Database Develop

GPS-lag: A misunderstood feature

Hi,
I read a lot of threads about GPS-lag on the Diamond, and found no such effect on my device. Finally, I remembered one thing which I learned about GPS-devices a long time ago:
Most of them use a feature called "static navigation" which effects the behaviour at slow speeds or stand-still, especially when walking. This is a feature which the developers of the devices may choose to activate, but it is usually not at the user's discretion to enable or disable.
When static navigation is active, the device will give less information when it moves at low speeds, typically at least up to 6km/h (ca. 4mph). Above this fixed speed, it behaves normal, under this speed, it will not give speed- or directiondata, and will often average the location data, so not every movement will be reported to the software.
When static navigation is not enabled, the reading tends to "jump" when the device is standing still, like in front of a traffic light. I remember my first receiver which had no static navigation, and when I stood at a crossing, the software would reroute after some seconds. The reason: My GPS showed me on the wrong lane and in the wrong direction, and the software believed that I was on the wrong road and had to reroute.
While static navigation is a little annoying for pedestrians, it is a blessing for people who use their devices in a car or on a bike. Here, it will smoothen the operation with road-bound software a lot.
Fwiw: I can experience the same thing. When I move by foot, the reading in Google Maps will lag a little, however when I'm on my cycle or in my car, the reading is very accurate. I have no real problem with the lag in GMM, and prefer a device which works well with Route 66.
Have fun!

this information isn't new it's in most of the threads and your post is misleading. early on you claim you don't have a problem on your device. whereas what you mean is that your device behaves as everyone else's but it doesn't bother you.
edit: I see you have edited

i interpret that as,
"my device behaves as everyone elses, and here's why.."

my icon is shown about a block behind where i actually am while driving through nyc at 30mph. that's unacceptable. your big words and lengthy explanation don't make it no better lol

MY GPS works fine once it gets a lock. But it takes a while to getb that first lock. No real lag that is noticable.

[REQ]No-ring areas

Not sure if this was requested before or done, but I figured it would be really useful if there is an app on the Fuze which detects where your location is through the phone's GPS and can automatically turn the phone to vibrate, or silent, or even off in certain areas on a map, and even at certain times.
This could be useful for someone who does not want to have his or her phone ring inside a church/temple/synagogue/place of worship, classroom, library, at home, or anywhere that can be located on a map. Even during certain time periods of certain days.
The user could map out a radius (circle or perimeter) around the coordinates of the spot of which the phone is required to switch to silent or vibrate upon entering the radius. Obviously this could only work outdoors, and certain places indoors, but a lot of us do travel outdoors and have areas where we do not want our phones to interrupt our personal business.
I know google maps can detect your exact location, or at least detect your location inside a radius, but can it be used for an application to command your phone to change its settings? Just thought I could start a discussion on this and see what the XDA community thinks of the idea and if it's plausible or just not worth the effort. Thanks.

Check out G-Profile... There is also another app in Dev and Hacking with this function.

I like the problem solving creativity...
but no, it is not worth it. Not sure how much you've experimented with gps but in addition to draining your battery rapidly the phone needs to be able to listen to the satellites very clearly, something that is not easy when it's not on your dashboard or you're holding it out from you and upright in a wide open area. So for your purposes it's not a practical option.
As far as Google Map's tower calculation poor man's gps goes, that is easier on the battery and you don't need a perfect signal however if you're not in a dense area with a lot of towers you'll be getting at the very best 600 meter accuracy. Not good enough if you don't want false positives or negatives for your application.
What it is adequate enough for however is, say, if you're driving home from work, your phone detects a cell tower twenty miles from your home and sends your computer a signal to fire up the lights, air conditioner and pool heater (search for trackme by strayton).
As for toggling rings for when you step inside a library, church or classroom, you'll have to stick, in my recommendation, to using the long end key vibration press yourself. Or just leave it on vibrate if you're in these places so frequently that you come up with this idea.
Still, I like the way you think; that's why we keep getting sweet apps so keep on thinking brotha.
Doug

Yes, GPS polling is quite expensive for a relatively simple task.
G-Profile works well because much of it is event-driven (eg: profile is activated only at a certain time, or only when you plug in a headset, etc) and therefore there is close to no battery overhead. Keep in mind, it also works with more than just schedule-based profiles (time, day). You can configure profiles based on which accessories are connected. I think you might also be able to configure profiles based on which wifi network you're connected to (eg: Home network vs School/Work network).
Using GPS location is conceptually a more elegant solution, but either way you will still have to manually define different profiles, so using a program like G-Profile is no more complicated than a GPS-based profile switcher, and actually much more flexible/precise.

