Position lost and out of bounds COG and SOG

[Poolster]

I have a vanilla system setup which contains a Navnet Touch 3d plotter, a SC-20 compass, and a NAVpilot-711C connected via N2K. The plotter runs the latest software version.
After two hours of sailing the plotter displayed suddenly “Position Lost” and also the SOG displayed wrong values up to 95 knots instead of 6 knots (the actual speed). The “Position Lost” message could be cleared but the SOG did continue to display wrong values. The SC-20 has been installed as per the installation directive. On the plotter I also noticed that the course line was changed 180 degrees every now and then. Please advice.

 

[Johnny Electron]

Sounds like the SCX 20 is mounted with range of an RF source or Radar beam. Do you have photos of the installation?

 

[Poolster]

The radar was not active when we encountered the strange SC-20 behavior.

 

[Kris]

In what area of the sea are there problems?
I'm in the Baltic Sea and sometimes I have problems with SCX-20 because Putin interferes with GPS work.

 

[Sparky Wire]

Seriously if I break my ear drums by being blasted by RF, how good will I hear one hour later when the RF is gone while I am trying to listen to my sports show? Reception antennas need to NEVER in the beam of a radar or other powerful RF source.

 

[Johnny Electron]

I am not seeing any immediate obvious problem with RF with one exception. If this antenna is a Cell phone or wifi booster it looks like a pretty big issue with RF. What is that antenna used for?

 

[Poolster]

The structure on the port side on the antenna mast is a 4G antenna, but it was inactive during our sail.

 

[Poolster]

Hi John,

I spent some time going through all the setting on the Navnet plotter and I noticed that the system initially has chosen to use TZTZ16 (do not know if I spell that correctly) for Position and SOG instead of the SC-20 compass. That observation was triggered by the fact the Heading was and stayed correct all the time while the system sometimes lost its Position and also the SOG varied a lot.

When changing this towards the SC-20 compass all symptoms went away.
I mentioned in my opening post that I had a vanilla system. So I did not change anything. I expected the system to give preference to the SC-20 compass for Heading, Position, COG and SOG but apparently it did not.

Apologies for bringing the matter up like this, but I am glad that I have a proper working system now because I love the Furuno system suite.

 

[Johnny Electron]

I am glad you have it working. The 4G antenna is likely going to be a issue over time for all your GPS, Sat Radio, and Sat Compass devices over the long term due to the power and location. It can also be an issue for any near by boats you park near depending on where its RF hits and with how much power. I have seen them Jam GPS for other boats at the dock. Once the front end amp is damaged it won't get better. It is very much true what @Sparky Wire says about the eardrum comparison.

 

[Poolster]

Allright and thanks. I will take your concern into consideration. I can move the 4G antenna to the other end of the roof which is 6 meters from the antenna mast.