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GPS stuff in here?


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#11
GoToy

Posted 06 April 2005 - 10:15 PM

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apples and oranges???

Your GPS will not give you the accuracy of a compass.

I guess we are talking about different things heres.

For one I don't wish to enter into any debate about the accuracy of a GPS
over the compass. I have used both over the years. A GPS may give you the
position, but for following on a bearing is a bit hit miss as far as I am
concerned.

As I have stated here before, my prime navigation tool is a compass, this
can be backed up with a GPS, but I stopped using mine a few years back.

If your in a vehicle for sure its GPS. If your long distance trekking,
your GPS batteries are a concern.......thats where you just use the GPS
just for a position check and you follow the bearing on the compass.



#12
tact

Posted 06 April 2005 - 10:28 PM

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as a matter of interest:
two modes of use for GPS or compass.

Whats more important? Route? Or destination?
1. Sometimes the route is most important. You MUST stick to the plotted
route as accurately as possible and not deviate on the way to the
destination. (eg. traversing a safe path thru a minefield, a crevasse
field, marine channels thru reefs etc)

Both map/compass and map/GPS can handle this. With standard GPS the "safe
path" better be at least 50M wide tho! :)

Perhaps over short distances compass can be "more accurate" and a permit a
narrower "safe path".

In this case "Compass wins". *wink*
(however this case is not very often encountered!)

2. Sometimes its the destination thats important. Knowing where it is.
How you get there (the actual track) not being so important. No hazzards
like minefields etc. Just walk in the BEST path, not the EXACT path.
Glance at the GPS at any time to see what direction the destination is now.

Using compass you can SOMETIMES achieve something like the same freedom of
movement by looking in the distance for recogniseable feature ON the
bearing, pocket the compass and walk the BEST path til you reach that
feature, then look for the next recognisable feature on the bearing and
repeat.

No matter what tho - using compass you MUST return to the actual track line
whenever you refer to the compass for direction (not a requirement for GPS
nav).

This can only be done in relatively open ground using compass. In thick
jungle? Cannot Mah! some times the furthest ahead you can see is a few
metres! How to pick a feature several hundred metres away on the bearing
line, and then take the easiest path to it?

In this case "GPS wins!" *wink*

(ya lah GPS does not work constantly under thick canopy either but you are
"free" to walk to a place where you got signal and then know where is
destination, not chained to the bearing line before referring to your device.)


#13
GoToy

Posted 07 April 2005 - 09:06 AM

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"This can only be done in relatively open ground using compass. In thick
jungle? Cannot Mah! some times the furthest ahead you can see is a few
metres! How to pick a feature several hundred metres away on the bearing
line, and then take the easiest path to it? "

ROLF! Just like walking through thick fog! Actually the best way to nav
in the jungle is to follow the streams and use the natural features
around them as your reference points. You don't have to pick a feature a
few hundred metres away. Trust the bearing and follow it.


GPS Shop.

I was Low Yat plaza yesterday, top floor, theres a small shop selling
GPS, mainly Garmin, directly opposite the escalators. The guy did not
pressurise me at all to buy one. Dunno if his prices are competative, but
you guys can have a look if your there.


#14
keewes337

Posted 07 April 2005 - 01:07 PM

keewes337

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Guys,

Just got to know one of the founding members for the GPS mapsource works
in the same company as me. Spoke to him if you want to have routing
capability you should download the corresponding city maps (mind you only
some are. take note of any info written to say what the file is)For maps
that are okay for reference are the MAL46XX series.

He uses the garmin CS for the maps.

What do you guys think of the Garmin eTrek Lengend C? Checked the reviews
and looks okay for my requirement. Gotoy was there one at Low Yat?

#15
GoToy

Posted 07 April 2005 - 01:17 PM

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Keewes337

Garmin eTrek legend.....not sure but they had 8 or 9 different models, so
I would think so!

Hey, whats this MAL46XX series? Is it a JUPEM map? I can't find the
series in the listing. I use the DNMM 5101 series from JUPEM.

Yes, I am looking at a Garmin MAPXXCS...seems pretty good. I want to know
if its suitable for use under the jungle canopy. If not, its useless to
me.

