[QUESTION] symsync_create_kaiser() design

[pfeatherstone]

Can you explain the fc and As parameters in the following? I don't understand the choices.

liquid-dsp/src/filter/src/symsync.proto.c

Lines 232 to 236 in 9f32eb7

	// design interpolating filter whose bandwidth is outside the cut-off
	// frequency of input signal
	// TODO: use _beta to compute more accurate cut-off frequency
	float fc = 0.75f; // filter cut-off frequency (nominal)
	float as = 40.0f; // filter stop-band attenuation