New GPS issues - does the boat needs to move to in order to get the first fix?

[Squanderbucks]

What I don’t understand is why you called Garmin. The unit that is not showing location fix is the new Simrad? Why not call Simrad?
Chartplotter do not have to move to get a fix.first thing I would do is disconnect the unit from the 2000 backbone and turn it on and see what happens when it uses its internal gps antenna.
Then disconnect all other data supplying units from the 2000 network including any radios , etc and plug them back in one at a time to find the conflict.

[Wotname]

Originally Posted by Squanderbucks

What I don’t understand is why you called Garmin. The unit that is not showing location fix is the new Simrad? Why not call Simrad?
Chartplotter do not have to move to get a fix.first thing I would do is disconnect the unit from the 2000 backbone and turn it on and see what happens when it uses its internal gps antenna.
Then disconnect all other data supplying units from the 2000 network including any radios , etc and plug them back in one at a time to find the conflict.

The OP's new Simard does't have any display, he would have to connect it to some other unit to read the 2000 data.

[CarinaPDX]

I just confirmed that the Simrad GPS and the Garmin chartplotter use the same PGNs (129025, 129029) for navigation (no surprise there). Unfortunately Garmin's documentation is lacking on important details, but the two places to look are Configure/Communications/Preferred Sources for choosing the Simrad GPS as the source of position/speed/time/heading info, and possibly something under Configure/Communications/NMEA 2000 Setup.

Greg

[sgel]

Thanks again everyone for your suggestions and insights!
Since some people asked, ill clarify some points:
1) There is no internal GPS,
2) I am talking about the actual position and NOT on the COG/SOG
3) I called both Garmin and Simrad support, (btw I choose the gs25 since it have an internal direction sensor, compare to the Garmin 19x, and the direction sensor do work).
4) I took apart the nmea2000 network and remove all unnecessary devices.
5) I cannot move the boat since it on the hard, and once ill be in the water Ill have less time to investigate before Ill need to move her, I tried to move the antenna with no affect, but ill try to do it again.
6) I tired to search for preferred source configuration in the plotter or any configuration but couldn't find anything useful (there is no setup for position) ill try to search again. perhaps the nmea 0183 bridge configuration on the plotter causing some conflict, maybe I need to disable the gps pgn on that interface (all the wires are disconnected anyway)

Last update:
I called Garmin again , different guy, he confirmed it is weird and gave me some instructions how to get the debug information such as the pgn from the network and save it to the SD card(cool ) Ill do it later this week and send it to him.

Once ill get some updates / results Ill come back and update the thread.
In the mean time, happy new year everyone and thanks again for your help!
Sgel

[sgel]

Originally Posted by CarinaPDX

I just confirmed that the Simrad GPS and the Garmin chartplotter use the same PGNs (129025, 129029) for navigation (no surprise there). Unfortunately Garmin's documentation is lacking on important details, but the two places to look are Configure/Communications/Preferred Sources for choosing the Simrad GPS as the source of position/speed/time/heading info, and possibly something under Configure/Communications/NMEA 2000 Setup.

Greg

Thanks for looking into this!, I also compared the Simrad gs25 and Garmin 19x pgn and they look the same

[tanglewood]

You have an 0183 to N2K converter that's operational? A possibility is that the Garmin is confused about which device to listen to for position, the converter or the GS25. My recollection is that garmin does source selection using Device Instance Numbers where there are multiple sources for a particular piece of data. But I'm not sure as I've never used a garmin, and am just going based on what I've read. Unfortunately different manufacturers do source selection differently, and it can create all sorts of odd problems, not unlike what you are seeing.


It sounds like the garmin can display a list of the N2K devices that it sees on the network? If so, does it also show each device's Device Instance Number? Check to be sure the GS25 and the 0183 converter have different Instance Numbers.


Unfortunately without some tools to see what's actually going on, we are all kind of guessing and poking in the dark. Seeing the actual PGN coming from the GS25 would be helpful, and tell you conclusively whether the issue is with the GS25 or the Garmin. My guess is the garmin, but it would be nice to know, not guess.

