What is the accuracy of an iPad angle measurement?

[John Harmon]

Simple question:
Q: What is the accuracy of an iPad angle measurement app?
http://i.cubeupload.com/6CPUl7.jpg

A search finds angle-measurement tools are easy to come by for iOS:
A. Wheel Align for ALiSENSOR Wheel By Gloi AB
https://itunes.apple.com/us/app/wheel-align-for-alisensor/id513879710
B. iHandy Level Free By iHandy Inc.
https://itunes.apple.com/us/app/ihandy-level-free/id299852753
C. Clinometer + bubble level + slope finder (3 in 1) By Peter Breitling
https://itunes.apple.com/us/app/clinometer-+-bubble-level/id286215117

Reading each blurb for what the attainable angle-measurement accuracy is on
a typical iOS iPad, this blurb for Angle Pro By 5fuf5
( https://itunes.apple.com/us/app/angle-pro/id750327028 ) shows typical
marketing wording of "accurate angle meter" but they typically fail to
specify the attainable accuracy.

Reading reviews for measuring angles in iOS also typically fail to specify
the attainable accuracy. For example, this article says you can "set the
tolerances between 0.1 to 1 degree" but that doesn't mean that the accuracy
is actually that granular.
"Measure Level And Slope With Great Accuracy With iPhone"
http://appstouse.com/measure-level-and-slope-with-great-accuracy-with-iphone/762

Even a direct search for the accuracy comes up with lots of hits of
articles which seem to fail to specify the accuracy of an iPad angle
measurement:
https://www.google.co.kr/search?q=accuracy+ipad+angle+measurement

This is a simple question, which simply asks what the accuracy is for a
typical iPad angle measurement.

TIA
--
You know who I am so please simply post on-topic replies helpful to all.

[David Taylor]

On 08/12/2016 17:14, John Harmon wrote:
[]

> This is a simple question, which simply asks what the accuracy is for a
> typical iPad angle measurement.
>
> TIA

Accuracy, or precision?

--
Cheers,
David
Web: http://www.satsignal.eu

[John Hill]

David Taylor <david-...@blueyonder.co.uk.invalid> wrote:

> On 08/12/2016 17:14, John Harmon wrote:
> []
> > This is a simple question, which simply asks what the accuracy is for a
> > typical iPad angle measurement.
> >
> > TIA
>
> Accuracy, or precision?

Now that ring a bell…

In my postgrad days I spent some time teaching in the physics labs. I
was frequently brought experiment results worked out to four or five
significant figures. When I asked the student to work out the errors (a
thing they rarely thought about, until pointed in that direction) it
usually turned out that the accuracy of their result was maybe three
significant figures.

So their results were very precise, but not all that accurate :-)

John clearly had his question precisely and accurately framed.

J.
--
Please reply to john at yclept dot wanadoo dot co dot uk.

[John Harmon]

John Hill actually said:

> So their results were very precise, but not all that accurate :-)

It has been a while since I took physics, but what we need in any
instrument is the ability to repeat the same measurement, and for that
measurement to be withing a plus-or-minus margin of error.

That's pretty much what I'm asking for the spec on the iPad.

My specific application is to see if it is possible to measure static
camber using my iPad on a very flat garage floor where the static camber
measurement margin of error is plus or minus 2 minutes as shown in this
graphic from the manufacturer.
http://i.cubeupload.com/cfaDWp.jpg

Can I get within that plus-or-minus 2 minute measurement spec with an iPad?

[John Harmon]

John Harmon actually said:

> http://i.cubeupload.com/cfaDWp.jpg
>
> Can I get within that plus-or-minus 2 minute measurement spec with an iPad?

Ooooops.

The toe is 2 minutes. The camber is 1 minute.
http://i.cubeupload.com/cfaDWp.jpg

So the question becomes this simple:
*Can an iPad repeatably measure angles to plus or minus 1 minute accuracy?*

[Lewis]

In message <o2c4e0$mhg$1...@news.mixmin.net>

John Harmon <Harmo...@example.com> wrote:
> Simple question:
> Q: What is the accuracy of an iPad angle measurement app?
> http://i.cubeupload.com/6CPUl7.jpg

Isn't it a bit soon for your nymshift?

--
You know a thorn can main / But a lover does the same / A gem will
reflect light / And a Fool will marvel at the sight / A fool such as me,
/Who sees not the gold, but the beauty of the shine

[W. Wesley Groleau]

I doubt that accuracy; moreover, does any app exist
that will _display_ that precision?


--
Wes Groleau

[Davoud]

John Harmon:

> > So the question becomes this simple:
> > *Can an iPad repeatably measure angles to plus or minus 1 minute accuracy?*

W. Wesley Groleau:

> I doubt that accuracy; moreover, does any app exist
> that will _display_ that precision?

I also doubt it. In fact, I /feel/ quite certain that an iThingie
cannot achieve that accuracy.