Benchmarking GPS Performance - Brainstorming

Ok..this is going to be a little long-winded so bear with me.
So there seems to be a new fix posted for gps every other day, some are just snake-oil while others might actually be doing something. The problem is how to tell what is working and what is not...and to what degree. Trusting the word of some guy on a forum with 200 posts is NOT the answer. What we need are some objective tests that produce quantitative data. It would also be nice to objectively compare our device's performance to the performance of other android devices out there too...to get an idea of what a realistic gps performance expectation would be.
So far MyTracks seems to have been the best approach but it's still a very poor method for several reasons:
The software acts as an abstraction layer - it's unknown what kind of filtering may be occurring here.
The data is only meaningful to the originator; we don't know which street(s) you were really on.
At best only 1 dimension of the error is preserved; we might be able to assume you were driving down street X, but how do we know how far down the street you actually were when the sample was captured?
Bottom line, there is no way to programmatically extract quantitative results.
I've got half of the solution: Collect a series of samples from a stationary position and collect lat/lon/alt/time, reported gps accuracy, number of satellites used, time to lock, device make/mode, device uptime (to weed out the "I rebooted and it works!" phenomenon) etc.
With this data we can calculate things like jitter, deviation, acquisition latency and all kinds of other interesting things.
I know that sounds like lots of work, but I've already done all of the above (scroll down to the bottom to read more about that) and for the most part the data collection and result presentation components work. The problems I am running into are related to the details of how the above data maps to real world performance.
So let's talk about some potential algorithms:
1. Deviation
This was my first hope as a solution; grab bunch of gps coordinates and use the lat/lon positions along with reported accuracy to get a centroid location. Then using the centroid, calculate the distances between each point and the centroid to measure accuracy. In theory, if the distribution was random, this would work. In practice however, I found that:
A - You get A LOT of duplicate points that throw off the statistics.
B - Even if you throw out duplicates, the coordinates you get are usually very close to one another, in spite of being far from the true location. In hindsight, I think that should have been obvious. Oh well.
In any case, let me illustrate:
I took 30 samples sitting in front of my office. The distribution looks like this:
http://maps.google.com/maps/api/staticmap?size=512x512&maptype=hybrid&markers=color:blue|label:1|37.280015489448,-121.943445407709&markers=color:blue|label:2|37.280015489448,-121.943445407709&markers=color:blue|label:3|37.2799150689755,-121.943469689324&markers=color:blue|label:4|37.2798287737251,-121.943507481842&markers=color:blue|label:5|37.2797409130025,-121.943532462122&markers=color:blue|label:6|37.2796490544446,-121.94354159922&markers=color:blue|label:7|37.2796117648545,-121.943468886907&markers=color:blue|label:8|37.2796034813727,-121.943455640717&markers=color:blue|label:9|37.2795946561935,-121.94344227994&markers=color:blue|label:10|37.2795861462627,-121.943431154687&markers=color:blue|label:11|37.2795786087998,-121.94342342341&markers=color:blue|label:12|37.2795720667083,-121.943418240036&sensor=false&sensor=false
And the centroid I calculated from these looks like this:
http://maps.google.com/maps/api/sta...7,-121.943465819874&sensor=false&sensor=false
Looks pretty good so far right? Not even close. You can almost predict where the gps will say I am going to be next just by looking at those points. Unfortunately, there's no data there about where I actually am. I was actually standing outside of the building, smack in the middle, which is about 30 meters south of the closest sample I got.
Which brought me to idea #2:
Measure reported accuracy, sampling frequency/jitter, time it took to acquire the initial lock and call it a day.
Which brings me here - I'd like to do this right and so I'd love to get anybody's feedback on what kind of algorithm to use to characterize gps performance.
Also, if anybody wants to take a peek at whats been done so far, here's a link to a page with the latest version of the android client. Just install it and start it up. It will pop up and error if it can't connect to the server and the server does go down from time to time, so if you get a connection error, try again a little later. The other thing to be aware of is that I enforce the "stationary collection" rule by monitoring the accelerometer. When you hit start you will have 3 seconds to put your phone on a table or the sidewalk or somewhere else that isn't moving. Once the collection starts, it will monitor GPS until it gets 30 samples. You can cancel at any time by moving the phone. If any samples were collected, they will be uploaded and you will get an option to view the results. The results aren't too terribly meaningful for now, but there are a couple interesting statistics there and you will be helping me out by stress testing the server. Feedback appreciated!
Thx

The only problem is I believe there may be some hardware variation. I've read some posts where they took two completely identical stock phones and got completely different results.

I don't see a problem with stationary data. It will always jump around. That's hardware. The hardware cannot accurately track anything less than 10 meters.
I'm more worried about why it's jumping around and losing accuracy when it's in motion.
I would make a data collection for TTTF , satellites in view, satellites with fixed, signal strength (SNR), bearing, hasAlmanac(), hasEphemeris() and accuracy.
I was thinking of writing an app but I really don't have the time for it. I have a bunch of projects lined up and really won't see any real free time until a month or two. I program for a living and currently have a private android application that uses GPS that I wrote for my clients. It's a shame the GPS is borked with the Galaxy S because I was going to use it to market my application. I have to resort to the Xperia X10. My interest in fixing the GPS is both personal and business related.
Regardless, if you need any help, let me know.
PS: I believe we need a program to really compare our "fixes" and narrow down what changes makes things better and worse. I would like to get to the point where we can calculate: X # of satellites with an average of Y dbHZ of signal strength gives you Z% accuracy

ThisWasATriumph said:
The only problem is I believe there may be some hardware variation. I've read some posts where they took two completely identical stock phones and got completely different results.
Click to expand...
Click to collapse
I dont really think that the variations are hardware related, at least I've not seen any solid data to support that assertion. Different results, even wildly different between two identical phones is expected to some degree...theres too many variables involved to directly compare two phones and expect to get identical results, even side by side. For instance, reboot one of the phones and try again. The rebooted phone will have much better performance. If we get some averages based on device and software version / configuration with a large number of samples behind it, actual differences should emerge from the noise. In any case, if there truely is a hardware problem, that will probably also be discoverable as an abnormally high standard deviation compared to other devices.

CLShortFuse said:
I don't see a problem with stationary data. It will always jump around. That's hardware. The hardware cannot accurately track anything less than 10 meters.
I'm more worried about why it's jumping around and losing accuracy when it's in motion.
Click to expand...
Click to collapse
In theory, there shouldnt be any functional difference between a moving receiver and a stationary one. At least over relatively short distances. Yes one will be cross cutting various geometric relationships with the satellites, but they are so minute that its a moot point.
On top of that, benchmarking while moving introduces two problems:
1 - Telephone poles, buildings etc. Will periodically obstruct the signal introducing an error that cannot be subtracted out.
2 - As mentioned above, there is no known point of origin. One of the consequences of that is that the conditions surrounding the data collection of user A can vary wildly from those of user B. In essence you stop measuring performance alone and start measuring performance plus the dynamics of the neighborhood. With a stationary position at least you know that your gps shouldnt be showing you moving.
From my own testing, I can say that the Captivate typically does not even calculate stationary locations correctly, as seen in the links posted above. Sadly the error signal bears no obvious relation to the true origin. And although there is a definite pattern I don't know how to analyze that pattern. I'm humble enough to admit that I'm not smart enough to figure it out. Hopefully somebody else here is though At the very least, I think that the error patterns generated from a stationary position are a solid basis for a standard test.

