AIS Transmission/Reception depends on the AIS Class

• A Class B AIS transponder transmit at 2 watts whereas a Class A Transponder at 12.5 watts. The Class B+ SOTDMA transponder transmits at 5 watts. This difference in power has a huge impact on the transmission range of each transponder.

 

• For a Class B AIS transponder, the transmission range is usually 5 to 7 miles in perfect conditions. This means using a good VHF antenna, placed as high as possible and clear of other antennas. The cables and connectors must also be in good conditions. For a Class B+ 5W SOTDMA, it typically transmits at up to 15 miles.

 

• However, for the AIS reception, a Class B/Class B+ transponders can receive Class A AIS at up to 30 miles.

 

If you don’t have a good range

• If you are using a VHF antenna splitter for your transponder, make sure it is a ZeroLoss VHF Splitter like our SPL1500, SPL2000. You must also check the connectors and the cables between the VHF splitter and the AIS.

 

• If you are using a dedicated VHF antenna for your transponder, then make sure that it is at least 2 meters away from other VHF antennas. Also, you must check the VHF antenna, its cable and connectors.

 

If you don’t have a good range, we suggest you testing with another VHF aerial to check if you have a better range.