Altitude Readings - GPS or Altimeter (barometer) ?

[Uncle Fester]

Very Interesting



2cm they say... Ok. Who are we to disagree, no one else has the technology

Well I own one of these:


which can be used as an altimeter up to 120m above ground (ground radar) with an accuracy of 2 mm !

[Uncle Fester]

Not kidding, mate......my phone is a Telstra flip-phone.....and Austech and my email are the sum total of my personal involvement in the virtual world

You know what they say - just because you're paranoid doesn't mean that they're not really out to get ya

Not paranoid though.........just place a high value on my privacy, and maintain a healthy skepticism of the methods and motivations of modern corporations (and governments, for that matter).

That opens up a different world
Sure hope you are not using Windows.
Kind of envy you but I am too sucked in to be without a smart phone.
Since my colour Palm PDA when I was reading ebooks in 2001 and basically had all the smart features that phones lacked back then, I was already eyeing for a wifi module to go online with it.
Today I have become the total opposite in this Brave New World with all this universal connectivity.

You could of course just use one without SIM card and no WiFi connection. Then download all the apps as APK without Google like I do, that work totally offline.
Those MATE 10s should be very cheap second hand now and has all the sensors for a lot of nifty tools, good camera too for a phone. Mine was very low on bloat. Samsung are the worst, they have so much shyt in them I think simply plugging them into a PC could be a massive privacy risk with their propriety data transfer software like KIES on older versions, although some got them working on Linux without it.

[eeprommemory]

Its not you know, not even close
That point is in deep bush.....off a cliff.

That orange triangle is so inaccurate on that map its not funny
In fact, if you change view on the map (Satellite), you will see exactly that.





Google Maps is even worse, has Mt Cowley 4ks to the NW of where it actually is.


(Mt Cowely is bottom left, Google Maps marked Top Right)

Must have been a busy day working on the Comms Tower recently



Not sure what the "1285" number represents, its stamped over the tower in the above screenshot

If you scroll to the bottom of this page, a HAM Radio chap deployed some fun and games up there, pics show the area

WTF those orange markers are supposed to be accurate.
is there a reflector strapped to the edge of a cliff ???.
the 1285 is the target number for the bombing order during the Chinese invasion.

[ol' boy]

I just spoke to a friend that has also been to Mt Cowely a lot for his job
He has never seen a marker either.
Next visit i will go and take pics and use the Altimeter App when there

When you say those markers are supposed to be accurate
Do you mean when positioned on an electric map??

Or in real life?

[eeprommemory]

Further to my comments about the snowfields, and the recent events in Thredbo, I tried to find out a bit more about smartphone performance in low temperatures vis-a-vis PLBs.

The GME PLB I use is rated "Exceeds IP67" for immersion........the latest Samsungs cite IP68.

The PLB is also rated as "Buoyant in fresh/salt water" - I don't think the phones float

But in the temperature stakes, the PLB is rated as Operating: -20 to+55C:



It is very difficult to find a definitive temperature range for any smartphone.......statements like:





is all that I can find.

None of the phone specs I could find stated a definitive operating temperature range, but the Samsung and Apple sites refer to this "0 to 35C" range with no reference to a lower reliable limit.

There are a number of articles on the 'net relating to phone issues experienced in colder climates.

Interestingly, Garmin car GPS units also have an operating temperature range of -20 to +55C, same as the PLBs.



Makes me wonder just how much use a smartphone would be in an emergency in the Alpine environment at certain times of the year.

Maybe that bloke at Thredbo was close to finding out.

OK just to make things clear.
The battery is the only thing that is not going to like being cold.
i have not opened a newer device old unit had enegizer battery's
mobile phones have lipo's
a massive discussion over battery's is POINTLESS and here is WHY.
eeprommemory's SAFE extended operating conditions are -2c~40c.
dummy's that need a PLB going into -20C to +55C for extend times need a Darwin award.
i cant even think of the level of stupid someone has to be to go into an Alpine environment not knowing what they are doing.
and the point of this is DON'T GO PLACES that are out of the SAFE extended operating conditions -2c~40c.
Garmin built to a price using the cheapest parts.
iridium sat phone built to a standard using the best parts.
witch one do you take with you if you are going to some crazy location.

[Thala Dan]

Before I respond,I’d like to make one thing clear also – I am looking for a discussion here, not an argument. Hope you feel the same.

