Hi Ron,
  Signal strength probably is a problem is some cases and could have been the
reason for such on my recent trip to Oshkosh.  But I have seen problems
sitting here on my couch with full signal and the antenna not moving with a
clear view of the Southern sky.  Twice have I seen the radar display disappear
for one five minute cycle..once on the Oshkosh flight and once on the couch.
  In flight, it was of greater concern. ;-) Earl
 

Ron, Earl, Et Al....

 

If I remember correctly, XM radio signals are not good in the South West or North of a certain latitude.....  Maybe all who are using XM radio weather data should mention where they are experiencing the difficulty.