PLBs send a signal directly to authorities. This is unlike the consumer “SPOT” product. The beacon transmits a 406 MHz signal to satellites overhead. The beacon includes your location in the transmission from its onboard GPS receiver. It also has a bright strobe light that operates when the beacon is active.
There is no subscription fee for a PLB, but you must register it with NOAA after you purchase it. Note that it is a violation of federal law to misuse a PLB. They are only
for emergencies where a life, a limb, or eyesight is in jeopardy.