Integrated hardware for MUOS (Mobile User Objective System) connectivity while on the move.
Here are some technical specifications of the PRC-158: an prc158 manual
"No RX? TX light stuck? The manual doesn't just say 'antenna broken.' It makes you check three things: The time-of-day offset (because if your clock is off by a second, frequency hopping fails), the encryption key index (because the PRC-158 uses separate keys for voice and data), and finally, the RF cable. In that order. Most guys skip to the cable. They waste an hour swapping parts they didn't need to." Integrated hardware for MUOS (Mobile User Objective System)