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How Hermes Uses the Ionosphere to Link Remote Communities

by Margo AndersonIEEE Spectrumpublished

Hraness cites a source capture. The source author remains the source.

IEEE Spectrum's Margo Anderson interviews Rhizomatica founder Peter Bloom about HERMES, an open-sourced HF shortwave stack and Mercury modem that push file transfer and optional encryption onto radios that otherwise crawl at hundreds of bits per second. Small ~20 W sets bounce off the ionosphere for reliable 400–600 km links in places too hard for terrestrial infrastructure. Field work in Bangladesh, Brazil, and Ecuador includes a Bay of Bengal SOS that coordinated a crew rescue.

  • Ionosphere as the satellite. HERMES uses HF (3–30 MHz) skywave reflection instead of orbiting infrastructure, so sparse radios can reach distant peers with little ground gear.
  • Files beat voice for ops. Photos, GPS coordinates, manifests, parts lists, and telemedicine notes travel as files rather than read aloud over the air.
  • Encryption is optional by design. Ham rules differ by country; partners in sensitive areas can enable encryption when cleartext capture would put them at risk.
  • Impact shows up offshore. Artisanal fishers in Bangladesh used HERMES GPS plus SOS traffic to rescue a boat 100–200 km into the Bay of Bengal.
  • Throughput stays modest but usable. Ordinary shortwave digital rates are often hundreds of bits per second; HERMES treats HF as a data pipeline for real messages, not broadband.

We use the ionosphere as our satellite—or mirror—which helps us move information, voice, and data over really long distances.

Peter Bloom, describing skywave as the long-haul path.

we can pretty reliably do 400- to 600-kilometer links between two radios.

Peter Bloom, stating power and range for remote links.

HERMES allows you to send pretty much any file.

Peter Bloom, framing HERMES as an HF data pipeline.

They were able to send their GPS position and an SOS that they were having trouble.

Peter Bloom, recounting the Bay of Bengal rescue.