Hellschreiber

Compared to contemporary teleprinters that were based on typewriter systems and were mechanically complex and expensive, the Hellschreiber was much simpler and more robust, with far fewer moving parts.

[clarification needed] It has the added advantage of being capable of providing intelligible communication even over very poor quality radio or cable links, where voice or other teledata would be unintelligible.

Any on-signal could in any case last no shorter than 8 ms, however, both because of having to restrict the occupied bandwidth on the radio, but also for reasons having to do with the mechanical makeup of the receiving machinery.

Improvements that came as a result of software implementation: Hellschreiber has also spawned a number of variants over the years, many of them due to radio amateur efforts in the 1990s.

Examples of them are: Slowfeld is an experimental narrow band communication program that makes use of the Hellschreiber principle – requiring that the transmitter and receiver both use the same column-scan speed.