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Looking for smartphone

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ital2:
Hi.

I'm sorry. The other thread is just 1 month old, but I didn't pay attention to it, and its page 4 is a mine of information indeed, thanks to you.

I wasn't aware of there being several signal sources, had just heard of gps, but after posting yesterday, I thought there probably are quality differences between the gps devices in the phones/tablets/navigation devices, so it would probably be a good idea to search for comparative tests looking for that.

Now there are so many different signal sources, I suppose that not every map software is able to get data from all of these, so that would be another factor.

I admit my compass misunderstanding or better not understanding compasses has grown. First. You say electronic compasses sense the magnetic field of the earth, but then they probably would be deviated by car magnetism in some way, as magnetic compasses do, since for sensing magnetism, there would be some magnetism, some magnetic sensor? But perhaps they do it differently, after all.

Second, I always thought that both direction and position were calculated from the difference of signal strength of different gps satellites, so if a device, smartphone, etc., gets its position, it also gets the info where is North, since different gps satellites also send some sort of positional data of their own, so the device knows where they are, and hence can calculate the compass data, without sensing the magnetic field?

While in the other thread, it's said - between what is worded I mean - that for pedestrian purposes, a compass should be there since you would have to march straight into one direction for some time in order for the device establishing gps data history, from which then only it could identify both direction and position, and from that only, compass data?

Besides, my wish for a N/E/S/W arrow within the 10 o'clock and the 2 o'clock range was understood to be mutually exclusive, I meant one big arrow, with either a big N, E, S or W character, just one of them, within that screen part, in order to indicate the direction in which you are heading on-the-spot, while a full compass, with N AND E, S and W is much less able to indicate your direction with just one quick glance when driving, possible in narrow streets. I know that range is a third of a full circle, but I really meant just a quarter of a full circle, something between minus 8 and plus 7 minutes there, so that just one direction arrow would appear there at any time, not two, and if that's South, it goes without saying that to your left, it's East, and West to your right, and so on.

4wd:
I wasn't aware of there being several signal sources, had just heard of gps, but after posting yesterday, I thought there probably are quality differences between the gps devices in the phones/tablets/navigation devices, so it would probably be a good idea to search for comparative tests looking for that.

Now there are so many different signal sources, I suppose that not every map software is able to get data from all of these, so that would be another factor.-ital2 (January 21, 2017, 08:29 PM)
--- End quote ---

What do you mean by 'so many different signal sources'?

There are only GPS satellite signals needed for GPS receivers to calculate your position.  Although, technically, there are other sources for GPS signals such as Differential GPS that are transmitted by ground stations but they require a receiver that can handle them.

I admit my compass misunderstanding or better not understanding compasses has grown. First. You say electronic compasses sense the magnetic field of the earth, but then they probably would be deviated by car magnetism in some way, as magnetic compasses do, since for sensing magnetism, there would be some magnetism, some magnetic sensor? But perhaps they do it differently, after all.
--- End quote ---

In my experience I've yet to have a vehicle, magnet, or some other interference affect the internal electronic compass of my phone.  Doesn't mean it can't happen, get near a MRI and you'll find it will but then you have other problems like the phone wanting to stick itself to the MRI ;D

Second, I always thought that both direction and position were calculated from the difference of signal strength of different gps satellites, so if a device, smartphone, etc., gets its position, it also gets the info where is North, since different gps satellites also send some sort of positional data of their own, so the device knows where they are, and hence can calculate the compass data, without sensing the magnetic field?
--- End quote ---

Here's a question for you:
Looking for smartphone

Given that the receiver has located your (You) position from the signal strengths (more precisely, time delay between transmission and reception) of the three satellites (A, B, C) how does the receiver know which direction you are facing since no matter which way you turn on the spot, the signal strengths from each of the satellites is going to be the same?

GPS can only provide position, not direction - as soon as you start moving then your position has changed and everything can then be calculated from that change: direction, speed, distance, etc.

Here's a good explanation of how GPS works.

While in the other thread, it's said - between what is worded I mean - that for pedestrian purposes, a compass should be there since you would have to march straight into one direction for some time in order for the device establishing gps data history, from which then only it could identify both direction and position, and from that only, compass data?
--- End quote ---

No, it only takes a change in position of a few metres, 5 is usually more than enough, (I've found only 2 or 3 metres is sufficient on my receiver), unless reception of GPS is abnormally bad.

There is no data history, there is only the last position and the current position used for calculations concerning direction, speed, etc.

Besides, my wish for a N/E/S/W arrow within the 10 o'clock and the 2 o'clock range was understood to be mutually exclusive, I meant one big arrow, with either a big N, E, S or W character, just one of them, within that screen part, in order to indicate the direction in which you are heading on-the-spot, while a full compass, with N AND E, S and W is much less able to indicate your direction with just one quick glance when driving, possible in narrow streets. I know that range is a third of a full circle, but I really meant just a quarter of a full circle, something between minus 8 and plus 7 minutes there, so that just one direction arrow would appear there at any time, not two, and if that's South, it goes without saying that to your left, it's East, and West to your right, and so on.

