1. UNCERTAIN SUBSTANCE
TOM KEENE
A part of the Hands-On Ideas series
September 4th 2013

2. www.theanthillsocial.co.uk
Artist who critically engages with
technology.
Worked with bacteria, face recognition,
participatory/community arts.
Self taught programmer & maker: wood,
metal, electronics.
MA in Interactive Media: Critical Theory
& Practice in 2012, Goldsmiths
University, London.

3. Inspiration
Wirelessness “Radical Empiricism in
network cultures”: Adrian Mackenzie.
Open Systems Association (OSA)
www.opensystem.org.uk
YoHa: Graham Harwood + Matsuko
Yokokoji. www.yoha.co.uk
Evil Media: Matthew Fuller and Andrew
Goffey.
www.yoha.co.uk/sites/yoha.co.uk/evilmedia

4. What I wanted
to explore
How an algorithm is able to
construct the world we live in.
How it operates outside of any
design intent.
A different concept of control.
An open ended process led
methodology – make mistakes.

5. Uncertain Substance:
The Viterbi Algorithm
An algorithm searches radio waves looking
for conversations about money

6. About the project
Explored the history of the
algorithm.
Attempted to understand the
mathematics.
Built contraptions/devicesas a
means toreveal how it operates:
- Primitive transmitter.
- Software defined radio.
- Speech recognition system.

10. Abstract
•The probability of error in
decoding an optimal
convolutional code transmitted
over a memoryless channel is
bounded from above and below
as a function of the constraint
length of the code. For all but
pathological channels the
bounds are asymptotically
(exponentially) tight for rates
aboveR_{0}, the computational
cutoff rate of sequential
decoding...
•Viterbi, A.J. 1967

11. Convolutional encoding
Add bit “e” to beginning, shift bits
to right and discard last “0”.←
←Add “x” drop “0”.
←Add “a” drop “0”.
←Add “m” drop “0”.
←Add “p” drop “e”.
←Add “l” drop “x”.
←Add “e” drop “a”.
“000000e000xe00axe0maxepmaxlpmaelpm”Transmit:
(shift register)

12. Decoding Trellis

13. Like talking across a noisy room
Because we know grammar
we can decipher what is
said without hearing every
word or letter.
The Viterbi will search for a
particular structure of data
and is able to take a guess
based on the current
available information.

14. Harry Grindell
Matthews
Early experimenter in
wireless communications.
Patented worlds first mobile
phone in 1909.
And the Death Ray in 1924
which he possibly sold to
the French...
Spark gap transmitters.

18. Used £10 USB TV Tuner with
GNU Radio, a SDR system.
Read about on hackaday:
http://bit.ly/1a3Yrpg
Linux build Instructions:
www.theanthillsocial.co.uk/sketch/207
Software Defined
Radio (SDR)

19. www.github.com/csete/gqrx
 Enables audience to easily see FM/Other tuning.
GQRX: Frontend for GNU radio

20. CMU Sphinx: Open Source
Toolkit For Speech
Recognition.
www.cmusphinx.sourceforge.net
Likes the word “money”
Hacked phython code:
www.theanthillsocial.co.uk/projects/uncer
tain-substance
Voice Recognition

23. CCTV

25. Post-Project

26. Further experimentation
Miniaturisation: What
potentials are revealed
when the system is made
smaller?
Social output: Buying
shares, setting a price on
a commodity.
Exploring other uses of
the Viterbi.

27. How you can build
off my work
The technological:
- Improved speech
-recognition.
- Tune into TV.
- Install on small devices.
The theoretical:
- Investigate the dull grey
& boring.
- Think about
technological objects as
complex assemblages.

28. Questions and Answers