[s/v Jedi]

The ignorance and confusion in this thread is disturbing

if no position shows up on plotter nor multi-function display, then a "source select" may be set wrong, an "instance id" may be set wrong.

In cases like this, I connect either my Maretron or Actisense USB converters and use the laptop to inspect PGN's for correct data.

[sgel]

Originally Posted by tanglewood

You have an 0183 to N2K converter that's operational? A possibility is that the Garmin is confused about which device to listen to for position, the converter or the GS25. My recollection is that garmin does source selection using Device Instance Numbers where there are multiple sources for a particular piece of data. But I'm not sure as I've never used a garmin, and am just going based on what I've read. Unfortunately different manufacturers do source selection differently, and it can create all sorts of odd problems, not unlike what you are seeing.


It sounds like the garmin can display a list of the N2K devices that it sees on the network? If so, does it also show each device's Device Instance Number? Check to be sure the GS25 and the 0183 converter have different Instance Numbers.


Unfortunately without some tools to see what's actually going on, we are all kind of guessing and poking in the dark. Seeing the actual PGN coming from the GS25 would be helpful, and tell you conclusively whether the issue is with the GS25 or the Garmin. My guess is the garmin, but it would be nice to know, not guess.

The bridge is internal functionality of the plotter, not an external unit, but perhaps even without a source it creates some conflicts, I already rest the setting but ill try to disable it completely.

[sgel]

Originally Posted by s/v Jedi

The ignorance and confusion in this thread is disturbing

if no position shows up on plotter nor multi-function display, then a "source select" may be set wrong, an "instance id" may be set wrong.

In cases like this, I connect either my Maretron or Actisense USB converters and use the laptop to inspect PGN's for correct data.

on my last call to Garmin support I got some instruction how to access the hidden debug menu, so I could record the network traffic (send it to them) and inspect the pgn. ill try that when Ill be back on the boat and update with the results.

[continuouswave]

The claim that the GPS receiver must be in motion in order to get a position fix is hard to understand in the context that the satellites the GPS receiver is using to obtain pseudo-ranges are already in motion at rather impressive speeds.

With orbits of ~12,550-miles above earth and earth radius ~3959-miles, the satellites are moving in a circular path of ~103,729 miles circumference. One orbit takes ~12-hours, so the speed of the satellites is then ~8,644-MPH.

The influence of motion of the GPS receiver at 5-MPH won't have much effect on the deduced position.

[Dr. D]

Actually, even 5 mph is a lot. GPS receivers use both pseudo-range and Doppler shift to calculate position and speed. The use of Doppler shift for speed can be even more accurate than using two fixes and time.

[NavPak ECS]

It's better to find the "Hidden Debug Menu" while she's on the hard, rather than on that dark, stormy night, when everything stops working.

[OS2Dude]

Did you make sure the new Simrad unit is not in DEMO mode? I have a Simrad NSS EVO2 and it was defaulted to DEMO mode.

[Icarus]

Originally Posted by sgel

Hi All,
I removed an old 0183 Garmin GPS and connected a new Simrad GS25 GPS to my existing NMEA 2000 network (I have Garmin 5212 chart plotter and two Gramin GMI 10 instruments). Although I can see the new GPS in the device list and on the sky view I can see at least 10 satellites with green bars (in all 3 devices), It doesn't show the location / I don't get a fix.
I called Garmin support, and the guy told me the that I didn't get a fix since I haven't moved yet, and only after ill move the boat it will start updating and ill get the first fix.(he was very confidence). Does it make sense?, since I am on the hard it will take me a while until I could test this theory...
I would appreciate your insights,
Thanks
Sgel

As said elswhere you dont have to move the boat to get a fix.
GPS updates the position regardless of movement.
Maybe your plotter is faulty?

[Icarus]

Originally Posted by sgel

Thanks!, I looked on other menus but haven't thought of checking the speed setup, ill try that

Yacht move very slow, speed setup in my books is not really relevant unless you travel at 20kn.
At high speeds the processor caculates a probable position till the next satellite fix is available.
Same as having a GPS in a car which moves at anhthing between 0 to 100km an hour.