# Why isn't my GPS getting a fix? ## GPS fix time expectations Getting a GPS fix takes time - particularly on a cold start (first power-on or after being stored). Under normal outdoor conditions:
ConditionExpected fix time
Cold start, outdoors, clear sky30 seconds - 5 minutes
Warm start (powered recently)5-15 seconds
Indoors, near window2-10 minutes (often fails entirely)
Indoors, no windowWill not get a fix
## Common Causes of No GPS Fix ### Indoors GPS signals are extremely weak (-130 dBm from satellites). They are heavily attenuated by buildings and concrete and effectively blocked by metal. High-sensitivity receivers can sometimes get a fix near a window, but reliable acquisition requires going outdoors with a clear view of the sky. ### Antenna not connected or loose Boards with a U.FL GPS antenna connector (T-Beam, some RAK boards) have a small snap-fit U.FL connector between the GPS module and the antenna. This connector can come loose in shipping. Open the case and verify the connector is fully seated - it should click into place. ### GPS module disabled in firmware If you (or a previous configuration) disabled GPS to save power, the module will not attempt to acquire satellites. For most users, the easiest path is the app: **Radio Config → Position → GPS Mode** → set to Enabled. Advanced (requires the Meshtastic command-line tool, a separate install, with the device connected over USB): ``` meshtastic --set position.gps_mode ENABLED ``` ### Power brownout If the GPS module is not receiving adequate voltage (often seen when running from a nearly depleted battery), it may fail to initialize. Try with a freshly charged battery or USB power. ### AGPS data expired Some boards support AGPS (Assisted GPS), which provides almanac data to speed up acquisition. If the AGPS data is stale (more than 2 weeks old), fix time increases significantly. Re-upload AGPS data via the app when connected to the internet. ## Testing GPS Without Going Outside Place the device on an outdoor windowsill with the GPS antenna facing up toward the sky. This is the minimum viable indoor setup for GPS - results vary significantly by window direction and whether metal frames or low-E glass are present. ## T-Beam GPS Note GPS modules vary by T-Beam variant: older T-Beam v1.x units use a Quectel L76K or NEO-6M module, while the newer T-Beam Supreme uses a different module and layout - so the specifics below apply mainly to the classic T-Beam, not necessarily the Supreme. The NEO-6M found in older T-Beam versions has been discontinued; Quectel L76K in newer units is generally faster to acquire. The GPS is connected to the ESP32 via UART2 - if you see GPS-related errors in the serial console, check that the GPS power is enabled (some T-Beam versions have a GPS power pin that must be asserted).