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Chart image jumping or jerking.

Old 04-05-2015, 03:25 AM
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Default Chart image jumping or jerking.

Can anyone explain why my chart image appears to jump or jerk in relation to the boats position. This is very annoying when trying to anchor over a mark and the boat icon jumps back and forth.

MFD: Raymarine Classic C120
Chart: Navionics Gold, mini SD card into a genuine Raymarine CF adaptor.

I've uploaded a video that shows the problem. Please excuse the video quality, it was taken by my wife on her phone at sea in one metre waves.

https://www.mediafire.com/?vp8ee3cpbn11m9h
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Old 04-05-2015, 06:53 AM
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Are you using an NMEA antenna or a Raystar 125? Seen this happen with NMEA antennas on C-classic mfd's
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Old 04-05-2015, 09:02 AM
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Originally Posted by mstyle8517 View Post
Are you using an NMEA antenna or a Raystar 125? Seen this happen with NMEA antennas on C-classic mfd's
Thanks for your reply. I'm using a Raystar 125 with the internal battery replaced recently. However the Raystar 125 does go into an NMEA input on a Brookhouse AIS-C multiplexer.

The original setup before I added AIS through the AIS-C multiplexer was just the Raystar 125 and VHF into the C120.

I thought it may be the new Navionics Gold card, but I get the same effect with my original CF card which is a few years old.
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Old 04-05-2015, 09:46 AM
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Thats almost definitely your issue, you need to get that 125 going in through Seatalk. If you need the 125 through NMEA for other devices, just switch the 125 to seatalk and NMEAout your position to the multiplexer.
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Old 04-05-2015, 09:54 AM
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This is just a thought. I have a C120 Classic. I would never second guess mstyle8517, he is a Bad Ass when it comes to electronics. That said, there was an article on here some time ago about the chart moving around. It had to do with North up vs Course up.

Again just to throw it out there.
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Old 04-05-2015, 03:51 PM
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The 125 was a one hertz antenna, so at slower speeds it was common for the chart to be moving around as you increased speed the chart would stabilize. The only way to fix is to add a smart heading sensor this would increase refresh rate to ten hertz and give you a more stable chart at slow or drift speeds.

FoReel, you were speaking of relative vs true motion. In heads up in RM the boat icon is stationary and the chart moves around, in north or course up you can switch to TM and the boat moves across the chart.
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Old 04-05-2015, 04:50 PM
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Originally Posted by mstyle8517 View Post
Thats almost definitely your issue, you need to get that 125 going in through Seatalk. If you need the 125 through NMEA for other devices, just switch the 125 to seatalk and NMEAout your position to the multiplexer.
I have two vacant Seatalk sockets at the back of the C120, but I would imagine not the Seatalk2. How would I connect the Raystar125 to Seatalk then back into the multiplexer?
I would have to buy an interface cable which has a screen/ground wire and a red and yellow wire, the yellow wire is data and red +12Ve.

Thanks for any advice.

tpp517
The 125 was a one hertz antenna, so at slower speeds it was common for the chart to be moving around as you increased speed the chart would stabilize. The only way to fix is to add a smart heading sensor this would increase refresh rate to ten hertz and give you a more stable chart at slow or drift speeds.
With my present system I have a Simrad AP16/AC10 NMEA connected through the Brookhouse AIS-C mux which I think has a fast heading sensor.
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Old 04-05-2015, 06:09 PM
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Okay, I'm confused. This is definately a thinker here...if you look at the beginning of the video, pause it. He's definately in North Up. There is a heading vector but the whole speed and rotation thing is not the issue here, if he were in course up, yes, but north up, unless I'm missing something, heading/course/etc. has nothing to do with the actual boat icon jumping. I've seen C-series classics not like the nmea antennas, giving erroneous SOG readings and such. While I have never seen this EXACT instance, I've dealt with enough Raystar 125's to know that when you hook them up through Seatalk, they work right.

All of this NMEA crap with multiplexers and such is, in my opinion, like playing a game of telephone. The end result just doesn't seem to be the same every time.

You have two seatalk ports, don't worry about seatalk 2, the seatalk 1 port is what you use. 3 pin flat connector, we sell them on eBay all day. Power to red and shield on the seatalk wire, green and red on 125 wire to red on seatalk pigtail, yellow on 125 wire to yellow on pigtail, brown and shield on 125 wire to shield on pigtail.

Now your unit can OUTPUT the same position through the R08004 cable to the multiplexer (may already be hooked up). It shouldn't matter to the multiplexer whether the GPS signal comes in through NMEA from the antenna or the C-series, right?
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Old 04-05-2015, 06:38 PM
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Thanks for that detailed information. The first thing is to buy the Seatalk cable. When I have one and connect things up, I'll report back into this thread.
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Old 04-05-2015, 09:47 PM
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Could opting of Relative Motion ( as appears on your screen along with N -Up) possibly help the sync in this case, until you can try the Seatalk interface?
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Old 04-06-2015, 01:59 PM
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Originally Posted by TTaxi View Post
Could opting of Relative Motion ( as appears on your screen along with N -Up) possibly help the sync in this case, until you can try the Seatalk interface?
Many thanks, I'll try that as well as buying the Seatalk cable.
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