--- End quote ---

It might take a while but you may be able to find a navigation app that put the compass heading across the top/bottom of the screen which is probably better than a small compass rose.

eg.

Across the top you'll have something like:
Looking for smartphone

With it sliding left/right according to direction faced.

BTW, just wondering, but why the concern with compass direction?
In over 30 years of 4wding my only concern w.r.t. as to direction has been: forward, backward, left, right or more correctly, just pointing and saying 'that way'  ;D
Given a map, I've never needed to know exactly what heading/bearing I'm on as long as I'm heading the way I want to go.

ital2:
Hi.

I am sorry, my post above was meant to be in the original thread: http://www.donationcoder.com/forum/index.php?topic=43427.msg405922#msg405922

You mentioned those other signal sources, beyond GPS: A-GPS, Glonass, TTFF, BDS - so these are all GPSsignals, just from non-GPS satellites, or in other words, technically, they are all the same, but they are named differently since the organizations behind them are different? And you spoke of 3m accuracy, your device getting signals from 18 out of 27 satellites. That seems perfect. So I suppose it depends on the device if it is able to get those signals other than GPS, too, and perhaps it's also a question of the map software then if it, or some intermediary software proper to the device itself, can aggregate all this info. You now also mention D-GPS / Differential-GPS, I suppose high-end navigation devices can treat them.

I believe you on your compass signal not being deviated in your car. It's just that I had had, with 3 different magnetic compasses, including 2 car compasses, at least they were sold as such, in 3 different cars, deviations of up to 100 degrees.

Thank you for the link which explains it very well. I admit my idea of differing signal strength for positions that are 100 or 200 m apart was a stupid one, but minute length differences are as surprising. But to answer your question, I thought the satellites also sent their position and an identification code, and that the receiver also receives lists of which satellite is where when or does what orbit and such, but you're right, spatial thinking is not for everyone, that's why I so heavily rely upon maps and compasses, and to be frank, my not wanting to buy a traditional navigation device for years was due to the fact that with maps on the passenger seat, I at least have an idea where I am, while traditional navigation devices of the kind I knew told you to go straight or to turn, but all between departure and arrival, you did not know where you were, except for city-limit signs on the road.

I've seen the slider in some map on my pc and agree that would be fine on the move, had not understood it there since on my pc it did not slide so as to the real direction coming into center. So this slider is no other that what I had imagined, plus the neighboring directions in order for people not having to remember that West is alway to the left of North, etc.

You sometimes speak of your receiver, which is obviously very, very good, and then you speak of your smartphones or tablets. What is your current receiver, or do you mean the one built into your current smartphone? 2m is awesomely impressive! Perhaps we could deduct that some makers use better gps receivers in their smartphones/tablets than others. This interests me a lot, since when in some town I do a 90-degree turn, it would be nice to have the map rotating after 15, 20 m instead of 150, 200 m only!

4wd:
You mentioned those other signal sources, beyond GPS: A-GPS, Glonass, TTFF, BDS - so these are all GPSsignals, just from non-GPS satellites, or in other words, technically, they are all the same, but they are named differently since the organizations behind them are different?-ital2 (January 22, 2017, 07:04 PM)
--- End quote ---

GPS - generically refers to all Global Positioning Systems or just the USA implementation which was the first in orbit (1978).
GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema) - Russian implementation of GPS
BDS (BeiDou Navigation Satellite System) - Chinese implementation of GPS
Galileo (Global Navigation Satellite System) - EU implementation of GPS

There are probably others by now.

The main reason behind why there are so many different implementations is to prevent lockout by a country if there was only a single system.

TTFF isn't a signal, it's an acronym for Time To First Fix - the time taken to get a position fix after switching on the device.

A-GPS is Assisted GPS, not a signal either but rather a function that allows for faster TTFF by downloading of GPS Almanac data from the internet (rather than the GPS satellites) and providing an approximate position using trilateration from mobile phone signals.  GPS devices will work without A-GPS.

BTW, there is actually two types of data transmitted by GPS satellites:

* Almanac - which is orbital data about the whole system, this data is good for a month or more.
* Ephemeris - which is accurate course/clock data concerning that particular satellite, only good for about 30 minutes. (If a receiver has been turned off longer than that it needs to obtain this data again from the satellite.)
And you spoke of 3m accuracy, your device getting signals from 18 out of 27 satellites. That seems perfect. So I suppose it depends on the device if it is able to get those signals other than GPS, too, and perhaps it's also a question of the map software then if it, or some intermediary software proper to the device itself, can aggregate all this info.
--- End quote ---

Accuracy is provided by the GPS receiver hardware, nothing to do with the software or maps. The GPS receiver reports it's position, the software interprets that and displays it on a map - if the software/map is calibrated wrong, then it will show your position as somewhere you aren't.

