Custom Engineering · Platform and Payload Customization

Communication Link Configuration

Link configuration is specified against the worst point in the route, with the failsafe behaviour defined and tested.

6 of 10Method note

Overview

State the required link quality at the furthest and lowest point of the mission, not at the launch site.
Choose the band with the local spectrum environment in mind; congestion is site-specific and changes.
Define what the aircraft does on loss of link, and brief it as an operational procedure.
Test with the payloads running, at full power, because payload emissions are part of the link budget.

Design the link from the mission, not from the equipment

Link configuration is usually approached by choosing equipment and then discovering what it can do. The better order is to state what the mission requires of the link and then find equipment that meets it, because the three requirements — range, throughput and latency — trade against each other and the correct balance is mission-specific.

Range is how far the link holds. Throughput is how much it carries, which sets video quality and whether payload data can be downlinked at all. Latency is the delay between an event and the operator seeing it. For the same power and spectrum, more range generally means less throughput, and the latency characteristic is a property of the system rather than a setting.

So state them in mission terms. Pre-planned survey flights tolerate latency and care about little beyond command and control. Close inspection, flight near obstacles and any operation where the operator reacts to what they see treat latency as a safety parameter. Live video matters for the second group and often does not for the first.

Spectrum and the regulatory boundary

Which bands may be used, and under what conditions, is a regulatory matter that varies by country. Some require licensing, some are shared with other services, and some carry power or duty-cycle limits. This constrains equipment selection before any technical comparison, and it should be established for every market the programme will operate in.

Interference is the practical consequence of sharing, and it is environment-specific. A link that performs well in a quiet rural area can degrade substantially near transmitters, industrial equipment or dense infrastructure. Assess in the operating environment rather than in the demonstration environment.

Modern link equipment mitigates this by sensing the spectrum, selecting clear channels and hopping as conditions change. Where the operating environment is busy, that capability is worth more than raw power, because it addresses the cause rather than overpowering it. Our P-ELRS module is built for exactly that situation.

Geometry, terrain and lost-link behaviour

Most aerial links are substantially line-of-sight, and terrain, buildings and dense vegetation between the aircraft and the ground station degrade them non-linearly — partial obstruction can produce a large loss. Plan the link as a geometry problem: where will the aircraft be relative to the ground station, and what will be between them.

This has an operational consequence on long routes: the aircraft may fly beyond reliable link range while still well within flight capability. The answer is a relay, a moving ground station, or a mission designed to be autonomous past a certain point — decided in planning, not discovered in flight.

Lost-link behaviour must be configured deliberately and briefed. Whether the aircraft holds, returns, continues or lands on link loss is the difference between a link problem and a lost aircraft, and it should be a written setting rather than a default nobody checked.

Verification

Link performance is verified by flying the actual route with the actual ground setup and measuring: link margin at the route's extremes, latency under load, and behaviour at the point where the link degrades. Bench tests do not reproduce terrain, interference or antenna placement effects.

Antenna placement at the ground station is worth testing specifically. An antenna at ground level behind a vehicle or near the operator's body performs differently from one elevated and clear, and where margin is tight this is usually the cheapest improvement available.

This work is part of interface and integration testing and it runs alongside data link configuration on the product side, which covers selecting the equipment itself.

Commissioning a link configuration

Send the mission type, operating range, terrain and environment, the countries you will operate in, and what must be live versus recorded. We will propose a configuration and the antenna and lost-link settings that go with it.

We will also state the limits: the range at which the link degrades, the throughput available at that range, and the latency the system exhibits under load. Those are the numbers a planner needs and they are more useful than a headline range figure.

Contact our engineering team with your route and environment description, and see operating environment requirements where the environment itself is the constraint being designed around.