That said, my iPhone with "Clinometer" or "iGradient" is sufficiently
accurate for the purpose of checking that the declination and
right-ascension axes on my German-equatorial telescope mount are
parallel to the N-S and E-W horizons, respectively, a necessity before
initiating the mount's control software. The proof is in the first
"go-to" command; the selected object will be near enough to the center
of the field of view as does not matter. That indicates a precision in
the measurement of just a few arcmin. (Precise positioning is done with
a hand-controller, and either a reticle eyepiece or a camera whose
controlling software puts a bulls eye at the center of the real-time
aiming and focusing image, then a re-calibrate command is issued to the
mount and the mount is set for accurate go-to's for that night and
future nights, providing the mount is not moved while parked and turned
off.) <http://www.primordial-light.com/technique.html>

--
I agree with almost everything that you have said and almost everything that
you will say in your entire life.

usenet *at* davidillig dawt cawm

[John Harmon]

Lewis actually said:

> Isn't it a bit soon for your nymshift?

Hi Lewis,

The simple goal here is to find the simple answer to a simple question:
Q: *What is the accuracy of an iPad angle measurement?*

As always, you completely fail to understand that simple question.

You fail to understand that the thread contains *all* the information
required to understand the question. The only line in the header that is
significant is the subject line. The rest of the header is just metadata
which is to be modified as needed to protect privacy.

While I give you credit for being on the English-language newsgroups (which
I hve been part of for decades myself), you get demerits for wasting
everyone's time on the iPad newsgroup by *never* posting an on-topic
response.

Mostly that's because you have absolutely zero technical knowledge about
iPads (to wit, you can't answer the question posed in the subject line
alone).

Since you can't answer the question in the subject line, you attack the
other headers, all of which are meaningless.

Why do you waste everyone's time?

My opinion on this thread, and *all* threads where a technical question is
asked, is that the only responses should be technical answers to the
technical question, or, if necessary, technical questions to hone the
technical question posed in the subject line.

If this thread had only a *single* correct technical response to the
technical question posed in the subject line, it woudl be a success. All
other results are a failure.

It certainly is a failure when you deliberately troll with your inane
attacks on non technical issues which are meaningless to the technical
topic.

That others have to wade through your trolling, and my attempt to get you
to stop trolling, is the crime here, because it detracts from the simple
goal of finding a simple answer to a simple question:

Q: *What is the accuracy of an iPad angle measurement?*

[nospam]

In article <o2ehop$lqm$1...@news.mixmin.net>, John Harmon

<Harmo...@example.com> wrote:

> Lewis actually said:
> > Isn't it a bit soon for your nymshift?
>
> Hi Lewis,
>
> The simple goal here is to find the simple answer to a simple question:
> Q: *What is the accuracy of an iPad angle measurement?*

no it isn't.

the answer is simple: an ipad is the *wrong* tool to align tires on a
vehicle, no matter how good it is.



from the android group:

In article <o2ceqt$cv4$2...@news.mixmin.net>, John Harmon
<Harmo...@example.com> wrote:
> >> Q: What accuracy is *needed* to measure camber at home?
> > .01 degree or better.
>
> Thanks for that answer because this is a critical number we must know to do
> any aligment reasonably well.

...

> But I don't (yet) know how to convert 1 minute to inches.
> Does anyone want to take a stab at how to run that conversion?

[John Harmon]

nospam actually said:

>> The simple goal here is to find the simple answer to a simple question:
>> Q: *What is the accuracy of an iPad angle measurement?*
>
> no it isn't.
>
> the answer is simple: an ipad is the *wrong* tool to align tires on a
> vehicle, no matter how good it is.

Hi nospam,

The simple goal here is to find the simple answer to a simple question:
Q: *What is the accuracy of an iPad angle measurement?*

In the automotive newsgroups, we found out that it's certainly easily
possible to do what we need to do if our angle-measurement tool is
sufficiently accurate.
http://www.gnttype.org/techarea/suspension/alignment.html

Certainly a digital level is often used to measure camber at home:
http://i.cubeupload.com/XocXQ9.jpg

The only question is whether in iPad has the required accuracy & range.

The range needed is plus or minus 3 degrees.
The accuracy needed is plus or minus one minute.

The simple and purely technical question remains:
Q: *What is the iPad angle measurement accuracy in that range?*

[John Harmon]

Davoud actually said:

> I also doubt it. In fact, I /feel/ quite certain that an iThingie
> cannot achieve that accuracy.

Hi Davoud,

I read with interest your response, and I don't disagree with anything you
said, but, I must add that people here are making judgements about an
iPad's accuracy without even knowing what that accuracy is.

That's not tenable without knowing what the accuracy actually is nor what
the measurement range is.

The measurement range I think I need is plus or minus three degrees.
The measuring accuracy I think I need is plus or minus one minute.
http://i.cubeupload.com/cfaDWp.jpg

This thread only asks this simple iPad technical question:
Q: *What is the iPad angle accuracy (in the plus-or-minus 3 degree range)?*

[John Hill]

John Harmon <Harmo...@example.com> wrote:

> Lewis actually said:
>
> > Isn't it a bit soon for your nymshift?
>
> Hi Lewis,
>
> The simple goal here is to find the simple answer to a simple question:
> Q: *What is the accuracy of an iPad angle measurement?*
>

I cannot for the life of me understand why you bothered to reply to
Lewis' comment.