You now also mention D-GPS / Differential-GPS, I suppose high-end navigation devices can treat them.
--- End quote ---

Usually only required by people who need that kind of accuracy, eg. surveyors.

There are also GPS satellites in orbit that provide a measure of accuracy improvement, WAASw (Wide Area Augmentation System) and EGNOS, (although I've just seen there are others now).  As usual, the GPS receiver has to be capable of utilising data from these sources.

But to answer your question, I thought the satellites also sent their position and an identification code,
--- End quote ---

They do.

and that the receiver also receives lists of which satellite is where when or does what orbit and such,
--- End quote ---

It does.

But without some means of identifying which direction you're facing, how is the device supposed to indicate your bearing?
Hence the need for an internal compass.

that's why I so heavily rely upon maps and compasses,
--- End quote ---

I still use paper maps, I've never needed a compass. All my maps are topographic, I can work out my position from what terrain I'm on, heading towards, or have driven through.

You sometimes speak of your receiver, which is obviously very, very good, and then you speak of your smartphones or tablets. What is your current receiver, or do you mean the one built into your current smartphone?
--- End quote ---

My GPS receiver is a 14 year old Garmin Geko 201, it's not very very good, it was cheap but it does the job.  I don't I've seen better than 5m accuracy on it, (also called HDOP, Horizontal Dilution Of Precision).  Before that I had a Garmin GPS38 which was even slower and less accurate.

My use of GPS, (whether dedicated or phone/tablet), is almost 100% for a track log, not as a navigation aid - I'm more interested in where I've been rather than where I'm going.  I have very little interest in following a pre-programmed track.

eg.
Looking for smartphone

2m is awesomely impressive! Perhaps we could deduct that some makers use better gps receivers in their smartphones/tablets than others. This interests me a lot, since when in some town I do a 90-degree turn, it would be nice to have the map rotating after 15, 20 m instead of 150, 200 m only!
--- End quote ---

I have had my phone report 1m accuracy but that's rather rare so I don't bother quoting that figure, plus that degree of accuracy in not something you should rely on in a device that costs less than US$130.

ital2:
Hi.

The main reason behind why there are so many different implementations is to prevent lockout by a country if there was only a single system.
--- End quote ---

Yes, I remember now to have read that GPS had been invented for military reasons, so a plethora of Chinese gps signals, on top of the American ones, will only become of interest when the U.S. satellites send out deviated signals, for the aforementioned reasons, but I suppose we'll have bigger problem than then sightseeing. But to be serious, I now understand why the shear number signals received is irrelevant, it's the quality the receiver that counts, or in other, as you say, don't buy cheap.

I still use paper maps, I've never needed a compass. All my maps are topographic, I can work out my position from what terrain I'm on, heading towards, or have driven through.
--- End quote ---

This made me spontaneously laugh out, not because I don't believe this but to the contrary, admirably, I believe you 100 %, you're an expert in these questions and know what you do, even in the wilderness.

I admire this all the more so since I do get lost rather often - I always try my best to train my senses, and then it's just another case of getting lost, so all I train is my sense of humor.

As for OS and size, it's difficult, "one size fits it all" does not apply. I'm really enormously fond of that Android 8" thing, don't want to name it for a third or fourth time here, but it's so cute, brilliant quality, and you can take it everywhere; it's got just the right size (and good resolution) for even looking up data and such, but it's not too big to go in your hand or in your purse. But for a quick glance in the car when driving AND getting all the necessary info you need, it's simply not big enough. And then, you always need to take it with you, some 500€ 10" or 12" device clearly visible in a parked car is an invitation to take it immediately away from you. So, even if you were willing to buy 2 such devices, which I'm not really, you would have to take the bigger one with you all the same, so to buy the 8" one for convenience reasons is thought to short since you will then have 2 of them to carry with you.

Which means when you need 10", you'll have to buy them, and then you will them carry around anyway, convenient or not, so no need for an additional 8". The S2 is available in 9.7", too... So no mobile ListPro for me, probably. I'll need it in Summer (travel season)...

Tablet prices have risen sharply in the E.U. but E.U. allows to send hardware back after trialing for some days, so I'll have to well prepare my double trial software-wise, and then I need both iPad and another tablet to be delivered more or less at the same time, and then I should even try them both in parallel for navigation, gps receiver quality and all. That's immoral, but prices are immoral, too: Apple prices anyway, and surprisingly, the Korean's prices do not show real clemency either. Well, they have big losses battery-wise to recover from.

But oh well, you know something about navigational matters!

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