rarely do i work with wireless cams, the reason being they are unreliable at best.

if its an intermitant signal loss, the reasons could be numerous: battery failure, corroded contacts, rf interferance, receiver malfunction due to: same as above, overheating, to name a few. in order to boost signal you will have to have a stronger transmitter.

Think of a cordless phone, it can only go so far from the house, and even then you can get a bad channel one day and a good the next, in the same spot of the yard your standing in.

you also have to remeber LOS means nothing in the way, you have three floors of concrete, not to mention wood, steel and electrical lines (interior lines). Concrete is a pain to get a signal through, and steel is even worse.

also, the cam is posted as 800 mW, never heard of that, mW i assume is mega watts and any signal is going to be using megaherts, just like the phone, but the phone is 900+ now adays

hope that helps

p.s. also, could be the transmitter has to resync with the receiver every couple of hours. is it a constant thing, that happens at roughly the same time every day? if so that may be your case, but with that small of a unit, i doubt thats it