Reviving Teletext for Ham Radio

2026-04-22 · Source: IEEE Spectrum · Field: Technology & Digital — Software Development & Engineering, Artificial Intelligence & Machine Learning, Emerging Technologies & Innovation · Depth: Intermediate, short

Summary

The author explores the concept of teletext, a digital information service prevalent in Europe during the 1980s and '90s, exemplified by Ireland's Aertel. Teletext utilized blank lines in analog television signals to transmit a carousel of constantly updated pages, accessible via a three-digit code on remote controls. It featured a 40-by-24-character grid, enabling a full page of multicolor text to be stored in just one kilobyte of memory, half that required by systems like the Commodore 64. The system achieved high legibility for alphanumeric characters through the SAA5050 chip, which interpolated pixels to an effective resolution of 10 by 18 pixels. Inspired by its efficiency, the author developed "Spectel," a ham-radio version of teletext, using the AX.25 protocol to transmit teletext screens over VHF/UHF at 1,200 baud (11 seconds per screen) and HF bands at 300 baud (44 seconds per screen), with automatic data combination for corrupted rows. The Spectel system was developed using AI-assisted "vibe coding" with Anthropic's Claude.

Key takeaway

For amateur radio enthusiasts considering digital text transmission, Spectel demonstrates how teletext's efficient, legible format can be adapted for ham radio. You should explore implementing similar low-bandwidth, error-correcting protocols like AX.25 to reliably send information over HF bands, potentially leveraging AI tools for initial development to accelerate project timelines, while remaining mindful of the learning trade-offs.

Key insights

Teletext's low-bandwidth, legible text display on analog signals offers a robust model for digital information services.

Principles

• Low-bandwidth protocols enhance resilience.
• Character interpolation improves text legibility.
• Redundant transmissions ensure data integrity.

Method

The Spectel system transmits teletext pages via AX.25 protocol, encoding data as audible tones. It sends pages multiple times, allowing receivers to combine data for error correction, and uses Python for portability.

In practice

• Use AX.25 for low-bandwidth digital radio.
• Implement redundant data transmission.
• Explore AI for rapid prototyping of complex specs.

Topics

• Teletext Revival
• Ham Radio Applications
• AX.25 Protocol
• Vibe Coding
• Spectel System

Best for: Software Engineer, Creative Technologist, Domain Expert

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Editorial summary, takeaway, and curation by AIssential. Original article published by IEEE Spectrum.