Altitude Readings - GPS or Altimeter (barometer) ?

[ol' boy]

Looking to take height / altitude readings while out 4WDing
I don't want to rely on map gradients, i'd like a real time, accurate reading.

Anyone know what is better or more reliable?
Would like a digital read out that is always on if possible.
Or a passive analogue altimeter if they are the go

Have seen there are Apps for phones, no idea if these are accurate.
With GPS i believe i need at least 4 satellites to give Altitude and for accuracy, one has to be directly over head, not great if you surrounded by trees.

Resolution only needs to be down to 10 - 20 meters, not sub meter

Thanks

[Thala Dan]

For the price, something like this might be worth a spin:





Heaps of them on eBay, but this bloke has the best feedback....something I take a fair bit of notice of these days.

Rechargeable battery with Mini-usb on top means you could run it in the 4bee all day.

All the listings quote Resolution, but no Accuracy figures.....but should be adequate for your application....and you don't have to see those pesky satellites to get the answer.

In fact, I might even grab one myself, now that you've raised the subject

Edit: Interesting info here from Garmin:

Understanding the Accuracy of the GPS Elevation Reading

GPS heights are based on an ellipsoid (a mathematical representation of the earth's shape), while USGS map elevations are based on a vertical datum tied to the geoid (or what is commonly called mean sea level). Basically, these are two different systems, although they have a relationship that has been modeled.

The main source of error has to do with the arrangement of the satellite configurations during fix determinations. The earth blocks out satellites needed to get a good quality vertical measurement. Once the vertical datum is taken into account, the accuracy permitted by geometry considerations remains less than that of horizontal positions. It is not uncommon for satellite heights to be off from map elevations by +/- 400 ft. Use these values with caution when navigating.

[ol' boy]

Thanks mate, i actually saw that type on a Google Image search, but never went on with it
Yes, agreed, looks exactly like what i'd need.

Will be interesting to cross reference some maps i have at the actual altitude

[Thala Dan]

I've put in an offer of US$20 with that bloke.....see what happens......I'll get one regardless but probably won't have it before mid-late Sep (although quite often China surprises to the upside with deliveries)........we've got a hill in town here with a trig point on the summit....elevation is 367m.....when I get this unit I'll take it up there, along with the eTrex 10 and the Oregon 600, and see who lies the least.

I've been meaning to get something along these lines for the dashboard for quite a while now , so you've spurred me into action.

[ol' boy]

I've been meaning to get something along these lines for the dashboard for quite a while now , so you've spurred me into action.

I'll make you a deal, i'll get us the Altimeter's, you get us the Eaton True Trac

[Thala Dan]

I'll make you a deal, i'll get us the Altimeter's, you get us the Eaton True Trac

Might have to get you to help with some of the more difficult negotiations at home from time to time

[eeprommemory]

has everything you need and no need to carry more junk and one less thing to charge.
i am guessing you have a smart phone.
and the cool thing is you will have it with you at all times unlike a gps /some toy thing.

[ol' boy]

has everything you need and no need to carry more junk and one less thing to charge.
i am guessing you have a smart phone.
and the cool thing is you will have it with you at all times unlike a gps /some toy thing.

Is that just using my GPS position to a corresponding Map Reference?
Or am i missing something?

Yes, i really should have Oziexplorer, been down the road many times and never done it.

[Thala Dan]

Is that just using my GPS position to a corresponding Map Reference?
Or am i missing something?

I'm a bit confused too (hell, what else is new!!).

It seems that Oziexplorer just allows you to plot up a route, etc on maps on your PC or tablet, and then transfer that route and waypoints, etc. onto your phone or GPS.

And you then use the GPS in your phone.....is that correct?

I don't see any reference to Altitude in the OE description.

Does this mean that altitude is determined either using the gradients on the phone map (assuming it has one), or from the altitude given by the GPS system?

If OE is using the GPS in your phone, doesn't that still leave the issues of GPS availability (rugged mountain country with heavy tree cover) and GPS vertical accuracy (as per Garmin note in post #2).

If all that is required is a real-time readout of altitude at any point along a 4WD traverse that potentially involves poor to non-existent GPS coverage, wouldn't a simple barometric system be the most reliable?

I know bugger-all about smartphones and their capabilities, so would be happy to be put on the straight and narrow.

[ol' boy]

Here is another seller Thala, i dropped him an offer of $25 AUD

[Thala Dan]

Here is another seller Thala, i dropped him an offer of $25 AUD

And here's the user manual for you to read while you're waiting to hear back

[Thala Dan]

There's this slightly upgraded model too (FR510)......got a limited capability GPS....and a few other extra readouts:



Edit: I assume that the Altimeter is still barometric, rather than GPS.......can't seem to find an online manual for this model.

It certainly seems to spend a bit more effort on the altimeter side of things.....even gives you a rate-of-climb/descent.

Will keep looking for the manual......and probably have to buy a bigger toy-box

[Uncle Fester]

There's this slightly upgraded model too (FR510)......got a limited capability GPS....and a few other extra readouts:



Edit: I assume that the Altimeter is still barometric, rather than GPS.......can't seem to find an online manual for this model.

It certainly seems to spend a bit more effort on the altimeter side of things.....even gives you a rate-of-climb/descent.

