Expedition Navigation Software 
1 of 1- kwelch
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Unsteady position data in Expedition using H5000
I have an H5000 system connected to Expedition using H-Link. The GPS data on the H5000 system is coming from a Zeus2 MFD (7") that has an integrated GPS -- allegedly 10hz like the ZG100. When you zoom in very closely to the vessel track you can see a very jagged line and the boat bounces around quite a bit.
I don't know if there is a configuration issue on the Zeus2 to control the data rate and whether the high speed output (if it indeed exists) is passed on by the H-Link.
I do not get this jagged track when I use a high-speed GPS connected directly to Expedition (for example the excellent iStarGPS that is no longer in production).
Anyone have any ideas?
- Nick
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Re: Unsteady position data in Expedition using H5000
Do you have two GPS feeds into Exp such as HLink and an AIS?
- kwelch
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Re: Unsteady position data in Expedition using H5000
This is a good question -- I have a B&G V50 VHF which puts AIS information on the network - although when I look at the devices available it is not listed as a GPS source. When I select sources from my B&G graphic display only one GPS source is listed -- myW7 iGPS (from the Zeus2 chart plotter).
By way of illustration, when I zoom in closely (I wish I could paste a picture here) the track is very jagged and at rest the boat seems to jump around. Very weird...
Last edited by kwelch (6/20/2016 4:52 pm)
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Thread Starter- Nick
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Re: Unsteady position data in Expedition using H5000
Is the HLink input the only input into Exp?
Which version of Exp too? If not the latest, the first step is always to update.
- kwelch
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Re: Unsteady position data in Expedition using H5000
H-Link is the only input into Expedition and it is the latest version (10.4.5 4D), although I don't have any C-MAP charts installed at present.
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Thread Starter- Nick
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Re: Unsteady position data in Expedition using H5000
In that case, it has to be something in the HLink input. You probably need to save some from Exp's raw data window and examine the position.
It will look something like:
L,3750.950,N,12225.349,W*60
- sheldon.haynie
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Re: Unsteady position data in Expedition using H5000
Nick,
looking at my log file in excel, I get 5 digits of precision for lat/lon. At 1852 meters/nm and 1 deg lat = 60 nm I get about 1.1m resolution in the log output. I can't find a listing of the precision supported in the 129029 PGN on NMEA web, but elsewhere see 6 or 7 digits shown, which would support 1-10cm differential
(Accuracy is a whole different question)
Lat Lon
37.78473300 -122.26326700
37.78475 -122.263267
37.784783 -122.263267
37.7848 -122.26325
37.784817 -122.26325
I'm running a ZG100 to a H5000 (Hercules) which should have 10 Hz updates and am logging at 1 Hz. With the H5000 damping set at 0.
Is the precision of the ZG100 limited to 5 digits, or is it truncated?
Do you output a simple downsample or moving average for position/COG/SOG?
regards,
Sheldon
Last edited by sheldon.haynie (6/21/2016 8:29 am)
Semiconductor Development Engineer, Retired Viticulturalist, Occasional sailor
"Lioness" 1962 Hinckley Bermuda 40 Custom Yawl
- Nick
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Re: Unsteady position data in Expedition using H5000
You may not be able to rely on Excel to show exactly what is there. My log files are mostly with 6 decimal places, but trailing zeros get truncated.
Units in NMEA 2000 are mostly 1e-7 of a degree resolution.