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Specifications
- Ublox ZED-F9P GPS Receiver
- Ultracap backup power for fast (hot-start) restarts
- EMI shield over receiver for improved EMI immunity
- IST8310 Magnetometer
- Safety-switch and safety LED
- RGB LEDs for status indication
- NCP5623CMUTBG I2C Driver
- BMP388 Baro on I2C bus
- External, active antenna (Maxtena M7HCT)
- SMA connector
- STM32 MCU for future CAN-based communication
- FW updates through USB connector
- Connectivity:
- USB-C
- 2-way USB Switch to MCU and F9P
- SMA for active antenna (20mA max)
- 4-pin CAN Bus (dronecode compliant)
- 8-pin UART/I2C
- Power:
- Input from either (diode OR'd):
- USB (5V)
- CAN (4.7 to 25.2V)
- UART (4.7 to 25.2V)
- Power Consumption <1W
The performance of RTK over long distances is typically limited by:
- Telemetry link: You must have a telemetry link between the aircraft and ground station,
- RTK degradation over distance: As the aircraft moves away from the base station, the RTK accuracy will degrade. The F9P RTK GPS receiver spec is 0.01m CEP (Circular Error Probability) + 1ppm for both vertical and horizontal.
- For example, at 10km distance from base station, the typical accuracy would be 0.01m + (1km * 1/1,000,000) = 0.02m CEP
GPS coordinates reported from this base station are centered around a point 35mm from the base of the antenna.
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For use on Alta, the following is necessary:
- Alta X
- Two RTK Modules (Rover and Base Station)
- Alta SW 1.3 or above
- Datalink (FRX Pro recommended)
- Computer (Mac or Windows) running Alta QGC 1.3 or above
- Sturdy mount for base stations GPS. Tripod with 1/4-20 mount is recommended
- USB C cable
Description | PN | I2C Address (7-bit) |
RGB LED Driver | NCP5623C | 011 1001 ($39) |
Barometer | BMP388 | 111 0111 ($77) |
Magnetometer | IST8310 | 000 1110 ($0E) |
Peripheral CANbus for future expansion.
Pin | Signal | Voltage (V) |
1 | VCC | +5V to 25.2V |
2 | CAN_H | +5V |
3 | CAN_L | +5V |
4 | GND | GND |
Peripheral CANbus for future expansion.
Pin | Signal | Signal Notes |
1 | VCC | +5V to 25.2V |
2 | SERIAL: FC to GPS | 3.3V TTL |
3 | SERIAL: GPS to FC | 3.3V TTL |
4 | I2C-SCL | |
5 | I2C-SDA | |
6 | SAFETY SWITCH | 3.3V = PRESSED 0V = NOT PRESSED 4.7k pull-down |
7 | SAFETY LED | 3.3V, pull low to turn on LED.
20mA sink |
8 | GND | GND |
The following antennas have been tested with the Freefly RTK GPS module:
- Maxtena M7HCT
- UBlox ANN-MB multi-band antenna
The Freefly RTK modules are shipped with Maxtena M7HCT multiband antennas. However, the GPS is compatible with other SMA, L1/L2 multiband antennas.
The IST8310 defines its coordinate system using left-hand rule, which is corrected in PX4 to be right-hand. Orientation is shown below in both native and PX4-corrected coordinates.
When installed on Alta X, the PX4 orientation is with respect to the front-left vertical mounting surface. In other words, when installed on the front-left (where the standard GPS is installed), the "external mag" orientation should be set to Yaw 0° (ie, No rotation). When installed on the diagonal side (rear-right), the orientation should be set to Yaw 180°.
Last modified 1yr ago