Editing Distress signal (section)

===Automated radio signals===
In addition, distress can be signaled using automated radio signals such as a [[Search and Rescue Transponder]] (SART) which response to 9&nbsp;GHz radar signal, or an [[Emergency Position-Indicating Radio Beacon]] (EPIRB) which operates in the 406&nbsp;MHz radio frequency. EPIRB signals are received and processed by a constellation of satellites known as [[Cospas-Sarsat]]. Older EPIRBs that use 121.5&nbsp;MHz are obsolete. Many regulators require vessels that proceed offshore to carry an EPIRB.

Many EPIRBs have an in-built Global Positioning System receiver. When activated these EPIRBs rapidly report the latitude and longitude of the emergency accurate to within {{cvt|120|m|ft}}. The position of non-GPS EPIRBs is determined by the orbiting satellites, this can take ninety minutes to five hours after activation and is accurate to within {{cvt|5|km|mi}}. Marine safety authorities recommend the use of GPS-equipped EPIRBs.<ref>{{cite web|title=GPS versus Non-GPS: A comparison of GPS vs non-GPS 406 MHz distress beacons|url=http://beacons.amsa.gov.au/gps.html|publisher=Australian Maritime Safety Authority|access-date=21 March 2014}}</ref>

A miniaturized EPIRB capable of being carried in crew members' clothing is called a Personal Locator Beacon (PLB). Regulators do not view them as a substitute for a vessel's EPIRB. In situations with a high risk of "man overboard", such as open ocean yacht racing, PLBs may be required by the event's organizers. PLBs are also often carried during risky outdoor activities on the land.

EPIRBs and PLBs have a unique identification number (UIN or "HexID"). A purchaser should register their EPIRB or PLB with the national search and rescue authority; this is free in most jurisdictions. EPIRB registration allows the authority to alert searchers of the vessel's name, label, type, size, and paintwork; to promptly notify next-of-kin, and to quickly resolve inadvertent activations.

A DSC radio distress signal can include the position if the lat/long are manually keyed into the radio or if a GPS-derived position is passed electronically directly into the radio.