New parameter: GPS satellites required for setting home

[GoogleCodeExporter]

Currently my home position is set as soon as the GPS has a 3D lock, usually 5 
or 6 satellites. As the location is not that accurate at this stage I often 
find my home position is 50m or more away from my actual location. Today this 
put my home location over a nearby road.

I know the home position can be set with the Mission Planner, but I don't have 
a telemetry radio so I rely on it being set automatically after GPS lock.

Please add parameter for specifying number of GPS satellites to be acquired 
before the home position is set. That way I can ensure my home position is 
accurate.

Original issue reported on code.google.com by efu...@gmail.com on 5 Aug 2012 at 9:33

[GoogleCodeExporter]

I second this wholeheartedly. 
Even the lowly Remzibi OSD has a changeable parameter to set the number of 
satellites seen before establishing the home position. 
It does make sense if you want an accurate home position and are not using a PC 
hooked up to telemetry.

Original comment by graham.d...@gmail.com on 15 Aug 2012 at 7:28

[GoogleCodeExporter]

This could be a dangerous feature.  It encourages running without proper 
telemetry and people doing this are also the ones that will launch right after 
they get a 3D fix.  If the home location isn't set at that point they'll be 
flying with no valid home location  which will disrupt a lot of features.

Original comment by jakestew...@gmail.com on 20 Aug 2012 at 7:07

[GoogleCodeExporter]

Noted. But a "number-of-satellites-before-home-fix" parameter would also 
prevent the blue LED's (3D fix) from going solid before the home location is 
set, therefore they should only launch when that LED goes solid (as they do 
now).

Also I suspect there are currently easily more people flying without telemetry 
than with it. 

Original comment by graham.d...@gmail.com on 20 Aug 2012 at 7:20

[GoogleCodeExporter]

@Jake I don't use telemetry and I never use the Auto mode. (although I admit I 
may try it one day) I fly FPV and I bought APM specifically for the RTH 
feature. Stabilization, Loiter and other features were added bonuses.

I certainly don't fly as soon as I get a 3D fix, I do my other pre-flight 
checks. Despite this I often end up with a home location that is up to 50m 
away. What is the point of RTH if it's really RT(somewhere over there)? 
Admittedly my in the field tests have resulted in RTH being cancelled while 
still a few hundred meters away, but what if I really need it one day and it 
sends the plane circling over some nearby houses?

Original comment by efu...@gmail.com on 20 Aug 2012 at 11:55

[GoogleCodeExporter]

I think this sounds like a good idea, however I would modify the suggestion in 
two ways. First why not use a hard coded minimum number of satellites required 
for a lock and then allow a user to input a number greater than that say up to 
12. This would ensure at least some level of quality to the solution. Second 
prevent arming the motor(s) until lock has been achieved, thus preventing 
flight until a lock has been achieved.

Original comment by kvca...@gmail.com on 3 Jul 2013 at 1:54