ep-4yy13 DSP – week 13

“I think its just the biggest conceptual art project uninentional or otherwise that anyone ever made. it puts Christo and those other guys to shame. Its planetary”

Roman Mars “Episode 97 – Numbers Stations” from 99% Invisible

Radio

• Measuring the invisible
• What is the difference between sound waves and radio waves?
• What is an antenna?
• Wave propagation is frequency dependent
• Sunspots and magnetic fields http://spaceweather.com
• Extreme frequencies, negative frequencies?

examples

• A simple arduino AM transmitter https://reactivemusic.net/?p=4450 (antenna pin D8)
• Transmitting music using light https://reactivemusic.net/?p=8487
• Analog signals. Digital signals.
• Crystal sets. Inadvertent radio. Patch Cords.
• Software defined radio (cellphones, wiFi, bluetooth, etc., )
• Software defined radio in Max http://zerokidz.com/radio (The user guide http://zerokidz.com/radio/docs/maxsdr5.pdf and tutorials provide a basic introduction to working with radio signals in the audio domain.
• rtl-sdr – inexpensive software defined radio
  • information http://sdr.osmocom.org/trac/wiki/rtl-sdr
  • Where to buy one: http://www.nooelec.com/store/sdr/sdr-receivers/tv28tv2-sdr-dvb-t-usb-stick-set.html#.U2BX1K1dVKk
  • installation https://reactivemusic.net/?p=8360
  • sub-reddit http://sl.reddit.com/r/RTLSDR/
  • Max and Pd externals https://github.com/tkzic/pd-rtlsdr
• Raspberry Pi FM transmitter https://reactivemusic.net/?p=10186
• Transmitting signals in water https://reactivemusic.net/?p=853
• The noise floor: Noise Floor: Exploring the world of unintentional radio emissions by Melissa Elliott: http://www.youtube.com/watch?v=5N1C3WB8c0o

Internet radio streams and recordings

• Roman Mars: Numbers Stations: http://99percentinvisible.org/episode/numbers-stations/
• You are listening to: http://youarelistening.to/boston
• broadcastify: http://www.broadcastify.com/listen/feed/15433/web
• the listening post: http://www.chilton.com/scripts/radio/R8-receiver
• Very Low Frequency: http://www-pw.physics.uiowa.edu/mcgreevy/

• Macbook trackpad: Noise 5 mHz. (try holding radio near screen too)
• Macbook AC adapter: Noise 600-1400 kHz. (~1000)
• AC adapters, LED’s, Utility poles: 3.2 Khz
• Arduino transmitter: AM 1330 kHz.
• Laser light at 650nM
  • What wavelength goes with a color? http://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html
  • Frequency of red light is 4.6 * 10e14  = 300,000,000 / .000000650 (460 THz)
• Wireless micorophone (Orange-brown): Wide FM 614.150 MHz. (R band)
• Cordless phone: Narrow FM 926 mHz.
• Cell phone: Digitally encrypted trunking FM 836 mHz.
• Wifi: Digitally encoded PCM 2.4 gHz.
• FM broadcast band: Wide FM 89.7 mHz (Raspberry Pi example 98.1 Mhz)
• TV audio 600 mhz/660 mhz FMW
• The sun http://www.ips.gov.au/Solar/3/4

Topics not covered

(due to snow and stuff)

Visualization

 

• d3
• processing
• jitter
• hardware control

Statistics

• What are the chances?
• What to do next?
• improvisation. Randomness.
• r: http://www.r-project.org/
• Infinity row by Karlheinz Essl https://reactivemusic.net/?p=9222 
• Music recognition. Deep learning.

Miscellaneous