The Spektrum system seems to be very notorious with brownouts, and even with the DSMX system they are still more prone to it than any other system. The thing about the original FASST system in Futaba receivers is that apart from being a spread spectrum system that has been out for many years (it is the main one used in cranes for example, and is has been used for many years, so they had a chance to perfect a system as cranes need to be 100% safe to use and be foolproof to interference), that has 2 antennas not just to feed information to the receiver from more variety of angles, but actually each antenna goes to its own individual receiver circuit within the "brick", so if one fails, it's like having a "backup" on board, but also because the actual system it uses rather than just changing from one frequency to the other at lightening speed and feeding it to the servos, it actually scans the data it is receiving, and if it happens to receive from more than one source, it compares it to the data that it has already been receiving to assess which of the packages it is receiving is the most likely to be the right one. What this means is that if the aircraft flies into an area where there is interference from saturation of frequency, in the case of most others (like Spektrum) it will follow the strongest of all those it is receiving which complies with the protocols, where as FASST makes an analysis to see if it follows the patters of what it was receiving previously (type of commands, pulse rate, signal strength, which of the 2 receiver circuits is getting which signal to determine general direction of source being the same, etc.) and decides which is the one it should take commands from, which isn't always the strongest of those sources. ACCST have tried to follow this system but at the same time keep the costs low, like using just the one receiver with 2 antennas system and things like that, but also does the assessment, although not as many times per second as FASST, but this makes it a great, safe alternative.