Question 33D4

406 MHz satellite EPIRBs (Emergency Position Indicating Radio Beacons) are crucial for maritime and aviation distress signaling. Their core function involves transmitting a distress signal to the Cospas-Sarsat satellite system. * **A) 121.5 MHz emergency homing transmitter:** This is a standard component. After the 406 MHz signal is detected by satellites and rescue forces are dispatched, the 121.5 MHz signal acts as a short-range homing beacon for aircraft and vessels to pinpoint the EPIRB's exact location. * **B) Emergency transmission on 406.025 MHz:** This is the primary frequency for transmitting the distress message, including the beacon's unique ID and position data, to the Cospas-Sarsat satellites. The 406 MHz band is specifically allocated for this purpose. * **C) Float-free release bracket:** Many maritime EPIRBs are housed in a hydrostatic release unit (HRU) within a float-free bracket. This system automatically releases and activates the EPIRB if the vessel sinks to a certain depth, ensuring it deploys even if the crew cannot. * **D) Aural locator signal:** EPIRBs do not emit an audible signal. They rely on radio signals (406 MHz for satellite, 121.5 MHz for homing) and often a visual strobe light to aid search and rescue teams. An aural signal would be ineffective for long-range detection or in noisy marine environments.