Mobile phones & their GPS accuracy?

 
  Ads Deputy Commissioner

Location: Melbourne
Hello,

A question for those with knowledge on the matter;
I am looking to purchase a new mobile phone.

My current phone is a circa 2011 model and comes with the standard GPS & A-GPS sensors.
With this phone, I've found the GPS signal to be fairly accurate, however it does often take a long time (2+ minutes) to initially pick up the signal when standing in the open outdoors.  


I'm trying to choose between a 2017 model with only GPS & A-GPS, or one of the more 'high-end' phones, a 2016 model which comes with a more substantial list of sensors: Accelerometer, Barometer, Compass, GPS, A-GPS, GLONASS, Gyroscope, Proximity Sensor.

I've had a quick research and read as to what all these sensors do, however my understanding is still a little vague.

In short, is it safe to assume the phone with more sensors will provide a more reliable and accurate GPS signal when compared to the basic phone with only GPS & A-GPS?

I understand there are other factors at play when it comes to picking up an accurate GPS signal, but generally speaking would there be much of a difference between the two phone's capability?

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  Clyde Goodwin2 Chief Train Controller

Probably not a lot of difference between them as most for general public use devises are i have been told at around 5m of accuracy,We were talking about this during a training night on Navigation devices( Garman etc) that we use.
  mikesyd Chief Commissioner

Location: Lurking
Regardless of model, consider just where you are in regard to the satellites - the more your device finds the better.

That 20 storey building a couple of km away could be blocking some out, or at least interfering with the signal.

https://in-the-sky.org/satmap_worldmap.php
  justapassenger Minister for Railways

I'm trying to choose between a 2017 model with only GPS & A-GPS, or one of the more 'high-end' phones, a 2016 model which comes with a more substantial list of sensors: Accelerometer, Barometer, Compass, GPS, A-GPS, GLONASS, Gyroscope, Proximity Sensor.

I've had a quick research and read as to what all these sensors do, however my understanding is still a little vague.

In short, is it safe to assume the phone with more sensors will provide a more reliable and accurate GPS signal when compared to the basic phone with only GPS & A-GPS?

I understand there are other factors at play when it comes to picking up an accurate GPS signal, but generally speaking would there be much of a difference between the two phone's capability?
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Go for the 2016 phone. Both should be about the same if you stand still out in the middle of a paddock and give them time to refine the position, but it will be far better when you're using it for driving directions.

The basic idea is that GPS positions you in the middle of a box, not at a point. The smaller the box, the more precise your position.

The precision of a GPS device is all about the ability of the device to determine what is good data (direct path signals) and what is bad data that should be discarded (reflected signals). The phone with the additional sensors will be able to tell if it really is moving that quickly if it receives a reflected signal from a GPS satellite which would have the position jerk around wildly.

The biggest difference from having the extra sensors would be that using the phone to give you directions when walking/driving would be more effective, the display will rotate according to the orientation of the car and the position will move smoothly rather than refreshing every few seconds.

Can you tell us exactly which smartphones you are comparing? I doubt that many 2017 smartphones would not have at least an accelerometer and gyroscope even if they weren't listed on the spec sheet you were reading, otherwise it would not be able to rotate the screen when you turn it sideways. If indeed it was missing all of them, that would suggest to me that it is a cheap and nasty model that is certainly skimping in other areas too (I'd like to look into the processor etc) including build quality.

It pays to consider the details when it comes to electronics. Not all product lines advance at the same rate.
  petan Chief Commissioner

Location: Waiting to see a zebra using a zebra crossing!
As some know, we are a Geocaching team, where we also use our Petan user name and a check of https://www.geocaching.com/ will explain this sport. In short, it involves using satellites to find small well hidden caches which generally speaking are small containers hidden in the bush. These caches contain a logbook, sometimes a pencil and occasionally some trinkets such as very small toys for the younger members of this family standard outdoors game.

Some  geocache members have hand held GPS devices and some use mobile phones. Both hand held GPS devices and mobile phones suffer from what might be termed 'cloudy day' problems where the weather conditions and other factors sometimes results in very slow GPS lock-on by sufficient satellites. Accuracy varies as some days we can get accuracy of two metres and five metres on other days in the same weather conditions, using both the hand held GPS and the mobile phone.

My suggestion is to monitor a forum or Facebook group run by sports that use GPS devices and note any remarks about their experiences with GPS devices, both mobile phones and hand held GPS devices such as Magellan brand or Garmin brand such as etrex 30 https://www.ja-gps.com.au/Garmin/etrex-30x-gps/
  woodford Chief Commissioner

For what its worth, I have  a Garmin GPSmap76Csx, this is a hand held marine unit (water proof and has an output to a boats autopilot) and I have checked its accuracy against both permanent survey markers and Cooridinates obtained from 1 in 25,000 maps and I have found it accurate to around plus or minus 10 metres under all conditions including heavily treed areas. I purchased the unit because of its sensitivity and its price was in the area around $800, ie not cheap crap. Its around 5 years old and has never missed a beat, being built like a battle ship.

