Using external GPS receivers (iPhone)
CrewNerd works transparently with most external GPS receivers. Most GPS units have an app that you can use to pair the device with your phone and install firmware updates as needed. Once your GPS receiver is paired, CrewNerd will automatically use it whenever it is turned on and has a connection to your phone.
Some GPS receivers, like the Dual Electronics XGPS150 and XGPS160 support a sample rate up to 10 times faster than the iPhone, depending on the model and firmware version. This can provide smoother, more accurate speed and distance measurements in addition to extending your phone's battery life.
When using an external GPS receiver, be sure that no background applications are also using the iPhone location service as this may force the XGPS receiver to use the slower, standard sample rate.
When an external GPS receiver is providing "fast" samples (anything greater than one per second), CrewNerd will indicate this by adding a bullet character ("•") next to the units for the speed/pace data field.