It contributed nothing to the topic under discussion, and can only have
been intended to wind someone up.

Seems it succeeded

Don't feed trolls.

--
Please reply to john at yclept dot wanadoo dot co dot uk.

[John Harmon]

John Hill actually said:

> I cannot for the life of me understand why you bothered to reply to
> Lewis' comment.

Hi John,

I completely understand your response as I have been on Usenet for decades
and therefore I am fully aware of the maxim to not feed the trolls.

However ...

When you think of that maxim, you have to understand there are two types of
threads and two types of people who author those threads; so the maxim to
not feed the trolls only applies to three of those four types of threads.

> It contributed nothing to the topic under discussion, and can only have
> been intended to wind someone up.

I was shutting Lewis up by showing him what he is, which is that he is a
troll who contributes absolutely nothing of technical value to *any* thread
in this ng.

You'll notice that I don't bother to shut Lewis up in all the other threads
which I didn't author and which are NOT written to garner a specific simple
technical answer to a question.

For all *those* threads (which I don't care about resolution of), I follow
the maxim to not feed the trolls.

> Seems it succeeded

Lewis's contribution to this ng is worse than worthless because it's
negative; hence, he needs to be shut up (in the threads that I care about
getting to a reseolution).

Otherwise he will fill up any thead with his useless drivel which only
proves how stupid he is (he has *never* contributed any value ever).

> Don't feed trolls.

On threads that I don't author in which I couldn't care less whether they
get to a technical resolution, I don't call out the trolls for what they
are.

However, on the threads I author, where I care about getting to a
resolution, I do call out the trools, so as to shut them up.

It's a strategy carefully crafted over the decades, which works on "most"
trolls; but it doesn't work on the worst of the trolls (where, as you know,
nothing whatsoever will stop them).

Getting back on topic, nobody here seems to know what the accuracy is of a
typical iPad angle measurement. Davoud found the accuracy was good enough
for his telescope adjustments, but we don't know the actual number yet.

I will keep on searching, but if there are no more responses in this thread
that are off topic, I'd be happy since the only thing we're looking for (in
this thread) is a number that is correct for the accuracy of an iPad's
angle measurement.

This article talks about the iPhone sensor "bias" but I don't know enough
to understand if that applies to our question of the accuracy:

How reliable is the iPhone bubble level?
http://www.macworld.co.uk/review/mac-software/iphone-spirit-level-review-3476379/

[quote]"the iPhone 5s uses a Bosch Sensortec accelerometer, as opposed to
the STMicroelectronics accelerometer used in previous iPhones.
Reality Cap CEO Eagle Jones says ?the typical bias for the ST part is +/-
20mg, while the Bosch part lists +/-95mg. This almost 5x greater offset
range is confirmed by our measurements".

"Apple could potentially fix this issue by manually adjusting the bias in
the manufacturing process" says GigaOm?s Alex Colon.[/quote]

I'm not sure I understand how the iOS device even calculates angle if
they're talking "mg" as their units (instead of degrees).

[nospam]

In article <o2f2e1$n8g$1...@news.mixmin.net>, John Harmon

<Harmo...@example.com> wrote:

> Getting back on topic, nobody here seems to know what the accuracy is of a
> typical iPad angle measurement. Davoud found the accuracy was good enough
> for his telescope adjustments, but we don't know the actual number yet.

it's insufficient for a proper wheel alignment. simple as that.

in fact, trying to do a wheel alignment with an ipad is stupid.

> I will keep on searching, but if there are no more responses in this thread
> that are off topic, I'd be happy since the only thing we're looking for (in
> this thread) is a number that is correct for the accuracy of an iPad's
> angle measurement.

here's your number: à-1

[Savageduck]

On 2016-12-09 19:58:58 +0000, John Harmon <Harmo...@example.com> said:

<<OCD Verbosity Snipped>>

> This article talks about the iPhone sensor "bias" but I don't know enough
> to understand if that applies to our question of the accuracy:
>
> How reliable is the iPhone bubble level?
> http://www.macworld.co.uk/review/mac-software/iphone-spirit-level-review-3476379/

[quote]"the
>
> iPhone 5s uses a Bosch Sensortec accelerometer, as opposed to
> the STMicroelectronics accelerometer used in previous iPhones.
> Reality Cap CEO Eagle Jones says ?the typical bias for the ST part is +/-
> 20mg, while the Bosch part lists +/-95mg. This almost 5x greater offset
> range is confirmed by our measurements".
>
> "Apple could potentially fix this issue by manually adjusting the bias in
> the manufacturing process" says GigaOm?s Alex Colon.[/quote]
>
> I'm not sure I understand how the iOS device even calculates angle if
> they're talking "mg" as their units (instead of degrees).

