I purchased and installed the A013 Low Interference Converter and tested the AIS performance again today, from the same location. This time I was able to detect a greater number of vessels, more quickly and at greater ranges. Definitely an improvement. Perhaps this hardware should have been incorporated into the A024 design from the start, even if it cost £15 more?

I should say that my marina test location is partly surrounded by buildings which must block AIS signals to some extent. When offshore, I can detect many ships at 10 miles or more. But sometimes I have seen large ships under way much closer (less than a mile), with no sign of an AIS signal.

A key issue for me is using AIS info about course and speed of other vessels when crossing Traffic Seperation Schemes, such as those in the channel. I want to ‘see’ over the visual horizon to decide when to start my 5kt dash for the other side. I don’t want to start my crossing only to find a 20kt container ship bearing down, already constrained by overtaking slower vessels.

There is a difference between limited range (which is predictable and easily associated with power supply noise, rf interference or poor coax cables, etc.) and apparently random non-detection of nearby vessels. The latter suggests a signal processing issue where a specific vessel’s AIS signals are sometimes discarded as malformed or erroneous. I would like to know that such a possibility has been examined.