G7VRD[/M]

Olivia

There are lots of ways of making contacts on Amateur Radio.
You can obviously use voice
You can also use digital modes. These convert your typed message into audio, which is then sent out over the air. The other end detects the audio, and converts it back into text, in much the same way that modems do.
However, the difference between modems using phone lines, and digimodes using HF is that HF is much less reliable.
Some problems include:

This means that a good digimode has to have error correction in it, which usually takes the form of Forward Error Correction. This is where extra data is sent, to allow the receiving end to reconstitute parts of the message stream that were lost. Forward Error Correction avoids the need for requests for expensive and time consuming resending of parts or all of the message. The point of amateur radio is to make contacts. A contact isn't always a 15 minute natter. It's exchanging information correctly and without errors.
So a good digimode in my mind has to have robust error correction.
Obviously, the more Forward Error Correction applied, the larger the message sent, and the longer it will take. However, I prefer a mode that sends slowly, but is correct over one that is fast, but has lots of uncorrected errors. Olivia is one of these modes.

One of my favourite modes is Olivia. It is a multi frequency-shift keying mode.
It has various versions of the mode, which use differing number of tones, and differing bandwidth. These variations give a wide range of speeds and signal sensitivity.
I have compiled the following table which details the length of time in seconds to send a specific piece of text, and is ordered by the fastest Olivia mode first.

Speeds

NameTonesBandwidthSeconds
Olivia 2/10002100012
Olivia 4/10004100012
Olivia 8/10008100015
Olivia 2/500250020
Olivia 16/100016100021
Olivia 4/500450021
Olivia 8/500850027
Olivia 2/250225038
Olivia 4/250425039
Olivia 16/5001650041
Olivia 8/250825051
Olivia 2/125212575
Olivia 4/125412575
Olivia 16/2501625080
Olivia 8/1258125100
Olivia 16/12516125157
Olivia 32/1000321000?

I can't quite see what the relationship between the tones, bandwidth and speed is, which is why I thought I'd publish this.

Sensitivity

Here are the same modes, but sorted by maximum sensitivity (found on various pages

NameTonesBandwidthMax S/N (dB)
Olivia 4/1254125-15
Olivia 8/2508250-14
Olivia 16/50016500-13
Olivia 4/2504250-12
Olivia 32/1000321000-12
Olivia 8/5008500-11
Olivia 16/1000161000-10
Olivia 4/5004500-10
Olivia 2/100021000
Olivia 4/100041000
Olivia 8/100081000
Olivia 2/5002500
Olivia 2/2502250
Olivia 2/1252125
Olivia 16/25016250
Olivia 8/1258125
Olivia 16/12516125

If anyone knows what the formula is for calculating the rest, get in touch.

Frequencies

Because Olivia can be successfully decoded down to the level where the signal is hard to hear with the ear or see on a waterfall, the usual method of scanning around the frequencies searching for signals doesn't work as well.
For this reason, standard frequencies for Olivia have been adopted. Here is a table of the frequencies I am aware of.
Please note - these are centre frequencies. The centre frequency is your dial frequency, plus your audio offset. I don't understand why people give the frequency as dial frequency + audio offset.

FrequencyModeNotes
1808.7516/500
1809.2516/500
1826.98/250Calling frequency
1840.7516/500
1841.2516/500
3522.7516/500
3523.032/1000
3572.98/250Calling frequency
3577.7516/500
3578.032/1000
3583.2516/500
3616.032/1000
3621.032/1000
5368.0Be careful on 60, as different countries have different allocations
7043.2516/500
7072.98/250Calling frequency
7073.2516/500
7076.2516/500
10142.2516/500
10142.98/250Calling frequency
10143.2516/500
14072.98/250Calling frequency
14075.416/500
14076.416/500
14078.416/500
14106.532/1000
14107.532/1000
14108.532/1000
18102.98/250Calling frequency
18103.416/500
18104.416/500
21072.98/250Calling frequency
21087.2516/500
21087.7516/500
21130.2516/500
21153.532/1000
21154.532/1000
24922.2516/500
24922.98/250Calling frequency
28076.7516/500
28077.2516/500
28122.98/250Calling frequency
50087.2516/500
50287.2516/500
50292.2516/500
144136.2516/500

Even if you can't hear anything on the calling frequencies, leave your radio decooding on them. There might be a signal there that you can't hear.