Swarm Vs. Iridium: Which Satellite IoT Service Is Right For You?

In a world where it seems like everyone’s face is glued to a device screen, the idea that wireless service might be anything other than universal seems just plain silly. But it’s not, as witnessed by vast gaps in cell carrier coverage maps, not to mention the 70% of the planet covered by oceans. The lack of universal coverage can be a real pain for IoT applications, which is a gap that satellite-based IoT services aim to fill.

But which service is right for your application? To help answer that question, [Mike Krumpus] has performed the valuable work of comparing the services offered by Swarm and Iridium in a real-world IoT shootout. On the face of it, the match-up seems a little lopsided — Iridium has been around forever and has a constellation of big satellites and an extensive ground-based infrastructure. But as our own [Al Williams] discovered when he tested out Swarm, there’s something to be said for having a lot of 1/4U Cubesats up there.

[Mike] picked up the gauntlet and did head-to-head tests of the two services under real-world conditions. Using the same Swarm development kit that [Al] used for his test, alongside an Iridium dev board of his own design, [Mike] did basic tests on uplink and downlink times for a short message on each service. We couldn’t find specs on the test message length, but Swarm’s FAQ indicates that packets are limited to 192 bytes, so we assume they’re both in that ballpark. Iridium was the clear winner on uplink and downlink times, which makes sense because Swarm’s constellation is much smaller at this point and leaves large gaps in coverage. But when you consider costs, Swarm wins the day; what would cost over $1,500 with Iridium would set you back a mere $60 with Swarm.

The bottom line, as always, depends on your application and budget, but [Mike]’s work makes it easier to do that analysis.

A Hybrid Helical Antenna For The Es’hail-2 Geosynchronous Repeater

Amateur radio operators like to say that working a contact in space can be done with a simple handheld transceiver and a homemade antenna. And while that’s true, it’s true only for low Earth orbit satellites such as the ISS. If you want to reach a satellite in geosynchronous orbit it’ll take a little more effort, and this dual-feed helical “ice cream cone” antenna could really help.

Until recently, the dream of an amateur radio repeater in geosynchronous orbit remained out of reach, but that changed with the launch of the Qatari satellite Es’hail-2 last year. Since then, hams from Brazil to Thailand have been using the repeater, and UK-based [Tech Minds] has been in the thick of the action. The antenna he presents is a hybrid design, needed because of the 2.4-GHz band uplink and 10-GHz downlink on the satellite, also known as QO-100. Both require a largish dish antenna, with the downlink requiring a low-noise block downconverter (LNB) and feed horn. The uplink side of [Tech Minds]’ antenna is a helical design, with three-and-a-half turns of heavy copper wire and a tuning section of copper strapping that attaches directly to an N-type connector. The helix is just the right size for the feed horn of an LNB for the downlink side, nestled in a hole in the helical antenna’s aluminum reflector disc. There are 3D-printed parts to support everything, plus a cone-shaped radome to keep it all safe from the elements.

It looks like a great design, but sadly, North American and East Asian hams can only dream about building one, since QO-100 is below the horizon for us. We’re jealous, but we’re still glad the repeater is up there. Check out this article for more on how Es’hail-2 got the first geosynchronous ham repeater.

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