QK-A024 missing ships

[Anonymous]

My QK-A024 is missing ships. Big seagoing ships, just a few miles away. About 1 in 5 of them. I conducted a test today, engine running at my marina berth, comparing the AIS signals from my A024 with internet AIS (Boat Beacon). There are several docks within 10 miles of my location. I picked up all the 7 ships at the nearest dock within one mile. Two small vessels about 1.5 miles away were not detected, although a larger ship was. In a dock 2-2.5 miles away, there were 9 ships, of which 7 were detected by the A024. 3 out of 4 ships in a dock 5.5 miles away were detected. The most distant ship detected was 8.7 miles, but at this dock about 20 ships were not detected.

I am using iNavX on an iPad, using the wired NMEA output from the A024, routed via a AS03 bridge board and a VYacht WiFI MUX. I have a 15m high masthead antenna with active splitter, a high quality USB car charger socket powering the A024, plus a ferrite choke on the unit’s power cable.

I have read the previous thread on this topic. It suggests that electrical noise or interference is the main issue. Should I use one of your A013 5v power conditioners?

[Quark Elec]

Hello

This is very common for customers to see more ships on AIS live or any other internet based AIS receiver. This is due to the collaborative effort of satellites, AIS base stations, military and civilian vessels all reporting there AIS transponder information to their servers. This gives enormous coverage even for small marinas. Marine traffic has an article that may help shed some light on this conundrum.

https://help.marinetraffic.com/hc/en-us/articles/204582978-AIS-MarineTraffic-and-Station-Owners-Interplay” class=”bbcode_url”>https://help.marinetraffic.com/hc/en-us/articles/204582978-AIS-MarineTraffic-and-Station-Owners-Interplay

What kind of cable are you using to connect between your antenna and A024? This can have a big effect especially at 15 metres you could be losing 1.5DB. Please see the link below that we have created to help. I would suggest shortening the cable length and moving the AIS unit closer.

https://www.quark-elec.com/blog/wp-content/uploads/2018/09/HOW-TO-MAXIMISE-YOUR-AIS-RECEPTION-AND-RANGE.pdf” class=”bbcode_url”>https://www.quark-elec.com/blog/wp-content/uploads/2018/09/HOW-TO-MAXIMISE-YOUR-AIS-RECEPTION-AND-RANGE.pdf

In regards to your question about power converter then I would definitely suggest having one instead of cigarette lighter port (which we do not recommend). We would recommend the AS03 because it is low noise and will remove any interference from that area especially if they are close.

I hope this helps, AIS can get interference and noise from lots of places. I can upload an article on the possible areas where interference can come from if you would like. Please let me know how you get on.

Best regards

[Anonymous]

It suggests that electrical noise or interference is the main issue. Should I use one of your A013 5v power conditioners?

[Quark Elec]

Hello

Using our power converter is a step in the right direction. Using USB won’t be the main cause for issue though. Adaptors, active splitters and cable can make the real difference and of course location of antenna. It is best to play about to find the perfect set up. That is why we created the blog post.

Best regards

[Anonymous]

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.

[Anonymous]

Good morning Dolphinicity.

I have at times observed a mismatch between screen and eyeball,

with an undetected vessel approaching through other vessels.

The situation persisted from first sighting (5NM or so), through close quarters, to disappearance.

The CG could see the vessel with their antennae, which would have been higher than my 14m dedicated antennae.

Might I ask what you are viewing the signal on?

[Author]

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