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TELESONIEK ATELIER RELAY NO. 05

VIDEO AND OSCILLOSCOPE IMAGING

During 2000 till 2007 some video equipment was brought to the studio to be able to capture the oscilloscope images that were generated through the analog computer and test & measurement instrumentation studies and experiments.
Please find some examples here >>http://www.youtube.com/user/edda673


PREFACE
Apart from reading voltmeters and the study of ink written graphs on sheets of paper put down by XY or X(t) recorders, the output of analog computer system simulations is also presented on the screens of oscilloscopes.
As bandwidth and computation speed increase, equation solutions can be presented at higher frequencies during repetitive computation mode. The operator can now adjust and optimize system parameters in real-time by turning pots and observing the beamed curves at the scope screen.
A variety of scope phosfor types are available e.g. for introducing afterglow of the travelling beam to allow observation of time history of the function displayed.
The ability to control the scope beam in both X and Y direction by means of a varying dc voltage (and on most scopes the Z control, actually the brightnees of the beam) has attracted artists soon after WW II.


SCOPE ART INTRODUCTION
Ben Laposky is one of them, composing/producing his 'Oscillons', photo stills of scope images produced by connecting various carefully adjusted function generators to the scope inputs. Mary Ellen Bute did about the same in combination with music fragments to produce moving pictures. At the same time John Whitney used a mechanical analog computer to transfer oscillating images directly on film.
During late 60's and early 70's work was also done by Herbert Franke, but soon scope art was used in the happening/performance scenes, and digital computers gradually took over the world of electronic machine generated graphics. Video became popular because of its' directness of the medium (record/playback) and the specific effects of video was the area to explore (e.g. video monitor-camera feedback). Alongside the rise of analog modular synthesizers using voltage control many systems for analog voltage controlled video synthesis were developed (Beck, Sandin et. al).
In general, all this developed in the continuing line of abstract film, which started in the early 1920's by Oskar Fishinger et al. (please refer to: Vasulka; die eigenwelt der apparatewelt)


PRACTICAL
The best close-by opportunity for scope art is using a multi-mode filter if available in your analog modular synthesizer. The filter is then used as an analog computer by using the different outputs for X and Y scope input as they are 90 degrees apart in phase. This technique is called Phase Plane Plotting generating spirals (damped oscillations).
A real medium sized analog computer is a perfect starting point for generating interesting scope images.
Lots of circuits/patch programs for oscillators and function generators, just put something on the X and something elso on Y input and start adjusting the amplitude and frequency parameters.Then go on to study the analog computation literature and discover even more interesting programs, like this one, a circuit to generate
3-dimensional images:


fig. XYZ rotation,
from Hitachi Technical Information series no 3, 1967


SCOPES AND VIDEO
The image on the scope screen is beautifull, to capture that on film/video is a bit of a problem because of the shutter frequency interference, so the results on video are different or demand frequency alterations of the original scope image..needs concessions, can be pro or con...anyway, the real scope image is the best.
Our movie "scope" was composed out of shots by various single and multi position cameras aimed on oscilloscope screens, and later editted and post produced on the digital computer (by M. Cooymans). Telesoniek Atelier composed and produced the electronic sound track. In ''neumen'' the voltages that produced the image were at the same time used as controls for the VCO, VCF, and VCA of an Arp 2600 analog synthesizer for sound, a one-on-one relation of sound and image, it works here, but in most other applications sound and moving image should have their own time development.
It suits better with eye and ear perception.


OTHER VIDEO WORK
The video ''Knowledge and not-knowing" was part of a audio/video installation in 2001, and was produced by filming moving tree branches through colored glass. The electronic sounds were projected through various loudspeakers located around the expo space.
The Plane movie was part of camera/TV monitor feedback experiments; the audio track was produced in the Telesoniek Atelier Studio.
It was very educating to also have access to waveform and vector displays (tektronix).
If there would be additional time and space, more work would emerge.

Hans Kulk, spring 2014


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