It is an accelerometer, so think G-force and you will have your answer
for "mg v. degrees".

--
Regards,

Savageduck

[dorayme]

In article <091220161039530292%nos...@nospam.invalid>,

nospam <nos...@nospam.invalid> wrote:

> In article <o2ehop$lqm$1...@news.mixmin.net>, John Harmon
> <Harmo...@example.com> wrote:
>
> > Lewis actually said:
> > > Isn't it a bit soon for your nymshift?
> >
> > Hi Lewis,
> >
> > The simple goal here is to find the simple answer to a simple question:
> > Q: *What is the accuracy of an iPad angle measurement?*
>
> no it isn't.

Typical sly nonsense from you. The original was

"Simple question:
Q: What is the accuracy of an iPad angle measurement app?
http://i.cubeupload.com/6CPUl7.jpg"

--
dorayme

[nospam]

In article
<do_ray_me-6E3DB...@46.sub-75-242-165.myvzw.com>, dorayme

<do_r...@bigpond.com> wrote:

> > > Lewis actually said:
> > > > Isn't it a bit soon for your nymshift?
> > >
> > > Hi Lewis,
> > >
> > > The simple goal here is to find the simple answer to a simple question:
> > > Q: *What is the accuracy of an iPad angle measurement?*
> >
> > no it isn't.
>
> Typical sly nonsense from you. The original was
>
> "Simple question:
> Q: What is the accuracy of an iPad angle measurement app?
> http://i.cubeupload.com/6CPUl7.jpg"

he might have said those words, but that is definitely *not* the goal.

the goal is to troll.

[dorayme]

In article <091220161827132705%nos...@nospam.invalid>,

nospam <nos...@nospam.invalid> wrote:

> In article
> <do_ray_me-6E3DB...@46.sub-75-242-165.myvzw.com>, dorayme
> <do_r...@bigpond.com> wrote:
>

...

> > Typical sly nonsense from you. The original was
> >

...

> he might have said those words, but that is definitely *not* the goal.
>
> the goal is to troll.

You are implying it was *not* typical sly nonsense. OK. It might not
have been nonsense even, nor sly. But surely you would agree, it was
typical.

Just btw, a troll can have some genuine concerns about questions
raised, nothing to do with stirring up trouble or attempting to gain
attention.

The things people imagine wanting to do with their iPads!

--
dorayme

[Davoud]

John Harmon:
> ...I have been on Usenet for decades...

> I was shutting Lewis up by showing him what he is, which is that he is a

> troll...

But you didn't shut Lewis up. He, too, has been on Usenet for a long
time, honing his troll skills. You just provided him with what a troll
needs to survive.

I shut him up the first time I saw a post from him years ago -- I
kill-filed him. Yes, sometimes I run into him, as in this thread, but
since I have, in a previous post, contributed everything that I can to
this subject, I am now killing this thread so as not to be accidentally
exposed to more of Lewis's nonsense.

[John Harmon]

dorayme actually said:

> The things people imagine wanting to do with their iPads!

To your point, all I want to do with either the iPad or the Android mobile
device is to measure angles.

Here is a photo of what I'm trying to measure:
http://farm4.static.flickr.com/3027/3025271110_ffee13e89e.jpg

Specifically, to measure camber where the angles are in the range of plus
or minus 3 degrees, and, as it turns out, the accuracy doesn't have to be
all that great (maybe a tenth to a half of a degree, in practical reality,
despite the manufacturer's spec of plus or minus 1 minute).

There is a useful thread on the Android newsgroup that nospam is completely
aware of (which he pretends to be ignorant of) where a similar question is
asked of the Android devices.

The difference between the two threads is that I'm aware that the iOS
newsgroup is *different* than the Android newsgroup (very very very very
very very very very very different), so there are far more details in the
Android newsgroup thread.

Here is that Android thread:
- Advice requested from those of you who have successfully checked camber
at home
https://groups.google.com/forum/#!topic/comp.mobile.android/i4L53W4boJ8

I didn't want to complicate the iOS thread with issues about camber and
toe, so I kept the iOS thread super simple (becuase iOS users are vastly
different than Android users, and the iOS newsgroup has far too many trolls
who will waylay *any* conversation, especially, as we see from Lewis, from
those where they can't provide any technical value whatsoever).

So that's why this thread is super simple (that other thread is far more
complex, but the users on that thread can handle the complexity).

This thread simply asks one simple question, where the correct answer is
currently unknown, but when it is figured out, it will simple be a number:

Q: *What is the accuracy of an iPad angle measurement?*

http://farm4.static.flickr.com/3053/3024441885_60f9b7c555.jpg

[John Harmon]

nospam actually said:

> it's insufficient for a proper wheel alignment. simple as that.
>
> in fact, trying to do a wheel alignment with an ipad is stupid.

http://farm4.static.flickr.com/3027/3025271110_ffee13e89e.jpg
http://farm4.static.flickr.com/3053/3024441885_60f9b7c555.jpg

[John Harmon]

Savageduck actually said:

> It is an accelerometer, so think G-force and you will have your answer
> for "mg v. degrees".

