Shortwave radios provide a means of communication between locations on Earth with minimal infrastructure. However, they have limitations, particularly in transmission rates for digital data, which are typically measured in hundreds of bits per second, unlike satellite communications.
Peter Bloom, founder of Rhizomatica, a nonprofit based in Philadelphia, has developed a digital shortwave-radio set called the High-frequency Emergency and Rural Multimedia Exchange System (HERMES). This system operates in the high-frequency (HF) band from 3 to 30 megahertz, alongside its digital modem, Mercury. Rhizomatica staff travel globally to remote areas in countries such as Bangladesh, Brazil, and Ecuador, utilizing HERMES to connect local communities to the outside world.
In an interview with IEEE Spectrum, Bloom explained how HERMES enhances data rates and encryption for shortwave radios. He described the system's ability to use the ionosphere as a satellite or mirror, enabling the transmission of information, voice, and data over long distances. With small radios that output around 20 watts of power, HERMES can establish reliable links between radios over distances of 400 to 600 kilometers, particularly in areas lacking terrestrial infrastructure.
HERMES is designed as a software stack that allows for the transmission of various file types, including photos, emails, and voice memos, as opposed to just voice communication. Bloom emphasized the importance of sending data in emergency situations, where individuals can transmit their GPS coordinates and other critical information quickly and efficiently.
Regarding the inclusion of encryption, Bloom noted that regulations vary by country for amateur radio operators. The encryption feature is optional and was implemented to protect sensitive information for partners operating in vulnerable areas. An example of HERMES in action involved a pilot project with artisanal fishers in Bangladesh, where a boat in distress was able to send an SOS and GPS position, facilitating a successful rescue operation.
This article appears in the October 2026 print issue as “Peter Bloom.”