You should try cognition 2.2 with CLShortfuse's jupiter tweaks. For the first time I was driving 55mph with 9-11/11 sats locked on the whole time, kept an accuracy of 5-10 meters and it accurately reported my speed dead on with my speedometer. I'm pretty satisfied with the performance right now.

Have you done any tests at a benchmark site to see how accurate it is? I have been at a benchmark site one day and gotten really accurate results, only to return on another day and have trouble getting within 300 ft. accuracy. And this was done with a "real" GPS.... I think that it is going to be difficult to get good results with a smart phone acting as a handheld GPS device. Maybe I am wrong ..... I'm no engineer or programmer...
Sent from my custom EVO PC36100 Using XDA app

halfhp said:
From my own testing, I can say that the Captivate typically does not even calculate stationary locations correctly, as seen in the links posted above. Sadly the error signal bears no obvious relation to the true origin. And although there is a definite pattern I don't know how to analyze that pattern. I'm humble enough to admit that I'm not smart enough to figure it out. Hopefully somebody else here is though At the very least, I think that the error patterns generated from a stationary position are a solid basis for a standard test.
Click to expand...
Click to collapse
I haven't taken a look at your program but collecting mass amounts of information is a start. We can draw a correlation between signal strength, # of antenna and accuracy.
There is another option, that I believe would be best to identify the underlying issue. Have different Android GPS units side by side both running the same application, and have them report data for each satellite (based on PRN). They SHOULD be identical (azimuth, elevation and if possible, the reported time). Also, we would check the system times and see if they are synchronized.
According to Garmin:
Sources of GPS signal errors
Factors that can degrade the GPS signal and thus affect accuracy include the following:
Ionosphere and troposphere delays - The satellite signal slows as it passes through the atmosphere. The GPS system uses a built-in model that calculates an average amount of delay to partially correct for this type of error.
Signal multipath - This occurs when the GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby causing errors.
Receiver clock errors - A receiver's built-in clock is not as accurate as the atomic clocks onboard the GPS satellites. Therefore, it may have very slight timing errors.
Orbital errors - Also known as ephemeris errors, these are inaccuracies of the satellite's reported location.
Number of satellites visible - The more satellites a GPS receiver can "see," the better the accuracy. Buildings, terrain, electronic interference, or sometimes even dense foliage can block signal reception, causing position errors or possibly no position reading at all. GPS units typically will not work indoors, underwater or underground.
Satellite geometry/shading - This refers to the relative position of the satellites at any given time. Ideal satellite geometry exists when the satellites are located at wide angles relative to each other. Poor geometry results when the satellites are located in a line or in a tight grouping.
Intentional degradation of the satellite signal - Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. Department of Defense. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers.
Click to expand...
Click to collapse

rtdrumz said:
Have you done any tests at a benchmark site to see how accurate it is? I have been at a benchmark site one day and gotten really accurate results, only to return on another day and have trouble getting within 300 ft. accuracy. And this was done with a "real" GPS.... I think that it is going to be difficult to get good results with a smart phone acting as a handheld GPS device. Maybe I am wrong ..... I'm no engineer or programmer...
Sent from my custom EVO PC36100 Using XDA app
Click to expand...
Click to collapse
I have neither used nor heard of gps benchmark sites - do you have any that you've used that you recommend?
I'm fully expecting the variance you are talking about, but I also believe that the variance is there because of measurable variables...it's just a matter of identifying enough of those variables to make the results understandable. For example, we know a reboot can temporarily fix gps issues so we wouldnt want to compare the gps results of a device that was just rebooted with the results of one that has been running for days.

CLShortFuse said:
There is another option, that I believe would be best to identify the underlying issue. Have different Android GPS units side by side both running the same application, and have them report data for each satellite (based on PRN). They SHOULD be identical (azimuth, elevation and if possible, the reported time). Also, we would check the system times and see if they are synchronized.
According to Garmin:
Click to expand...
Click to collapse
I briefly started down that road by grabbing the raw NMEA sentences but quickly abandoned that path due to the volume of data being pumped. Maybe I should take a second look.
Regarding the dual phone test, thats an interesting idea. I wouldnt have expected the clock times to vary at all. I'll check into it!

Also, for whoever is interested, here is a link to some results generated by the app in progress:
http://www.halfhp.com:8080/ggs/results/show/1?mode=mobile
It only shows a small subset of the data collected, but you get the general idea of what I'm going for.

I disabled the automatic time sync. I'm going to look for an app to synchronize my clock. I'm going to disable AGPS and take a test run. It could be wrong timing that makes it unable to grab a fix
WOW, talk about a difference. I disabled time sync and I used an application called "Micro Second".
Clock difference: 5.41638 seconds
That GPS trailing/sliding issue seems about 5 seconds as well......

CLShortFuse said:
I disabled the automatic time sync. I'm going to look for an app to synchronize my clock. I'm going to disable AGPS and take a test run. It could be wrong timing that makes it unable to grab a fix
Click to expand...
Click to collapse
Shouldnt the chip be keeping track of it's own time? One common use of gps is to provide a time signal accurate to the microsecond. As far as I know, all gps devices are capable of that kind of accuracy - they have to be in order to work at all, they just dont advertise it because many dont provide a physical interface to the PPS necessary for external devices to utilize it.

halfhp said:
Shouldnt the chip be keeping track of it's own time? One common use of gps is to provide a time signal accurate to the microsecond. As far as I know, all gps devices are capable of that kind of accuracy - they have to be in order to work at all, they just dont advertise it because many dont provide a physical interface to the PPS necessary for external devices to utilize it.
Click to expand...
Click to collapse
"Should" and "does" aren't the same thing. That's under the assumption that the NMEA data is provided by gps device itself. I don't believe it is. I think the GPS device gives raw satellite data and the driver wrapper calculates NMEA data back to Android.
Also, factoring the clock desync from the correct atomic-based time should be in the data.

CLShortFuse said:
"Should" and "does" aren't the same thing. That's under the assumption that the NMEA data is provided by gps device itself. I don't believe it is. I think the GPS device gives raw satellite data and the driver wrapper calculates NMEA data back to Android.
Also, factoring the clock desync from the correct atomic-based time should be in the data.
Click to expand...
Click to collapse
I think you might be at least partially right as far as the NMEA sentences being generated outside the chip. I did a little bit of digging on the BCM4751 chip and it appears that the protocol used is MEIF, which according to the internet is a proprietary nokia protocol. I havn't found a description of the protocol yet, but I would think that it offers at least the same amount of data that NMEA offers, meaning time is kept on-chip as expected. I just cant imagine the system clock being anywhere close to useable for such a time sensitive calculation as gps triangulation. I'm gonna keep looking though.

Something else to consider guys...
I've seen lots of people referencing GPS accuracy when in motion versus standing still. I'm not so sure that all of them are complaining about what they think they're complaining about.
My primary vehicle is a motorcycle. For crappy weather, I've got a Jeep Wrangler with a fiberglass hardtop. In both cases, the phone has no sheet metal between it and the sky. And in both cases, the GPS appears to track just fine. It may not show me in the proper lane of a multilane highway, but it at least always shows me on the right side of the road, and it never lags behind my actual position. Nor does it suffer from any 'inertia' problems. When I turn, so does it. When I stop, it does too.
Now... I'm out of town at the moment on a business trip and am driving a rental car - one with a fixed sheet metal roof (no sunroof either). Since my GPS had been working at home, I was expecting it to work over here as well. Wrong! It takes forever to get a lock, and when it finally does, it drifts in and out of lock. And as I'm driving along, it's sometimes as much as 5 seconds behind me. Or sometimes along side me on a side street. Or when I stop it keeps going. You know, all the crap that everybody's been complaining about.
So. Is it a setting issue, a driver issue, or is it a problem with the hardware? I can't tell you. But what I can say is that when there's any significant metal obstruction between the phone and the sky, the GPS is hit and miss... mostly miss.

[Q] HTC One strange G-Sensor problem

Good afternoon,
I am having the strangest problem with my HTC One: I ride a Buell 1125r (the 'muscle car' of motorcycles) and when I am riding I like to listen to music through headphones. The odd problem is that when accelerating, especially when putting on a large burst of speed, it causes the music player (Google Play Music) to skip to the next song...and the next...and the next...and the next...etc. Something interesting is that if I immediately drop acceleration, sometimes it will stop skipping and play the song it landed on. If I keep going at the speed I achieved (sometimes as low as 50 mph), I can stop at a stoplight and watch the cover art flick by over and over; it doesn't stop skipping for several minutes. I try shaking the device when stationary to see if it is some sort of shake to shuffle, but nothing happens.
WTF...? Please help...tearing hair out...
HTC One UL
Android Revolution HD 30
KitKat 4.4.2

CryptoCombat said:
Good afternoon,
I am having the strangest problem with my HTC One: I ride a Buell 1125r (the 'muscle car' of motorcycles) and when I am riding I like to listen to music through headphones. The odd problem is that when accelerating, especially when putting on a large burst of speed, it causes the music player (Google Play Music) to skip to the next song...and the next...and the next...and the next...etc. Something interesting is that if I immediately drop acceleration, sometimes it will stop skipping and play the song it landed on. If I keep going at the speed I achieved (sometimes as low as 50 mph), I can stop at a stoplight and watch the cover art flick by over and over; it doesn't stop skipping for several minutes. I try shaking the device when stationary to see if it is some sort of shake to shuffle, but nothing happens.
WTF...? Please help...tearing hair out...
HTC One UL
Android Revolution HD 30
KitKat 4.4.2
Click to expand...
Click to collapse
That's quite strange indeed. I'll try this too next morning. If I also get the same error, maybe we will be able to fix it. Otherwise you might have to go to the HTC support.
Have you got a rooted One?

LibertyMarine said:
That's quite strange indeed. I'll try this too next morning. If I also get the same error, maybe we will be able to fix it. Otherwise you might have to go to the HTC support.
Have you got a rooted One?
Click to expand...
Click to collapse
S-Off
Rooted
G-Sensor is calibrated and working properly in other apps.

CryptoCombat said:
S-Off
Rooted
G-Sensor is calibrated and working properly in other apps.
Click to expand...
Click to collapse
Ok, I just wanted to know that in case of a return.
- Does this error also occure when you accelerate your phone when holding it in your hands? (not the classic shake you mentioned, for example making a circle in the air)
- In what position related to the ground do you have your phone when accelerating?
- How fast do you accelerate? Can you say it in m/s² ? Or you can also say how long you need to accelerate to 50mph or other speeds.
- I quickly want to calculate what acceleration your phone has to bear.
- What would be interesting. When you are on a constant speed of 50mph, do you also have this error after several minutes?

LibertyMarine said:
Ok, I just wanted to know that in case of a return.
- Does this error also occure when you accelerate your phone when holding it in your hands? (not the classic shake you mentioned, for example making a circle in the air)
- In what position related to the ground do you have your phone when accelerating?
- How fast do you accelerate? Can you say it in m/s² ? Or you can also say how long you need to accelerate to 50mph or other speeds.
- I quickly want to calculate what acceleration your phone has to bear.
- What would be interesting. When you are on a constant speed of 50mph, do you also have this error after several minutes?
Click to expand...
Click to collapse
- I don't know...I don't make a habit of riding with my phone in hand, much less laying rubber...I did try spinning in a circle and did not get that result. It was fast enough to make my hand tingle and flush.
- In jeans pocket so basically diagonal like a playing card on it's corner.
- 0-60 in 2.8 fastest but occurs at everything down to about 6 sec so about 9.6m/s² to 4.5m/s²?
- cool!
- Yes. Like I mentioned, the skipping continues until the speed is decreased.

CryptoCombat said:
- I don't know...I don't make a habit of riding with my phone in hand, much less laying rubber...I did try spinning in a circle and did not get that result. It was fast enough to make my hand tingle and flush.
- In jeans pocket so basically diagonal like a playing card on it's corner.
- 0-60 in 2.8 fastest but occurs at everything down to about 6 sec.
- cool!
- Yes. Like I mentioned, the skipping continues until the speed is decreased.
Click to expand...
Click to collapse
- ok... even more strange.
- ok... that's a legit position
- the phone is accelerated at maximum with 13.8 m/s² this is about 1.4 times the earth acceleration. Here the calculation that you can see it a bit better:
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
And this acceleration doesn't seem to be too extreme
- Ok... even MORE strange^^ Because if you are on a constant speed the phone doesn't experience acceleration. Some basic physic laws. It's the way it is, to change speed or direction there has to be a force. And if there is a force there is also an acceleration But you know this I think!
So maybe it has to do something with GPS? But this wouldn't explane the fact that it keeps spinning around when you stay still.
If you've got the time to do that, make a backup and make a clean reinstall of your ROM and try it out again.

LibertyMarine said:
- ok... even more strange.
- ok... that's a legit position
- the phone is accelerated at maximum with 13.8 m/s² this is about 1.4 times the earth acceleration. Here the calculation that you can see it a bit better:
<snip>
And this acceleration doesn't seem to be too extreme
- Ok... even MORE strange^^ Because if you are on a constant speed the phone doesn't experience acceleration. Some basic physic laws. It's the way it is, to change speed or direction there has to be a force. And if there is a force there is also an acceleration But you know this I think!
So maybe it has to do something with GPS? But this wouldn't explane the fact that it keeps spinning around when you stay still.
If you've got the time to do that, make a backup and make a clean reinstall of your ROM and try it out again.
Click to expand...
Click to collapse
I can try that, but it did this when I was on stock firmware too. As I mentioned before, the G-Sensor does work properly everywhere else...but it occurred to me that it may be a side effect of a magnetic field generated by the bike instead? That would explain the continued disruption at constant speed. But what would the field be affecting? the G-Sensor? The capacitive touch? Something else?
It should be noted that it has never done this in my car. of course that thing is a little Mazda M3 and doesn't have even half the acceleration as my bike...

CryptoCombat said:
I can try that, but it did this when I was on stock firmware too. As I mentioned before, the G-Sensor does work properly everywhere else...but it occurred to me that it may be a side effect of a magnetic field generated by the bike instead? That would explain the continued disruption at constant speed. But what would the field be affecting? the G-Sensor? The capacitive touch? Something else?
Click to expand...
Click to collapse
A magnetic field. Maybe... use a accelometer sensor logger during your next ride on your bike. And send the data to me... or look for some kind of "unexpected behaviour"
And this idea with the magnetic field. You would have to ask at the shop where you bought the bike if it emmits some kind of electromagnetic radiation. But this also shouldn't cause issues.
And because you did already try it on stock. Don't try it again. It most likely won't work.
P.S.
Sry, I won't answer today anymore. GTM +1

LibertyMarine said:
A magnetic field. Maybe... use a accelometer sensor logger during your next ride on your bike. And send the data to me... or look for some kind of "unexpected behaviour"
And this idea with the magnetic field. You would have to ask at the shop where you bought the bike if it emmits some kind of electromagnetic radiation. But this also shouldn't cause issues.
And because you did already try it on stock. Don't try it again. It most likely won't work.
P.S.
Sry, I won't answer today anymore. GTM +1
Click to expand...
Click to collapse
Attached logs.

CryptoCombat said:
Attached logs.
Click to expand...
Click to collapse
I'll analyse over the weekend. this is quite some data. I'll write a short program that reads it out^^

LibertyMarine said:
I'll analyse over the weekend. this is quite some data. I'll write a short program that reads it out^^
Click to expand...
Click to collapse
I parsed them into excel using csv format mode. Check out sheet two for a graph. the orange line (labeled sum) is the sum of the x,y and z readings' absolute values. there's some very interesting data in the magnetometer file. anytime I really hammered down on the gas, the magnetic field shot up. Beyond 100 in a spot or two in sum!

CryptoCombat said:
I parsed them into excel using csv format mode. Check out sheet two for a graph. the orange line (labeled sum) is the sum of the x,y and z readings' absolute values. there's some very interesting data in the magnetometer file. anytime I really hammered down on the gas, the magnetic field shot up. Beyond 100 in a spot or two in sum!
Click to expand...
Click to collapse
ok, I think the accelometer looks ok. but the magnetic field is indeed very strange. Today I tested it too.. but there was no special effect to the magnetic field.
Maybe ask your bike vendor if the bike emmits electromagnetic radiation. If yes, it's totally ok that your magnetometer on your phone mesures this. If not, there might be another reason.
But sorry, I can't give you more informations or ideas. But if I think about something possible I'll notify you.
---------- Post added at 05:34 PM ---------- Previous post was at 05:19 PM ----------
CryptoCombat said:
I parsed them into excel using csv format mode. Check out sheet two for a graph. the orange line (labeled sum) is the sum of the x,y and z readings' absolute values. there's some very interesting data in the magnetometer file. anytime I really hammered down on the gas, the magnetic field shot up. Beyond 100 in a spot or two in sum!
Click to expand...
Click to collapse
Sorry, I checked your accelometer graph again. You calculated the sum the wrong way. The actual way to calculate it is:
sum = √(a₁² + a₂² + a₃²)
And with that you get this graph:

Interesting update: with no headphones plugged in, the skipping does not occur. I started a playlist through the built in speakers and after a very fast drive it was on track to the second.
I'm guessing the magnetic field generated by the alternator is causing induction feedback in the headphone wires. Otherwise I'm stumped.
Sent from my HTC One using XDA Premium 4 mobile app

mmm
try a differnet pair of headphones maybe?

stldaniel said:
try a differnet pair of headphones maybe?
Click to expand...
Click to collapse
Yup. That's my next step. Sadface, these Beats earbuds are nice
Sent from my HTC One using XDA Premium 4 mobile app

CryptoCombat said:
Interesting update: with no headphones plugged in, the skipping does not occur. I started a playlist through the built in speakers and after a very fast drive it was on track to the second.
I'm guessing the magnetic field generated by the alternator is causing induction feedback in the headphone wires. Otherwise I'm stumped.
Sent from my HTC One using XDA Premium 4 mobile app
Click to expand...
Click to collapse
why didn't you mention or quote me? I would have been able to answer... but I didn't get any notification. Yes.. maybe, because this graph was quite strange. You can make an isolation with another magnetic field that compensates these fluctiations.

i am so glad i found this post. i just got my one and am having the exact same problem. i even have htc sending me a new pair of headphones. i was going to try using my old s3 headphones but the one wont even recognize them when i plug them in.
i have to say, all your graphs and math is way to much for me. all i know is my phone hates my motorcycle. whats really weird is, i can make it on the streets to the fwy. its once i get on the fwy that things go all skippy.
did you ever find a solution?

vvelvetelvis said:
i am so glad i found this post. i just got my one and am having the exact same problem. i even have htc sending me a new pair of headphones. i was going to try using my old s3 headphones but the one wont even recognize them when i plug them in.
i have to say, all your graphs and math is way to much for me. all i know is my phone hates my motorcycle. whats really weird is, i can make it on the streets to the fwy. its once i get on the fwy that things go all skippy.
did you ever find a solution?
Click to expand...
Click to collapse
I didn't get a notification about this post. Solution is to use almost any other headphones for anyone else having this problem. The Beats buds that shipped with the m7 Beats model have flat wires which as a general rule are much more susceptible to electrostatic interference.

CryptoCombat said:
I didn't get a notification about this post. Solution is to use almost any other headphones for anyone else having this problem. The Beats buds that shipped with the m7 Beats model have flat wires which are much more susceptible to electrostatic interference.
Click to expand...
Click to collapse
That is kind of what I did. I got a pair of skull candy headphones without the mic. Hard to find a pair without the mic. They still have a flat cable but work great.

GPS close to unusable :/

Hello there !
Just have a look at this:
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Top left: Note 4. Bottom left: S4. Right hand side: Z2 Tablet.
All devices are configured to use the built-in GPS receiver only.
The photo was taken after waiting for more than 5 minutes.
Z2 Tablet and S4 receive 23 satellites, S4 using 18, Z2 Tablet using 16 (after a couple of seconds). But Note 4 receives 11 satellites, uses 0 (ZERO) - even after 5 minutes.
Here's a quick and shaky video: http://youtu.be/nVOF2n8AYDk
Software: I used "GPS Test" by "Chartcross". Other apps show the same results.
I tried countless comparisons, using A-GPS data and without, tried resetting the radios via the service menu - nothing helps: Note 4 GPS receiver does "see" some satellites (but always less than other devices), but just doesn't get a fix, at least not indoors.
It DOES work outdoors, but the results are similar and very poor: Note 4 takes a lot of time for the fix, uses less satellites, provides a less precise position and/or permanently loses the fix again. Even with using A-GPS data, a fix takes ages if the Note succeeds with a sat fix at all, situation becoming even worse if moving in a car. Z2 Tablet and S4 provide an almost instant fix, don't drop the fix again.
Of course I searched the net (and XDA) for that issue, found just some posts claiming the same.
Problem: Most users just see it does work outdoors, but don't realize the poor, close to subzero performance. So they believe it's all ok.
It is not.
I really hope it's just a software bug. If not, our Note 4 GPS becomes close to unusable if used in forests, under heavy rain, indoors or under other adverse conditions.
Please do a comparison yourself, check against any other GPS-enabled device - let's see if your results differ or are similar.
Please note: It does not help if your GPS just works outside. It does. But it's far, far worse than other devices - just see the photo above.
----
I found two videos showing a part of the problem (without being noticed by the "reviewer"):
https://www.youtube.com/watch?v=jHDVZEKBD8M
GPS test starting at 3:41. Note that the Note 3 retains it's satellites after the fix (8/21), while the number of the satellites used by the Note 4 wildly changes.
At 4:17, it drops to 4, causing losing the fix for a moment - note that the colors of the satellite signals momentarily change from green to yellow/grey.
Similar with the other video of the same reviewer:
https://www.youtube.com/watch?v=5X3Ucqnu9_g
GPS test starting at 3:57. Note that the Note 3 retains it's satellites after the fix (14 to 15 of 22), while the number of the satellites used by the Note 4 again constantly changes.
At 4:34, it drops to 2, causing losing the fix for a moment - note that the colors of the satellite signals momentarily change from green to yellow/grey.
That's what I observe with my Note 4, too.
And that's what causes that expanding and shrinking of the blue "GPS accuracy" circle around your position in Google Maps, that's what causes showing a momentarily wrong position while driving.
I am not sure if this is a real fault or just the results of a different approach by Samsung - MAYBE they try to use a kind of diversity algorithm causing that short "dropouts".
In any case - it's a bad thing. And an issue wreaking havoc in the background, broadly unnoticed by the majority of Note 4 owners (which regard the GPS as working perfectly just because the sat fix doesn't take long), I fear.
But it might be model or firmware specific.
So please check if your Note 4 shows the same behavior.
The speed of a GPS fix does not say anything as there are too many different factors of influence involved; sorry.
---
I had been asked why indoor reception is important at all. Here's the answers:
1) Indoor reception is an indicator of the sensitivity of a GPS receiver. Under the open sky, just every GPS receiver delivers a sound performance - so you cannot see differences.
But if you've got a good indoor reception, you'll also get a high sensitive under problematic conditions - e. g. under bad weather conditions, in cities where you are surrounded by tall buildings, or in regions like forests or even underwater. Performance in locations like forests is highly important for outdoor enthusiasts or people doing geocaching.
And you'll be quite happy if your navigation software leads you to your destination even if it's raining cats and dogs - instead of being forced to leave your car to ask for directions.
So if your device performs well indoors, it is very likely to also perform well in every demanding outdoor situations.
Practical, personal example: Every year, I leave for a months vacation to Asia. I usually don't follow the beaten tourist tracks, I prefer the secluded, more unknown places. That often leads me into jungle regions, tall trees everywhere. If I can't rely on a solid GPS fix, I can get lost in no time.
If I know that my Note 4's indoor reception is pretty good, I can be assured it won't leave me if I'm out in the middle of nowhere.
2) Most of the time, you use for mobile phone indoors. At your home, at shopping malls, you name it.
Of course you know where you are, so it might sound needless to know your GPS position.
But just have a look at your power options, at the information about your battery drain: Settings > Power Saving, tap the chart.
Then have a look at the "Location on" graph.
You'll notice that your GPS receiver is active pretty often - even if you don't use it actively and knowingly.
That's because many apps use the GPS in the background - like Google does; GPS is used every time you utilize e. g. Google Now, or use your browser (remember the question if you wish to allow the browser know your location ? - If you agreed, it will use GPS, even if you aren't aware of that).
If you've got good GPS reception, GPS will be used just for a very short time. But if the reception is bad (e. g. caused by bad indoor reception), the GPS receiver will be on for a long time; could be for hours.
That drains your battery significantly.
So good indoor reception is also one of the keys to good battery life.
You see, it's not just over nothing. It SEEMS like that at first sight - but be rest assured: I am a very practical person (e. g. I don't care at all about benchmarks - if a device just fulfills my needs, I don't need any more information). I don't care if e. g. the front camera distorts my pretty face.
But I care if a malfunction shortens battery life or leads to vital features becoming unusable if external conditions aren't optimal.
And please don't forget about the most important impact of such discussions: This way, Samsung gets aware of a problem. So there's a chance that the problems will be solved by an update - for the benefit of ALL users, even if they weren't aware about the problem at all.
If you report the problem to the Samsung "support", you can be sure nobody will care about it. I checked that myself (for Germany, to be precise): I reported a problem more than seven times. Always the same problem, always using a different name. The staff always assured me that the issue was stored in the system and forwarded to the technicians. Guess what ? - At every next call (or chat), I was told that I was the only one reporting it, nobody else had that problem.
But threads at XDA are likely to be noticed by Samsung - and the media.
For me, if it can get me from place A to B when I'm driving or walking in an unknown area, then it's OK.
Click to expand...
Click to collapse
That's one of the reasons why I raise that problem.
As said: If your GPS receiver works well, it WILL navigate you safely from A to B. But if it's sensibility is weak, it will do so under bright sunshine, but will fail if there's heavy weather, as such conditions attenuate the GPS signal strength significantly. Result: Under heavy rain, your device will be unable to navigate you safely from A to B.
If you search the net a bit, you'll also find a lot of similar threads where people ran into exactly that situation with the Note 4: On the road, the GPS lost position, leading them nowhere, showing their location 100 m away from the street, and so on.
---
Here's three COMPARISON (!) videos I just took.
Note 4 GPS vs. Z2 Tablet GPS - indoors, good conditions (near window)
Note 4 GPS vs. Z2 Tablet GPS - indoors, worse conditions
Note 4 GPS vs. Z2 Tablet GPS - outdoors
Identical device settings (internal GPS use only, A-GPS data loaded).
If you wonder why the Note 4 performs worse outdoors: It's because the device is flat on the ground. Reception is better with the Note 4 slightly angled.
We got a GPS fix in all three cases; in two cases, the Note 4 achieved a real quick GPS fix.
That's what's making most of you cry out in ecstasy: "Oh ! I've got a fix ! And so fast ! It's such a great device !"
But: Note 4's GPS sensitivity proved far worse than the Z2 Tablet's GPS in all three cases.
THAT'S THE PROBLEM, GUYS.

What I ended up doing once is opening the phone and pulling the springs a bit for better contact with the GPS antenna. Was good to me on the Note 3.

you have a defective phone. i just measured time to cold fix and it was 1.5 seconds indoors on my 910U.
Mine is set to GPS only, google location services OFF.

Have the same lousy gps and bad reception compared to my iPhone 6 plus. Got the phone replaced today but still bad gps and bad signal so in my house I can't even call with it when the same sim in my iPhone gives enough signal for calling. Gonna return the note, feels like they did a "Apple" antennagate with som bad antenna design
Skickat från min iPhone med Tapatalk

What "Location Mode" do you have on? When mine is on "high accuracy" it jumps all over. When i set it to "gps only" its pretty good. Not sure this has anything to do with you issue or not.
I just tried that software, and after about 60 seconds it was locked on 14 and accurate to 12 feet, sitting indoors.

ChickenWingSoup said:
What "Location Mode" do you have on? When mine is on "high accuracy" it jumps all over. When i set it to "gps only" its pretty good. Not sure this has anything to do with you issue or not.
I just tried that software, and after about 60 seconds it was locked on 14 and accurate to 12 feet, sitting indoors.
Click to expand...
Click to collapse
If you open Google Maps and scroll in all the way, how far is the dot from where you're actually sitting in your house?
Like right on the money or 5', 10', 20', ?
My S4 was on the money. My Note 3 consistently has me about 30-50' from where I actually am.
It's one of the reasons I'm considering an N4 upgrade.

@Class said:
What I ended up doing once is opening the phone and pulling the springs a bit for better contact with the GPS antenna. Was good to me on the Note 3.
Click to expand...
Click to collapse
As far as I saw, the GPS antenna is not in the cover; so it won't help pulling any springs. :/

ChickenWingSoup said:
What "Location Mode" do you have on?
Click to expand...
Click to collapse
Tried both modes, results are similar. Right now the Note 4 is next to me, trying to get a fix.
Number of used satellites is permanently changing second-wise: 4, 3, 2, 3, 2, 1, 3, 3, 2, 2, 3, 1, ...
I just tried that software, and after about 60 seconds it was locked on 14 and accurate to 12 feet, sitting indoors.
Click to expand...
Click to collapse
Doesn't help much as an indoor fix heavily depends on many factors like satellite positions, positions of windows and phone, wall material, and so on.
Sometimes I get a quick fix indoors, in most cases it just fails.
Different with Z2 Tablet and S4: Just ALWAYS a fast fix, S4 even fets a sat fix in the basement, where the Note 4 doesn't even see a single satellite.
We need comparisons with other devices.

