VPT

Vessel Profile Transmitter

The equivalent of a modern day transponder. It transmits telemetry information for use in the LRS and TCAS components.

Mode A

Continually provides relative position information to all interrogating vessels.

In addition, it can selectively provide

• IVR
• Hull registry
• Discreet type (used to be inferred from IVR but changed in revision 2.2)
• Registered owner
• Stolen, repossession, tow, and other flags recorded by various agencies

Mode C

Continually provides Mode A data plus altitude information to all interrogating vessels.

Mode S

When a vehicle is embedded in another vehicle (such as ARJs or small cars or trucks in a larger vehicles' bay) the Mode A and C continuous stream is inhibited. Upon request, the parent vehicle will provide a list of all nested objects as well as their Mode A and C data streams.