have good satellite coverage. The stream is there and that's all we need to see to start showing you HSI info.

 

[funflying]

Is navsrc a select button on the Dynon menu?

 

[dynonsupport]

Yes, it should be there when you bring up the menu for the DG.

 

[funflying]

Thank you. I should be out the hangar tomorrow, but it is snowing AGAIN in the Denver area so I would get to test fly until maybe Saturday.

 

[funflying]

Thanks for the help over the phone. After our conversation about things to check, it was the system setup on my GPS. Once that was set the feed came in just fine in the hangar (expect of course, "no fix detected" because of the inability to see the sky. I received the GPS in the magenta color, upper left corner of the HSI screen, and the menu items were displayed (NAVSRC, scale, and bug).

One of the other questions I had was about the Garmin 196 streaming information in simulator mode. I tried it and it did NOT work or provide the information based on the simulated information I created (like speed and destination). For testing purposes this would be nice, but not necessary.

 

[TRCsmith]

: Teach me...On the SL-30 does the serial data output (pin 5) handle the Glide slope, and VOR information???

Tom

 

[dynonsupport]

The serial line on the SL-30 handles everything the SL-30 can do. VOR, LOC, GS, etc.

 

[TRCsmith]

:-? One more question

On the SL-30 pin 4 (RxD1) is that required on the D100?
also on the SL-30 pin 3 (Ser Gnd) does this go to the avionics gnd?

The reason I ask is that when I recived my SL-30 installation manual on pg 21 someone circled those connections (3,4,5) in hight lite and wrote "this connects to Dynon" that's why Im asking.

otherwise thanks for a great product & great support.

 

[dynonsupport]

The D100 does not send anything back to the SL30, so the serial rx connection is not utilized on the SL30. You can connect the ground to a ground on the EFIS, but since they're both grounded through your electrical system anyway, this isn't strictly neccesary.

 

[TRCsmith]

Thank you, Just what I wanted to hear.
Next week the SL-30 goes in and after that, I get current.