When the GPS doesn't work

Submitted: Monday, Mar 23, 2009 at 08:17
ThreadID: 67098 Views:2451 Replies:11 FollowUps:10
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I note with interest that during the recent Victorian fires, some crews had to use paper maps because the smoke etc made the eir GPS unable to work correctly.
I would imagine that sat phones wouldn't fare much better.
Satellites aren't of much use when there's a decent cloud cover (storm or rain).

So...good old fashioned dinosaur technology hasn't quite had its day.

Incidently I was on the south island of New Zealand on Black Saturday. The locals kept telling me that the funny sky was due to smoke from the Vic fires. I said I don't think so, but in retrospect.....?
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Reply By: Member - Toolman (VIC) - Monday, Mar 23, 2009 at 08:26

Monday, Mar 23, 2009 at 08:26
Footloose,
Your comments remind me of the time in the late '80's when an estimeemed senior manager came into our office and was justifying funding and staff cuts to our mapping organisation by saying "paper maps would become obsolete in 5 years".

Toolman
AnswerID: 355584

Follow Up By: Member - Footloose - Monday, Mar 23, 2009 at 08:31

Monday, Mar 23, 2009 at 08:31
I am hardly a techical Luddite, but I have a long history of warning about throwing the baby out with the bathwater.

Sadly I have rarely been in a position to determine policy, and always been in a position of having to deal with the effects a few years later.
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Reply By: MEMBER - Darian (SA) - Monday, Mar 23, 2009 at 08:47

Monday, Mar 23, 2009 at 08:47
Smoke from Aussie fires has been across the Tasman before (not sure about this time though).....can be seen on Sat photos at times - and it was in Adelaide too - we had a light smoke haze around here for about a week on and off - BOM said it was the Vic fires..... enough to notice the smell.
AnswerID: 355590

Reply By: obee1212 - Monday, Mar 23, 2009 at 09:00

Monday, Mar 23, 2009 at 09:00
to borrow a quote from a very good nav book, a good navigator will have every thing available to use in his craft.

Everything one thing is a compromise in one small respect or another. Backups like a paper map and a compass are cheap and easy to store. They dont depend on batteries. A cheap gps with a b&w screen will give co-ordinates that can be used with a map that has the same. Some use penlight batterys which are easily replaced. In the meantime a gps with a good map on board is a dream to use.

On a lighter not I have a friend with an electronic chart but he cant set a course or use a compass. He goes for where he judges it to be and then he runs down the latitude or longitude as the case may be. It works but such a waste of fuel.

Owen

AnswerID: 355592

Reply By: DIO - Monday, Mar 23, 2009 at 09:25

Monday, Mar 23, 2009 at 09:25
Smoke from Vic fires DID reach Southland (NZ).
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Follow Up By: Member - Russnic [NZ] - Wednesday, Mar 25, 2009 at 10:22

Wednesday, Mar 25, 2009 at 10:22
There was a strong NW air flow over the Tasman at the time and the smoke definatly covered most of the South of NZ. the brown haze kept the temperature down from the forecast high of 30+ degrees to about 24 degrees.
It is not the first time it has happened,it was the third time that I can recall.
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Reply By: Mick W - Monday, Mar 23, 2009 at 10:19

Monday, Mar 23, 2009 at 10:19
Too True,

a GPS is just another tool available to help with art of navigation.
AnswerID: 355610

Reply By: handy - Monday, Mar 23, 2009 at 10:35

Monday, Mar 23, 2009 at 10:35
i remember over 30 yrs ago when the blue mountains copped a good fire they found burnt leaves from the fire over in NZ.
AnswerID: 355613

Follow Up By: Member - Graham H (QLD) - Monday, Mar 23, 2009 at 18:43

Monday, Mar 23, 2009 at 18:43
In the early 60's the ash from Aussie bushfires coated the mountains in Fiordland on NZ's South Island.
I was working on the Milford Track at the time and for several years we could tell the amount of snow melt as when it got well back the snow would go brown again.
There was some left still into the 80's as i was over there and the staff didnt know what it was.

Trust Aussie to export its rubbish to Gods Own

ROFL


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Reply By: austastar - Monday, Mar 23, 2009 at 11:56

Monday, Mar 23, 2009 at 11:56
Re GPS not working through smoke.
I have an etrex and a mouse type GPS that I tested against each other the other day after getting what I thought was an impossible track recorded when we stopped in Coles semi-underground car park on our way to a trip up the coast.
The Mouse GPS recorded me parking and moving under a huge slab of concrete, where as I have had the etrex cut out in light tree cover.
The etrex would only record a position when placed out side our kitchen window, the mouse gps worked inside on the table. (yes I know, not a very quantitative test)
More testing is needed, but the difference here would indicate that there is potential for large differences in GPS performance in marginal conditions.
AnswerID: 355633

Follow Up By: Member - Footloose - Monday, Mar 23, 2009 at 12:06

Monday, Mar 23, 2009 at 12:06
Hmm...sounds promising, doesn't it .
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Follow Up By: Member - Stephen L (Clare SA) - Monday, Mar 23, 2009 at 13:32

Monday, Mar 23, 2009 at 13:32
Hi Austastar,
The new "H" model eTrex are very accurate and are designed for dense tree coverage or in high building areas.
I have a couple of eTrex Vista's, one being the Vista C and the other the Vista H Cx
The new H model pulls is a fix very quick and is more accurate. Even in the tall timber country north of Appollo Bay and around Cape Ottway, it was still managing 3 - 5 metres accuracy, compared to 7 metres plus on the standard Vista C

Cheers

Stephen
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Follow Up By: austastar - Monday, Mar 23, 2009 at 14:48