OK….now:

OK just to make things clear.
The battery is the only thing that is not going to like being cold. .

Well, not strictly correct, from what I can see:

According to Apple, iPhones and iPads should be kept in temperatures ranging from 32ºF to 95ºF. Outside of that operating temperature range, your device may experience shortened battery life, touchscreen issues, and trouble charging. In extreme cases, the device may even shut down altogether.

Is the Cold Destroying your Smartphone?

Typically, as long as the temperature stays close to 0 Celsius, your phone should function just fine. However, with predictions of a harsh winter, 2016 might be looking to take yet another thing from you before it comes to an end, your smartphone. As the temperature drops into the negatives, there are certain effects that you might notice your Android and iOS devices succumbing to:

Battery Life Drain
Touchscreen Issues
External and Internal Component errors

Plenty more where they came from Googling "Cold weather effects on smartphones".

a massive discussion over battery's is POINTLESS and here is WHY.
eeprommemory's SAFE extended operating conditions are -2c~40c.

Thredbos' lowest temperature so far this year was -10 on June 20......not accounting for wind chill.

dummy's that need a PLB going into -20C to +55C for extend times need a Darwin award.
i cant even think of the level of stupid someone has to be to go into an Alpine environment not knowing what they are doing.
and the point of this is DON'T GO PLACES that are out of the SAFE extended operating conditions -2c~40c.

I agree that there are some world-class dummies around, but two comments here:

1. Conditions can change in the blink of an eye in the mountains. Many of the people that get caught up there are caught because conditions changed suddenly.

2. Not going to places that are below -2 for extended periods would rule out most 4wdriving, fishing, camping and hiking in the mountains, and probably send most ski resorts to the wall.

Garmin built to a price using the cheapest parts.
iridium sat phone built to a standard using the best parts.
witch one do you take with you if you are going to some crazy location.

As far as I was concerned we were talking about smartphones....not Satphones.....they are a whole different ball-game......I'd be more than happy to have one of them with me....if I could afford it.

"Crazy location"....how do you define that?

Many of the people who get into trouble in the mountains are generally found within a few kms of camp, village, vehicle, etc.
They were not in a location that would be considered "crazy" under normal circumstances.
The problem often is simply that they were not properly prepared for the not uncommon contingencies that can occur in the mountains.....and I don't consider having a smartphone with you to qualify as "properly prepared".

Here's some good advice:

Why You Can't Rely On Your Phone In The Great Outdoors

If you’re old enough, you may remember carrying maps in your car and telling family the phone number of the place you’re going. But who does that these days, when you just have your phone on you at all times? Well, if you’re heading out for a hiking or camping trip, you may need to resurrect some old-school habits.

There is obviously a place for smartphones in our society....the evidence speaks for itself in that regard.

I just don't happen to believe that the place for them is as a primary safety device in the not-even-crazy outdoors.

[ol' boy]

Satellite-Based Augmentation Systems (SBAS)

Ironically, just watching ABC news and they are talking about Augmented GPS in Australia (SBAS)
Where by you can define any 3D location with in centimetres.

[Thala Dan]

I think they've been reading this thread, OB

Precisely to the point; the promise of satellite-based augmentation

When you consider the differences between mean sea level and the GPS ellipsoid plus take into consideration the effect of temperature on barometric altimeters then, depending on where you are in Australia, your height might be higher or lower than indicated on the GPS,’ Kreusser says

.

Because your smartphone is not an aviation-certified device it can take full advantage of the Australian SBAS trial’s experimental signal. Whereas before it located you in your street, your phone might now show your location on the couch of an evening when you are idly thumbing it.

.....or whatever

There'll be nowhere to hide, mate.

[ol' boy]

Very interesting

When i am at another house, i noticed when using Google Maps via GPS and 3G HSPA, it first places the "blue dot" across the road, then it moves to our house, then after a moment, it moves the "blue dot" do where i am sitting in the house!
It will move as i move...

This house is also in the middle of 3 Mobile Towers i can be connected too

So i wonder if it uses some kind of Packed Timing from the Towers to get a more exact position?

Now, back to SBAS

SBAS will also bring an important gift—vertical guidance. ‘GPS is impressive for lateral guidance, but it was never designed to indicate height with the same accuracy,’ says CASA’s aerodromes and airspace aviation safety inspector Steven Kreusser. ‘SBAS adds vertical guidance to the system.’