Will keep looking for the manual......and probably have to buy a bigger toy-box

Now we are talking, a barometric GPS combo.
I was just about to complain that your first suggestion does not include speed and distance while maintaining a height resolution of 1m.
I can get that with every $20 bike speedo these days, the altimeter of my last one I had definitely could detect me correctly up one flight of stairs but GPS speed and return data is the big seller here, that you find only on vastly more expensive bike units + I can walk off with it and not get lost.
Yeah there are apps for phones but I find them impractical on a bike, while walking or even in a car where you could get heavily fined because it might be very hard to prove that you were using an accurate altimeter as a driving assistant for a land based vehicle that already has inbuilt GPS and not quickly covering up you Facebook with it. Of course not every phone has a pressure sensor.

[Thala Dan]

Now we are talking, a barometric GPS combo.
I was just about to complain that your first suggestion does not include speed and distance while maintaining a height resolution of 1m.
I can get that with every $20 bike speedo these days, the altimeter of my last one I had definitely could detect me correctly up one flight of stairs but GPS speed and return data is the big seller here, that you find only on vastly more expensive bike units + I can walk off with it and not get lost.
Yeah there are apps for phones but I find them impractical on a bike, while walking or even in a car where you could get heavily fined because it might be very hard to prove that you were using an accurate altimeter as a driving assistant for a land based vehicle that already has inbuilt GPS and not quickly covering up you Facebook with it. Of course not every phone has a pressure sensor.

Bit of a mixed bag here in these 17 Amazon reviews:



The comments about the Chinese manual probably explain why I haven't been able to find an on-line English version.

I've never owned a smartphone, and I doubt that I ever will, so I'm in no position to judge them.

But it seems to me that there is an "all my eggs in one basket" mentality building up around them.......which may be fine in an urban environment.....but perhaps not so much off the beaten track.

[ol' boy]

Some pretty poor reviews, that is a shame,
I found this when reading about the upgraded unit Thala

The BeiDou Navigation Satellite System is a Chinese satellite navigation system. It consists of two separate satellite constellations

Bloody communist navigation

[eeprommemory]

I'm a bit confused too (hell, what else is new!!).

It seems that Oziexplorer just allows you to plot up a route, etc on maps on your PC or tablet, and then transfer that route and waypoints, etc. onto your phone or GPS.

And you then use the GPS in your phone.....is that correct?

I don't see any reference to Altitude in the OE description.

Does this mean that altitude is determined either using the gradients on the phone map (assuming it has one), or from the altitude given by the GPS system?

If OE is using the GPS in your phone, doesn't that still leave the issues of GPS availability (rugged mountain country with heavy tree cover) and GPS vertical accuracy (as per Garmin note in post #2).

If all that is required is a real-time readout of altitude at any point along a 4WD traverse that potentially involves poor to non-existent GPS coverage, wouldn't a simple barometric system be the most reliable?

I know bugger-all about smartphones and their capabilities, so would be happy to be put on the straight and narrow.

it displays a map on your phone showing your track heading and altitude using the phones gps.
i have gone to hilltop makers and there is a brass plaque telling you the height and other stuff my gps was off by 1 meter in height.
i walked though walpa gorge at the olgas and still had good signal.

[ol' boy]

it displays a map on your phone showing your track heading and altitude using the phones gps.
i have gone to hilltop makers and there is a brass plaque telling you the height and other stuff my gps was off by 1 meter in height.
i walked though walpa gorge at the olgas and still had good signal.

Ah ok, so the GPS on your phone is acurate to with in a meter?
That is essentially what i want to check, the so called published height of a location against the actual height.

As there are Mountains i go to, where finding the published height shows conflicting results
So i just wanted to know the true actual height for my own reckoning

What GPS system does your phone use?

[eeprommemory]

Ah ok, so the GPS on your phone is acurate to with in a meter?
That is essentially what i want to check, the so called published height of a location against the actual height.

As there are Mountains i go to, where finding the published height shows conflicting results
So i just wanted to know the true actual height for my own reckoning

What GPS system does your phone use?

find a hill top marker and take photo of brass plaque has info in it and compare with gps data.
hill top markers are a tripod thing with a radar reflector on top easy to find.
NOTE: old gps units are not as good as the gps units in phones old units are pretty deaf and need clear sky to work.
my phone is a Samsung galaxy S5 runs oziexplorer fine.
NOTE #2: most new phones HAVE a barometer in them you can download apps from the play store.
my stone age Samsung galaxy S5 has a barometer.

[eeprommemory]

i am a map junkie and have 40gb of maps and made a few from satellite images i have been stuffing around with a laptop and a trimble gps for years mobile phones replaced all that crap.
if you are registered with any 4WD forums look for some HEMA map torrents for your area.
try find some 50k ones.
i have some 25k ones but it's for mining areas.

[ol' boy]

Yes, did the HEMA download years ago for my area, but never went ahead and purchased Ozi.
Just seemed too complicated.

Looked into making own maps from Google tiles at full res.
Noticed a few had done it.
An old member that no longer posts here was also right into it.....
I'd love my RoofTop paper map collection in a digital form.

So getting back to the Altitude readings, using your phone, there is No Altimeter, so i take it you are using just a 4 axis calculation from your GPS chipset?
And being that Vertical is 4 times less accurate than Horizontal using GPS... you still get with in a meter of actual? Interesting.

The kids use that Trimble stuff on the tractor for doing the paddocks
They don't set up a local repeater for corrections, just from Sats to the Tractor.