Chippmann Omega-PhiCS-8 Series, Руководство пользователя

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CS-8 Series Omega-Phi Rev1.04, Oct. 2015
-19-
For Depth at full CW a voltage range of 2 V at the PWM input jack controls the
total range of this parameter.
Shape/Shape/Depth : The Shape -controller breaks the saw-tooth wave during
passing through at a further point. The graphs illustrate how. In the middle
position one obtain a saw-tooth with double frequency and half amplitude (5
Vpeak-to-peak instead of 10 Vpp). Both in full CCW and full CW position one
obtain a full saw-tooth wave displaced by a half triangle wave (180°) (that's not
the same as inverting!). The
Depth
-controller in full CW voltage range of 5 V at
the
Shape
jack controls totally this parameter.
Ramp-jack/Saw-switch : The
Saw
-switch selects for the saw-tooth output the
direction either rising (position "up") or falling (position "dwn/act") for both
Omega section and Phi section. In position "dwn/act" the jack
Ramp is
activated. A voltage of +5 V or floating input means "falling" and 0V "rising".
Because this function equals a multiplication with
1, one obtain a semi-
analogue/semi-digital ring modulator !
8.4. The linear frequency modulation FM
In Abb. 3a above the U
Lin
-input of the e-generator, which finally is fed with the
FM voltages, goes to the output of a Rectifier . (There may exist different
solutions for the realization of a thru zero oscillator, but the realized approach
here seemed to be the most elegant one.)
To imagine generally how FM works and how a carrier waveform becomes
influenced by modulation, some explanations based on graphs will follow. Fig.
5a shows (top) the non-modulated sine wave (carrier) of the oscillator, the next
graph below shows the rectifier output (modulator); this curve modulates now
the carrier at the U
Lin
-input of the e-generator. It was chosen a cosine-curve
with same frequency as the carrier to obtain more intuitive wave shapes,
because the FM-result depends strongly on the phase relationships of carrier
and modulator. The modulation amplitude was chosen, that the minimum at
the rectifier output exactly becomes zero. The modulation index is =1. I.e.,
Would one omit the cosine modulator, the rectifier output would be 1 in
graph. This is the normalized so-called bias (pre-voltage). With the switch
Bias : it could be switched on (position "Norm") or off (position "Zero"). If it is
switched off the oscillator will stop oscillate without any voltage at the FM