Re: hand held radio for man overboard
So there are 3 different incompatible digital signals which are or can be used for distress signals which include location information.
- International Cospas-Sarsat Programme based EPIRBs which transmit to Satellites on 406Mhz. There is no practical or cheap way for the ship which lost a passenger to detect this signal. Search and rescue is delayed until a false alarm is ruled out.
- AIS transmissions on the VHF marine radio channels. A man overboard AIS beacon will be visible on any AIS equipped ship at least 4 miles away. It is also possible to receive these signals from satellites. Google is considering adding real time AIS information to Google Earth. The rescue authorities do not monitor AIS for distress signals, and there is no guarantee that nearby ships would notice a man overboard on their displays. Correct me if I'm wrong, but AIS wasn't really designed with a means of receiving distress signals, although they can be sent over the network.
- VHF radios with DCS + location reporting: The Coast Guard monitors DSC transmissions on the VHF marine band from shore, as do ships with modern radios and competent users. Search and rescue is delayed until false alarms can be ruled out. Radio contact will be attempted, and if radio contact is made the rescue will begin immediately. DSC alone with with no radio contact will result in a much delayed rescue.
Last edited by steel; 11-05-2012 at 11:36 AM.