[MilCom] VHF Low Band Open

[O S]

2007/06/04 Local morning
QTH: Mobile near Eagle Pass, Texas / Piedra Negras, Mexico

VHF low band is open this morning - heard military control towers on 
40.350, 46.625 and 48.800 all with 150.0 tone.  Any idea where these are 
used? 

48.800 appears odd as it is allocated stateside to oilfields and 
pipelines.  I monitored it from several locations at some miles apart so 
I don't think it is an image but I don't know for sure.