U.S. Army Sgt. 1st Class Armando Filmore, an Observer Controller Trainer (OCT) from the 3rd of the 290th Regiment, installs a Single Channel Ground and Airborne Radio System (SINCGARS) during the 91st Training Division’s Warrior Exercise on Fort Hunter Liggett, Calif. June 15, 2017. SINCGARS uses 25 kHz channels in the very high frequency FM band, from 30.000 to 87.975 megahertz. (Photo by Spc. Eric Unwin/released)