STAGGERED INTERLEAVED NYQUIST REGIONS AVOID GUARD BAND INDUCED HOLES WHEN SAMPLING A BAND LIMITED SIGNAL

摘要

Staggered interleaved Nyquist regions associated with differing ADC clock rates (F_CLK) avoids spectrum lost through disjoint guard bands at the end of or between adjacent Nyquist regions. The staggered interleaved Nyquist regions overlap by an amount at least as much as is consumed by the guard bands. Selectable anti-aliasing filters associated with each Nyquist region and its ADC clock rate are used to enforce the staggered Nyquist regions and their various guard bands. For example, and neglecting guard bands, an initial raw band of operation RB₁ may be the First Nyquist region for a basic sampling frequency F_s. An adjacent raw band of operation RB₂ that overlaps RB₁ may be the Second Nyquist region for an alternate sampling frequency 2F_s/3. An adjacent raw band of operation RB₃ that overlaps RB₂ may be the Second Nyquist region for the basic sampling frequency F_s. These raw bands interleave and overlap: RB₁: DC to F_s/2 1^st Nyq. for F_CLK = F_s RB₂: (2/3)F_s - (½)(2/3F_s) = F_s/3 to 2^nd Nyq. for F_CLK = 2F_s/3 2(2F_s/3)/2 = 2F_s/3 RB₃: F_s - (½)F_s = F_s/2 to 2(F_s/2) = F_s 2^nd Nyq. for F_CLK = F_s In this example the smallest overlap is F_s/6. We then select widths for guard bands that do not exceed F_s/6. Additional ADC clock rates and anti-aliasing filters may be used to operate in still higher Nyquist regions.