VHF NEMA0183 position data Issue

[dtfeld]

I have an Icom 400BB VHF that gets position data from my Raymarine system. Specifically I have a SeaTalkNG to NEMA0183 converter wired to the VHF. Most of the time, It works great.

However, If I start the engines (probably have a low voltage in the system somewhere), the VHF will partially or completely lose the position data. I have to completely power down all the electronics for several minutes in order to get the position data back. Sometimes it comes back, others, it doesnt. Wiring has been verified. Its almost like the two lose "sync".

Sometimes I get No Position/No Time.

Other times I get alternating ?? then good data about 1 second apart...

Thinking maybe try another converter?

 

[alnav]

David, what is the quality of your position data on the RayMarine side when you start engines? You probably have a GPS satellite and position status screen you could bring up during start. If you are losing GPS position on that side, perhaps it's just taking a while to come back up then to start transmitting on the NMEA/SeaTalk bus.
BTW, seems to me my previous RayMarine systems all disliked engine starts and there was guidance to have them off when starting engines.

 

[Skybolt]

Dave @dtfeld What GPS antenna do you have? Is it powered on/off with your MFD's? But I have to agree with Al in that low voltage is causing issues with it.

Because of similar issues I don't turn on the electronics until after the engine(s) are started. I rewired the electronics to turn on through two different rocker switches. Both of which are turned on after the engine(s) starts.

 

[dtfeld]

The GPS is a new RS150 which is SeaTalkNG networked. It’s very accurate, and quick to acquire a fix (maybe 5-10seconds). I’ve looked at that on the Axioms, and I’m pretty sure that’s not it. The Axiom onboard GPS was much slower/ had bad accuracy, and I had the same problem prior to upgrading to the RS150.

All electronics are switched and only powering them after engine start doesn’t always solve the problem.

 

[dtfeld]

To add a little more info, I start the engines, then turn on all electronics via dash switches and all is well. If I shut down the engines, then restart all the electronics mid day , I start getting these issues.

 

[Skybolt]

So your saying, for instance, anchored out and engines and electronics off, then start the engines and then the electronics and it doesn't re-acquire? Or only the VHF doesn't display the position?

If the later then it's something to do with the 0183 converter. Doesn't the Axiom have 0183 directly out? If so I would use that instead.

 

[dtfeld]

So your saying, for instance, anchored out and engines and electronics off, then start the engines and then the electronics and it doesn't re-acquire? Or only the VHF doesn't display the position?

If the later then it's something to do with the 0183 converter. Doesn't the Axiom have 0183 directly out? If so I would use that instead.

To answer your first question, yes. Anything other than a "cold" startup of the electronics loses the position fix.

Everything in the system has a good position fix regardless of the order in which they were powered up, except the VHF radio. The RS150 acquires a fix almost instantaneously without fail, and its shared across the network (looking at the Axiom I can see the satellites, fixes and good HDOP I can also see the RS-150 GPS broadcasting position).

It has to be an issue with the Raymarine converter, or the VHF radio. Trying to decide the cheapest way to address. A new NEMA0183 converter, or swapping out to a different radio. The Ray 90's are N2K out of the box and coming down in price. Selling the old radio makes both options pretty close in cost.

 

[Skybolt]

To answer your first question, yes. Anything other than a "cold" startup of the electronics loses the position fix.

Everything in the system has a good position fix regardless of the order in which they were powered up, except the VHF radio. The RS150 acquires a fix almost instantaneously without fail, and its shared across the network (looking at the Axiom I can see the satellites, fixes and good HDOP I can also see the RS-150 GPS broadcasting position).

It has to be an issue with the Raymarine converter, or the VHF radio. Trying to decide the cheapest way to address. A new NEMA0183 converter, or swapping out to a different radio. The Ray 90's are N2K out of the box and coming down in price. Selling the old radio makes both options pretty close in cost.

On the VHF, do you only have the Rx connected or both Rx/Tx, guessing both. This won't help, but try only using the Rx of the VHF to t-shoot. If that works ok then it's possibly the converter, if it does nothing then possibly the radio.

The RM 0183 converter isn't 100% 0183, and could be the problem. You probably have already read this article, but in case you missed: https://forum.raymarine.com/showthread.php?tid=7646

 

[dtfeld]

On the VHF, do you only have the Rx connected or both Rx/Tx, guessing both. This won't help, but try only using the Rx of the VHF to t-shoot. If that works ok then it's possibly the converter, if it does nothing then possibly the radio.

The RM 0183 converter isn't 100% 0183, and could be the problem. You probably have already read this article, but in case you missed: https://forum.raymarine.com/showthread.php?tid=7646

A secondary article here references the converter operating in “Sense Mode” for the first 20 seconds. I think the way I have the converter powered in an always on condition. This may explain its behavior that I described as losing sync.

Here—> https://forum.raymarine.com/showthread.php?tid=28

I think I may need to move the converter to a section of my network that is toggled on/off with the radios.

Let me try that and report back.