I tend to use the gps for the speedo, the factory speedo reads faster then what the car is doing, but, i do also watch the obd speedo. Where i live in australia there's a couple of radar speed traps that just flash up the speed limit if your over so i've been able to test the gps to obd speedo.

But, do not take the gps speedo as the gospel truth in speed. I've tested that out between my android nuvifone, my old garmin gps and some cheap gps that the father-inlaw has. They all read about 2km difference between each one. It also depends on the day as well with how many satellites are above you to just how accurate the receiver is. Most days my accuracy is around 2 metres, on occasion its been around 12 metres.

The obd speedo will stay the same with its accuracy day in, day out. The only time it'll change is when the size of the tires are changed or the diff or something on the car.

Hi!

GPS is very accurate at measuring distance travelled, and also when measuring speed whilst travelling at a constant velocity.

For faster updates, the OBD speed will be the best choice, it's usually pretty accurate as well.

Speedometers in instrument clusters will always be calibrated to over-read. However the speed as provided by your OBD link will be very accurate (to within about 0.1 to 0.3mph)

There's also a GPS vs OBD speed difference widget to show how much your OBD speed is out when travelling at a constant velocity.

Quote from admin on July 19, 2011
There's also a GPS vs OBD speed difference widget to show how much your OBD speed is out when travelling at a constant velocity.

Is it possible to graph both the OBD & GPS speeds?
Would be nice to see graphically how they differ as speed increases.

Just set torque to log both GPS and OBD speed, then graph them manually in Excel afterwards!

Mobile phone GPS is actualy fairly reliable and repeatable, mobiles use aGPS, or assisted GPS. Basically where the GPS signal is lost due to trees/building etc, your location is still worked out using triangulation to network masts. Therefore dropout is not nearly as much an issue with the likes of torque as it is with other non aGPS based devices.

I don't think you are going to get one that is "more accurate" within a +/- 3 km range..

I've tried the following at the same time

1) Handheld GPS
2) Car mounted GPS
3) Phone GPS
4) Dash Board
7) OBD

None of them consistently agreed within 2-3 KM difference.. I'd have maybe 2-3 the same for 1 min, but after accel/decel I'd get different combination's.

even the Dashboard compared to the OBD where 4km difference (OBD was 4km lower then dashboard).

GPS is not very accurate at measuring velocity whilst your are accelerating or decelerating, but quite accurate when you are travelling at a constant velocity and direction, so seeing +/- 3mph difference between units sounds about right given the sampling time used for GPS and that each of your GPS units may well be sampling at staggered or different intervals

Dashboard speedometers are calibrated to over-read. OBD speed will be the most accurate (if you haven't changed wheel diameters) and typically can be below 0.3mph out. If you also have a high rate of change of direction or speed then it will definitely be the most accurate.

When travelling in a straight line, at a constant speed (with good GPS satellite coverage), then you will be able to see the difference between the OBD speed and the GPS speed where the GPS will be at it's most accurate.

HI Noob question here

I have a full track car, with a minimal engine wiring harness only, I do have an ODB-II.

I am looking to swap my regular gauges for the Torque software on a 7 or 8" tablet.

My question is what measures the vehicle speed, since I have a minimal wiring harness, I do not think I can get that information from the ODB-II, so I would have to rely on GPS

What would provide the GPS signal to the Torque software ?
Do you need a GPS enabled tablet/phone, and in turn does this need to have a connection with the internet to obtain the GPS info ?

Is there any tablet that you know of that has GPS build in that does not rely on an internet connection ?

Thanks in advance

Mike

Ian can you shed some light on my question ?

Thx
Mike

There are tablets that have GPS Witstech is one but I don't recommend it. I upgraded to a nook color($145 Refurbed) and cyanogen mod(full android) with an external bluetooth GPS mouse. So far it works great. Screen is bright and nook is fast. It works great with Co-pilot for mapping and Torque for information.

Thanks I was looking at the Galaxy Tab, that has GPS

The problem is that a lot of tablets state "assisted GPS", which means they do not work without internet connection

I am trying to find out if any GPS (assisted/non-assisted) will do for Torque,

Rather not spend $ 300 to find out it does not work, since I am not getting info from the ECU about the speed of the car

Mike

I believe the assisted GPS thing is more software based.
I currently have an HTC Desire HD (I know, it's a phone and not a tablet but hear me out).

My phone has A-GPS and GPS.
The A-GPS works with google maps (which download the map around where you are from the internet).
The GPS works with Route66, the maps are downloaded and stored directly in the phone (memory card) so when you're travelling with the GPS on and using Route66, it's feeding the GPS info direct into the map that's on the phone so there's no need for it to go online to pull up a new map section.

Thanks for the feedback

I am not looking to use maps in my track-only car, it is just to get the GPS info to Torque

Mike

Hi

Next version of the app will support external 10Hz bluetooth GPS units. It may be of interest to a couple of people.

Ian you know which GPS I have to get for it to work with Torque

Assisted or non assisted

I was planning on buying the Galaxy Tab 7" Wifi would that work, since I won't have internet on the track

Thx
Mike

If the tab has bluetooth you should be able to use a bluetooth gps unit

Yes it has Bluetooth, but I do not want to have x devices to get things done, I would like to have one device doing all that needs to be done, especially if that device is $ 300

Plus in the case of an extra GPS BT device I would have to share the Bluetooth with the GPS and the ODB-II device, and that in turn might not work well with torque

Hopefully somebody can chime in that has that combination

Thx
Mike

Some devices don't work well with multiple bluetooth connections, others seem to be perfectly fine - basically it's down to the version of android you are running, and the broadcomm bluetooth driver integration with the OS. If you find you get frequent disconnects over bluetooth, then you may have an affected handset. Torque will however attempt to work around several issues to keep a reliable connection going (after a lot of work getting around various bluetooth bugs)

Any android device with inbuilt GPS will work. A-GPS only affects the ability to lock on to a satellite (basically you download an almanac of pre-calculated satellite locations rather than wait for it to be received from each satellite), this then enables you to get a faster lock, but won't affect compatibility at any other level.

Any NMEA compliant external bluetooth GPS will also function with the app in the next update

Hi Ian,

Thanks thta is what I wanted to know
I rather not share the Bluetooth connection, one for one purpose especially since we will do a lot of logging while on the track

Thanks
Mike

The next version includes USB support for the OBD connection (so things like the Scantool.net OBDLink should work). It will however require Android 3.1 or above (Honecomb, and hopefully Ice Cream Sandwich versions of the OS)