The Aerotenna uLanding altimeter is compact microwave rangefinder that has been optimised for use on UAVs. With a sensing range of 45m, it is useful for applications including terrain following, precision hovering (e.g. for photography), anti-collision sensing etc. Particular advantages of this product are that it can operate effectively in all weather conditions and over all terrain types (including water).

The rangefinder is not automatically included in most firmware, and hence cannot be used just by setting a parameter through QGroundControl (as is possible with some other rangefinders). To use it you will need to add the driver to firmware and update a configuration file to start the driver on boot. The sections below explain how.

## Supporting uLanding in Firmware

### Add the Driver to the Firmware

Add the following line to the cmake config file which corresponds to the target you want to build for:

drivers/ulanding


If you are running a Posix build and want to use the uLanding driver, your config file will need to include -D__PX4_POSIX in the add_definitions section. An example of how to do this is in either of the OcPoc config files (posix_ocpoc_cross.cmake or posix_ocpoc_ubuntu.cmake) - but you do not need an OcPoc as the driver will run on any Posix build.

### Start the Driver

Update the system to start the driver for the radar during system startup. You can simply add the following line to an extras.txt file located on your SD card.

ulanding_radar start /dev/serial_port


In the above command you will have to replace the last argument with the id of the serial port used to connect the hardware. If you don't specify any port the driver will use /dev/ttyS2 which is the TELEM2 port on Pixhawk. If either of the OcPoc config files are used (posix_ocpoc_cross.cmake or posix_ocpoc_ubuntu.cmake) the default port will be /dev/ttyS6.

If you are connecting the radar device to TELEM2 then make sure to set the parameter SYS_COMPANION to 0. Otherwise the serial port may be used by another application and you will get unexpected behaviour.

## Hardware Setup

The rangefinder is supported by any hardware which runs a NuttX or Posix OS and which can offer a serial port for the interface. Minimally this will include most, if not all, Pixhawk Series controllers.

You can connect to any free serial port - e.g. TELEM2, but you will need to start the driver on this port (as above).