Here’s the list of external GPS receivers to be used with RaceChrono. While RaceChrono supports many more receivers, these are the ones we recommend on buying based on our extensive testing. The devices are in order of most preferable first.

On iPhone and iPad:

1. RaceBox Mini / Mini S: Very reliable and accurate and updates at 25 Hz. Also has a built-in IMU sensor.
2. Qstarz BL-1000GT: This is Qstarz’s first receiver with iOS support. It’s very accurate and updates at 10 Hz. You also might consider the cheaper model without the memory card slot, BL-818GT (not to confuse with other devices with almost similar model name that do not support iOS).
3. Dual XGPS 160: Decent accuracy with GLONASS support and updates at10 Hz.

Notice: Popular Bluetooth GPS receivers like Qstarz BT-Q818XT/X and similar will not work on iOS.

On Android:

1. RaceBox Mini / Mini S: Very reliable and accurate and updates at 25 Hz. Also has a built-in IMU sensor.
2. Qstarz BL-1000GT: Very accurate and updates at steady 10 Hz. You also might consider the cheaper model without the memory card slot, BL-818GT (not to confuse with other devices with almost similar model name).
3. Dual XGPS 160: Decent accuracy at 10 Hz and supports GLONASS satellites.
4. Garmin GLO and GLO 2: You’ll get 7-8 Hz update rate and supports GLONASS satellites with decent accuracy.