While alone on day 6 of a week long elk hunt in the remote idaho wilderness, at about 0200 hrs i was lying awake in my tent after sleeping for a while trying to get back to sleep. i was camped on top of a ridge about 500' above the majority of the terrain. as i was lying on my back i started to hear a hum to my left which was east down along the top of the ridge. this area is far from anyone else in the area and very remote so i was really trying to figure out what the hum was. it was low to my left not very high above me at all so i didn't think it was some kind of plane. it was gradually getting louder and very close. it was a low pitched pulsating hum and it actually scared me so i went completely in my sleeping bag trying to hide from it. i would estimate it was moving about 20-30 mph and only about 100' above me by the sound and how i could feel it. it was directly above me not changing speed and it kept following the top of the ridge moving at that steady speed and now going away from me to the right and in a west direction. i had a feeling that i couldn't move or it would find me so i kept very still and hidden in my sleeping bag not even breathing. eventually the hum got more quiet and and then got far enough away so i couldn't hear it. in 2003 i had been in the air force 20 years and i have never heard a plane or helicopter that sounded and felt even close to this. there were no lights that i was able to see through my tent as it approached a position above me but there could've been but i was hidden in my sleeping bag. i am very adventurous and daring and even had my rifle in the tent with me but this had me taking a position of hiding as something told me to fear it as it approached closer. now i wish i would've opened my tent and looked above me but maybe something didn't allow me to do that at the time. now i often think i did the right thing by hiding and maybe being completely in my sleeping bag prevented a heat signature that would've revealed me inside the tent. i had a feeling it was searching for something and something just told me to hide. this was 100% not a helicopter or anything that pushed air downward as it was a very calm and still night with no breeze at all. i would've felt any air being pushed down as i was in pine trees and there was no movement of the trees i could hear. this was a craft that was directly above me less than 100' up and moving much too slow to be a plane. it was definitely following the top of the ridge that went many hundreds of yards in a straight line before and after it passed over me. exact coordinates of my tent was 44.403408. -115.430168