Oscillator waveforms
Oscilators
: emit basic waveforms, which can be represented graphically as waveshapes by an oscilloscope, a mechanical device which analyzes waveforms; measures rise and fall of voltage from 0 to maximum positive/negative and back to 0 while transients (ie envelopes) contribute to the nature of a sound, the chief reason we distinguish between different sounds is due to their harmonic content.
1. sine wave: most noncomplex sound; contains no overtones
2. triangle wave (delta)
contains harmonics, but not a full set
contains all odd # partials
n 1 3 5 7 9
1/n2 1 1/9 1/25 1/49 1/81
Hz 100 300 500 700 900
3. sawtooth wave (ramp)
contains all harmonic overtones of the fundamental
harmonics have relative amplitudes that decrease exponentially as they exist higher in the harmonic series
n 1 2 3 4 5
1/n 1 1/2 1/3 1/4 1/5
Hz 100 200 300 400 500
4. pulse wave (rectangle)
variable shape
instantaneously positive, then negative, whereas above types exhibit gradual rise & fall between +/- states
a. square wave- "on" portion is 1/2 portion of cycle
considered to be a basic wave shape
1:2-indicates haronic content
duty cycle is "on" portion of entire cycle
harmonic=normal inverse relationship @ 1/n strength
ratio of duty cycle to rest of wave gives indication of waveform harmonic content
1:2 every 2nd harmonic is skipped 1 3 5 7 . . .
1:6-every sixth harmonic is skipped 1 2 3 4 5 7 . . .
any pulse not a square wave is called a rectangle wave
when "on" portion is slight, resulting waveform is known as a "spike wave" 1:30