AIS message type
AIS message type 17: DGNSS broadcast binary message
Differential GNSS correction data broadcast by a reference station. What type 17 carries, who sends it, how often, and how to read it.
What type 17 is
Type 17 lets a base station with a differential GNSS reference receiver rebroadcast RTCM correction data on the AIS channels, so ships can improve their own position fixes.
How to read it
Correction data for receivers, not a position of anything. Rare in practice.
Decoding it
The AIS message decoder reads the message type and sender MMSI of any sentence, including this one, but does not unpack the body of type 17.
All message types
| Type | Name |
|---|---|
| 1 | Position report, scheduled (Class A) |
| 2 | Position report, assigned schedule (Class A) |
| 3 | Position report, response to interrogation (Class A) |
| 4 | Base station report |
| 5 | Static and voyage related data (Class A) |
| 6 | Binary addressed message |
| 7 | Binary acknowledge |
| 8 | Binary broadcast message |
| 9 | Standard SAR aircraft position report |
| 10 | UTC and date inquiry |
| 11 | UTC and date response |
| 12 | Addressed safety related message |
| 13 | Safety related acknowledgement |
| 14 | Safety related broadcast message |
| 15 | Interrogation |
| 16 | Assignment mode command |
| 17 | DGNSS broadcast binary message |
| 18 | Standard Class B equipment position report |
| 19 | Extended Class B equipment position report |
| 20 | Data link management message |
| 21 | Aid-to-navigation report |
| 22 | Channel management |
| 23 | Group assignment command |
| 24 | Static data report (Class B) |
| 25 | Single slot binary message |
| 26 | Multiple slot binary message with communications state |
| 27 | Long-range AIS broadcast message |