double track in opencpn

[ChristineP]

Hello,

I installed Openplotter 3.6 on a raspberryPI4. I connected a GPS, a VHF and an AIS , any of all via a usb port. 
I filtred the connection AIS to have only frame VDN of nmea0183 via "ignored sentences:VTG,RMC,GGA,GLL,GSV". I have only AIS targets. it is ok. For the vhf, i have output events "nlea0183out" to post position to the vhf (it hasn't gps chip), it is ok. I received position GPS correctly from GPS.

The gps is connected to gpsd. VHF ans AIS are connected to SignalK. In Opencpn, I have only the connection to SignalK.

But i am a problem: in opencpn, i have a "strange" track, like the boat move forwards and backwards. I think : perhaps, opencpn  display two positions (one from GPS, the other to VHF with an offset of few meters?

What do you think?
I am french and actually in navigation, with a poor connection 4G and a poor english langage...
Thank you.

[BlackSea]

Do you have VDM sentences? If yes, filter out

[ChristineP]

If AIS is off, I don't have sentences VDN. And  i have always the display problem .

[BlackSea]

Sorry, my fault. I meant VDO

[ChristineP]

Hello, it's OK by suppress the VDO, i have not the double track.
Thank you very much.

I said "If AIS is off, I don't have sentences VDN. And  i have always the display problem ". But not, it's not true. But I had to restart Opencpn to read the new parameters, and i have not do it. If AIS is off, i have not the problem.

I do'nt find information on all the sentences of nmea0183, only on the principals (RMC, GLL, GGA).

Thank you and have a good day.

Christine (on the ship Hikayat)