Hi Savageduck,

I have to admit, I was thoroughly confused when I saw the mg vs degrees,
but, I have to also admit that I never once prior thought about *how* they
managed to measure degrees.

Thanks for the insight.

[nospam]

In article <o2g0er$gab$1...@news.mixmin.net>, John Harmon

<Harmo...@example.com> wrote:

> There is a useful thread on the Android newsgroup that nospam is completely
> aware of (which he pretends to be ignorant of) where a similar question is
> asked of the Android devices.
>
> The difference between the two threads is that I'm aware that the iOS
> newsgroup is *different* than the Android newsgroup (very very very very
> very very very very very different), so there are far more details in the
> Android newsgroup thread.

there's mostly been one person responding over there, who had this to
say:

In article <dguj4c5ai0rapme3s...@4ax.com>,
<cl...@snyder.on.ca> wrote:
> If you are going to measure the toe with a string, you may as well
> forget about it. You can NOT get enough accuracy or repeatability to
> determine if the toe is correct or not. Without pro equipment, to get
> that granular in your measurement you NEED to extend your measurements
> 5 or 10 feet and measure with a goor steel tape measure, or extend the
> displaced centerline accurately and measure with a steel rule. Using
> the simple tape measure will give you the total toe - which will be
> double the specified toe per wheel, and will not tell you if you are
> off-center.

In article <aquj4c9ev2k911uog...@4ax.com>,
<cl...@snyder.on.ca> wrote:
> On Thu, 8 Dec 2016 21:13:33 -0000 (UTC), John Harmon
> <Harmo...@example.com> wrote:
> >But what is 1/60th of a degree in inches?
> That depends whether it is at 12.5 inches, 12.5 feet, or 12.5
> miles.......
> You REALLY need to study your high-school math.

In article <cfpl4cd1v5a2145mc...@4ax.com>,
<cl...@snyder.on.ca> wrote:
> But I'm wasting my breath - You've been told this several times and it
> has not gortten through to you. Stop being a cheap-assed wannabee,
> find a good mechanic - and TRUST HIM. Pay him what the job is worth.
> If you can't afford to proain a bimmer, drive a bloody Chevy!!

In article <3vtj4cpj2njsmnitt...@4ax.com>,
<cl...@snyder.on.ca> wrote:
> You want to know if anything is worn or bent - and measuring CASTER is
> required as well to know. You really don't have your head around the
> concepts well enough to understand WHY an alignment check should be
> done properly. Your "quick check" is just that - and if you are at all
> in tune with your car as a driver you will know there is something
> wrong just as well by simply driving the car. If you are not "in tune
> with the car" the Bimmer is wasted on you --- (as it is on the vast
> majority of Bimmer owners)

[John Harmon]

Davoud actually said:

> in a previous post, contributed everything that I can to
> this subject,

I do thank you for your advice that it's accurate enough for the telescope.

I'm currently looking up the accelerometer specs, since, according to
Savageduck, that's where the spec for the angle accuracy is going to lie.

[Lewis]

In message <091220162201579348%st...@sky.net>

Davoud <st...@sky.net> wrote:
> John Harmon:
>> ...I have been on Usenet for decades...

>> I was shutting Lewis up by showing him what he is, which is that he is a
>> troll...

> But you didn't shut Lewis up. He, too, has been on Usenet for a long
> time, honing his troll skills. You just provided him with what a troll
> needs to survive.

Fuck off Davoud, you're a fascist shit.

--
You know, in a world in which Bush and Blair can be nominated for the
Nobel Peace Prize, "for having dared to take the necessary decision to
launch a war on Iraq without having the support of the UN" I find myself
agreeing with Tom Lehrer: satire is dead. - Neil Gaiman

[Savageduck]

You are misquoting again.
All I said was the reason for the accelerometer using mg v. degrees was
due to it being an accelerometer not a protractor, so G-force
differential comes into play, but it has nothing to do with measuring
angles.
If you want to know how an iOS device measures angles, the three-axis
gyro is where you need to look.
<http://www.livescience.com/40103-accelerometer-vs-gyroscope.html>
<http://www.stuff-review.com/2011-03/what-is-the-gyroscope-inside-the-ipad-2-and-whats-in-it-for-you/>
<https://www.lifewire.com/sensors-that-make-iphone-so-cool-2000370>
<http://www.macrumors.com/2014/09/26/iphone-6-6-plus-two-accelerometers/>
--


Regards,

Savageduck

[Savageduck]

...and
>
this:
<https://developer.apple.com/library/content/documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/motion_event_basics/motion_event_basics.html>
--


Regards,

Savageduck

[nospam]

In article <201612092110011842-savageduck1@REMOVESPAMmecom>, Savageduck

<savageduck1@{REMOVESPAM}me.com> wrote:

> On 2016-12-10 04:40:39 +0000, John Harmon <Harmo...@example.com> said:
> > I'm currently looking up the accelerometer specs, since, according to
> > Savageduck, that's where the spec for the angle accuracy is going to lie.
>
> You are misquoting again.

expect nothing less.

