Some interesting points, I think I may try to contact a radio engineer.
I understand what you are saying David, wasn’t trying to quote you as saying there was a particular problem, sorry if it came across wrong.
IO540 - I agree, if the anti GPS brigade were a bit more open for discussion then people may be more willing to come forward with there experiences.
With regards to getting GPS into the PPL, perhaps it may be a good step to include it in the Navigation theory –that way people may understand the limitations of GPS thus increasing safety?