You can use many of the nRF apps available in the Google Play store and using one of those BLE apps, connect the phone to any of SDK ble_peripheral examples flashed into your nrf device. Then test until how far they keep connected.
You can use many of the nRF apps available in the Google Play store and using one of those BLE apps, connect the phone to any of SDK ble_peripheral examples flashed into your nrf device. Then test until how far they keep connected.