SIYI Technology (Shenzhen) Co., Ltd. HM30 Full HD Digital Image Transmission

The HM30 from SIYI Technology (Shenzhen) is a digital Full HD transmission system for video and data, meant for commercial mid-size multicopters and supporting two operators. It belongs to the class of combined systems that carry video, control and telemetry over one connection, built for inspection, mapping and camera work, not for racing or freestyle.

The picture is 1080p, and latency is 150 ms according to the product page. That is clearly more than digital FPV systems and is enough for camera moves, not for fast flying by goggles. The manufacturer gives the 20 km range for clear line of sight and without distinguishing FCC from CE; under CE rules it often turns out clearly lower in practice, so it is not a planning figure for the EU. The system provides 16 communication channels. The air unit weighs 74 g, or 109 g with a voltage module for 4S to 18S, and measures 70 x 55 x 16 mm including the fan.

In the EU, equipment may be operated only in the approved frequency ranges and power levels; for a system advertised with 20 km range, the CE conformity of the version delivered should be clarified before use. In the open category visual line of sight applies; long ranges are no selection criterion there, but they are for operations in the specific category.

When choosing, supply counts: the 4S to 18S voltage module makes the system usable with batteries of different size but costs 35 g of extra weight. A fan is a wear part that suffers in dust and moisture, and heat dissipation of the air unit has to be planned in the aircraft. Antennas and connectors are the mechanical weak points.