There are commercial products for less than $100 that do this for the L1 C/A signal - such as [1].
You can rebroadcast at substantially higher power than the signal coming directly from the satellite, so the direct signal gets drowned out. After all, the satellite has to broadcast to cover half the world, while you only have to cover a few square meters.
Now, I'll grant the receiver may see a change in signal strength, some cycle slips, and an increase in clock skew. But you get those in normal GPS operation anyway. If you're going to detect GPS attacks and self-destruct your drone you'll want a very low false-positive rate, and I'm not sure that's feasible.
You can rebroadcast at substantially higher power than the signal coming directly from the satellite, so the direct signal gets drowned out. After all, the satellite has to broadcast to cover half the world, while you only have to cover a few square meters.
Now, I'll grant the receiver may see a change in signal strength, some cycle slips, and an increase in clock skew. But you get those in normal GPS operation anyway. If you're going to detect GPS attacks and self-destruct your drone you'll want a very low false-positive rate, and I'm not sure that's feasible.
[1] http://www.diplomat.co.uk/products/hardware-products/active-...