[QC102]

Guess I am looking in the wrong place 

Not planning mods...just trying to figure out how to install, set up and  try it out. 
I think my first problems were due to a defective Revolution - that  may be disproved when my next order arrives.

[TheOtherCliff]

There is a "walk before you run" issue here.    Adding GPS will not fix problems, other than new pilot issues.  GPS assumes that the quad is set up and flying well and actually uses Attitude mode internally.  Generally speaking if you want to fly GPS modes, you should consider using an aux mag.

The current release, 15.09 only supports one kind of aux mag, and that is the one on the OP GPSv9 which is not made any more and very expensive when you can find one.

The coming release will add support PixHawk GPS/mag and DJI/Naza (lite) GPS/mag.  You will have to solder connectors for either.  The PixHawk uses separate ports for GPS and mag, but the DJI puts both on a single port (that frees a port up for other things).

The good and bad is that any PixHawk GPS will work.  That is good because there are many to choose from, but it is bad for the same reason.  Which to choose?  Make sure your PixHawk GPS has two cables (4 wire for GPS and 2 wire for mag).

You can get either a clone or an authentic DJI/Naza GPS.  There are many brands and qualities of clones.  Authentic DJI/Naza cost $43 (shipped) and up.

So to start out, you should probably get "next" and a DJI/Naza isn't a bad bet.  You compile "next" yourself, or there is a thread where a forum user builds it for others to use.

DJI/Naza GPS/mag
http://www.ebay.com/itm/251862698572

[QC102]

Thanks Cliff, 
Having seen posts which advise as you do - that GPS is not a magic trick to stabilize a poorly set up quad.  While I am not expert and do not  fully understand the relationship of PIDs - I think my stuff is OK for "park flying". What I have found is that badly ( or inexperience) built quads  are a bigger problem than PIDs.   

I have seen youTube stuff and read on this and other forums of GPS modules being added and simply decided to see what it was about.   I have purchased a Revolution FC and a NEO M8N GPS module (in the photo attached above.)  This module has two sets of wires - which I gather  get plugged into the the main and  a flexi port.

Last night I read about the need to bag up the FC and freeze it!   And I am  still going through the  online pages - I have also started trying to layout the info to create a PDF -   which I find easier to use for quick reference. ( I am "rural" Central Coast of NSW Aussie - and broadband connections are slow, not always reliable - and more expensive than than a village in Siberia would pay)
I may be  missing a lot but  my impression from most  threads on these M7N - M8N  is that  they are plugged in and then needed calibration.
I do/did not plan to add camera's or expect it to return  home etc,.   so maybe I should  just wait and see what happens in future LP GCS version.

Thanks again

[TheOtherCliff]

Coming version has AutoTune too!    It sets your PIDs for you.

When I thermal calibrate, I sometimes start with 10-15 minutes in the freezer in a plastic bag.  That is only so the calibration extends to freezing, in case I want to fly in the winter.  The plastic bag is to protect it from condensation when you remove it from the freezer.

M8N GPS works fine.  That is one of the ones I test sometimes.  You need to keep the mag wiring short, maybe even twist with a ground wire.  Next release will enable some extra, programmable pullups to help the mag communications.  Either way, you should test because if the wires are too long, the mag communications can hang and the FC can reboot.

[QC102]

Don't suppose  you will be  considering moving to Australia - near me!
I was reading  about the freezer thing last night ( iPad and boring TV) and I  tried it today.  Failed!  I'll read it all again and  try it.
Thanks for  more advice on  the M8N.. Just  a thought on  wire's and  twisting.  I am no electronics expert, but from somewhere long ago I seem to remember being told NOT to  coil cables because it creates inductance. This came to mind seeing youTube vids and  all they builds seeming to  wrap the  ESC connection wires to the FC, around posts or bundled them up and tied together. 

I am fairly new to all this and learn better watching things being done... but find youTube sometimes confusing - especially when it comes to PIDs. 
I know the guys dealing with the coding and building the up coming version are working as fast as they can and things  need testing etc,. - but I am hoping it will come soon