Olivia MFSK

Lore & Background

The protocol was developed at the end of 2003 by Pawel Jalocha. The first on-the-air tests were performed by two radio amateurs, Fred OH/DK4ZC and Les VK2DSG, on the Europe-Australia path in the 20-meter amateur band. The tests proved that the protocol works well and can allow regular intercontinental radio contacts with as little as one watt RF power. Since 2005 Olivia has become a standard for digital data transfer under white noise, fading and multipath, flutter (polar path) and auroral conditions.

Olivia modes are commonly referred to as Olivia X / Y (or, alternatively, Olivia Y / X), where X refers to the number of different audio tones transmitted and Y refers to the bandwidth in hertz over which these signals are spread. Conversations using Olivia are by convention initiated using either Olivia 16/500 or Olivia 32/1000. Once communications have been established, the communicating parties mutually decide if another mode would better suit the current propagation conditions. The possible number of tones are 2, 4, 8, 16, 32, 64, 128, and 256, with higher numbers of tones giving more data redundancy but slower throughput. Available bandwidths are 125 Hz, 256 Hz, 512 Hz, 500 Hz, 1000 Hz, and 2000 Hz.

Since Olivia signals can be decoded even when received signals are extremely weak (signal-to-noise ratio of −14 dB), signals strong enough to be decoded are sometimes below the noise floor and therefore impossible to search for manually. As a result, amateur radio operators have voluntarily decided upon channelization for this mode. By common convention amateur stations initiate contacts utilizing the 8/250 mode and then switch to other wider-bandwidth modes to continue the conversation.

Reader's Guide

Olivia MFSK's significance lies in its ability to provide reliable digital communication under extremely adverse propagation conditions, including white noise, fading, multipath, flutter, and auroral conditions. Its two-layer forward error correction system—combining MFSK modulation with Walsh function coding—allows it to decode signals even when the signal-to-noise ratio is as low as −14 dB, meaning signals can be received below the noise floor. This capability has made it a standard for weak-signal work on the high frequency bands since 2005. The protocol's flexibility in tone count and bandwidth allows operators to adapt to changing conditions, trading throughput for redundancy as needed. The voluntary channelization established by the amateur community ensures that even imperceptibly weak signals can be properly tuned for reception and decoding, preventing interference and enabling reliable contacts. Olivia's legacy is as a robust, practical tool for intercontinental communication with minimal power, and it remains a benchmark for digital modes designed for difficult shortwave paths.