> All I said was the reason for the accelerometer using mg v. degrees was
> due to it being an accelerometer not a protractor, so G-force
> differential comes into play, but it has nothing to do with measuring
> angles.
> If you want to know how an iOS device measures angles, the three-axis
> gyro is where you need to look.

he doesn't.

[dorayme]

In article <o2g0er$gab$1...@news.mixmin.net>,

John Harmon <Harmo...@example.com> wrote:

> dorayme actually said:
>
> > The things people imagine wanting to do with their iPads!
>
> To your point, all I want to do with either the iPad or the Android mobile
> device is to measure angles.
>

...

>
> This thread simply asks one simple question, where the correct answer is
> currently unknown, but when it is figured out, it will simple be a number:
>
> Q: *What is the accuracy of an iPad angle measurement?*
> http://farm4.static.flickr.com/3053/3024441885_60f9b7c555.jpg

Yes, very sensible sounding. To think, nospam thinks you are a troll!
I would not take that sort of thing lying down ..., John.

--
dorayme

[W. Wesley Groleau]

On 12-09-2016 09:14, John Harmon wrote:
> As always, you completely fail to understand that simple question.

Oh, I guess I was little slow to recognize a new name for the same old
troll.

--
Wes Groleau

[John Hill]

John Harmon <Harmo...@example.com> wrote:

> To your point, all I want to do with either the iPad or the Android mobile
> device is to measure angles.
>
> Here is a photo of what I'm trying to measure:
> http://farm4.static.flickr.com/3027/3025271110_ffee13e89e.jpg

No that's really useful.

May I humbly suggest:

Create a test serface approximating to that you want to measure.

Measure the inclination using all four edges of the iPhone. Note the
values.

Turn the iPhone to face in the other direction and repeat.

Examination of the spread of the results should give you a *practical*
estimate of the accuracy.

Repeat as rquired varying the slope of your test surface slightly if you
require further evidence.

Typed in haste...

J.


--
Please reply to john at yclept dot wanadoo dot co dot uk.

[John Harmon]

John Hill actually said:

> Examination of the spread of the results should give you a *practical*
> estimate of the accuracy.

This is a good idea, and it will be easy to do since there are plenty of
flat surfaces!

[John Harmon]

dorayme actually said:

>> Q: *What is the accuracy of an iPad angle measurement?*
>> http://farm4.static.flickr.com/3053/3024441885_60f9b7c555.jpg
>
> Yes, very sensible sounding. To think, nospam thinks you are a troll!
> I would not take that sort of thing lying down ..., John.

We have since found out some good information on the android newsgroup
which is that the sensor in a typical mobile device is not an inclinometer,
which is generally accurate to 1/10th of a degree as shown by any look at
any level in any of the box stores.
http://www.sears.com/craftsman-10-in-digital-lasertrac-reg-level/p-00948292000P?sid=BVReview


That's six minutes of accuracy, which, fron one standpoint (the
manufacturer's spec) is not enough since BMW specifies 1 minute of
accuracy.

However, six minutes of accuracy is fine for *most* camber checks, since
camber isn't all that critical anyway, at least for the average homeowner.

So what matters is that you have a "smidge" of negative camber, for
example, which can be anything less than zero (e.g., 1 degree, or 2 degrees
is fine for my application).

Same thing on toe, but toe is problematic because we have found on the
Android newsgroup that most smartphone devices use an accelerometer in
conjunction with a magnetic compass to calculate angle, which is fine for
camber (although it may be unduly influenced by steel wheels) but it
doesn't work for toe (because you can't move gravity to a new plane).

So, on the Android newsgroup, we're learning a lot about how the sensors
are designed to work and on the rec.autos.tech newsgroup we're finding that
you really don't need the kind of accuracy that the manufacturer specifies.

In fact, most toe is a "smidge" positive (about 1/16th or 1/32nd per wheel
to the centerline) and most camber is a "smidge" negative (about a degree
or so).

A smartphone can't be used for measuring toe angles but it can be used for
camber given those wider constraints.

[John Harmon]

nospam actually said:

> there's mostly been one person responding over there, who had this to
> say:

Clare is a well-known curmudgeon on the alt.home.repair group.
He is *not* on the android newsgroup, nor on the auto tech group.

He says the same thing all the time whenever *anyone* asks.

He always tells people to "call a plumber" or "call a refrigerator repair
guy" or "call a garage door guy", whereas I install my own plumbing, I
repalced my own refrigerator starter cap and I replaced and wound my own
torsion springs without getting killed.

[nospam]

In article <o2i8ro$n3v$5...@news.mixmin.net>, John Harmon

<Harmo...@example.com> wrote:


> and I replaced and wound my own
> torsion springs without getting killed.

there's always next time.