Monday, Mar 23, 2009 at 14:48
Thanks Stephen, I wasn't aware of the new models.
Just had a look on GPSOZ to check the details.
Looks similar to mine (visual) which is about 6yrs old, but I can't compare the specs off the top of my head.
Will do that later.
cheers
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Follow Up By: Bonz (Vic) - Thoughtfully- Monday, Mar 23, 2009 at 17:35

Monday, Mar 23, 2009 at 17:35
the sIRF III chipsets work in amazing places, my BT338 will even work in the glove box once its got a fix, or under the seat, pop the non sIRFIII Gps under the seat and you lose your fix quickly
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Follow Up By: Member - Graham H (QLD) - Monday, Mar 23, 2009 at 18:46

Monday, Mar 23, 2009 at 18:46
Great arent they Had my Bt 338 and my phone with TOM TOM in my pocket when I went into a shop.

When my pocket said "Make a U turn the girl at the counter nearly gave birth"






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Follow Up By: Member - Footloose - Monday, Mar 23, 2009 at 18:50

Monday, Mar 23, 2009 at 18:50
hahahahah....
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Follow Up By: stretchlizard - Tuesday, Mar 24, 2009 at 11:16

Tuesday, Mar 24, 2009 at 11:16
My amazing reception was on the lower vehicle deck of the Bruny Island Ferry with a steel vehicle deck above. My PDA/GPS with no external antenna was windscreen mounted and the vehicle was a number of rows back with only a small sight through the front of the vessel.

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Reply By: Robin Miller - Monday, Mar 23, 2009 at 15:11

Monday, Mar 23, 2009 at 15:11
There are a lot of different senarios Footy, but not to many in which a paper map is a lot of help.
I think you need to carry the lot, maps ,GPS and still even a compass (I won a 4wd event - helped by a little compass, when I and the competition lost there GPS signal).

In our recent brush with the fires we never had less than 50 meters visibilty and GPS was a of real assistance (mostly being used as an intelligent compass).

However for others, the lack of knowing where they were was, well simply tragic.

As other posters are saying there are better and worse GPSes and going further some of the newer commerical systems are available with partial internal navigation senors that can assist by feeding back electronic compass and vehicle speed information to fill in temporay holes in coverage.

For most situations though these days simply having an external aerial for the GPS assists greatly in adverse conditions.

I don't reccomend this unless you really are prepared for the consequences, but part of the way I learn is to play out all reasonable senarios, wether its driving the car till it runs out of fuel or driving at night without lights across paddocks
to waypoints using just GPS. One thing that quickly becomes apparent is that its very hard to have faith in your instruments and drive blind.

In one test we did (heavy fog), we had an upmarket car with a very good long range parking sensor system - it could detect a tree further than you could see in the fog and I will be looking further into this simple system.
Robin Miller

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AnswerID: 355677

Reply By: stevesub - Monday, Mar 23, 2009 at 15:47

Monday, Mar 23, 2009 at 15:47
I have a 7 year old Etrex with maps on it and it only gets used when off roading if we may have to backtrack down or a check to make sure we are where we think we are. In the boat, we have it on (same eTrex) but only use it if the weather reduces visibility and we have a pre-recorded waypoints.

It did save us once when out on a mates boat in NZ when a storm came up and he headed for South Amercia where he thought home was. I pulled out the GPS and redirected him 180 degrees. If it wasn't for the GPS, we would be out in the middle of the ocean with no fuel. He now has a compass and GPS

Our own boat in OZ is 28ft long and we go a long way at times but have no problems at all wit the charts. We met some other boaties a couple of years ago in the Mustang Club (Mustang boats) and they were lost without their big screen, show them where they are, multiple colour GPS. Also they did not venture out in more than 0.5m of sea.

They could not believe that we do even quick tricky navigation just around reefs, sand banks, etc from charts - and the good old mark 1 eyeball, even if they are getting tired now.

Old fashioned charts/maps and compass do us fine.

Stevesub
AnswerID: 355682

Reply By: Rossc0 - Monday, Mar 23, 2009 at 19:11

Monday, Mar 23, 2009 at 19:11
"Satellites aren't of much use when there's a decent cloud cover (storm or rain)."

Not sure this is exaclty correct.

The sat dishes (3m parabolic) at work get swamped by heavy rain but are trying to transmit as well as receive and are relatively low power. With cloud cover only no problems.

The gps stil works no problems.

I think the problem lies more in antenna and hardware design of the gps than the smoke/cloud cover.

All aviation gps I've used have never had a problem with cloud cover otherwise they would be no use for instrument approaches and departures.

Using a permanently mounted MR-350 on the F100 in all kinds of weather, monsoon up here, cold and wet in Adelaide, TS out west, etc have never had a drop out. Only problem with this is it would probably melt on a fire truck as it's made of plastic.

I wonder if the heatshielding on the fire truck windows was actually the problem.

Mind you I still have dinosaur technology as a backup whatever vehicle I'm using.

Cheers
Ross
AnswerID: 355735

Reply By: StormyKnight - Tuesday, Mar 24, 2009 at 21:07

Tuesday, Mar 24, 2009 at 21:07
I have an older USB Mouse GPS & in a valley in victoria we came across a very heavy downpour. The GPS lost lock & we didn't get it back till the rain eased considerably.

That GPS unit took ages to get a lock & would not work inside the house at all, even near a window.

My new GPS is a MioMoov300 selling for a s little as $199 from HN at times & it will get a lock within about a meter of the window, but also once the lock has occured, I can move it to the centre of the house & still hold the lock.

Make sure your new GPS has a SirfIII chipset or eqivalent - signal down to -159dB.

Cheers

AnswerID: 355954

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