Mitsubishi Outlander PHEV Forum

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 Post subject: Re: Altimeter reset
PostPosted: Wed Jan 20, 2016 12:59 pm 
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Joined: Fri Oct 30, 2015 10:49 am
Posts: 96
a copy of a MMCS manual on http://www.cp-club.ru/upload/Instructions/mmcs_EN.pdf (too lazy to go outside to get my manual) refers to the 3D location not being updated when not enough GPS satellites are being deleted and 2d positioning being used with the height assumed to be the same as the last reading.

So that seems to be to confirm that the altitude is from GPS and if not changing you are either not getting enough satellites where you are or there is a hardware issue or a GPS problem.


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 Post subject: Re: Altimeter reset
PostPosted: Wed Jan 20, 2016 11:35 pm 
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Joined: Fri Oct 30, 2015 10:49 am
Posts: 96
Did a check this morning on my car.

Initial reading was 350ft with a pressure of 999mbar

During the drive which are one stage by definition was almost down to sea level since I was driving along side the sea!! the readings varied but...

Altimeter only varied by units of 100ft, so read 150ft min, 250ft and 350ft only

Baromenter only varied by units of 5 and with the same number of readinging, 999, 1004 and 1009

So despite the manual saying that some height readings are from the GPS (Perhaps only on the sat nav screen?). The altimeter and barometer seem limited to a certain range (which may depend on the starting reading, I need another test to check that) and are limited to a rather large degree of inaccuracy,

In the case of the orginal poster. if you are not driving somewhere with a large height difference then it staying at 150ft would be consistent with my first test where at around 20ft above sea level to say 200ft it said 150ft.


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 Post subject: Re: Altimeter reset
PostPosted: Thu Jan 21, 2016 1:44 am 
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Joined: Fri Jul 18, 2014 4:46 am
Posts: 2789
raymie wrote:
Did a check this morning on my car.

Initial reading was 350ft with a pressure of 999mbar

During the drive which are one stage by definition was almost down to sea level since I was driving along side the sea!! the readings varied but...

Altimeter only varied by units of 100ft, so read 150ft min, 250ft and 350ft only

Baromenter only varied by units of 5 and with the same number of readinging, 999, 1004 and 1009

So despite the manual saying that some height readings are from the GPS (Perhaps only on the sat nav screen?). The altimeter and barometer seem limited to a certain range (which may depend on the starting reading, I need another test to check that) and are limited to a rather large degree of inaccuracy,

In the case of the orginal poster. if you are not driving somewhere with a large height difference then it staying at 150ft would be consistent with my first test where at around 20ft above sea level to say 200ft it said 150ft.


and your figures are 100% consistent with a barometric altimeter - the accepted standard pressure at sea level is 1013mb with a pressure change of about 12mb per 100m - so your 999mb would equate to an altitude of almost exactly 100m - pretty close to your 350 feet.


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 Post subject: Re: Altimeter reset
PostPosted: Thu Jan 21, 2016 3:44 am 
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Joined: Thu Jul 31, 2014 5:25 am
Posts: 1102
Location: South Australia
I have an altimeter in my model plane, about $50, that reads to 1ft resolution up to 10 readings per second. Now how can I incorporate this into my PHEV? :lol:

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 Post subject: Re: Altimeter reset
PostPosted: Thu Jan 21, 2016 4:16 am 
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Joined: Fri Jul 18, 2014 4:46 am
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gwatpe wrote:
I have an altimeter in my model plane, about $50, that reads to 1ft resolution up to 10 readings per second. Now how can I incorporate this into my PHEV? :lol:


And it will be pretty accurate a lot of the time, but there will also be times when the satellite constellation is not favourable and it could be hundreds of feet out with no easy way to correct it. That is why aircraft do not use GPS altitude as their primary navigation source - barometric will wander off all over the place with changes in the weather, but the errors are predictable and correctable. The pilot just has to check with the airport he is heading for and get their ground level pressure measured on a calibrated barometer, then he can feed the correction figure into his instruments and it will be predictably accurate to a few feet. His GPS altitude is probably accurate to the same level most of the time, but it can fluctuate wildly over a few minutes when the constellation is poor and the errors are very difficult to predict or correct.


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 Post subject: Re: Altimeter reset
PostPosted: Thu Jan 21, 2016 5:19 am 
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Joined: Fri Oct 30, 2015 10:49 am
Posts: 96
I think basically it is fair to say that the components in the outlander are far too vague to be reliable, if it bears out that a) it does use air pressure and b) it does so only in units of 5mbar then the height will be out almost all of the time.

Right now my home station is reading 996.3. yesterday it varied between 999 and 1018, which would give my house varying in altitide by over 600ft in the space of a day.


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 Post subject: Re: Altimeter reset
PostPosted: Thu Jan 21, 2016 5:44 am 
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Joined: Fri Jul 18, 2014 4:46 am
Posts: 2789
raymie wrote:
I think basically it is fair to say that the components in the outlander are far too vague to be reliable, if it bears out that a) it does use air pressure and b) it does so only in units of 5mbar then the height will be out almost all of the time.

Right now my home station is reading 996.3. yesterday it varied between 999 and 1018, which would give my house varying in altitide by over 600ft in the space of a day.


when we were discussing this here some time ago, I came to the conclusion that the car probably needed to include a barometer anyway to provide input to the engine management system, so some designer decided that they may as well add a screen to display its output.


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 Post subject: Re: Altimeter reset
PostPosted: Thu Jan 21, 2016 6:10 am 
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Joined: Fri Oct 30, 2015 10:49 am
Posts: 96
That perhaps makes more sense, they need the air pressure and as a side effect added in a misleading screen misusing that figure.


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