There was a nice discussion (check the "Comments") on Panbo.com
It would appear that this is a jamming device that will be operating from an aircraft at about 10,000 FT. Therefore planes' receivers at 40,000 FT have a greater radius than those at lower elevations.
Just a reminder to all of us generally mindless users of these devices that THEY CAN'T BE COMPLETELY COUNTED-ON to be operating. Just like celestial navigation is only available when you can "see" the sky ;^).