Is it possible to intergrate Safesky into Skydemon?
I understand there is an issue regards the barometric pressure and collision avoidance feature on Skydemon.
Ref. “One thing to bear in mind is that SafeSky aircraft “transmit” their GPS derived altitude and not one referenced to1013.2 hPa, which is what devices like Mode S ES transponders and SkyEcho 2 use.
This will mean that SkyDemon’s collision avoidance algorithms won’t work that well if you are receiving both SafeSky positions and ADS-B Out positions.
*I believe that SafeSky is aware of this issue and is trying to figure out how to ensure that SafeSky altitudes are compatible with ADS-B Out (1013.2) referenced altitudes.”
I know it’s possible to use them both together running them side-by-side, but not integrate like easyVFR does.
However, I can only imagine that SkyDemon is using GNSS altitude (that is send as WGS84) for collision detection and not barometric. Because as far as I am aware ADSB, Flarm, OGN etc should use WGS84 altitudes and not barometric.
ADSB (ES at 1090) can send also barometric next to GNSS (WGS84 I currently assume) .
I am not sure what altitude is using when positions are derived using MLAT.
so, I son;t have a true answer for you, just wanted to ask you about where you read about the SkyDemon altitude issue.
The integration of SafeSky traffic into the SkyDemon navigation application has been an operational feature since June 2021. And it’s working really well!
You can find tutorials, videos and a user manual that explains everything in great detail.
Here are some links: www.safesky.app
As for the barometric pressure, I think that the person whose comments you’re sharing is misinformed.
The altitude visible and transmitted by SafeSky is of course the GPS altitude, which is very close to the altitude displayed on your altimeter when the latter is set to the correct QNH. SkyDemon, like SafeSky, works with GPS altitude (WGS84). SkyDemon will display the information transmitted by SafeSky, there is no re-interpretation made by SkyDemon in processing the traffic information transmitted by SafeSky.
In the traffic aggregated by SafeSky, some traffic arrives at the standard setting or with the actual GPS altitude. Before transmitting the altitude to users, we transform the standard altitude into the actual altitude, taking into account the local QNH by region and in a precise manner.
I hope you find this information useful.
You should also know that if you install the free version and subscribe to our newsletter, you will receive a free one-month trial of the Premium version. The Premium version is required to access traffic sharing.
SafeSky sends its GPS position and altitude to SkyDemon.
SkyDemon does not convert or correct altitudes received by SafeSky.
We took the time to check and test the scenarios.
Today, SafeSky sends its GPS position and altitude to SkyDemon using WGS84. Traffic is therefore sent using the WGS84 datum.
SkyDemon does not convert or correct the altitudes received by SafeSky, which is a good thing because our location and other traffic are all at the same level.
In theory, GDL90 states that altitudes should be based on 1013hPa. We’ve just tested SkyEcho, using both “Generic GDL90” and “SkyEcho”, and the altitude appears as WGS84 on SkyDemon. So either SkyEcho isn’t following the specification or it knows it should be sending WGS84.
The good news is that when we combine SkyDemon, SafeSky and SkyEcho, our position remains WGS84 and all combined SafeSky and SkyEcho traffic is based on the same datum. The smallest differences are due to rounding during conversion and recovery of the different technologies.
SafeSky remains a Traffic Awareness solution, and informs you of the position of other traffic, but this in no way removes the need to look outside to validate the traffic announced by SafeSky, or other devices, and then manoeuvre to avoid a collision.
