I have been carrying out some tests of SafeSky when integrated with Skydemon.
When in “flying mode” I have noticed that Skydemon displays aircraft at altitudes of 200- 300 ft LOWER than they actually are.
This is not the case for when a SkyEcho 2 is used to detect aircraft instead of SafeSky.
I have reported the issue to Skydemon Tech Support and will report back.
It may be a Safesky issue or a Skydemon one.
Keep a very good lookout…
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Good information when talking about altitudes is to mention is how did you reference your altitude? Was that based on QNH or GPS Altitude?
Usually conspicuity devices are using GPS altitude, not taking into account local pressure and temperature and if you reference it to QNH then you might see altitude differences.
SkyEcho might compensate for this. With skydemon it depends if you connect over Bluetooth or AirConnect that uses NMEA and GDL90.
How does SkyEcho 2 connect to SkyDemon and do you happen to know if SkyEcho also has a barometer inside, and thus must be used inside NOT inside pressurised cabin?
Also, does the difference in day-to-day change the altitude differences?
All appropriate corrections were made for local QNH. The SafeSky radar display is correct; it is the display in Skydemon that is wrong (low) by 200 ft.
Skydemon with my SE2 works correctly (WIFI connection) and checked outside in fresh air and also in the cabin of my 1948 vintage aircraft (non-pressurised!). Yes, the SE2 contains a baro sensor.
I believe either SafeSky is sending wrong data or Skydemon is incorrectly applying some kind of offset.
I will report back when I hear back from Skydemon.
I reported this problem almost a year ago.
But it‘s still present.
I use Stratux and a iPad mini with Safesky and Skydemon running on in.
Everything works fine….BUT…the shown traffic in Skydemon from SafeSky is 200 to 400 ft too low.
Why can this problem not be solved for a year?
Greetings Kai
Hello Kai,
That is interesting…
SafeSky is aware of the issue and is working on a fix/solution.
Also, Skydemon technical support confirmed to me that Skydemon doesn’t alter the GDL90 data at all. It simply displays what SafeSky sends it.
Regards
Tony
Tony,
thanks for your reply.
When I only use Skydemon and Safesky on my iPad everything works fine.
The altitudes are correct.
When I use Skydemon, Safesky and Stratux the shown problem occurs.
The heights in Safesky are true and displayed correctly.
The heights shown in Skydemon are wrong.
When the displayed targets in Skydemon toggle between eaXXX (Stratux) and syXXX (Safesky) the heights also toggle.
That is interesting.
I suspect that SafeSky is adjusting the Stratus data (detected aircraft altitude) before it gets sent to Skydemon.
When I was querying a similar issue (that I had noted with SafeSky/Skydemon a few months ago), Skydemon technical support confirmed that they do not modify the GDL90 data in any way. They simply display what SafeSky sends. SafeSky fixed that issue (SafeSky/Skydemon operation).
Hello @Maverick , thanks for responding this issue. Looking at the screenshots, I suspect a geoid difference that gets lost in the mix for Stratus only. I tested with PilotAware, PowerFLARM and SkyEcho2, it’s all fine. We are going to test with Stratux and reproduce, I will keep you posted,
Tristan
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Thanks @Tristan
Hello @Maverick , we are confirming the geoid difference with the Stratux device only. The next release will include the fix for it.
Thanks again for having spotted this,
Fly Safe,
Tristan
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Great 