#16
moat

Posted 07 April 2005 - 01:18 PM

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for magellan

Dealers for Malaysia:

Company: BETA ELECTRONIC MARKETING
Address: 1-2-6 UNION HEIGHTS
JALAN AWAN DANDAN
KUALA LUMPUR 58200
Phone: 603-1333-1199
Fax: 603-7982-5968
Product Lines: Handheld Products, Marine Products

Company: SUPRATECHNIC (M) SDN BHD
Address: 2 JALAN ANGKASAWAN U1/39
SEKSYEN U1 HICOM GLENMARIE IND
SHAH ALAM
SELANGOR DARUL EHSAN 40150
Phone: 60 3 5569-1500
Fax: 60 3 5569-2251
Product Lines: Handheld Products

Company: SUPRATECHNIC (M) SDN BHD
Address: NO 2 JALAN ANGKASAWAN U1/39
SECTION U1 HICOM-GLENMARIE
40150 SHAH ALAM SELANGOR DARUL
WEST MALAYSIA 629048
Phone: 0203 5569 1500
Fax: 0203 5569 1522
Product Lines: Handheld Products, Marine Products, PDA Products




#17
endurasoon

Posted 07 April 2005 - 04:13 PM

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its only one way to decide GPS or compass... one will use GPS and the
other one will use compass, each will be given a map with some waypoints.
see who get to the destination first...heeeheee :-)

this is still too deep for me to understand but don't mind i have few
question?
1. for beginner like me, what feature gps shud i have? colour or no colour?

2. brand? Garmin, i heard they have many maps available for download from
the net. If so can I incorperate those maps into my gps unit?



#18
GoToy

Posted 07 April 2005 - 04:27 PM

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If I am trekking I will use the GPS as a tool for finding exact location.
Inorder to save the batteries I use the field compass for the bearing.
Others (not directed at anyone by the way!) have different ideas, but
thats the way I use, after all, the GPS could fail. The advantage of the
method I use is that you actually have two systems for your navigation.
Should one fail, you have the other as backup. You also use each system
to double check the other....then you have confirmation of where you are.


1)Colour or non colour. What suites your pocket! Colour is nice, but more
expensive and heavier on batteries. I would say none colour.

2)I used to favour Magellen, but Garmin is just as good and Garmin is the
only one at the moment that has loads of maps for download. Not sure why
this is just Garmin. Yes you can download these maps into your GPS, but
some of them are not so detailed. Your GPS used in conjunction with a
1:50000 map of an area will be your most effective means. Just get the
location, and plot it on the 1:50000 map, then you are reasonably sure
your within 100m (or less) of your postion.

I`ll show you what I mean when we are in Sg Lembing.

#19
cvlchin

Posted 07 April 2005 - 07:52 PM

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Hi all,

I must say this is a lively discussion on map work, GPS and compass or
things to do with getting from a point to the next.

I am with GoToy on the fact that a GPS is first and foremost the best aid
in position fixing, giving you the lat and long or combi thereof... other
features in the GPS are quite secondary to position fix.

But here in lies the issue of accuracy. Unless your GPS is reading on
corrected signals, be prepared to have a fix that can be way out to
easily 100 meters....you can check this out instantly just by switching
on your GPS, and see the accuracy or inaccuracy.

tact mentioned about pencil width....yes of course that's part of the
operators in built error, for which if you have an additional 25 meters
error on your GPS, you'd then be away at least 50 meters, rendering the
fix quite in error, and requiring map reading skills to complement.

No, an uncorrected GPS does not give you a workable accuracy in any
professional work....but for trekking in areas w/out easily recognizable
featu8res, yes, a GPS and a compass will make the treek more interesting.

Wonder if anyone ever has within 25 meters accuracy on an uncorrected GPS?





#20
tact

Posted 07 April 2005 - 09:18 PM

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Just do some reading or search on GPS accuracy these days on the web.

Whether true or not I am not sure, but all I am reading says Selective
Availability (SA), thats the US Govt deliberate introduced error that
meant best expected accuracy is about 100M.... has been turned off about
5yrs ago.

Apparently the common wisdon is that nowadays domestic civilian GPS units
with no correction accuracy about 25M is normal.

That is less then the width of a pencil line on a 1:25000 map as already
noted. Its less than 1/4 of a pencil line on a 1:100,000 map!

How much "accuracy" do you need if you just jungle bashing? This far
supercedes the need.

All my comments are relative to "accuracy". Its not saying a compass is
not needed. I carry an orienteering compass in my vehicle always, right
next to the GPS in the glovebox.

Real practicalities? On the ground... I get out the GPS and on it when
driving into a new place simply to map the entry point and any turns along
the way, points of interest and campsites. So I can go back anytime I
like. On it, let it do its thing. Off it. Nice