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Old 03-12-2017, 12:21   #1
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OpenCPN jumping map

Hello everyone,

So im new here, and my first act as a new member is to ask a question. Yeah selfish from me, so i apologize for that.

So i have Raspberry Pi 3 with OpenPlotter and OpenCPN. All of that is connected through RS422 converter to onboard RPi UART, for connection to an Icom CLASS B MT-500R AIS.

From AIS i take info on AIS targets and GPS. Everything is fine except,

Sometimes my position is lost. Not lost in loss of signal, but the red boat, which is me , moves far off chart to another km. Im using it as inland chart. So basically im on lets say 1111km and im moving slow at 5km/h and a minute later navigation says im on 1105km which is impossible. Im not a damn jet

So i have a problem here, now im sure that maybe the problem is with onboard UART, loosing data...so im going to fix the clock of RPi to something stable.......

Anyone had similar problem?
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Old 03-12-2017, 14:48   #2
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Re: OpenCPN jumping map

Hmmm, before you go changing the clock source on your Pi, are you sure the location information is coming from a reliable source? Does the ICOM have a nice clear view of the sky? Are you seeing NMEA checksum errors in the incoming data stream? Can you capture the incoming NMEA data with the VDR plugin and post it here?

I have an Openplotter based Pi-3 with a U-Blox GPS feeding in over USB and I have never seen large changes in location. Occasionally there is a small amount of jitter, generally around a meter or two.

Aedan
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Old 03-12-2017, 21:17   #3
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Re: OpenCPN jumping map

I have a similar problem, and the nmea data stream that I save with VDR recorder. And you can see it. Also my date and time are not there.

Save/record a vdr file if this and upload, it here.

Also search for my thread about this on win10. I think I have to simplify and improve my nav wiring etc. The gps signal is messed up.

Look at properly formed gps sentences and your saved nmea data stream.
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Old 03-12-2017, 21:18   #4
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Re: OpenCPN jumping map

Also try a different gps source and make sure you are only getting one gps signal during testing & diag.
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Old 03-12-2017, 23:37   #5
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Re: OpenCPN jumping map

Its a bit cold, so ill do that in a few days. Hmmm im thinking one more thing. I used UTP cable to connect AIS to my Ecdis. Bout 3 meters. Could that be a problem? To be honest, im an electronics engineer but never worked with RS422 before and from experence in other fields i know its not always as written.

So at least im npt the only one. I have one of those gps mouses i can try with. And as far as Icom goes it doesnt report GPS LOS. Maybe its cable..... I probably need better one, i used utp as fast solution
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Old 04-12-2017, 10:49   #6
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Re: OpenCPN jumping map

Yes try the gps puck it will probably work better. That's how I normally use opencpn.

Mine jumps when I am using my b&g zeus touch 12 chartplotter gps signal, when converted from n2k to nmea 0183 with the raymarine converter, and I may have a nmea backloop coming from the autopilot nmea connections which I have to trace. I need to sort this next spring.
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Old 04-12-2017, 11:44   #7
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Re: OpenCPN jumping map

The UTP wonít be a problem in the short term but as itís a single conductor wire itís not the best to use in a marine environment. RS422 can go very long distances as itís differential, thus I donít expect your problem is there. A data stream captured with VDR will tell you a lot, once itís warmed up a bit. :-)
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Old 04-12-2017, 12:01   #8
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Re: OpenCPN jumping map

https://opencpn.org/wiki/dokuwiki/do...:serial_cables
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Old 04-12-2017, 12:35   #9
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Re: OpenCPN jumping map

Would it be worthwhile to add a link in Supplimental Hardware, like this for UTP?
With some additional information?

UTP Wiring (Unshielded Twisted Pair)
Straight-through cable: Learn about UTP wiring and color coding
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Old 04-12-2017, 14:28   #10
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Re: OpenCPN jumping map

Its my friends boat,

So ill have a chance in a few days. But i just dont get it why would Icom make so many errors. Its gonna be hard making him to add the antenna

I did testing with Em Trac A100 and i had no problems with that one, maybe Em Trac is better in software part.

Im going to try to make it work with Icom, better cable, ill disconnect ground from one side, probably from AIS side, and im going to fix the clock rate on RPi and hope it works, if not, then climb add one more antenna, turn off GPS source from AIS, and add another connection, but would like to keep one single connection....

