Re: Help me decide

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arlen holder

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Mar 23, 2019, 10:57:40 PM3/23/19
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On Sat, 23 Mar 2019 18:49:08 -0700, sms wrote:

> My $130 LG tablet sees 18 satellites and gets uses 12 of them and
> crunches the data to narrow down the position. As it locks onto more and
> more satellites the accuracy keeps increasing. Here's a screen shot I
> just took outside where it locked onto 18 satellites within about 30
> seconds, with no A-GPS: <http://oi63.tinypic.com/2dvk46w.jpg>. Even
> inside the house, on the first floor, it sees 16 satellites, but the
> signal is weaker
>
> The same app on my Samsung Note 9 shows 15 satellites in view, and uses
> 12 of them (with much greater signal strength), and the same accuracy (3
> meters). It got a fix much faster, within about 5 seconds, because of A-GPS.

Hi Steve,

I'm confused by my fast fix test results below based on your suggestions.
<https://i.postimg.cc/CMfnxjpB/gpsfix01.jpg>

I've used GPS since the StreetPilotIII days (before cell phones) where I'm
amazed at not only how quickly, but how well indoors phones & tablets get a
fix.

I _think_ part of the fast fix is memory, as, I recall, in the olden days,
if I wanted my GPS to fix faster (in the days before cell phones) I would
enter the location into the GUI.

It _might_ be that your tablet "remembers" where it last was, which enables
it to get such a quick fix? (Dunno. Just asking about that location memory.)

> The app is this one:
> <https://play.google.com/store/apps/details?id=com.chartcross.gpstest>
> but there are a load of similar apps on the Play Store.

Thanks for that app suggestion.
o Here is some data where I ask knowledgeable people for analysis advice.
<https://i.postimg.cc/CMfnxjpB/gpsfix01.jpg>

The first time I ran it, I was inside my house where this happened...
o I put "GPS status" in my "Map" folder, and then tapped it to start it
o First "GPS status" asked to allow GPS
o Then it popped up a full-page ad (the teeny tiny (x) is at top left)
o Then it asked me to "calibrate the compass"
o Then it said my GPS "seems to be disabled"
o It then popped me into my "off" location in the Android settings
o I turned "Location" on which _defaulted_ (aurrgh!) to "high accuracy"
o I switched it instantly to "Device sensors only (GPS only)"
o Just to be sure, I turned off cellular data & Wi-Fi
(Would airplane mode have worked just the same?)

I then killed & restarted "GPS status", told it to stop showing me the
calibration suggestion, and then it popped up, seemingly instantly, with
the message of 12/17 satellites, 15M error, magnetic field 42uT, etc.

Then I turned on "Airplane Mode", where it acquired a fix, seemingly
instantly.

Hmmmm.... why so fast?

I decided to pull the sim card, so I did a shutdown & realized that in my
$130 LG Stylo 3 Plus, I have to removed both the battery and microSD card
to get to the SIM card (which I don't normally remove) and removed the SIM
card & powered it back up, still in Airplane Mode.

Putting it back sans both the sdcard and SIM card, the phone asked to turn
airplane mode back on, which I left off.

Tapping the "GPS status" app, it seemed to get a fix in something like two
seconds. with 10/17 satellites, error of 26M, magnetic field of 42.3uT.

I'm puzzled since nospam said the fix takes up to fifteen minutes.

While I'm very aware of what "up to" means, the fix was basically almost
instantaneous.

Why?

>> So, if one had a powerful dedicated GPS it would be doing a lot of sat
>> data receiving and crunching.  A phone (also) uses the info from
>> 'towers'.  Some phones and locations can't even get one tower,  Some
>> phones and locations can't even get one sat, which would be completely
>> useless for location.
>
> The phone uses towers for A-GPS, to get a faster satellite fix by
> knowing what satellites to look for based on the location.
>
> You can't run this kind of an app on an iOS device because iOS doesn't
> give the app access to NMEA data.
>
> I wonder why you think that a phone's GPS cannot access multiple GPS
> satellites.
>
> In any case, the bottom line is that you want to avoid buying any tablet
> that lacks a GPS receiver.

