What is the distress signal at sea?

Many people's first reaction may be to make a phone call. Yes, if there is a cell phone signal in the distress area, it may be the fastest to take out the cell phone in your trouser pocket for help. Direct help from relevant departments came directly and quickly. Well, let's introduce several channels and means that modern ships can use in turn after being in distress at sea.

First of all, we should introduce the concept of sea area. The ocean surface on the earth is divided into four sea areas: A 1, A2, A3 and A4, which are mainly divided according to the coverage of shore-based radio stations with different frequencies (of course, there are INMARSAT satellites, which will be mentioned later). A 1 The sea area is 20-30 nautical miles away from the coastline, on the shore of VHF. A2 is within 100 nautical mile (within MF coverage, but excluding A 1 area), and A3 is the sea area covered by INMARSAT satellite, which is roughly between 70 degrees north and south latitude. A4 refers to other regions except A 1, A2 and A3. The basic guide is the Arctic. Because Antarctica is basically land, it mainly refers to the Arctic Ocean.

Considering that only a few scientific research ships and nuclear submarines will go to the Arctic Ocean, most ships (mainly merchant ships) jump in areas A 1, A2 and A3.

Modern ships are equipped with a complete set of distress signal sending system.

Suppose we are in A 1:

1. VHF DSC

First of all, you can use the DSC (digital selective paging function) of VHF radio station, which is the thing in the picture below. When the small red button in the picture is pressed, the signal will be sent to the ship on duty around VHF radio station (shore-based VHF radio station) and then forwarded to the rescue center on shore. Ships around will certainly come to the rescue in time in the spirit of international rescue, and shore-based ships will also take helicopters or other rescue devices to save you. Accordingly, if it is in A2 area, use the DSC function of MF. A3 is a little more complicated. HF-DSC or INMARSATC station can be used to transmit signals to ground stations and rescue centers through space-based satellites.

2. Emergency pointing radio beacon

What if the DSC thing above is broken? There is also a backup plan, which is the following thing, "emergency locator", which also sends out "distress signal" through space-based satellites. Originally, there were two channels, but INMARSAT cancelled this service in 2006, and now it can only transmit to the polar orbiting satellite (COSPAS-SARSAT) through the dedicated channel of 406MHz. Generally, this device can be triggered manually on the wings of the cab or on the compass deck (the highest deck) of the ship. It doesn't matter if you don't press it in time. If the ship sinks, it will automatically send out a distress signal after sinking.

3. VHF and MF mentioned above are not only equipped with DSC function, but also equipped with wireless phones to verbally ask for help from shore-based phones, which are generally integrated with DSC in radio stations, so they are one of them.

These two main ways of asking for help are mandatory. Once they are sent out, things will be serious. Relevant government agencies in the surrounding areas will dispatch land, sea and air to search for you. If you report a false alarm,

Well, all the above signals are sent to special rescue agencies. If all else fails, there is no other way. Communication is so developed now, of course. Grab anyone and ask him to report to the rescue agency again. It's just a little slow. It's hard to say whether he can catch up and save you.