VBOX Sport Experiment

Discussion related to external and internal GPS / GLONASS / Galileo / BeiDou sensors
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gplracerx
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VBOX Sport Experiment

Post by gplracerx »

I continue to have problems with my VBOX Sport and iOS Location Services. I'm not going to return it because it works reasonably well with HLT. I'm assuming that the extrapolation problem with OBD data will be fixed eventually.

Here's an experiment that I would like someone else with a VBOX Sport and an iPhone to try. Go outside. Turn on your VBOX Sport and place it in a fixed location. Now open the Maps app in your iPhone and walk around while staying close enough to the VBOX Sport to maintain the Bluetooth connection. Does the blue dot move with the phone or does it stay at the location of the VBOX Sport? The answer for me is that it moves with the phone. That implies to me that Location Services is not using the VBOX Sport data.

Now turn on Airplane mode and enable Wi-Fi and Bluetooth and make sure the VBOX Sport is connected and has a GPS fix. Open Maps. Do you see a blue dot surrounded by an expanding blue ring? I don't. The blue dot and the ring are fixed. That is not the case when I have an Emprum Ultimate dongle plugged in. I get the blue dot and expanding ring that moves with the phone.

My VBOX Sport was returned to the factory where they were unable to replicate my problem. I have tried several iOS devices and always get the same behavior.
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bulls23
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VBOX Sport Experiment

Post by bulls23 »

Here's a little demo video. For me the location stays wherever the box is, no moving around with the phone as long as Bluetooth connection is working. I was around 20m away from the box while making the video. Especially at the end of the video, when I switch back to Bluetooth you can see that it takes some time before the Maps App picks up the new GPS source. One more info, my location with no Bluetooth is much too close to the VBOX's position in the video. As I said, I was 20m away, the internal sensor GPS lock must have been pretty bad that moment, the position of the VBOX is correct:

http://www.youtube.com/watch?v=Bo5NU2SF ... tube_gdata
gplracerx
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Re: VBOX Sport Experiment

Post by gplracerx »

Are you using iOS 6.1.3?
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bulls23
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Re: VBOX Sport Experiment

Post by bulls23 »

gplracerx wrote:Are you using iOS 6.1.3?
iPhone 5 running 6.1
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Harry
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Re: VBOX Sport Experiment

Post by Harry »

Some new insights into the way the Map view uses location services:

Image Image

In both snapshots I drive from South to North - that is the main direction. Actually both snapshots are taken with only a few seconds in between. The first one - entering the highway - leads into a tunnel I leave on the seconds snapshot. So far only to understand the scenario - the tunnel is not important for the rest of the mail.

The very interesting thing is the dots are ahead(!) of the current position shown! This effect became stronger when driving faster. This obviously means both positions come from a different source - the dots are added by LapTimer using the VBOX positions delivered directly, and the blue position is delivered by the internal sensor / location service! Initially I expected that both LapTimer's direct access and iOS's location service access the VBOX position... But thinking a bit about it from a technical side should make clear that is not possible. Why? When the VBOX is connected to the iPhone without an app like LapTimer accessing the data directly, its data is integrated into iOS's location service. This means the internal sensor is turned off and the VBOX data is feed into any app requesting positions. The update rate one can achieve is 10 Hz here - more is not possible as the BT bandwidth is used up utilizing Apple's integration lingo. The 20 Hz delivered by the VBOX are only accessible when using LapTimer's special integration based on RL's proprietary and compressed protocol. As the Map is not aware of LapTimer's position knowledge, it requests positions from Location Service. Given the bandwidth discussion, it would certainly not be possible to integrate the Location Service with the VBOX using the 10 Hz update rate and LapTimer's 20 Hz integration at the same time. So my assumption is the RL engineers did the following:
  1. The VBOX Sport usually integrates into iOS's Location Service. So when any app requests position information through Location Service, it enabled the Made for iPhone integration and delivers VBOX positions at 10 Hz. The internal GPS is turned off.
  2. Once an app accesses the VBOX directly, it disconnects from Location Service to have the full bandwidth available for the direct integration (delivering 20 Hz). As LapTimer does not access the Location Service while the VBOX is connected, the Location Service is not active.
  3. But there is a special refinement of item #2: when switching to the Map view in LapTimer, things change. The map objects accesses Location Service - not LapTimer's position information. This means Location Service turns on (the small arrow appears in the status bar) - and used the internal sensor (because the VBOX has made itself unavailable).
I believe all of this should be in line with the observation you guys made - and it is what can be done from an architectural side. There is one issue from my point of view: once the Map has been opened once in LapTimer, Location Service stays active - even when leaving it. The Map object is sitting in background and does not close the connection. LapTimer will remove the Map object in low memory situations - but this can be after hours. To make sure the internal sensor is off after having entered the Map view, one needs to actually kill the app and restart it.

Quite an expert thread...

- Harry
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gplracerx
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Re: VBOX Sport Experiment

Post by gplracerx »

There is one issue from my point of view: once the Map has been opened once in LapTimer, Location Service stays active - even when leaving it. The Map object is sitting in background and does not close the connection. LapTimer will remove the Map object in low memory situations - but this can be after hours. To make sure the internal sensor is off after having entered the Map view, one needs to actually kill the app and restart it.
Or you can turn off Location Services. You still get the fix dots on the map. In my experience when defining an autocross course, this drastically improves the accuracy of the POI locations. But that may be because I may have entered map mode at some point.
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Re: VBOX Sport Experiment

Post by gplracerx »

Update:

Upgrading to iOS 7 on an iPhone 4 seems to have fixed my problem with my VBOX Sport. It now seems to work as advertised. I hope that means that the frequency of dropped bluetooth connections will go down.
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Re: VBOX Sport Experiment

Post by Harry »

At least I can confirm Bluetooth stability is worse for Android :-(

- Harry
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Re: VBOX Sport Experiment

Post by gplracerx »

Harry,
The lag you see between the green fix dots and the blue location services dot appears to be a function of the connected GPS device. I get no lag at all with the XGPS160, a slight lag with the Emprum Ultimate and a huge lag with my VBOX Sport. On a short trip of a mile or so, the blue dot has been one minute behind with my VBOX Sport. The blue dot exactly follows the roads taken, but is way behind. That's with iOS 7. It didn't work with Location Services at all with iOS 6. Racelogic was unable to replicate this behavior with iOS 6 with my unit at their factory, however.
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Re: VBOX Sport Experiment

Post by gplracerx »

I got rid of the lag with the VBOX Sport by doing the Dual recommended reset: kill all running apps (which is done differently in iOS 7), forget all Bluetooth devices, reboot, re-pair. So maybe all the issues with Bluetooth in iOS have not gone away. I have to admit that I felt a certain amount of schadenfreude on hearing that Bluetooth is even less stable on Android.
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