I note some items of equipment that contain a GPS, (I have seen both phones and a camera in this category) only display the position down to the unit seconds (ie nothing after the decimal point), this implies an accurcay of worse than aprox 30 metres.

woodford
  Ads Deputy Commissioner

Location: Melbourne
I'm trying to choose between a 2017 model with only GPS & A-GPS, or one of the more 'high-end' phones, a 2016 model which comes with a more substantial list of sensors: Accelerometer, Barometer, Compass, GPS, A-GPS, GLONASS, Gyroscope, Proximity Sensor.
Go for the 2016 phone. Both should be about the same if you stand still out in the middle of a paddock and give them time to refine the position, but it will be far better when you're using it for driving directions.

The basic idea is that GPS positions you in the middle of a box, not at a point. The smaller the box, the more precise your position.

The precision of a GPS device is all about the ability of the device to determine what is good data (direct path signals) and what is bad data that should be discarded (reflected signals). The phone with the additional sensors will be able to tell if it really is moving that quickly if it receives a reflected signal from a GPS satellite which would have the position jerk around wildly.

The biggest difference from having the extra sensors would be that using the phone to give you directions when walking/driving would be more effective, the display will rotate according to the orientation of the car and the position will move smoothly rather than refreshing every few seconds.

Can you tell us exactly which smartphones you are comparing? I doubt that many 2017 smartphones would not have at least an accelerometer and gyroscope even if they weren't listed on the spec sheet you were reading, otherwise it would not be able to rotate the screen when you turn it sideways. If indeed it was missing all of them, that would suggest to me that it is a cheap and nasty model that is certainly skimping in other areas too (I'd like to look into the processor etc) including build quality.

It pays to consider the details when it comes to electronics. Not all product lines advance at the same rate.
justapassenger

Thank you all for your replies. I appreciate your help.
Some interesting information provided.

Personally speaking, I am not overly concerned about having a phone which is capable of a 'supreme' (for lack of a better word) level of accuracy.

It's more a case of whether or not the phone with the more sensors will have a noticeably better overall GPS performance compared to the cheaper phone.  

justapassenger - Yes you are correct the phone that comes only with GPS & A-GPS is indeed a cheap and nasty one - although it's not too nasty to be fair. Smile

If it's of any further benefit to the discussion, my phone choice is out of the original Google Pixel and the much cheaper LG Q6.
http://www.lg.com/au/smartphones/lg-LGM700DSK-q6-smartphone
http://www.ubergizmo.com/products/lang/en_us/devices/google-pixel,lg-q6/
  RTT_Rules Oliver Bullied, CME

Location: Dubai UAE
I have a 3 year old Samsung S5 (which is over loaded with Aps and background running stuff)

Just now I removed the battery
Turned on
unlocked
selected Google Maps
Blue dot appeared in 60 sec from turning on.
(standing half under my concrete house)

I've had older GPS and phones that take longer. I think my first hand held GPS was pushing 5min, the battery lost a bar waiting.

Newer phones are even faster.

When using google maps or WAZE for driving it generally knows which side of a divided road I am on and I would say accurate to within a few metres at worst.
  RustyRick Chief Commissioner

Location: South West Vic
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It depends on what you want to find. Petan is trying to find something as small as a "film canister" (remember those...), but I've used a phone to locate old station sites. Having the box narrowed to a couple of square metres is much better for locating those small objects.

With the sensors, there's really only 4 you need to be aware of.

GPS - Global Positioning System. The original USA satellite system
A-GPS - Assisted GPS. A method where your phone uses the mobile tower location data to figure out roughly where it is in the world, then starts looking for the appropriate GPS satellites.
GLONASS - the Russian version of GPS. It basically doubles the number of satellites your phone looks at and calculates its position with greater accuracy.
Barometer - GPS is lousy at calculating accurate heights. The barometer helps improve that.

Cheers

Rick
  Ads Deputy Commissioner

Location: Melbourne
Thanks for that Rick.
So in theory having GPS + GLONASS working together should be more efficient than just the GPS sensor alone?

I would only be using the phone's GPS to occasionally track/map my daily walks - in the suburbs.

It would also be nice to have for the rare times I hire a car while travelling interstate (mainly rural areas) to save costs on hiring a navigation system with the hire car.

While driving in the rural areas and the phone's reception drops out I assume that would rule out any use of A-GPS.
Perhaps then the phone with GPS + GLONASS would be better suited for this scenario?
  justapassenger Minister for Railways

It's the accelerometer, gyroscope and compass that would be of more use than the GLONASS capability when driving in a rural area.

GPS+GLONASS is only a theoretical upgrade over just GPS, because a smartphone can still only track one satellite at a time.
  RustyRick Chief Commissioner

Location: South West Vic
A-GPS works with GPS, so really GPS and GLONASS track the satellites and A-GPS helps with the initial location calculations. And yes, having both systems tracked is better.

There’s a lot of free apps you can use for tracking walks. I use Map my walk, but there are others. Just be careful using the inbuilt maps for travelling. They could be downloaded as you go, and will chew through your data. Also running the GPS constantly will drain the battery so you’ll need a car charger.

Rick
  Aaron The Ghost of George Stephenson

Location: University of Adelaide SA
Signal acquisition times can vary for all sorts of reasons and climatic conditions. Not only can climate affect the signal quality in the first place, it can also impact your device’s performance.

For what it’s worth, once established on a positioning signal from more than four satellites most devices will be about as accurate as the US military allows them to be. That is, the biggest error in GPS/GLONASS position comes from the arbitrary inaccuracy built in for non military devices by the satellite owner.

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