--- title: Horizon Aircraft Installation description: "Install Horizon in your craft: wire it to the flight controller and power, mount it, place and connect the LOS and SAT antennas, and verify power-up." url: "https://docs.somewear.app/unmanned/installer/receive/aircraft-unit-installation/" updated: "2026-10-22" requires: {} facets: hardware: - horizon: since: baseline client: [] satcom: [] --- ## General Guidance > **Caution** > > Ensure all power is off before making hardware connections. > **Caution** > > Do not transmit with antennas disconnected. ## Flight Controller Connection 1. Connect the flight controller interface cable to the **TELEM1** port on the flight controller board. The I/O connector is a 12-pin Molex Nano-fit. Refer to [Hardware Description](https://docs.somewear.app/unmanned/installer/receive/hardware-component-description/) for the full pinout. Connect UART\_TX (pin 4) to TELEM1 TX and UART\_RX (pin 5) to TELEM1 RX . For hardware flow control, connect UART\_RTS (pin 2) to RTS output and UART\_CTS (pin 3) to CTS input. 2. Connect VSUPP (pin 1) to the positive supply and GND (pin 7) to the negative/return lead of a 2S/3S LiPo battery or a high-quality regulated supply (6–13V DC). | Pin | Name | Type | Description | | --- | --------- | ------ | ---------------------------------------------------- | | 4 | UART\_TX | Output | UART TX data line | | 5 | UART\_RX | Input | UART RX data line | | 2 | UART\_RTS | Output | UART hardware flow control — RTS output from radio | | 3 | UART\_CTS | Input | UART hardware flow control — CTS input into radio | | 1 | VSUPP | Power | Main power input (6–13V DC) | | 7 | GND | Power | Power/signal ground — recommended: VSUPP return lead | ![Figure — Flight Controller Pinout](https://docs.somewear.app/_astro/flight-controller-pinout-detail.C1jn1PuJ_26G32m.svg) > **Note** > > The USB-C connector cannot be used to power the Horizon Hardware Unit. The I/O connector VSUPP pin is the only valid power input. > **Note** > > Keep power supply leads as short as possible and size them to accommodate peak current draw. See [Power Specifications](https://docs.somewear.app/unmanned/installer/specifications/power-specifications/) for current consumption data. ## Aircraft Mounting ### Thermal Considerations The unit requires no intensive thermal management, but must not be thermally coupled to other heat-generating devices without provisions for supplemental cooling. ### EMI Considerations The Horizon Hardware Unit contains board- and enclosure-level EMI shielding, but this shielding does not provide perfect isolation. Horizon should not be mounted in close proximity to significant sources of electromagnetic interference, such as spark-ignition engines and their ignition systems, brushed DC motors, large brushless DC motors, electronic speed controllers (ESCs), and alternators. Additionally, avoid co-locating Horizon with other radios operating within the 902-928 MHz LOS tuning range or the 1616–1626.5 MHz BLOS tuning range. If co-location is unavoidable, frequency deconfliction measures must be taken. RF coaxial cables carry sensitive signals and must be routed carefully. The coaxial shield attenuates interference but may still pick up common-mode noise, which degrades RF performance. - Do not route RF cables parallel and in close proximity to cables carrying high current or unshielded, unbalanced high-speed digital signals. - Keep RF cable runs as short as practical. Maximum recommended BLOS feedline loss is 3 dB. BLOS link quality depends heavily on a clear view of the sky. This is generally less of a concern for airborne units than for the GCS. - Avoid testing or operating BLOS indoors, surrounded by tall buildings, or under heavy tree canopy. - Iridium coverage is global, including polar regions. Inmarsat coverage is global between approximately ±82° latitude — GCS antenna placement should account for the look angle to the appropriate Inmarsat satellite. ## Antenna Placement — Aircraft > **Caution** > > The LOS1, LOS2, and SAT ports are standard-polarity SMA female jacks. Maximum mating torque is 5 in-lbs (0.57 N-m). Do not exceed this torque — excessive force may damage the connector. If additional vibration resistance is required, apply staking compound to the exterior of the connector after mating only. Do not apply compound directly to the connector threads. 1. Connect the two 915 MHz whip antennas to the **LOS1** and **LOS2** ports using the provided RP-SMA-to-SMA adapters and SMA coaxial extension cables. 2. Connect the Iridium satellite antenna to the port labeled **SAT** using an SMA coaxial cable. 3. Mount antennas to the aircraft airframe. Exterior mounting is preferred for all antennas; interior mounting is acceptable only if RF permeability of the compartment is specifically engineered. Ensure the Iridium antenna has an unobstructed view of the sky, with its main radiation lobe pointed toward the sky — consult the antenna datasheet for radiation pattern. 4. Maintain at least **33 cm (\~1 wavelength at 915 MHz)** of separation between each LOS antenna and nearby conductive objects, and at least **19 cm (\~1 wavelength at 1.6 GHz)** of separation between the BLOS antenna and nearby conductive objects. 5. Separate the two LOS antennas by a minimum of **8 cm**. Where possible, orient them at **right angles** to one another (e.g., one vertical, one horizontal) to gain polarization diversity. > **Note** > > Metallic materials and coatings are not the only conductors that may perturb an antenna. Many types of carbon fiber composites are also conductive and may de-tune antennas. Keep antennas clear of carbon fiber structures where possible. > **Caution** > > Do not violate the [absolute maximum RF ratings](https://docs.somewear.app/unmanned/installer/specifications/electrical-specifications/) even if acceptable performance appears achievable with less antenna separation. ## Power-On Verification 1. Power on the aircraft and flight controller. 2. Confirm the **STATUS** LED on the Aircraft Hardware Unit turns solid green (power good).