With the popular WSJT FT8 digital mode absolutely taking over the high frequency bands, some among us have been left looking for a return to something with little more… personality.
There’s something to be said about digital modes that offer the next generation of amateur radio operators a classic take on modern text-based communication. This series of blog posts is designed to showcase some of the interesting, but lesser known digital modes available.
Olivia: The Magical Mode
Olivia was first developed in 2003 by Paweł Jałocha with the intent to improve upon weak signal communications. It is a high duty cycle transmission mode which enhances the popular multi-shift frequency keying (MFSK) technique, providing an additional layer of forward error correction. It is this additional layer of error correction that allows Olivia to be a high signal-to-noise ratio champion.
The modulation layer of the Olivia transmission system in the default mode sends one of 32 tones at a time. Each tone thus constitutes a symbol that carries 5 bits of information. For the FEC code, 64 symbols are taken to form a block. Within each block one bit out of every symbol is taken and it forms a 64-bit vector coded as a Walsh function. Every 64-bit vector represents a 7-bit ASCII character, thus each block represents 5 ASCII characters.
This way, if one symbol (tone) becomes corrupted by the noise, only one bit of every 64-bit vector becomes corrupt, thus the transmission errors are spread uniformly across the characters within a block.
This all adds up to a mode that is capable of clear and readable ASCII text, while using weak signal transmissions up to 10-15 decibels below the noise floor. Not unlike the popular FT8 mode, Olivia shines in the worst of band conditions, enabling a rag chew style conversation.
A Word About Bandwidth
There are 40 Olivia bandwidth and tone combinations available. Each offers more or less bandwidth occupation in the spectrum, leading to faster or slower transmissions, depending on the bandwidth and number of tones. The most commonly used formats are 500/8, 500/16, 250/8, 1000/32, and 1000/16. You’ll find that the popular software offerings for this mode will allow users to easily switch between formats when desired, even mid-QSO.
Where Can I Find It?
Olivia signals can frequently be decoded by software even when the signal is so weak that it barely registers on a waterfall spectrum display. This means decoding is often possible even when you can’t hear the signals. As a result of this, the Olivia community has undergone voluntary channelization of communications. This means that Olivia can be found on very specific frequencies in each band; operators can easily find each other and relocate to another frequency.
Olivia can be found in all major digital HF software offerings including the commercial Ham Radio Deluxe and open source FLDigi. It’s as simple as running the software, connecting it to your transceiver, and calling CQ on one of the standard Olivia frequencies.
I recently experienced my first QSO in the Olivia mode for the first time and it was a lot of fun. Operating my Elecraft KX2 at 10 watts with an (indoor!) magnetic loop antenna, I sought out to make contact on the 40 meter band. Antenna pointed north / south I called CQ. Immediately after calling it once, I received a reply from Dan (VE9DAN) approximately 450 miles to the northeast of my station. Not bad considering how terrible the band conditions were and the nature of my compromised indoor antenna. I was able to clearly communicate with Dan (thanks to his patience) and had a nice chat. All in all, it was a great QSO and I will definitely be exploring this mode more.
If you’re looking for an easy to use, high noise tolerance digital mode, take a look at Olivia. Please let me know of your experiences with the Olivia mode in the comment section below.