[John Harmon]

Lewis actually said:

> Fuck off Davoud, you're a fascist shit.

Hi Lewis,

Why you consistently and repeatedly prove you can't answer even the
simplest of questions amazes me, since you troll incessantly still.

Nonetheless, the simple answer to the simple question will be found when we
find out the accuracy of the chip used in the iPad which is apparently the
ST MEMS chip AGD1 2022 FP6AQ (which is identical to the off-the-shelf ST
L3G4200D).
https://www.ifixit.com/Teardown/iPhone+4+Gyroscope+Teardown/3156

This is what ST says about its MEMS gyros:
http://www.st.com/en/mems-and-sensors/gyroscopes.html?querycriteria=productId=SC1288

That article says verbatim:
"with a resolution lower than 0.01 dps/?Hz for zero-rate level.
This guarantees the level of accuracy required by the most
advanced motion-based applications."

I'm going to have to look a little deeper into this 0.01dps/yHz figure.

Lewis: Can you help with that?

[John Harmon]

nospam actually said:

> expect nothing less.

Hi nospam,

Why you consistently prove you can't answer the question is beyond
trolling.

All you're doing is proving you're an idiot who can't resist posting
drivel.

Anyway, Savageduck hit upon the way to find the solution to the question
which is to find out the accuracy of the ST MEMS chip labeled AGD1 2022
FP6AQ.

Based on this article, that Apple-specific version is apparently identical
to the off-the-shelf STMicroelectronics L3G4200D gyroscope.
http://www.zdnet.com/article/inside-the-iphone-4s-vibrational-gyroscope/

So the simple answer to the simple question will be likely found once I
figure out the accuracy of either of those two chips.

[John Harmon]

Savageduck actually said:

> All I said was the reason for the accelerometer using mg v. degrees was
> due to it being an accelerometer not a protractor, so G-force
> differential comes into play, but it has nothing to do with measuring
> angles.
> If you want to know how an iOS device measures angles, the three-axis
> gyro is where you need to look.
> <http://www.livescience.com/40103-accelerometer-vs-gyroscope.html>
> <http://www.stuff-review.com/2011-03/what-is-the-gyroscope-inside-the-ipad-2-and-whats-in-it-for-you/>
> <https://www.lifewire.com/sensors-that-make-iphone-so-cool-2000370>
> <http://www.macrumors.com/2014/09/26/iphone-6-6-plus-two-accelerometers/>
> --

Hi Savageduck,

There is only one goal here which is to find the accuracy of a typical
mobile device angle measurement (specifically for camber angles).

On the Android group, they mentioned that smartphones use an accelerometer
combined with a magnetic compass, which may be affected by the metal of the
wheel being measured for camber angle.

On the home repair group, they mentioned that a typical "inclinometer" has
about 1/10th of a degree (six minutes) of accuracy, which they said was
more accurate than the accelerometer/compass method.
http://www.sears.com/craftsman-10-in-digital-lasertrac-reg-level/p-00948292000P

You are the first to mention the gyro, which I appreciate because the
others mentioned only the accelerometer and magnetic compass.

So all I really need to figure out is how accurate *that* gryo is!

Your first suggested article is great because it explains the different
methods (accelerometer versus gyro) for measuring angles:
http://www.livescience.com/40103-accelerometer-vs-gyroscope.html

The accelerometer measures vibration, while the gyro measures orientation.
But that article doesn't state the accuracy.

The second helpful reference you provided specified the ST MEMS chip that
comprises the gyro. That's helpful because we can't get better accuracy
than what that MEMS chip can get.

The gyro seems to be a MEMS chip made by STMicroelectronics labeled AGD1
2022 FP6AQ, for measurement in three axes (X, Y and Z).
http://www.stuff-review.com/2011-03/what-is-the-gyroscope-inside-the-ipad-2-and-whats-in-it-for-you/

The third recommended article didn't mention anything useful about the
accuracy of the gyro but it did explain the other sensors, so it's
interesting to note that it mentioned three related components for angle
measurement which are the gyro, accelerometer, and compass.
https://www.lifewire.com/sensors-that-make-iphone-so-cool-2000370

The fourth recommended reference showed that the iPhone 6 has two
accelerometers, and the article gave specs for those accelerometers, but
none were related to the gyro and none were in angle measurements.
http://www.macrumors.com/2014/09/26/iphone-6-6-plus-two-accelerometers/

Overall, your information about the gyro is almost certainly spot on the
mark where all I need to do is find the accuracy of the ST AGD1 2022 FP6AQ
MEMS chip and I'll be well on my way to finding the answer to the question
of:

Q: What is the accuracy of the iPad angle measurement?

[John Harmon]

W. Wesley Groleau actually said:

> Wes Groleau

Hi Wes,

How is asking such a simple question about iPad accuracy a troll?
Lewis trolled. Nospam trolled. You trolled.

I never troll.

I simply asked a basic question, and if there were zero posts from the
people who don't have clue what they're talking about (including you), this
thread wouldn't be filled with trolls from the likes of you, nospam, &
Lewis.

