When using UBLOX it is a good idea to use GPS auto configuration so your FC gets the GPS messages it needs.
Enable GPS auto configuration as follows `set gps_auto_config=1`.
If you are not using GPS auto configuration then ensure your GPS receiver sends out the correct messages at the right frequency. See below for manual UBlox settings.
Use UBox U-Center and connect your GPS to your computer. The CLI `gpspassthrough` command may be of use if you do not have a spare USART to USB adapter.
This will immediatly "break" communication to the GPS. Since you haven't saved the new baudrate setting to the non-volatile memory you need to change the baudrate you communicate to the GPS without resetting the GPS. So `Disconnect`, Change baud rate to match, then `Connect`.
Click on `PRT` in the Configuration view again and inspect the packet console to make sure messages are being sent and acknowledged.
Next, to ensure the FC doesn't waste time processing unneeded messages, click on `MSG` and enable the following on UART1 alone with a rate of 1. When changing message target and rates remember to click `Send` after changing each message.:
Next change the global update rate, click `Rate (Rates)` in the Configuration view.
Set `Measurement period` to `100` ms.
Set `Navigation rate` to `1`.
Click `Send`.
This will cause the GPS receive to send the require messages out 10 times a second. If your GPS receiver cannot be set to use `100`ms try `200`ms (5hz) - this is less precise.
Cleanflight will use `Pedestrian` when gps auto config is used.
From the UBlox documentation:
* Pedestrian - Applications with low acceleration and speed, e.g. how a pedestrian would move. Low acceleration assumed. MAX Altitude [m]: 9000, MAX Velocity [m/s]: 30, MAX Vertical, Velocity [m/s]: 20, Sanity check type: Altitude and Velocity, Max Position Deviation: Small.
* Portable - Applications with low acceleration, e.g. portable devices. Suitable for most situations. MAX Altitude [m]: 12000, MAX Velocity [m/s]: 310, MAX Vertical Velocity [m/s]: 50, Sanity check type: Altitude and Velocity, Max Position Deviation: Medium.
MTK 3329 | Tested on hardware serial at 115200 baud (default) and on softserial at 19200 baud. The baudrate and refresh rate can be adjusted using the MiniGPS software (recommended if you lower the baudrate). The software will estimate the percentage of UART bandwidth used for your chosen baudrate and update rate.