Hi all,
I am for Uni looking into using a GPS device (just a receiver) to pass your location to a PDA and with some work on some software on the device do some calculations and useful stuff re where you have gone, how fast etc. But the app on the PDA must be custom written
All i need from the GPS device is location (in longitude+latitude?) and this would be queried about every second.
a) how easy is it to get such an output from a receiver without a lot of premade software overhead?
b) just how accurate can GPS be? i read about 10m but down to 2/3m with WAAS?
c) anyone know of any good documentation on using GPS output for a PDA app?
d) any advice on good GPS devices that can do just this but as accurately as poss. i hear about the ability to get down to a few inches but this isnt publically available? (maybe wrong there)
any help or pointers would be very, very much appreciated.
Andy
Most GPS units send navigation data using the NMEA 0183 protocol, which is text-based (and thus easily parsable). Since you mention the XDA mini exec, I assume you're looking at Bluetooth GPS units -- these units will look like a COM port to the XDA, so you can use standard serial comms code to receive the NMEA data.
If you look around the net (e.g. google, sourceforge.net) you should be able to find a number of Windows applications that do what you want. Most of them will have been written for big Windows, but should be easily portable to the XDA platform.
Hi,
I am currently looking for a piece of software that will do a specific job, or possibly a better solution to what I am trying to do. Let me give you a little bit of background...
I have got an O2 XDA Mini S, and a Parrot hands-free kit that does not support the A2DP bluetooth profile (only the handsfree profile). I am currently using TomTom 6 on my XDA with a bluetooth GPS unit. Everything works really nicely together, except I cannot get instructions from TomTom through my parrot (which is ultimately my goal).
The only way I can see of getting the TT instructions through my Parrot is to make use of the programs floating about that allow you to turn on and off redirection of sound through bluetooth. The idea I had was that if there was a program about (or maybe even write something myself) that would be able to signal when the sound coming out of the XDA exceeded and then dropped back below a threshold level, and then somehow link that into the bluetooth redirection programs, I could basically have any sound that is produced go through the Parrot only when they occur (including obviously the TT instructions).
Does anybody have any ideas on this? Any help would be greatly appreciated.
Thanks.
Point UI, a UI wrapper, has a feature similar to what you're describing. It's used just to save battery power by turning on BT only when an incoming call is detected, and then killing BT after the call is ended. I don't know if it's open source, but you might want to head over to their forums and see if you can find out how they did it.
You probably also want to haunt any TomTom forum sites (if any even exist).
As a final option, look into Mortscripts. People have done amazing tricks with Mortscripts, and this might be just the ticket. Mort haunts these boards, and may pipe in with an "I can (or cannot) do that with Mortscript" too...
I have a question, though. What's wrong with using the Wizard's built-in speakers for getting directions?
Myrddin Wyllt said:
I have a question, though. What's wrong with using the Wizard's built-in speakers for getting directions?
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To be honest, it's not too bad through the speakers although if I have my radio on which I usually do, sometimes it can be a little bit hard to hear, and it would be nice to just have the radio mute while it gives me the directions.
It's more of a "want" than a "need" really.
Thanks very much for the info
Myrddin Wyllt said:
Point UI, a UI wrapper, has a feature similar to what you're describing. It's used just to save battery power by turning on BT only when an incoming call is detected, and then killing BT after the call is ended. I don't know if it's open source, but you might want to head over to their forums and see if you can find out how they did it.
Click to expand...
Click to collapse
It is quite easy for programs to detect when you're in a call - MortScript, I presume, probably can detect that quite easily as it's an overall Windows feature and will probably have a readily available part in the API.
The problem is not with turning the bluetooth on and off, it's actually detecting when TomTom is giving an instruction. To be honest I think I'll look into MortScript and if that can't do it then I'll probably just give up.
Detecting phone calls isn't that easy, and it's especially not easy to make a check in a simple procedural script language like MortScript (up to WM5, there's no way to check whether a call is active, you have to monitor all the time if a call is accepted or hung up).
Detecting sound output of another application is entirely impossible - at least for most applications. If the app opens the output channel only during output (which most don't because it takes valuable time and causes ugly "click" noises on some devices), one could maybe query the number of free output channels - but that would need a CPU hog monitoring all the time, or half of the message would be over until it's detected.
And even if that would work, there's simply no way to redirect output to a BT headset (except with A2DP). At least on most devices. Once there was a simple way to do that (you just had to open a virtual port, and as long as it's open, everything was redirected similar to the A2DP way nowadays), but most manufacturers didn't implement it, and nowadays it seems like no modern device supports it anymore. (Had it for test purposes in a MortPlayer beta, no user reported it works...)
So, to put it short: Currently it's impossble. Maybe WM8 might change that... (Few hope for WM7, it's proposed to have the same kernel as WM5 and WM6.x)
Just wondering if the Touch HD will get the same laging GPS receiver the Touch Pro and Diamond got? I sure hope not. Its the only thing that dissapoints me with my Touch Pro.
utvol06 said:
Just wondering if the Touch HD will get the same laging GPS receiver the Touch Pro and Diamond got? I sure hope not. Its the only thing that dissapoints me with my Touch Pro.
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It's not an issue of hardware, but software. That's like asking if it will have the same laggy TouchFlo3D because of its processor... It's just the software. My Fuze didn't have any of the complaints of slow TF3D or GPS lag, but it had the same GPS receiver as the European Touch Pro.
Black93300ZX said:
It's not an issue of hardware, but software. That's like asking if it will have the same laggy TouchFlo3D because of its processor... It's just the software. My Fuze didn't have any of the complaints of slow TF3D or GPS lag, but it had the same GPS receiver as the European Touch Pro.
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I think the cause is the hardware, because some people tried with an external gps antenna, sirf3, and no lag at all. And changing software doesn't eliminate the lag. I use iGo and TT and the lag is always there...
onesolo said:
I think the cause is the hardware, because some people tried with an external gps antenna, sirf3, and no lag at all. And changing software doesn't eliminate the lag. I use iGo and TT and the lag is always there...
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Hopefully HTC will be able to fix the GPS Lag in the diamond and Pro with a rom update...they are supposed to be working on it. I just hope the Touch HD wont share the same lag problem and that HTC sees that it doesn't before release.
Isn't the difference between the built-in GPS and an external GPS antenna the method? The built-in GPS is (AGPS) and an GPS antenna uses "normal" GPS....
No, that's not it.
Assisted GPS is something extra for a normal GPS system, not a different system. A basic GPS system will have to download the satellites' position each time it cold-starts, and that will take time. An A-GPS system will have an additional way to download the current position of all GPS satellites, in order to speed up the process, by knowing the position of your phone in a GSM network or by downloading an updated file containing the satellites' current position, through a data network (wifi or 3g). That's why the "gps assistance" files you download through this kind of assistance application (in HTC's case, it's called "Quick GPS") are only valid for 2-3 days: in 2-3 days, they expire and the satellites' positions aren't valid anymore.
All GPS systems must have an antenna of some kind, either internal or external. Mostly all PDAs with integrated GPS have an internal antenna, which does the job in most conditions, but it's not perfect. I used an external antenna for car navigation, and in most situations I went from 4-5 detected satellites (with so-so signal) to 7-8 with full signal, only by having an antenna on the roof of my car. However, this shouldn't influence by all means the GPS lag, only the precision of GPS positioning on the map (coordinates).
That's not it either.
Quick GPS downloads a file prior to GPS initiation. When started the GPS works off-line.
A-GPS is a hybrid technology that auguments the GSM satellite signal with GSM signal on-line.
You can use Quick GPS without A-GPS, which is the case of most users today, for compatibility reasons.
As for the previous question regarding GPS lag, here are two points (depending on what you understand by GPS lag):
1. the GPS chipset has a built-in refresh rate, which should be something like 0.5 seconds. This is the same for all devices sharing the same chipset.
2. when saying that the GPS performance depends on software, it does not mean IGO or TomTom, it means the Radio drivers. Newer Radio versions come up from time to time and may improve GSM / GPS signal strength or battery life, and in the very best cases both.
Follow the ROM Development threads for more info.
dani31 said:
That's not it either.
A-GPS is a hybrid technology that auguments the GSM satellite signal with GSM signal on-line.
You can use Quick GPS without A-GPS, which is the case of most users today, for compatibility reasons.
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Not to be a GPS-nazi but A-GPS doesn't necessarily imply the usage of a GSM network, but the usage of an assistance server. From Assisted GPS page on Wikipedia:
A typical A-GPS-enabled cell phone will use an internet connection to contact the assistance server. Alternatively, it may use standard non-assisted GPS, which is slower and less accurate, but does not lead to network charges for data traffic, which can be considerable.
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So, it can be done either through GSM networks, or through a data connection; therefore, the Quick GPS app is simply another form of A-GPS.
dani31 said:
1. the GPS chipset has a built-in refresh rate, which should be something like 0.5 seconds. This is the same for all devices sharing the same chipset.
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That I don't think would be visible to the end user. According to the NMEA/SiRF specs, the min refresh rate would be 1 Hz (one time per second), but the average among devices seems to be around 5 times a second, once every 200 miliseconds (5 Hz refresh). The GPS chip should do that without a problem (according to the manufacturer's specs), therefore the problem must be somewhere after the GPS data is sent to the device; either in communication to the CPU, either in the navi software. My 2 cents. We'll see.
Review from SlashGear
HTC Touch HD's review by SlashGear talks about the GPS lag..
this is the part about GPS performance of the Device:
"The HTC Touch Diamond has been criticised for its GPS performance, which can lag behind actual position when moving at speed. Hopes were high for the Touch HD to avoid such a fate, but unfortunately that doesn’t appear to be the case. Whether from the processor (the same 528MHz Qualcomm MSM7201A as in the Diamond) or the GPS receiver itself, when driving the indicated position is always 50-80ft behind. This makes navigating via the on-screen directions incredibly difficult. At lower speeds, such as when walking, the Touch HD has no problems, just like the Diamond. We’re still attempting to get hold of some alternative GPS programs, such as TomTom or Garmin Mobile XT, and will update this review when we’ve had an opportunity to try them out."
has anyone else bought the Touch HD yet who can confirm this?
i just hope the GPS lag isn't as bad as the HTC Touch Diamond/Touch Pro as i'm going to order one pretty soon.
For the sake of millions of readers and potential touch HD buyers like me,can someone who already own a touch HD,please be kind enough,do an experiment about this gps lag issue and give an absolute answer to this issue.Gps lag is very noticeble when you are navigating at high speed(eg:80-100km/h) or when doing multiple rapid turns(eg:driving on back alleys).at low speed(slow drive or walking),no lag is apparent.Currently i'm using ipaq 612c where it has this lag issue and its most noticeble when using Garmin XT.When using mapking or tom tom it is not that bad..Really waiting for all your answers.
Thanks in advance for all your help
iznee said:
For the sake of millions of readers and potential touch HD buyers like me,can someone who already own a touch HD,please be kind enough,do an experiment about this gps lag issue and give an absolute answer to this issue.Gps lag is very noticeble when you are navigating at high speed(eg:80-100km/h) or when doing multiple rapid turns(eg:driving on back alleys).at low speed(slow drive or walking),no lag is apparent.Currently i'm using ipaq 612c where it has this lag issue and its most noticeble when using Garmin XT.When using mapking or tom tom it is not that bad..Really waiting for all your answers.
Thanks in advance for all your help
Click to expand...
Click to collapse
Ok, I have performed an experiment. Hopefully it will help you and "millions" of readers to decide if GPS lag is a problem or not on this device.
Test setup:
PDA 1: Mitac Mio A701, GPS chip: SIRF III, navigation software: IGO8
PDA 2: HTC Touch HD, GPS chip: Qualcomm, navigation software: IGO8
Experiment:
I start IGO8 on both devices and select the same destination. They both pick up GPS signal and the show starts..
Result:
PDA 1: depending on your speed, there is a GPS lag. This is between 0-2 seconds. In distance I would say about 20 to 50 meters. Again, all depending on your speed. When you stop (which unfortunatelly happens a lot in the netherlands due to high traffic ) the GPS gives the right position.
PDA 2: see PDA 1. There is practically no difference. Sometimes PDA 1 is more ahead, sometimes PDA 2 wins. The voice commands start virtually at the same time "take a turn left", "leave the highway" and so on. Maybe PDA 2 is a bit faster (less GPS lag) since I heard the voice like a 10th of a second earlier than on PDA 1.
Conclusion:
GPS lag is a problem that practically all "cheap" GPS devices have, specially in a moving vehicle. Since your GPS data is refreshed every second, you would be one second off every time. Moving at 100km/h, that means an offset of 27 meters. Moving at 150km/h that is about 41 meters (and yes, I know I should not drive that fast in the netherlands ). Add to that the GPS errors and you will get an impression on how hard it can be to predict where you will be in a second.
You could then say that the navigational software should take that into account and predict where it would be, but that also has a negative side. Have you noticed what happens when you do not follow the course laid ahead by the navigational software? it stays on course for a couple of seconds and then it notices you actually turned left or right, thus the direction should change.
The more aggresive the prediction is, the more you will have a problem when deviating. The less prediction, the more GPS lag you will have.
Is this a problem while driving? I have never considered it a problem. On the highway you do not decide to take a turn within 50 meters (I hope ). In the city, you should have way less problems with GPS lag...
Last, for all the "millions" of readers, please read these two articles:
Article 1, an abstract about navigational state estimator
Article 2, a forum discussing this very problem in the i-Blue receiver. Pay special attention to the answers given by JakeRich
I hope this helps you all out...
David,
I am so very pleased you had these two devices with the software mentioned.
It just so happens that I too have a Mio A701 with iGo and my next purchase will be the Touch HD.
Your test served as a good starting block for me to build upon.
I did wonder how well the Touch HD would fare against my A701.
Many thanks.
Beards
Thanks for your test. What about TMC info with iGo8 ?
gergy said:
Thanks for your test. What about TMC info with iGo8 ?
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The device finds the TMC receiver (using 8.0.x version, 8.3.x version does not find anything) but then it does not find a channel. This would need a TMC expert to work out...maybe you need to change something in the sys.txt file of IGO8
Something I would add is that until last week I was using a SirfStarIII equipped BT GPS receiver linked to my Hermes and running TTN 6.03, now I'm using the Touch HD internal GPS and TTN 7.45. I have found that the GPS signal appears to be significantly weaker on the Touch TD. However, it does have the capability to pick up more satellites it seems.
In my standard journey between home and work the BT GPS receiver never picked up more than 8 satellites but never picked up less than 4 and spent most time tracking 5-6. The Touch HD at times picks up 10, maybe even 11(!), satellites but often drops to 2 and spends most time tracking 3-5.
Impression
I'm using Tomtom 7,451 now on my HD.
I tried it with the internal GPs and even with an external bleutoth GPS receiver from Tomtom itself.
The so called lag is the same in both cases.It is caused by the slow refreshing rate ( almost 1 second ).That is not a major problem and is the same that I experienced already with the Polaris,Cruise and Diamond.
So when driving try to think at least 1 second ahead.
When you're not moving I got a pefect lock on my position with Tomtom but with Googlemaps i'm of by almost 150 meter to the East.
So that's software I think.
BerreZ said:
I'm using Tomtom 7,451 now on my HD.
I tried it with the internal GPs and even with an external bleutoth GPS receiver from Tomtom itself.
The so called lag is the same in both cases.It is caused by the slow refreshing rate ( almost 1 second ).That is not a major problem and is the same that I experienced already with the Polaris,Cruise and Diamond.
So when driving try to think at least 1 second ahead.
When you're not moving I got a pefect lock on my position with Tomtom but with Googlemaps i'm of by almost 150 meter to the East.
So that's software I think.
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I get my touch hd today. looks like I wont be installing Google maps at all on it. I'm going to buy Co-Pilot 7 when I get the chance. I also like Windows Live search GPS app, but it may lag like google.
utvol06 said:
I get my touch hd today. looks like I wont be installing Google maps at all on it. I'm going to buy Co-Pilot 7 when I get the chance. I also like Windows Live search GPS app, but it may lag like google.
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Google maps is already preinstalled, at least on my Touch HD it was (Netherlands)
last word on gpslag?
Hi to All,
Personally, i start realizing the limitation of forums in producing real information.
First of all, most "commercial" and consumer GPS update their position every second, as correctly pointed out in this forum. Said this, faster position updates are possible for professional devices, see
http://www.dsprelated.com/showmessage/22833/1.php
but we can probably forget about it for the time being.
so, don't be surprised if - driving at 100 km per hour alias 30 m/s - you will miss the exit by 30 meters. Be reassured: Felipe Massa will miss the box by 100m if he would drive by looking to the GPS - and your braking distance was anyway 60 m....aaaghh....i hope i will never meet any of you while making the test.
My firm and conclusive opinion after extensive evaluation with Igo and Tomtom and gwatch:
The GPS LAG on the touch HD is a metropolitan legend invented by i-members!
If you check on igo8, there is a small dot representing the actual position, and the arrow or the car is the position compute by software interpolation/filtering etc. Everybody can notice that the dot moves instantaneously. It is a matter of software to decide how to filter this data, and how "reactive" you want the position change to happen. On top of this, it is obvious that updating a VGA or WVGA screen will be heavier than updating a small screen, so there should be a lag which is dependent on the navigation software you use and on the load on your telephone.
However, there is definitely no lag on tomtom....the problem is: how to buy version 7?
Here is video comparison omnia vs hd
It seems to me there is little lag on hd.
Colud somebody translate it?
http://www.youtube.com/watch?v=v45--rkRgjk