“2.4Ghz Scape” Sawako Kato sawako@troncolon.com + bio of sawako

"2.4GHz scape" is the 2.4GHz spectrum ambient sound installation and performance. The audiences can enjoy the realtime sonification of 2.4GHz signal around the place, and the ambient sound becomes one part of the immediate soundscape. Also, people can join the soundscape using their laptop or bluetooth devices such as the mobile phones to make the signal interference. 2.4GHz spectrum is widely used for WiFi, microwave ovens, bluetooth, baby monitors, cordless game controllers and others in USA and Europe. The signal map varies in different places, and the activities of the signal usage are changing in the hour, day and year. It is like the seasonal changes of air. The Signals "(encoded in many different ways) that interfere with one another and signals that are cleverly multiplexed so that they don't interfere, jammed zones and Faraday cages, and the endless busses and bursts of electromagnetic noise." ("Me++" William J. Mitchell ) Our world is resonating with various kinds of waves, and the waves make harmony in the air. Human beings can catch the very limited signals of waves with their ears and eyes and use them for their communication. Like some fishes living in the standing river communicates with electromagnetic wave, with radio frequency technology, people expand the ways of communication using signals and the range of the frequency used for the communication. Even though we don't realize, we are surrounded with the invisible signals like you are living in the invisible sound of ocean. With the experience of "2.4GHz scape", the audiences realize the invisible existence of 2.4GHz spectrum in the air. I’d like to create the composition of signal inside of air, just like I’m doing with sine tone and Super Collider. 2.4GHz Scape is originally the project for the Master Degree Thesis and Every Bit You Make class in Interactive Telecommunication Program, New York University. Then, the work is presented in CONFLUX festival, Brooklyn USA, in September 2006, and currently there is the plan to set it up as the office ambience installation of the Boston based technological design company, Synthesis Studios. Here you can check the article about Conflux festival and 2.4GHz scape (and other works) in we make money not art. ..... watch the VIDEO

Related Works

- DSP Music Syndicate’s “Upper Air” is the sound installation in City Hall Park which create a sonic fingerprint of the electromagnetic spectrum.

- Alvin Lucier's "Sferics" (1981) is a musical piece using the sounds of the ionosphere. It was 1967 when Lucier discovered a recording of a sound of atmospherics by an astrophysicist and started to get interested in the sferics, natural radio-frequency emissions in the ionosphere occurring in the human audible range.

Ambient Information

The main challenge of the sound design in the work is to exchange the 2.4GHz data for the ambient sound information. The application is created with the assumption that the user playback it whole day, and it tells the condition of the 2.4GHz spectrum in the room in a persistent and subtle way. In our real life, we get the information from the immediate environment unconsciously. Tangible Media Group in MIT media lab is one of the pioneers of the area where the environmental information displays as the ambient way. Their early work, “kazaguruma”, which displays the stock market data as the speed of windmill, shows the aesthetics vividly.

As the traditional example, the Japanese garden equipment, Suikinkutsu, makes sound with rain and the water of washing hand. The sound merges into the everyday life, and people feel the raining condition and existence of other people as the background information.

WiSpy ?

To capture the data, I use Wi-Spy, a USB 2.4GHz spectrum analyzer. The wi-spy tool for Macintosh is written by C and can be used inside of terminal or Max/MSP with shell external.

“ Wi-Spy™ is the world's smallest 2.4 GHz spectrum analyzer.”

TRIAL01: From File

As sketches for the bigger work, I did some trials with Processing and pre-recorded data. I draw the moving graph from the amplitude, frequency and time of the 2.4GHz signal data. For the sound part, if the signal amplitude is greater than 50dBm, the sample is playback with the pitch relative to the frequency and the amplitude relative to the amplitude. The bell sound and the sine tone are used for the experiments.

2D visualization 3D visualization

01:WiFi audio streaming	The signal is gathering around 2470MHz. The original data is downloaded from Wi-Spy site which is recorded in the place with less interference. So, you can see only the Wi-Fi signal cleary. This recording is the result of continuous downloading. In the recording of internet surfing, the spike continues only few mili seconds.
02: Codeless Phone (Frequency Hopping Type)	Spikes are happening in all frequency areas.
03: Sunday the 4^th floor in ITP	Comparing with figure01, the recording is noisy. Many interferences of signal from laptop, bluetooth devices, and microwave can be found here. At that time, 4 people were using laptop near me, and over 20 laptops were on the lounge area. Some people were testing their bluetooth applet on the mobile phones. You can see the outstanding spike around 2470MHz, and it is the WiFi signal from the laptop near me.

I recorded the data in my home, ITP floor and the Starbucks. All results of the usual home environment are something like 03 – with much interference of different devices and reflection of walls. Raffi, our Every Bit You Make class teacher, told me that, if people use many bluetooth devices in one place, the signal wave towards flat because all waves are added together. It reminds me additive synthesis with sound. Although we can examin the math of sound wave in your laptop with DSP tools freely, there is the restriction about the usage of radio frequencies. The new technologies in wide bands of frequencies like Dewayne Hendricks’s research are currently prohibited. TRIAL02: Standalone Application Based on the trial with Processing, I develop the Wi-Spy Ambient Sound Generator as the standalone application of Max/MSP. The Wi-Spy Ambient Sound Generator creates ambience sound from the signals captured by Wi-Spy. To use the application, you need the Wi-Spy tool and the Max/MSP runtime. The screen shot of the application. The Wi-Spy Ambient Sound Generator has four different modes -the morning mode, the afternoon mode, the night mode and the midnight mode -, and the sound samples and patterns change depending on the time. For example, in the morning mode the sound of birds are used. In future release, the random sound picking from iTune mode will be featured. Technical Issues While the frequency hopping signal are just noise, the Wi-Fi signal has the sharp spike on the specific area. The area can be controlled with the router. Applying the Wi-Fi signal for sound processing as the impulse response or granular synthesis is interesting challenge. Here are some screen shots of waveform in the trials. TRIAL01. Just dumping the signal into the buffer. The screen shot of the buffer. Clearly enough, the result sound is just a noise. TRIAL02. The result of 1 smoothing and 1 slide. About 3 frames are dumped into 1 buffer. (The red line shows each frame.) TRIAL03. The result of velocity and acceleration of the signal. Now, the signal becomes two sided. TRIAL04. This signal is the result of 3 smoothing and 1 velocity. 5~10 impulses (grains) happen in every 15ms. With the smoothing variable, you can change the size of impulse. Granular synthesis using the signal of TRIAL04 and the sampling sound is the interesting future implementation. Future Project

The screen shot of the icon.