Modulation techniques
Transcript of Modulation techniques
Modulation techniquesRM & AM
Live ElectronicsDigital Signal Proccessing (DSP)
• To modulate is to impress a modulator signal on a carrier signal
• The modulator might be an sine wave and the carrier might be the sound of an instrument.
• Carrier. The signal that’s being modulated.• Modulator. The signal that modulates the
carrier signal.
Lytteeksempler Ring modulasjon
– KarlHeinz Stockhausen: Mantra 0:00 – throughout, Piano, Crotales
– Arne Nordheim: Distance0:00 -, Synth Bells
Side bands
• Carrier and Modulator are multiplied– Carrier fc
– Modulator fm
– Lower Side Band (LSB): fc – fm
– Upper Side Band (USB): fc + fm
Frequencyfc fc + fmfc - fm
Lytteeksempler Ring modulasjon
– Black Sabbath: Paranoid1:24 - 1:46, Guitar
– Miles Davis at Filmore West: Spanish Key0:00 -, E.pianohttps://www.youtube.com/watch?v=YUxIOFPg0MI
Amplitude modulation
• Nine Inch Nails: The Wretched 0:00 - 5:24, Drums (Noise Snare)
• When modulator is a hearable signal and the carrier a sine wave, output is similar to ring modulation except that the carrier frequency can also be heard.
Amplitude modulation (2)
• Carrier fc
• Modulator fm
• Three hearable tones: carrier, difference and sum• fc
• fc – fm
• fc + fm
Amplitude modulation (3)
• Modulasjon med lavere frekvens enn 20 Hz vil høres i tidsdomenet (ikke klang/timbre) som variasjon i lydnivå, tremolo.
• Modulasjon med frekvenser mellom 20-70 Hz introduserer en ”røffhet”, grovhet i lydsignalet.
• Modulasjon med høyere frekvenser høres som distinkte, unike komponenter (LSB (low side band) carrier og USB (upper side band)
Referanser
• Roads, Curtis (1996) The computer music tutorial. P. 215-224 https://books.google.no/books?id=nZ-TetwzVcIC&lpg=PP1&dq=computer%20music%20tutorial&hl=no&pg=PP1#v=onepage&q=computer%20music%20tutorial&f=false
• Ring Modulation, Frequency Modulation and Amplitude Modulation in Ableton Live 9 Suite http://www.youtube.com/watch?v=e0B3mXQ5rpw