Not sure if many of you folks follow anything going on with emlid but they have released their newest module for UAS, the M2. Which is dual frequency L1,L2 etc… Although this will not solve gps issues in degraded environments it will improve your gps fix when using a base station (local or ntrip caster greatly) This is also the same brains that is behind their newest base station (or rover however you’d like to install it) the RS2. I am by no mean a salesman for them but have used their products extensively in our research and they have performed amazingly both on the ground and in the air!! You cannot beat the price and accuracy!!