September 1, 2015 at 12:45 am #461
As part of what we’ve covered in the past, internal GPS systems of the phones are decent for lap time only. They sample at around 1x per second (1Hz) but sometimes they aren’t as accurate as we would want. Most of this depends on the phone. Generally, the higher quality the phone, the higher quality the components and the internal GPS of the phone. For example, iPhones tend to have pretty good location services and GPS sensors, partly due to the newer iPhone 6 and 6+ having a dedicated motion CPU. Higher end WP and Android phones are decent too.
However, sometimes you want as accurate as possible for lap timing, data overlay or to really analyze the data from your sessions. In come the external GPS systems that connect through Bluetooth.
We currently have support for external GPS accessories and coded in a way that it should adopt quite any accessory you use, however, we have done the most testing the QSTARZ products.
QSTARZ sells a few different products and we highly recommend using the 818XT as it offers the ability to sample at 5Hz and 10Hz, while the 1000eX samples at only 1Hz and 10Hz.
10Hz is great but quite frankly, it’s a little overkill and sometimes we get more garbage data from accessory than in 5Hz. Unless you have a very specific reason, 5Hz is more than enough and it is much more stable. Further, the 818XT tends to be ~$25-30 USD less than the Q1000eX.
To use an external GPS, first make sure the phone and the accessory are paired through normal Bluetooth protocols. Each phone will be slightly different on how to do this but it’s easy. If it asks you for a code to pair, just use ‘0000’. That should work.
Once they are paired, open Track Attack and go to record your session like normal.
In Windows Phone – the app will detect that you have a Bluetooth accessory connected and ask if you want to use that accessory? It will ask this each time, which is annoying but this is a limitation between WP and BT devices. The connection does not reliably stay and thus we do this to force the connection.
In Android – the first time you start a session, it will be using the internal GPS by default. Click on the GPS radio button to the right side of the screen and select the QSTARZ from the list of BT devices. From then on, TA will try to use this as the default, if it is connected.
You can check to validate it is using the external GPS through the record screen as it will show the GPS source (Internal = Internal or it will show the brand of the device you are using).
Last thing is try to actually mount your external GPS somewhere on your car where there is a direct line of site to the sky. I mount mine on the front of the car, about halfway up the roll cage tube that is near the A-Pillar. I have it zip-tied in place ‘permanently’ and a dedicated power chord connected to it so that it is always good on battery.
That same USB charger (connected to my cigarette outlet) provides a cable to the GoPro camera (another topic) and the phone. In short, unless I accidentally forget to connect a device, I am good to go on power.
I’ve seen people put the QSTARZ on their dash and closer to the inside edge of the dash. Most of the time it is fine but at tracks like Pacific Raceways, where there is a downhill section that is covered by towering trees, I have seen them lose GPS accuracy. I’ve seen AIM products (full on MXL based solutions) also loose GPS signal at that section of the track.
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