So many problems from one simple connection. The best is it worked for first two days, then it began to be a problem. So it has to be a problem with one thing a didnt have in the lab, the damn cable. It runs with several other wires, maybe that makes the problem, maybe i have some ground loop. Ill have to check that.

I read others postes, they say they use AIS as source with no problem... But hey with me, im always the one with problems they haunt me all the time
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Old 10-12-2017, 01:59   #11
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Re: OpenCPN jumping map

Hello,
I know double post but just wanted to say whats wrong.

First Icom MA-500TR can work perfectly in AIS+GPS mode with OpenCPN.

My problem was, a brand new DB connector. Shiny lovely with "gold plated" pins, all new unpacked it from factory bag. And that brand new connector was loosing contact on one of the pins

So you cant trust even brand new stuff...... Chaos.

It was loosing connection momentarily and somehow OpenCPN understood that as ship jumping around. I didnt measure anything accidentally i moved the connector and that happened.

Thanks for all info and help and i hope this will help someone else.

All the best, safe voyage
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Old 10-12-2017, 09:07   #12
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Re: OpenCPN jumping map

Good slething, most of the time it is some new/old connection, so after I trace the nmea wiring from my ST4000 autopilot and make sure it is not sending an echo sentence from my B&G gps, I will then tackle the connectors to stop the stray GPS location jitters.

There is one other problem in that I am not getting DATE and TIME which should be in the RMC sentence and in any ZDA sentence. I would think that would come through loud and clear from the
B&G gps
-zeus12touch
-NMEA2000 protocol
-Raymarine Nmea Seatalk converter
-Seatalk bus
-Gadgetpoole Tiny ST converter
-nmea0183 protocol
-Opencpn

But maybe this is too much to expect. My puck works fine, but I want to record all kinds of data and gps location and data and time are necessary along with all the other data which are coming from instruments too.
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Old 11-12-2017, 13:47   #13
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Re: OpenCPN jumping map

I have a similar problem, Open CPN has jumping tracks whether positions are closely spaced together (e.g. at anchor) or steaming at full speed. I switched position input sources and the problem remained. I figured out that it's actually transposing two digits in the GLL NMEA sentence when the flaw occurs (e.g. 60 N becomes 06 N). Hence the long track lines.

Because the configuration application of the multiplexer (MPX Config) monopolizes the com port during use, I can't run Open CPN and MPX Config at the same time and therefore can't prove that OpenCPN, and not the multiplexer, is causing the mix-up. But only Open CPN shows the track error, and the multiplexer is not giving a data overload error so I am left with thinking that my problem is in OpenCPN.

No loose connections here...

If anyone can suggest a remedy or has similar problems?

I have a BU-353-S4 "puck" on order, but would really like to resolve the problem with my network before resorting to an outside position source.

Simrad NSS12
or
Standard Horizon CP150

Both MFDs output NMEA 0183 at 38400 Baud
Shipmodul Miniplex-41 USB

Open CPN 4.8.0 (problem also appeared in a previous version)
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Old 11-12-2017, 14:03   #14
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Re: OpenCPN jumping map

kodiacic:
Quote:
I can't run Open CPN and MPX Config at the same time and therefore can't prove that OpenCPN, and not the multiplexer, is causing the mix-up. But only Open CPN shows the track error, and the multiplexer is not giving a data overload error so I am left with thinking that my problem is in OpenCPN.

No loose connections here...
I'll do you a favor and not make any jokes about loose connections....
Opencpn is solid for me using a B-353-S4 gps puck, so IMHO OpenCPN is not the problem, you'll need to look elsewhere. Connections, EMR interference or converters.

It would be nice to have at least one installation's resolution, but my boat is up on the hard right now and really needs its cover.

Isn't your CP150 a chartplotter too? Does it have GPS too? How is it all wired? Generally during troubleshooting don't have two gps running at the same time! Does one stay steady by any chance? Do you have an autopilot connected? Which one and how is it wired? What happens when you leave the autopilot off?


.. But I agree, you could work the other way, and get O working without jumps using a puck. Then move on to your system
config.

Is this caused maybe by a bad/intermittant power source? Note what Douwe figured out about his heading sensor on RM EV1
Fast heading output from Raymarine EV1

He's done a good job of tracing.
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Old 11-12-2017, 14:08   #15
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Re: OpenCPN jumping map

kodiakic71

just show the NMEA Debug Window ...

So we will see what OpenCPN does receive on the COM port.

The rest is just guessing
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