> For the complete documentation index, see [llms.txt](https://docs.phoenixlidar.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.phoenixlidar.com/hardware-and-interfaces/navbox/air-navbox/questions-and-troubleshooting.md).

# Questions & Troubleshooting

## The unit is unable to obtain GNSS time synchronization which prevents the system from collecting data.

For single GPS antenna setups, please make sure that the external GPS antenna is connected to the GPS1 port on the front-panel of the AIR NavBox. Connecting the antenna to the GPS2 port will result in the unit not synchronizing GNSS time. 

## The Status LED keeps blinking blue in a fast sequence even though a micro SD card is inserted in the card slot.

In most cases, this will be caused by a wrongly formatted SD card which results in the unit not recognizing the SD card at all.\
\
All SD cards need to be formatted in the **exFAT file system** in order for the unit to detect the card.

## Is the micro SD card the only storage option or can an external drive be connected for data collection?

At this time, the micro SD card is the only storage option available. Connecting external drives such as a USB hard drive is not supported.

## The status LED stays constant RED after powering on the unit and no connection to the unit via SE seems possible.

This might indicate that the on-board CPU has not booted yet. Please check if the CPU button light is BLUE. If not, power on the CPU manually by pressing the CPU button once. The CPU button light should then turn blue.\
\
If the CPU will not turn on after pressing the CPU button, please unplug the power supply from the unit and let it sit for at least 1 to 2 minutes. Then reconnect power and check if the CPU button turns blue.


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