Chefproll said:
Tried both modes, results are similar. Right now the Note 4 is next to me, trying to get a fix.
Number of used satellites is permanently changing second-wise: 4, 3, 2, 3, 2, 1, 3, 3, 2, 2, 3, 1, ...
Doesn't help much as an indoor fix heavily depends on many factors like satellite positions, positions of windows and phone, wall material, and so on.
Sometimes I get a quick fix indoors, in most cases it just fails.
Different with Z2 Tablet and S4: Just ALWAYS a fast fix, S4 even fets a sat fix in the basement, where the Note 4 doesn't even see a single satellite.
We need comparisons with other devices.
Click to expand...
Click to collapse
Having the almost the same fix and locked satellites on my s5, note 4 and Note 10.1 tablet indoor concrete apartment building . They lock on 12 to 15 satellites in less then 30 seconds. no problem

I had the exact same symptoms with my lg g2. When set to high accuracy, the location would jump around. Also, it would see satellites, but take forever to get a fix.
When set to GPS only, it would work fine.
Never was able to fix it.
I have a feeling that it worked fine at first and that this weird behavior started after a firmware update. Could not verify, coz I did not know how to downgrade.
Sent from my A0001 using XDA Premium HD app

marleyb said:
Having the almost the same fix and locked satellites on my s5, note 4 and Note 10.1 tablet indoor concrete apartment building . They lock on 12 to 15 satellites in less then 30 seconds. no problem
Click to expand...
Click to collapse
Depends on your location; if your room is just under the roof, you'll experience less problems.
I added a quick video to my first post; just have a look. :/

Chefproll said:
Depends on your location; if your room is just under the roof, you'll experience less problems.
I added a quick video to my first post; just have a look. :/
Click to expand...
Click to collapse
Yeah I understand your Note has a problem just saying mine has not. Even with 8 floors above me I still have a fix within 30 seconds

Got a GPS fix inside my living room in less than 30 sec. 4 meters presicion. Can't post a screenshot cause I don't have enough posts yet lol.

I get instant. No problem so far. Mine is Exynos 7 (5433) edition - N910C.

@Chefproll
What processor do you have in your GN4?
I had 2 different AT&T Snapdragon GN4's with very bad GPS.

I've found the GPS to be outstanding on the note 4. It will even locate in an airplane in under 45 seconds at a point over a thousand miles from where it was when it was last on. My HTC EVO 4G lte could not do this, the original Evo could. As for day to day use, it's been flawless.

Yippee. Another considered "based on my expert opinion and test sample of one" thread from an XDA member declaring all Note 4's to have an issue. These "expose" threads get tedious.
Here' what AnandTech found in their testing and what they are reporting maps to my experiences...
At this point, it really goes without saying that the GNSS solution of choice is the one built into Qualcomm's modem. This allows for fixes based upon initial location and time data that the modem has, and therefore in practice every GPS fix is a hot fix and takes around 5 seconds for a lock in good conditions. In the case of the Note 4, with airplane mode on and no assistance data I saw that it took around 50 seconds to achieve a lock, but this is strongly dependent upon environmental conditions. Once locked, I found that the Note 4 had quite a strong lock and quickly went down to 10 foot accuracy level without issue.​​http://www.anandtech.com/show/8613/the-samsung-galaxy-note-4-review/9

BarryH_GEG said:
Yippee. Another considered "based on my expert opinion and test sample of one" thread from an XDA member declaring all Note 4's to have an issue. These "expose" threads get tedious.
Here' what AnandTech found in their testing and what they are reporting maps to my experiences...
At this point, it really goes without saying that the GNSS solution of choice is the one built into Qualcomm's modem. This allows for fixes based upon initial location and time data that the modem has, and therefore in practice every GPS fix is a hot fix and takes around 5 seconds for a lock in good conditions. In the case of the Note 4, with airplane mode on and no assistance data I saw that it took around 50 seconds to achieve a lock, but this is strongly dependent upon environmental conditions. Once locked, I found that the Note 4 had quite a strong lock and quickly went down to 10 foot accuracy level without issue.​​http://www.anandtech.com/show/8613/the-samsung-galaxy-note-4-review/9
Click to expand...
Click to collapse
For me it works that good when under open air. In the city between high building and threes it is totally worthless. I live in single-storey house made of wood and the Note 4 cant get a fix untill I leave the house. My old SGS 5 had no problems with that and not my current iPhone 6 Plus has no problems with it either. They both get a fix instantly when inside the house. But I have tested three Note 4 and no one of them get a fix inside the house. Think that is a pretty good sign that the Note 4 has worse GPS signal than most other phones. And even the carrier reception is worse with the Notes tested compared to iphone 6 Plus, a Moto G 2013 and a HTC One M8 I have tested in my house. If it is the metall rim or if it is fixable by software I dont know but I am disapointed with my Note, thought I had a faulty one first.

osetivo said:
@Chefproll
What processor do you have in your GN4?
I had 2 different AT&T Snapdragon GN4's with very bad GPS.
Click to expand...
Click to collapse
As mention mine is Exynos 5433 edition. I found most complain is Snapdragon 805 edition. This time Exynos perform better in every aspect.

BarryH_GEG said:
Yippee. Another considered "based on my expert opinion and test sample of one" thread from an XDA member declaring all Note 4's to have an issue. These "expose" threads get tedious.
Click to expand...
Click to collapse
And another "MY Note 4 is ok, so all others claiming their Note doesn't work as expected are wrong. So let's say something negative things about them and don't take it for real.".
You posted a screenshot, making it impossible to see if the device was used outdoors or indoors.
I also get a quite good reception if I am outdoors - but:
a) There's just no fix although the signal strength is sufficient. Here's a screenshot, taken OUTDOORS:
Note the time of the last GPS fix in the lower right corner. Note 4 had been on all the time, with all Google services active, so there had been a constant check for GPS positional data - with NO success all night long.
b) Indoors, reception is a horror - COMPARED WITH OTHER devices.
It's of no further use if you post a screenshot without comparing the reception with other devices.
Just be happy about YOUR device working - but this does not necessarily mean it's the same with other devices.