IGC logging requires foolproofing

[almonn]

Hi, I've been testing the SKydrop extensively (thanks for the fix for multiple tracklogs by the way)

My testing has shown that there is currently not an option to get a 'foolproof' log, my understanding is that the two options are: (i) Use FTime widget to manually start logger - the problem with this is you could easily forget in the heat of task planning or competiton. (ii) Use autologging - even with Logger/land set to zero (to prevent false 'stops') the start of logging doesn't actually happen until some time after takeoff - see my (driving) simulation in the picture below, showing both Skydrop and XCSoar tracklogs.

Three possible solutions are: (i) A new option, e.g. ALWAYS LOG, when ticked, start/stop of Skydrop always creates an IGC (ii) Logger/Start - when set to zero, this currently inhibits an auto start; perhaps zero could indicate always log? (i.e. a variation of solution (i) ) (iii) Always cache the last n positions when not logging, so that if logging automation starts, the track that would have been missed can be written to the IGC, i.e. 'playing catchup'

Regards, Nev (Neville Almond, UK)

[moyesboy]

Is it quite flat where you live? Probabycompared to me. My road s 20%/slope (1:5),/so in my car skydrop always starts a 'flight'. Do we have any instance of logger not starting on a real launch? I like the idea of cache of points and adding them to log on start, so igc contains all the flight and doesnt miss the first few seconds. But I see that skydrop are saying there is some extra battery use when logging, so probably caching points would use battery the same? Gordon

[almonn]

My driveway probably drops around 3~4 metres from 'House' to where the logging started.

If change of height is being used for autostart, then a 'late' autostart could easily be simulated by taking off and having no height change in 10, 20, 30 seconds until the height/parameter is reached. I think vigilant 'IGC tracklog checkers' may require a position on the IGC that is clearly at takeoff so that barometric altitude can be checked to be correct?

[fhorinek]

The car is always tricky, since the pressure is affected by A/C. Auto start is depend on baro pressure. I am thinking about two solutions

• Cache ~20 fix points before take off (will have to check the memory)
• Use GPS speed together with the baro change

but first I have to take a look on the strange IGC logging errors.

[almonn]

Agree re: priority of strange IGC logging - thanks for pursuing.

Autostart is always tricky; I know the XCSoar guys have various speed/movement algorithms, which works well for sailplanes, but can get tricky in the lower-speed world of HG/PG. Hence, why I suggested the option of 'always log when on', as many competitors (both comps and XC ladders) will be too scared to rely on automation, but also scared that they may forget to set the logger on manually using FTime. If when a Skydrop is turned on it is always logging (after GPS) acquire, then that fear has gone. :)

Nice accurate logging though - you can tell which side of the road I'm driving on :)