GPS ERROR?

[rod]

I have a Phillips Mk8 GPS with Simrad repeater on my HR382. Checking against my handheld and against known position the phillips shows a consistent error of around 250m. I have checked set up and seems ok. (Tried to contact Phillips who unfortunately seemed disinterested...old model and all that) Any suggestions?

Thanks

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[AlexL]

sounds like theyre working on different Datums - I've got a Phillips Mk8 and it has various different datums - check the manual . You should set it to WGS-84 which is the 'standard' datum used by pretty much everything.

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[jerryat]

Agreed, that's the most likely solution. I have the same GPS as Rod, along with handheld back-ups, and they normally show identical readings to two decimal places.

Only other thing I can think of is that the handheld is not being held in exactly the same position as the Phillips aerial, though this doesn't seem likely to give a reading that far out. Might it be affected by being close to some other electrical source?

Good sailing!

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[charles_reed]

Recalibrate it

to the known position. I have to do that every time I change a chart chip.

How you do it on the Philips unit I don't know but on mine it's a sub-menu on GPS full data.

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[discovery2]

I believe the Philklips Mk8 GPS uses 4 satellites for fixing position and most new receivers use up to 12 satellites. Could this be the reason for poorer positional accuracy?

David

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[philip_stevens]

The Mk 8 and the Mk 6 are both 6 channel parallel receivers. I have both Mk 6 and Mk 8, and both will display the same position - within a few metres.

They will track as many sats as they can "see", but only appear to compute those at a mid level - not the very high or very low sats.

I would hazard guess, like a previous post, that the datum is the culprit.

I hope we get to know the outcome.

<hr width=100% size=1>regards,
Philip

 

[pampas]

I to have a Mk8 and find it to very accurate, Have you been into "Settings" and set the off sets for the chart in use. Mine is set to Wgs84 + offsets, make sure that you have the correct one then scroll through settings, find offsets, press enter, load datum, press enter, should be ok. many new charts are already set for wgs84 so be careful and check each chart.

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[paul352]

I have a Philips AP Navigator which was reading a different position on the chart from my Raymarine GPS. The raymarine is set to WGS84, but I found that I couldn't enter this into the Philips settings. I emailed Philips and got no reply but have found that the datum setting 02, gives me a very accurate position. It was previously set to 03. Hope this helps.

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[Guest]

Have similar error on plotting. I have two charting PC PLotting programs and they give about the same error in position between them. Have checked all Datums etc. the GPS sends and also the PC uses - all correct !!

Have re-calibrated the charts - (both programs use the same charts ......) no change ...... then I get over the solent to another harbour and its vice versa or no errors .....

Very strange.


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[snowleopard]

your chart and gps need to be talking the same datum. there may be a note on the chart telling you to plot gps fixes a few yards from the original position.

pre-gps charts often contained small positional errors so your chart needs to be up to date.

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