How does the AIS acquire a Signal?

[Chuck - Raymarine - Moderator]

DRFASailboater,

AIS transmissions are broadcast/received via the VHF antenna which will be interfaced to the AIS receiver/transceiver. The Ray260 may be purchased with and without AIS receiver (not transceiver) circuitry. The AIS650 must not only be interfaced to the supplied passive GPS antenna (required for the AIS650 to determine the vessel's position, SOG and COG ... the AIS650 is not designed to utilize GPS data from other marine electronics products), but must also be interfaced to a VHF antenna. The part number for the passive GPS antenna included within the AIS650's package is R62241. Raymarine neither manufactures nor sell VHF antennas. Typically, VHF antennas will be sourced by the customer or installer from a dealer of Shakespeare, Digital, etc. Per my prior response and the AIS650's manual, it is recommended that the VHF antenna have a gain of no more than -3dB.