Hi Steve,
I'm confused by my GPS test results below based on your suggestions.

Since you use facts to form basic logic, I can't disagree with _anything_
you've said, where I'm just confused at the moment why my el-cheapo $130 LG
Stylus 3 Plus was able to seemingly "get a fix" inside my house, basically
almost instantly, with airplane mode on, and the SIM card removed.

With nospam insisting that it takes "up to" fifteen minutes to get a fix
o Why was my fix done, seemingly in just a couple of seconds?
<https://i.postimg.cc/CMfnxjpB/gpsfix01.jpg>

NOTE: Alt.Satellite.GPS added for help in answering the basic question.

nospam

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Mar 23, 2019, 11:24:06 PM3/23/19
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In article <q76rn2$3ak$1...@news.mixmin.net>, arlen holder
<ar...@arlen.com> wrote:

> Since you use facts to form basic logic, I can't disagree with _anything_
> you've said, where I'm just confused at the moment why my el-cheapo $130 LG
> Stylus 3 Plus was able to seemingly "get a fix" inside my house, basically
> almost instantly, with airplane mode on, and the SIM card removed.

because your test was a hot start, which will be near-instant.

> With nospam insisting that it takes "up to" fifteen minutes to get a fix

that's for a cold start without any cellular assistance, or if you
intentionally disable the cellular & wifi radios via airplane mode.

arlen holder

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Mar 23, 2019, 11:33:09 PM3/23/19
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On Sat, 23 Mar 2019 23:24:05 -0400, nospam wrote:

>> Since you use facts to form basic logic, I can't disagree with _anything_
>> you've said, where I'm just confused at the moment why my el-cheapo $130 LG
>> Stylus 3 Plus was able to seemingly "get a fix" inside my house, basically
>> almost instantly, with airplane mode on, and the SIM card removed.
>
> because your test was a hot start, which will be near-instant.
>
>> With nospam insisting that it takes "up to" fifteen minutes to get a fix
>
> that's for a cold start without any cellular assistance, or if you
> intentionally disable the cellular & wifi radios via airplane mode.

Hi nospam,

*What _else_ could I have done to make the start any colder?*

I was simply attempting a factual check of your "up to 15 minutes" claim.
o It took no longer than about a second or two to get a fix.

While I'm familiar with the reason marketing uses "up to" claims
o Your numbers are so far off from my tests that you need to clarify

I understand that you "claim" it was a "hot start", but what else could I
have done to make it a 'cold start' than what I already did?
o While indoors, sitting at my office desk with multiple floors above me
o I shut down the phone (and removed the case, back, & battery)
o I removed the microSD card & then the SIM card (leaving both out)
o I re-inserted the battery & rebooted the Android 7 LG Stylo 3 Plus
o The phone asked about turning off airplane mode which I left ON
o Then I ran the "GPS status" app, which got a fix almost instantly

*What _else_ could I have done to make the start any colder?*

danny burstein

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Mar 23, 2019, 11:37:22 PM3/23/19
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In <q76tpj$7t0$1...@news.mixmin.net> arlen holder <ar...@arlen.com> writes:

>I understand that you "claim" it was a "hot start", but what else could I
>have done to make it a 'cold start' than what I already did?
>o While indoors, sitting at my office desk with multiple floors above me
>o I shut down the phone (and removed the case, back, & battery)
>o I removed the microSD card & then the SIM card (leaving both out)
>o I re-inserted the battery & rebooted the Android 7 LG Stylo 3 Plus
>o The phone asked about turning off airplane mode which I left ON
>o Then I ran the "GPS status" app, which got a fix almost instantly

>*What _else_ could I have done to make the start any colder?*

At the least, you'd have to leave the unit off for umptity minutes [a]
until all the satellites it had been "listening to" have
moved over the horizon.

