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KDFX Reference
KDFX Algorithm Specifications
MutualFreqOffset modulates the two input signals (left and right) with each other. If one of the signals is
a sine wave, the algorithm behaves like Frequency Offset. Now imagine that one of the input signals is the
sum of two sine waves. Both of the two sine waves will modulate the signal on the other input. For
example, if the two sine waves are at 100 Hz and 200 Hz, upward modulation of another signal at 1000 Hz
will produce pitches at 1100 Hz and 1200 Hz. Obviously this is going to get very complicated to work out
when the inputs are more than simple sine waves. MutualFreqOffset may require extra gain
compensation so separate left, right input gain controls and a gain control for the final (wet) output are
provided.
Figure 96 Block diagram of MutualFreqOffset
With downward modulation, you will hear the pitch drop as you increase the frequency of the input
sound. The downward modulation is a difference (subtraction) in frequencies. If the difference drops to
negative values, the frequency will start to rise again. It doesn’t matter which frequency gets subtracted
from the other, since the result will sound the same. For example 1000 Hz - 100 Hz = 900 Hz will produce
the same pitch as 100 Hz - 1000 Hz = -900 Hz. Similarly, upward modulation is a sum of frequencies and
pitch will rise as you increase the frequency of input sound. However in a digital sampled system,
frequencies higher than half the sample rate (the Nyquist rate, 24 kHz in KDFX) cannot be represented.
When the summed frequencies pass the Nyquist rate, the pitch starts coming back down.
Both Frequency Offset and MutualFreqOffset provide panning with width of the dry input signals
directly to the output.
Parameters (Frequency Offset):
Page 1
Wet/Dry 0 to 100 %wet Out Gain Off, -79.0 to 24.0 dB
In Lowpass 8 to 25088 Hz
SSB
Modulator
Pan
Pan
Dry
Wet/Wet Gain
Up
Down
In Gain L
In Gain R
L Input
R Input
L Output
R Output
Low Pass
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