Logging software

[rogellis]

...but knowing glider pilots it will not have cost more than £5.

Ok, all the logger replay software systems appear to use the .IGC file format.  So if you can output an OGC file, it will work almost anywhere....

http://vali.fai-civl.org/documents/IGC-Spec_v1.00.pdf

And the cheaper logger replay systems include...

http://glidingweb.org
http://www.tasknav.com

R

[Ian Melville]

Hi R,
I had a look at that document earlier this week and spotted that there is an issue. *.IGC files are primeraly using barometric altitude, where as the GPS altitude is recorded in the PilotAware track file (*.trk). IGC files can, as a supliment, also include GPS data, but I cannot see how this is used.

I need to get an answer from Lee regarding the relationship between traffic and our own GPS position. Is the altitude difference reletive to GPS or BARO altitude?
If the difference is reletive to the GPS altitude, then I can substitutre BARO with GPS alt. Then traffic and your own flight log will be reletive too each other at GPS altitudes. The danger is that these IGC file created reletive to anoth track can be circulated with recipiants unaware of the history, or that the cannot be compared to a puka flight logger data.

If the altitude is with refrence to BARO altitude then there is not a lot that I can do. You could try persuading Lee to add BARO altitude data into the Track log. Or find some info on how GPS Altitude data is incorporated in the plotting software.

IGC file sore so much data that PilotAware chance of filling a full IGC file, hope you were not planning on using it as Poor-mans Flight Logger :-) not that it woul dever bee accepted as 'proof' of a flight.

[Admin]

Hi Ian (et al)

I thought I had answered this question, but here goes.

When passing information to SkyDemon, we (as in SkyDemon) use GPS data for the altitude.
All traffic data which is passed is relative (to us) altitude, so whether it was calculated from GPS or Baro is irrelevent, we only ever tell Skydemon and others, traffic is 200ft above or 200ft below.

In actual fact both barometric AND gps altitude are used for calculating the height differences, and it is dependant upon what the traffic is using as its reference.
Mode C/S of course use barometric, ADS-B can provide barometric and/or gps.
P3I and Flarm use GPS reference.

Coming back to the original request, I could add the $PGRMZ message

Thx
Lee

[rogellis]

When passing information to SkyDemon, we (as in SkyDemon) use GPS data for the altitude.
All traffic data which is passed is relative (to us) altitude, so whether it was calculated from GPS or Baro is irrelevent, we only ever tell Skydemon and others, traffic is 200ft above or 200ft below.

But on the PAW logging files, is the actual aircraft altitude stored (the altitude of the aircraft being flown), or only relative height between other contacts?  And if the actual aircraft height is recorded - is it baro (1013) flight levels, or gps (effectively QNH) altitude?   

I am surprised that glider data loggers would use baro flight levels (1013) rather than gps altitude (QNH).  What glider pilots want to display for badge and competition flights is QNH altitude, the altitude above sea level, and not flight levels.   Competition start-gates, for instance, are referenced to QNH, not 1013. 

R

[Ian Melville]

R, there is a lot of debate about this on gliding forums in particular hangliders and paragliders, which may not have BARO recorders. Whether they record QNH or Flight levels seems to depend on the flight loggers manufacture. As well as the tasks airspace busts also have to be considered, which could be measureed with ref to QNE, QNH or FL, a right pigs ear.

For the host aircraft, PAW logs the GPS altitude. all contacts are logged as a position reletive to this. I would need to calculate Lat/Lon/Alt from the host aircraft. Is it possible to find a sample IGC file where BARO was not available?

Thanks for the explanation Lee, $PGRMZ would be nice, but in reality it can only be applied to the host aircraft.

[rogellis]

Ian,

The loggers used at our club are predominently gps loggers (a usb thumb-drive worn around the neck).  And they are mostly gps only.  Like this popular device, which has no baro facility.

http://www.flywithce.com

As I say, I cannot imagine why any glider logger would want to have a baro altitude, as this has to measure flight levels (as do transponders).  GPS is much better, as it gives you a de-facto QNH altitude.

Since popular loggers like the one above only record gps QNH-type altitude, then the replay software packages must be able to use gps altitude.

R

[Ian Melville]

I don't doubt that software works with GPS alt only, I just need an example file to see how the data is presented. I assume you must have a few around ? Doesn't need to be long, a few minutes walking around would be enough.

[PaulRuskin]

...

As I say, I cannot imagine why any glider logger would want to have a baro altitude, as this has to measure flight levels (as do transponders).  GPS is much better, as it gives you a de-facto QNH altitude.
...
R

Except that most of the loggers, and certainly the more expensive ones, have a barometric pressure sensor and use that for their logging.  Indeed, you need a current calibration chart before you can use them for a badge claim or if close to airspace in a competition.

The cheaper loggers, like the one you mention, need an extra (100m) margin built in for the more basic height claims, to compensate for the extra difference between GPS and pressure altitude.

Paul

[rogellis]

I don't doubt that software works with GPS alt only, I just need an example file to see how the data is presented. I assume you must have a few around ? Doesn't need to be long, a few minutes walking around would be enough.

The BGA logger files are kept on the BGA ladder here.

https://www.bgaladder.co.uk/DispLadder.asp

Here is an example copy from that web page

https://www.bgaladder.co.uk/dnload.asp?DSN=82FVEQQ1%2Eigc&Season=2018

Hope they show you the file format....

Roger

[Ian Melville]

Thanks Roger, I'll spend some time disentangling that sample file, but..

Inital look shows it as having a pressure Alt sensor, not what I was looking for.

HFFTYFRTYPE:LXNAV,LX9050
HFGPSRECEIVER:uBLOX LEA-4S-1,16,max9000m
HFPRSPRESSALTSENSOR:INTERSEMA,MS5561C,max16000m

I also need to get an up-to-date version of the IGC file spec. That file has lots of stuff not refrenced in the Release 1 spec

[rogellis]

Thanks Roger, I'll spend some time disentangling that sample file, but..

Inital look shows it as having a pressure Alt sensor, not what I was looking for.

Ah, that may be because all these files are from the ‘pros’ who have all the top equipment.  I think the lower end loggers dont include baro.  I will try and get some ordinary logger files.

R

[rogellis]

Try this file. 
It has gone through my iPad, so I hope it has not corrupted it.

https://expirebox.com/download/d5d6b5f63324a9d10363abb6a09122e8.html

R

[Ian Melville]

R, i can call you R, can I 😊

That also has a Baro Sensor.

I think i will ask Lee if he can add Alt at ISA (1013.25) to the log. Lee, 🙏

[rogellis]

R, i can call you R, can I 😊

That also has a Baro Sensor.

I think i will ask Lee if he can add Alt at ISA (1013.25) to the log. Lee, 🙏

I'm surprised, as that was an el-cheapo unit.
      Made by El-Cheapo Inc, of El-Cheapo, in Cheapoland.
Ok.  Might be best to follow the herd....

R    (I respond to many appellations, some not mentionable in polite company...  )

[Ian Melville]

If it was that cheap then it could be faking it, like fake thing with a degree in fakeology from faketown university

Actually they are now so cheap and small that it is not difficult to add to an existing PCB. My phone even has one!