[a] I'm guessing that with orbits of roughly 90 minutes, you'd
need at least a half hour.

--
_____________________________________________________
Knowledge may be power, but communications is the key
dan...@panix.com
[to foil spammers, my address has been double rot-13 encoded]

arlen holder

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Mar 23, 2019, 11:40:08 PM3/23/19
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On Sat, 23 Mar 2019 18:15:14 -0700, sms wrote:

>> A key question is how much actual _cost_ does GPS add to manufacturing?
>
> Between the receiver and the antenna it's not trivial, several dollars
> for a phone maker, and for the industrial devices I design it's way more
> than that in small quantities, at least $25 for an integrated GPS module
> and an external antenna. The modules connect to a serial port on the
> embedded controller. The ones I sourced had both an embedded antenna as
> well as an antenna port, and there were only two sources for these that
> I could find.
>
> Fortunately, most Android tablets have included a GPS, all the way back
> the the first Nexus 7. The reason is that there are a load of apps that
> depend on the GPS, and that use NMEA data, not just navigation apps. But
> a small tablet is also an ideal GPS navigation device when paired with
> Google Maps, Waze, OSMAND, or CoPilot, and the latter two use downloaded
> maps by default.
>
> As screen sizes on larger phones (phablets) have increased to almost the
> size of a small tablet, there's less need for navigation on a tablet,
> though the larger tablet screen is still very nice and much safer than
> trying to look at a small phone screen. That's why newer vehicles use a
> large screen display.
>
> Here's my $130 LG 8" tablet, with GPS and MicroSD card slot, running
> OSMAND <http://oi65.tinypic.com/veaxrr.jpg> and in two of my vehicles
> with tablet and phone holders (not vent-type, and no drilling!). The LG
> tablet has a screen that is 185.6 square cm. The largest screen phone
> sold in the U.S., the Samsung Note 9, is 103.3 square cm (even though
> the diagonal measurement of the iPhone Xs Max is larger, the display
> area is slightly smaller than the Note 9 because of the notch on the Xs
> Max).
>
> A lot of industrial and commercial apps require a GPS so it's very
> useful. Unfortunately, even on an iPad or iPhone, the NMEA data isn't
> available to apps, you have to use an external GPS if you need NMEA data
> on an iOS device. We ran into this on a project I was working on. We
> just told the clients to use an Android tablet. It was cheaper to buy a
> low-end Android tablet with a GPS than to buy an external Bluetooth GPS
> for the iPad (besides the iPad being so expensive) and it was one less
> thing to charge. It's also a lot easier to distribute an Android app to
> a customer.
>
> Also remember that often you're traveling in areas with limited cellular
> connectivity so you must have a GPS receiver in the device to do any
> navigation at all.

Hi Steve,

It's interesting that the iOS apps can't access NMEA data.

I have both an iPad and an Android phone where I'd like to see that for
myself, since I'm always learning more about the differences between the
two platforms.

How can I test this lack of NMEA access on the iOS device versus Android?

nospam

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Mar 23, 2019, 11:42:28 PM3/23/19
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In article <q76u1h$8v8$1...@reader2.panix.com>, danny burstein
<dan...@panix.com> wrote:

> >I understand that you "claim" it was a "hot start", but what else could I
> >have done to make it a 'cold start' than what I already did?
> >o While indoors, sitting at my office desk with multiple floors above me
> >o I shut down the phone (and removed the case, back, & battery)
> >o I removed the microSD card & then the SIM card (leaving both out)
> >o I re-inserted the battery & rebooted the Android 7 LG Stylo 3 Plus
> >o The phone asked about turning off airplane mode which I left ON
> >o Then I ran the "GPS status" app, which got a fix almost instantly
>
> >*What _else_ could I have done to make the start any colder?*
>
> At the least, you'd have to leave the unit off for umptity minutes [a]
> until all the satellites it had been "listening to" have
> moved over the horizon.
>
> [a] I'm guessing that with orbits of roughly 90 minutes, you'd
> need at least a half hour.

