COFDM vs. IP vs. Mesh Video Data Links: Which Fits Your Mission

A video & data link is the component that turns "the aircraft flew" into "we saw what it saw, while it flew." Buyers routinely spec the airframe and the payload first, then discover that the link decided what the mission could actually do. This guide compares the three topologies that dominate professional procurement — digital point-to-point links (the family that includes COFDM-style multi-carrier modulation), IP-based long-range radios, and mesh networks — and keys each one to published numbers from the links we supply.

The three families in one table

What "COFDM" actually tells you

COFDM — coded orthogonal frequency-division multiplexing — is a modulation scheme, not a product class. It spreads a stream across many narrow carriers so that reflections off buildings and terrain stop destroying the signal. When a datasheet says COFDM, the practical promise is: it tolerates an imperfect sightline at short-to-medium range. It does not promise 100 km, and a vendor who implies otherwise is selling you a different problem to solve later.

The HM30 full HD system is this family done properly: dual-channel 1080p transmission at a specified 20 km range with 150 ms latency, carrying remote control, telemetry and video in one link, with dual-operator support on the ground unit and an OLED configuration display. For visual inspection, mapping sorties and any mission where a human is watching the feed, latency is the number that matters, and 150 ms sits in the "looks like a window, not a video call" band. The Fly More Combo exists for exactly the reason fleets fail — one spare air unit halves your downtime.

IP links: reach and spectrum discipline

The second family thinks like a network radio rather than a wireless camera cable. Our AEROLINK anti-interference series is representative: a 1.4 GHz operating band with real-time spectrum sensing and dynamic frequency hopping, custom band support, and ground-to-air ranges stepping from 30 km on the HK-T27 through 50, 100, 150 and 200 km up to 300 km on the HK-T46 with dual 40 W transmit power. Throughput is specified at 20 Mbps single-node (40 Mbps on the T27 class) — enough for one or two HD streams plus telemetry, not four 4K cameras.

Two procurement realities come with this family:

1. Spectrum is a legal question, not a specification question. 1.4 GHz licensing differs by destination country; the buyer obtains the licence, and custom frequency bands exist precisely so the radio can match whatever the regulator grants.
2. Range is bought with watts. The 300 km HK-T46 dissipates 172 W ±10 and weighs 1,082 g — that is a vehicle or rooftop ground system, not a backpack. The 30 km HK-T27 dissipates 8 W. Same series, completely different ground segment.

Interfaces tell you how it integrates: the T series exposes network ports, RS232, TTL and SBUS (configurable as RS422/485), and the larger members support up to three-node networking. If your mission is "fly a corridor beyond visual line of sight and stream one HD picture to a fixed control point," this is the right family, and you size it by the longest leg you must survive.

Mesh: coverage when the ground end moves

Mesh nodes are peers. Each radio relays for the others, so a vehicle around a corner, an aircraft behind a ridge, or a crew walking between buildings stays connected because the network finds a path — and if one node drops, traffic re-routes. The cost is arithmetic: every hop adds latency and splits the shared channel.

In our catalogue the HK-M series spans 50 km (HK-M30) to 300 km (HK-M46) with 40 Mbps maximum per node, combining mesh networking with the same spectrum-sensing frequency hopping as the T line. Two specialised members matter when you plan: the HK-D35 high-bandwidth mesh at 80 Mbps single-node for payload-heavy video, and the HK-X40 dual-band mesh at 150 km, which selects dynamically across a preset cross-band list — mesh plus spectrum discipline rather than either alone.

Choose mesh when you can name where the second and third nodes will sit: a rooftop, a vehicle, a tripod on the ridge behind the site. Choose it for UGV work, where the vehicle's own route is the reason line of sight keeps disappearing (long-range links for ground vehicles is a separate calculation).

The one-question-per-line checklist

• Who watches, and how far away? Operator in the same field → point-to-point HD. Remote operations centre → IP link with an explicit relay plan.
• Is latency a safety input? Close-proximity inspection demands a published figure under ~200 ms (HM30: 150 ms). Over-the-horizon survey tolerates several hundred milliseconds; it does not tolerate losing the link.
• Count streams against throughput. 20 Mbps is not 80 Mbps. One HD pod and a thermal feed are different budgets, and mesh divides further per hop.
• Say the band out loud. 1.4 GHz with hopping and custom-band support, or the congested licence-free 2.4/5.8 GHz gear that ships with consumer platforms. Know which you are buying, and what your regulator permits at what power.
• Size the ground segment. Mast height, antenna gain and whether the base station rides on a vehicle decide real-world range as much as the radio does; portable ground base stations exist in the same series for exactly this reason.

What it costs

The entry point for a professional full-HD link is the HM30 at $242 on the 5-unit EXW tier ($281 for the Fly More Combo) — frequently the cheapest line on the quotation and the one that most often decides whether the mission produced usable footage. The long-range AEROLINK family is configured per mission (band, antenna, node count), so it is quoted per set rather than list-priced: send the corridor length, the video budget and the destination country, and the proposal names the correct member of the T / M / S / D / X line.

Every figure above is published specification from the product pages, and priced pages carry the 5/20/50-unit tiers. When the topology question is settled, the video & data link category is where the sizing conversation starts.