AIS is short for Automatic Identification System, which is a globally developed protocol to increase safety. AIS sends and/or receives data through FM frequencies (same as the VHF). This is standardised information and is equal for all AIS (with special additions for class A AIS). It contains information about the ship: call sign, dimensions, course, speed, type, etc.
Although it is not intended to have 100% coverage, it offers important information about surrounding vessels.
Back in 2001 the preparations for a new global system to promote safety and communication between ships were in full progress. Several studies and initiatives were integrated by the IMO (International Maritime Organization).
In mid-2002 the first AIS were installed on deep sea ships finally it becoming obligatory for those type of vessels in 2008. For inland shipping the regulations are less standardized, however in most areas there is an obligation for all vessels over 20 meters (ft 65) and all commercial vessels.
Watcheye was founded in 2010 to make this great feature available for leisure shipping as well. At the time most people were unfamiliar with AIS, although as we provided information and explained the possibilities, we became the specialist in AIS. This knowledge is our foundation to keep on developing.
What is AIS?
AIS is short for Automatic Identification System, which is a globally developed protocol to enlarge safety. AIS sends and/or receives data through FM frequencies (same as the VHF). This is standardised information and is equal for all AIS (with special additions for class A AIS). It contains information about the ship: call sign, dimensions, course, speed, type, etc. Although it’s not intended to have 100% coverage, it offers important information about surrounding vessels.
There are three categories in AIS:
Which information does AIS transmit?
What is an MMSI number?
MMSI is short for Maritime Mobile Service Identity. This number will be officially allocated to your ship by the local authorities. The B transponder transmits this number, so you must apply for it before you can use your AIS.
Be aware that the MMSI number belongs to the ship, not to a person. So if the AIS is being reinstalled on another ship, another MMSI number must be programmed.
Because receivers don’t send information they don’t need an MMSI number.
What has VHF got to do with AIS?
The AIS uses VHF channels to transmit data. There are two channels available for AIS: when the first channel reaches its limit, the second channel will be enabled. A dual banded AIS transmits data through both channels, so you’re sure that there is no information missing.
When can I use AIS?
The AIS receiver can be used always and everywhere. Because it just receives information and it doesn’t send any data there are no restrictions.
The AIS transponder (class B AIS) is designed to use on ships. It is required to have an MMSI number programmed into the AIS. Because it sends data, it’s compulsory to have a VHF certificate and have the VHF radio switched on, so that others can contact you.
The pros and cons
Is Watcheye compatible with my other equipment?
AIS is an globally developed system. Which means that the data is standardised. It depends on the device to which the AIS is connected: is it AIS compatible? All manufacturers specifically mention if their product supports AIS.
There is a difference in which data protocol is used in the AIS. There are two universal protocols: NMEA0183 and NMEA2000. Watcheye is proud to mention that our products support both protocols.
What is a timeslot?
The background of the encryption of the data is based on TDMA, which is short for Time Division Multiple Access:
These intervals are described for the dynamic information.
A static report is transmitted only every six minutes (for both class A and B).