that would probably still be a warm start.

arlen holder

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Mar 23, 2019, 11:50:58 PM3/23/19
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On Sat, 23 Mar 2019 23:42:27 -0400, nospam wrote:

>> At the least, you'd have to leave the unit off for umptity minutes [a]
>> until all the satellites it had been "listening to" have
>> moved over the horizon.
>>
>> [a] I'm guessing that with orbits of roughly 90 minutes, you'd
>> need at least a half hour.
>
> that would probably still be a warm start.

I'll let it sit with the battery out overnight & test in the morning.
o Just before I shut it down, I'll turn off bluetooth, wifi, & location
o I'll also put it in airplane mode, just to be doubly sure.
o Then I'll shut it down, pull the battery & SIM card & let it sit

What do you suggest as a valid cold start procedure?
o I'll insert the battery (but not the SIM or microSD card)
o I'll boot it up and leave airplane mode on when it asks
o Then what?

Note that location on Nougat 7 on my LG Stylo 3 Plus defaults to
o High accuracy (GPS and networks)
Where I'll have to quickly switch it from that default to
o Device sensors only (GPS only)

Since I can't do both at the same time, which do I do first?
o Do I turn on Android "Location" first?
o Or do I turn on the "GPS status" app first?

nospam

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Mar 24, 2019, 12:38:16 AM3/24/19
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In article <q76ur0$9qs$1...@news.mixmin.net>, arlen holder
<ar...@arlen.com> wrote:

>
> I'll let it sit with the battery out overnight & test in the morning.

off is sufficient, however, one night is not.

there are apps that can delete the almanac & ephemeris, which might be
enough for it to be considered a cold start.

what are you attempting to prove? cold starts can take a long time and
assisted gps drastically reduces that to near-instant. that's how gps
works.

tablets and other devices that have a gps but no cellular won't have
assisted gps. a hot start should be quick, but a warm start and
certainly a cold start can take a while and using a fair amount of
power during that time.

phones, tablets and other devices that *do* have cellular can get a fix
within seconds at any time, regardless of when the gps was last used
(assuming the device is within cellular coverage, of course, otherwise
it's non-assisted).

arlen holder

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Mar 24, 2019, 1:47:52 AM3/24/19
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On Sun, 24 Mar 2019 00:38:15 -0400, nospam wrote:

> what are you attempting to prove?

That you're almost always full of shit, nospam.
o It generally only takes ten seconds to prove you're full of shit, nospam.

All you _can_ do, is spout your marketing bullshit "up to" mantra.
o When, in reality, the time appears to be vastly less than your claims

Instead of seconds, this may take overnight to prove you're full of shit.
o You're wrong more often than a coin toss, nospam.

The monkey has better credibility than you do, nospam.

arlen holder

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Mar 24, 2019, 9:20:55 AM3/24/19
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On Sun, 24 Mar 2019 03:37:21 +0000 (UTC), danny burstein wrote:

> At the least, you'd have to leave the unit off for umptity minutes [a]
> until all the satellites it had been "listening to" have
> moved over the horizon.
>
> [a] I'm guessing that with orbits of roughly 90 minutes, you'd
> need at least a half hour.

Hi danny burstein,
The phone has been off with the battery removed & SIM card out all night.
I'm going to run my test now.

The only thing I can't do at the same time is
o Turn on "Location" in Android settings & quickly switch to GPS only.
o Click on the "GPS status" app.

