about & FAQ

absorptions is a blog about my hobbies. So far it's mostly about signals, electronics and programming, but may pick up a random new field at any point. It's a place for me to direct my need to talk nerdy. Why? I like the smell of unsolved mysteries. Call them obsessions or special interests; I call them absorptions.

Here I've collected some questions often asked in the comments section etc.

Contact info

How did you learn about signals and could you suggest literature?

See my nerd story. I learnt by spending most of my free time SWLing, programming, and reading for many, many years. This geeky stuff is what I've always enjoyed doing and I find it relaxing as well. It's like when some people like listening to heavy metal or reading manga, and end up having a lot of knowledge on the subject as a byproduct.

As an introduction to signals, The Scientist and Engineer's Guide to Digital Signal Processing is pretty good.

Do you do talks or workshops?

Yes, I've talked about my blog at several events, notably Chaos Communication Congress (CCC) in Hamburg, 44CON in London, and t2 infosec in Helsinki. See above for contact info.

Videos of some talks:

What's your decoding software of choice?

I like to write my de/modulators from scratch. Simple and hassle-free. They work on raw floating-point PCM using Perl's pack() and unpack() and the built-in trigonometric functions sin(), cos(), or I may write them in C/++ if high throughput is required. I use SoX for sinc filtering, resampling, and file format conversions. For simple FSK stuff, minimodem is the perfect choice.

Have you heard about GNU Radio?

I have heard about GNU Radio.

What kind of radio hardware you've used in this blog?

In most radio-related projects I've used a cheap USB DVB-T receiver stick, also known as RTL-SDR. Some FM radio related projects were done using a modified "worldband receiver".

What's the software you use to draw graphics and waveforms?

For waveforms I use my own program called oscille (explained in a blog post). Baudline renders beautiful spectrograms. For graphics design and compositing I use Inkscape, GIMP, ImageMagick, and librsvg.

So you're a 'hacker'. That means you break into computers? Could you hack my friend's Facebook account?

Contrary to popular belief, a hacker is someone who misuses technology to learn and control how it works. See hacker definition controversy. Why I originally labeled myself a 'hacker' is explained in this post. I won't hack your friend's Facebook account.

Hui, olet siis hakkeri. Ethän murtaudu tietokoneelleni?

Vastoin yleistä käsitystä hakkerit ovat tietokoneiden ja muiden teknisten järjestelmien toiminnasta, muuntelusta ja rakentelusta innostuneita harrastajia.

Will you decode this signal / write this program for me?

Yes, I can be paid to do reverse engineering, see contact details above.

What do you do for a living?

I work as a programmer.

What's your educational background?

I'm a High School graduate, see my nerd story.

What are you working on right now?

I always have some posts as drafts, but there are no rigid plans or schedules. Sometimes I take pauses of several months to think about other things that are outside the subject matter of this blog. These include classical music, photography, and the universe, broadly speaking.

How is your name pronounced?

It's /ɔ:nɑ/ ("awna") — not */unɑ/, as in English, but I'm used to it as well.

I have questions!

I'm on ask.fm.


  1. Discovered the dial-up poster last year. Loved it.
    Discovered your blog today. Enjoyed it.
    Saw that you have a radio license. Congrats!

    de VA1DF

  2. I grew up hacking telephone systems, A lot of this for me is the old school of tech. Still, I find your signals analyses really interesting. Thanks again.


  3. Hi

    Great blog! Would you mind sharing the details of the HW you use for your investigations?


    1. Thanks, I've added info about that.

  4. Hi Oona,
    I started to follow your blog some years ago, congrats, I love this stuff... A personal question came up (sorry I'm curious), what's your type/result of Myers-Briggs test?


  5. Oona, what is the baudrate of the human ear and auditory processing system? What I mean is that someone could listen to and process a morse code transmission at 300 letters per second using just a single frequency (and different durations). If we added more frequencies could we double or quadruple this rate?

    1. Googling around, seems there's a world record for CW RX from 1939, at 75 WPM = 6 letters per second.

  6. hi, if you didnt know there is a nice project on SDR, modem, codecs. There is even a physics defying low power tests... http://www.rowetel.com/blog/


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