Trimble MB-Two

The Trimble MB-Two RTK GPS receiver is a high-end, dual-frequency RTK GPS module that can be configured as either base or rover.

In addition to providing precise position information, the MB-Two can estimate heading angle (it has dual-antenna support). This is useful for situations where a compass cannot provide reliable heading information, for example when flying close to metal constructs.

Required Firmware Options

The following firmware options need to be selected when buying the device:

• [X] [2] [N] [G] [W] [Y] [J] for 20Hz position updates and RTK support, 1cm horizontal and 2cm vertical position accuracy
• [L] LBAND
• [D] DUO - Dual Antenna Heading
• [B] BEIDOU + [O] GALILEO, if needed

Antennas and Cable

The Trimble MB-Two requires two dual-frequency (L1/L2) antennas. A good example is the Maxtenna M1227HCT-A2-SMA (which can be bought, for instance, from Farnell).

The antenna connector type on the device is MMCX. Suitable cables for the above antennas (SMA connector) can be found here:

• 30 cm version
• 45 cm version

Wiring and Connections

The Trimble MB-Two is connected to a UART on the flight controller (GPS port) for data.

To power the module you will need a separate 3.3V power supply (the maximum consumption is 360mA).

The module cannot be powered from a Pixhawk.

The pins on the 28-pin connector are numbered as shown below:

Configuration

For heading estimation the two antennas need to be on the same level and at least 30 cm apart from each other. The direction that they are facing does not matter as it can be configured with the GPS_YAW_OFFSET parameter.

Configure the serial port on which the Trimple will run using GPS_1_CONFIG, and set the baud rate to 115200 using SER_GPS1_BAUD.

To activate heading fusion for the attitude estimation, set the EKF2_AID_MASK parameter to enable GPS yaw fusion.