>>25523197
a standalone man portable device can't fit a radar (or any other ranging device), or a computer powerful enough to run decent image recognition fast enough to do realtime visual detection, or a sky scanning actuator to maintain 360 coverage, or a power pack big enough to run any of that with any sort of endurance, and suffers from horizon limitations due to poor elevation, and doesn't have an ergonomic way to communicate this data to the operator
that's detection alone, nevermind pointing and shooting a weapon at the target
for 'cheap' you get an aliexpress camera and a nvidia gpu strapped to your helmet that make beeping noises when birds fly by for two hours a day
you start addressing those problems and you end up with either an expensive ghetto-SPAAG that can still be easily saturated, or a networked system that needs a massive upfront infrastructure investment