I think eeprommemory has touched on this with L1 equipped gear and Trimble Ground Correction

[Thala Dan]

Back in the bad old days of Selective Availability we used to position offshore drillships to within a metre, or better, of required location using Differential GPS.

As I recall, the correction signals in that system were terrestrially broadcast to the GPS field receivers.

Easy to see why everyone is developing satellite-killer weapons these days.......take out a few satellites and your opponent is back to the Stone Age

I've just finished the barometric/GPS comparison......just gotta arrange some photos into a post, and you can see how it went.

[Thala Dan]

Oregon 600 on the left (barometric) and eTrex10 on the right (GPS).

Photos are time-stamped. GPS accuracy on the Oregon is a bit degraded as photos taken under cover due to potential rain.

Interesting that the poor old eTrex thought that it went walkabout to the tune of 284m, while it was sitting quite still on a picnic table the whole time.

Not what you would call major discrepancies between the two....fairly stable barometric pressure throughout probably helped minimise the difference.

Not a very definitive test, but interesting nonetheless.

[ol' boy]

Thanks Thala
Very interesting, 2 completely different systems giving more or less the same Altitude
I'd be happy with that outcome

[ol' boy]

I may need to be careful with my terminology

[Uncle Fester]

I may need to be careful with my terminology

Finally, now I won't get confused any more.

So generally I am more interested in Altitude, the distance until I impact ground.

And thanks again for starting this thread OB, has been the best read in General Chat since a long time. After all this is a technological forum

[ol' boy]

I was speaking to a friend that holds his Master 5 skipper ticket for marine vessels

I was asking him about Mean Sea Level and GPS etc...
He is retired now and did his Master 5 25 years ago.... Yet, he knew all these things we are talking about here.
They were all in the Master 5 course and exam.

Im sure a current commercial pilots course/licence would be extremely in-depth with all these systems

[ol' boy]

Finally, now I won't get confused any more.

So generally I am more interested in Altitude, the distance until I impact ground.

When you look at Thala's photos of his devices, both say "ELEVATION".
I only just noticed this now we are talking about it.


Yet, that App eeprommemory linked me is for an Altimeter
But it gives height above Sea Level, NOT height above ground.

So technically its not an Altimeter at all.

And therefore, GPS can not be used as an Altimeter??
Oh, my head hurts again

More stuff to fry the brain:

[Thala Dan]

When you look at Thala's photos of his devices, both say "ELEVATION".
I only just noticed this now we are talking about it.


Yet, that App eeprommemory linked me is for an Altimeter
But it gives height above Sea Level, NOT height above ground.

So technically its not an Altimeter at all.

And therefore, GPS can not be used as an Altimeter??
Oh, my head hurts agian

No wonder your head hurts....what with a fried brain and all

Just when you think you've gathered up all the loose ends, you find another untidy bit hanging out......always the way with this stuff, innit?

By the way, what was it we were talking about five pages ago? Something about your 4bee going up hills or something, wasn't it??

Second @nomeats comments........good discussion, much learned, but not quite as much understood

And @nomeat......apologies for not responding to your post #82......been busy today on the chainsaw replenishing the rapidly diminishing firewood supply, and dashing off occasionally to take photos of damn GPS units.

Yes, I'm a Win7/64 bit kinda guy.....have it running on two machines, one for online stuff like this, and the other one for all the stuff that I never want to get anywhere near online.
Never had a problem with it at all....keep it updated religiously.......but I'm dreading January next year......some difficult decisions might have to be made.
Took me years to finally let go of a nice stable Win95 for Win7.....I think it's going to be even harder this time around.
Change does not come easy these days

[Uncle Fester]

Oh, my head hurts again

OB, I think this should finally clear things up for you about altitude

These types of altitude can be explained more simply as various ways of measuring the altitude:

• Indicated altitude – the altitude shown on the altimeter.
• Absolute altitude – altitude in terms of the distance above the ground directly below
• True altitude – altitude in terms of elevation above sea level
• Height – vertical distance above a certain point
• Pressure altitude – the in terms of altitude in the International Standard Atmosphere
• Density altitude – the density of the air in terms of altitude in the International Standard Atmosphere in the air

[Thala Dan]

Now my bloody head's hurting!

[ol' boy]

I'm sticking with Elevation, seems to only be one of those