I'll do those two things as quickly as I can to test nospam's claim
o "up to" 15 minutes

I'll write back when I run the test as I'm writing down the steps
so that I can do it quickly.

arlen holder

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Mar 24, 2019, 10:09:03 AM3/24/19
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On Sun, 24 Mar 2019 13:20:54 -0000 (UTC), arlen holder wrote:

> I'll do those two things as quickly as I can to test nospam's claim
> o "up to" 15 minutes

It's now almost 7am where the phone has been like this since about 8pm:
<<https://i.postimg.cc/CMfnxjpB/gpsfix01.jpg>>

The phone was left disassembled & with location off & in airplane mode:
<https://i.postimg.cc/hGBhdQLD/gpsfix02.jpg>

At about 6:45am, I put _just_ the battery back, leaving the cards out:
<https://i.postimg.cc/tRwq6VbK/gpsfix03.jpg>

I boot up the LG Stylo 3 Plus (only the protector is cracked in that pic):
<https://i.postimg.cc/PNnnRYrN/gpsfix04.jpg>

Hmmm... it _knows_ that it's T-Mobile (even sans a SIM card):
<https://i.postimg.cc/vHyQXw1h/gpsfix05.jpg>

It boots at what it thinks is 8:09PM (it's really about 6:45am):
<https://i.postimg.cc/DZsTdxnR/gpsfix06.jpg>

By 8:10 I quickly set Location On, GPS Only & quickly start "GPS status":
<https://i.postimg.cc/L8XF09mt/gpsfix07.jpg>

Hmmmm... at indicated time of 8:11, it _still_ hasn't gotten a fix:
<https://i.postimg.cc/Dz4knxJm/gpsfix08.jpg>

BINGO!...

Still at indicated time of 8:11, we have a fix of 17/23 satellites:
<https://i.postimg.cc/WbNBhNFB/gpsfix09.jpg>

At _most_, it was _two minutes_ (actually less but I forgot to start the
timer in my haste to hurry up and get the testing sequence done!)

Yet again, as usual, nospam is easily shown to be chock full of shit.
o We already know nospam never expects anyone to read his cites
o Now we know he doesn't expect anyone to _test_ his statements out.

sms

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Mar 24, 2019, 7:59:08 PM3/24/19
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On 3/23/2019 8:33 PM, arlen holder wrote:

> I was simply attempting a factual check of your "up to 15 minutes" claim.
> o It took no longer than about a second or two to get a fix.

The tablet may know which satellites to look at based on the fact that
it knows, from Wi-Fi, the general location.

Just now, I VPNed into a server in Australia and then ran the GPS test
and it took nine minutes for the tablet to get a fix. The app first
looks for satellites based on where it thinks it is located, then tries
other satellites when it doesn't find enough "local" ones.

But of course this is immaterial. If you're flying around the world then
yes, when you arrive, and if you're not connected to a local Wi-Fi
signal, it will take a while to get a fix the first time you turn on the
device. No big deal. The next time you turn it on it will get a fix very
quickly.

nospam

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Mar 24, 2019, 8:17:25 PM3/24/19
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In article <q795k9$p9i$1...@dont-email.me>, sms
<scharf...@geemail.com> wrote:

> > I was simply attempting a factual check of your "up to 15 minutes" claim.
> > o It took no longer than about a second or two to get a fix.
>
> The tablet may know which satellites to look at based on the fact that
> it knows, from Wi-Fi, the general location.
>
> Just now, I VPNed into a server in Australia and then ran the GPS test
> and it took nine minutes for the tablet to get a fix. The app first
> looks for satellites based on where it thinks it is located, then tries
> other satellites when it doesn't find enough "local" ones.

nine minutes is unacceptably long to start using an app.

> But of course this is immaterial. If you're flying around the world then
> yes, when you arrive, and if you're not connected to a local Wi-Fi
> signal, it will take a while to get a fix the first time you turn on the
> device. No big deal. The next time you turn it on it will get a fix very
> quickly.

it absolutely is a big deal, when with assisted gps, the time to get a
fix is a couple of seconds, if that long, no matter where it's used or
how recently it was last turned on.
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