Elecraft KDSP2 Manual - Manual (Page 41)

41
Theory of Operation
The DSP process flow is shown above. Incoming signals are digitized at a 16 kHz rate. The samples are
then decimated, a process to provide higher performance filters with fewer coefficients. In the KDSP2,
decimation by 2 is performed, limiting the highest frequency to a little under 4 kHz.
At the output of the decimator is a bandpass filter, selected by the user for the desired characteristic.
The output of the mode-selected decimator/filter is then passed to the notch filter. This uses an LMS (least-
mean-squares) algorithm. A signal is always applied to the notch filter, even if it is not enabled, to
minimize “popping” if it is selected after having been idle.
The denoiser accepts input from either the notch filter (if the notch filter is selected) or from the decimator
(if the notch filter is not selected).
The output DAC receives its information from the appropriate decimator/filter, the denoiser, or the notch.
ADC Decimate
by 2 and
Filter Noise
Reduction
(denoise)
DAC
Notch