Build a valid AIS Type 1 position report from form inputs with step-by-step encoding.
!AIVDM,1,1,,A,15M67F@P1sG@9s0K;P83Ojmp0000,0*14000001000101011101000110000111010110010000100000000001111011010111010000001001111011000000011011001011100000001000000011011111110010110101111000000000000000000000000000
payload = 15M67F@P1sG@9s0K;P83Ojmp0000 (fill bits = 0)
AIVDM,1,1,,A,15M67F@P1sG@9s0K;P83Ojmp0000,0
*14
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The AIS Message Encoder builds a valid AIS Type 1 position report from plain form inputs. Enter an MMSI, navigation status, speed over ground, course over ground, latitude, longitude, and true heading, and the tool packs each field into its correct bit width, ASCII-armors the bitstream into 6-bit payload characters, computes the NMEA checksum, and assembles a complete !AIVDM sentence. It also shows each encoding step, so you can see exactly how the raw values become the final message.
It is built for marine software developers, AIS integrators, and students learning the ITU-R M.1371 standard who need to generate test sentences or verify their own encoders. Use this one because it is free, requires no signup, and runs entirely in your browser: your vessel data and coordinates are never uploaded to a server.
No. All encoding happens locally in your browser, so MMSI values and coordinates never leave your device. The tool is free and needs no account.
It produces a Type 1 position report (Class A scheduled position), packed into a single-fragment !AIVDM sentence with the standard NMEA checksum.
Fill bits indicate how many padding bits were added to the final 6-bit group so the payload aligns to a character boundary. The value (0β5) appears after the payload in the sentence.
Coordinates are scaled to 1/10000 minute and stored as signed integers, 27 bits for latitude and 28 bits for longitude, exactly as the AIS standard specifies.
Yes. The generated sentence is a standards-compliant !AIVDM message you can feed directly into a decoder to confirm it reads MMSI, position, speed, and course correctly.