Mode AIS

AIS: ship positions and identities.

Group	Maritime
Default frequency	162 MHz
Default sample rate	2 Msps
In the mode list	Ships, 162 MHz

Step-by-step: Tutorial-AIS

What AIS is

AIS is the transponder system on ships: identity, position, course and speed on two VHF channels near 162 MHz.

Frequencies and settings

Ship transponders.

Setting	Value
Start frequency	162 MHz
Tuning range of the mode table	156 to 163 MHz
Sample rate asked	2 Msps
Lowest working rate	250 ksps
Channel width	100 kHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is Ships, 162 MHz.

What OnAir shows

Ships on a map.

The mode's own tab has these screens: Map, Table, Messages, NMEA, Range. The other tabs (Overview, Receiver, Scan, History) are described on the Main window page.

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome.
• Which radio: Usually yes for narrowband signals: an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: Receiving ship and coast-station broadcasts is legal in many countries, with limits on using or passing on private traffic. OnAir is a receiver. Check the rules where you live. See Legal.

Related pages

• Ships with AIS
• All modes, Maritime
• Supported radios, Troubleshooting, FAQ
• More in Maritime: VDES, NAVTEX, DSC, Weather fax