Savageduck gave useful information about the gyro (in iPad 2 and iphone4
and above) and accelerometer accuracy (which I'm looking up). Davoud gave
useful information on the accuracy being enough for his telescope. Dorayme
kept on topic.

You, Wes.
You just troll because you don't have any technical value to add.

To remain on topic, I was unaware that the iPad had a MEMS gyro (I knew
about the accelerometer and compass and that it didn't have an
inclinometer.

Looking here, we find more information about the gyro:
http://www.stuff-review.com/2011-03/what-is-the-gyroscope-inside-the-ipad-2-and-whats-in-it-for-you/

The MEMS chip for the gyro in the iPhone4 is an STMicroelectronics AGD1
2022 FP6AQ.

One bit of confusion I have is how a "gyro" differs from an "inclinometer"
since we already know that any Sears or Home Depot level gage has an
inclinometer which has an accuracy to six minutes:
http://www.sears.com/craftsman-10-in-digital-lasertrac-reg-level/p-00948292000P

The "gyro" may be the same thing (or it might not be).

If it's the same, then it's likely to the 1/10th of a degree accuracy and
that would be the simple answer to the simple question.

[dorayme]

In article <o2ibgm$sr6$4...@news.mixmin.net>,

John Harmon <Harmo...@example.com> wrote:

> W. Wesley Groleau actually said:
>
> > Wes Groleau
>
> Hi Wes,
>
> How is asking such a simple question about iPad accuracy a troll?
> Lewis trolled. Nospam trolled. You trolled.
>
> I never troll.
>
> I simply asked a basic question, and if there were zero posts from the
> people who don't have clue what they're talking about (including you), this
> thread wouldn't be filled with trolls from the likes of you, nospam, &
> Lewis.

Absolutely correct! You did ask a simple question and most everyone
else are just egging you on in a most disgraceful manner and can
themselves be accused of the most outrageous trolling. I am shocked to
see this. Shocked! Don't take this lying down, tell them how it is and
please do not spare mention of Android. (An Android, some sort of
visitor from outer space?)

--
dorayme

[John Harmon]

Savageduck actually said:

> this:
> <https://developer.apple.com/library/content/documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/motion_event_basics/motion_event_basics.html>

Hi Savageduck,

I think your idea is the correct one, which is to figure out the resolution
of the gyro in the iOS device.

Apparently that gyro is the Apple-specific STMicroelectronics AGD1
2022 FP6AQ which is the generic off-the-shelf ST Microelectronics L3G4200D
which has a spec page here:
http://www.st.com/en/mems-and-sensors/l3gd20h.html

It may take me a while to figure out how to read that spec, and I certainly
doubt the incessant trolls here will be able to help (e.g., nospam, Lewis,
W. Wesley Groleau, etc.) because it will take actual intelligence to make
the transition between those specs and ultimate degrees of resolution
accuracy.

[John Harmon]

dorayme actually said:

> Absolutely correct! You did ask a simple question and most everyone
> else are just egging you on in a most disgraceful manner and can
> themselves be accused of the most outrageous trolling. I am shocked to
> see this. Shocked! Don't take this lying down, tell them how it is and
> please do not spare mention of Android. (An Android, some sort of
> visitor from outer space?)

Hi dorayme,

I must wholeheartedly agree with everything you said above.
Most people using iOS products aren't intelligent like you are.
They can't even understand that the STMicroelectronics AGD1
2022 FP6AQ MEMS chip holds the answer to the question.

You, on the other hand, have shown yourself to actually be intelligent.

Surely you know how to interpret these specs for the off-the-shelf ST
Microelectronics L3G4200D equivalent:
http://www.st.com/en/mems-and-sensors/l3gd20h.html

You dorayme are intelligent, are you not?

[John Harmon]

nospam actually said:

> there's always next time.

Look nospam,

While you incessantly troll, you're not as utterly incomprehensibly dumb as
Lewis is, so you can actually *understand* the question asked.

You are intelligent enough to actually understand Savageduck's suggestion,
which was one of the few helpful responses here, which pointed to the ST

MEMS chip AGD1 2022 FP6AQ (which is identical to the off-the-shelf ST
L3G4200D).

So the answer to the question lies in the fundamental accuracy attainable
by that chip.
http://www.st.com/en/mems-and-sensors/gyroscopes.html?querycriteria=productId=SC1288

The resolution of that chip is specified as "lower than 0.01 dps/yHz for
zero-rate level".

Now I don't yet understand that spec, but certainly the trolls here, such
as Lewis and W. Wesley Groleau, have shown themselves utterly incapable of
*understanding* such a spec, so they'll never be helpful in any question
which doesn't ask something trivial like "where can I get a pink iPad?"

But understanding that resolution spec won't be trivial.
So all the trolls here who love to post drivel will be of no use to anyone.

But you actually are actually intelligent.
Maybe you know how to interpret that spec into degrees of accuracy?