Distortion-free delta-sigma beamforming.
We have analyzed a compact, digital delay- and-sum beamformer using 1-bit delta-sigma A/D converters, where dynamic delays are applied directly to the delta-sigma modulated bitstream. It has previously been shown that the introduction of this time-variant operation into the time-invariant delta-sigma demodulator distorts the output signal, and several methods for minimizing this effect have been suggested. We have described the effect using standard system terminology. Based on this description, a new method for removing the distortion without any significant increase in system complexity is introduced. Its advantages, performance-wise, are supported by theoretical assessments and simulations.
Nilsen
Carl-Inge Colombo
CI
Dept. of Inf., Univ. of Oslo, Oslo, Norway. carlingn@ifl.uio.no
Holm
Sverre
S
D000703:Analog-Digital Conversion; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods