Innovative Demodulation Scheme for Coherent Detectors in CMB Experiments

TL;DR

This paper introduces a new demodulation method for coherent detectors in CMB experiments that enhances noise suppression and improves the noise floor by using a three-point differentiation scheme.

Contribution

The paper presents a novel demodulation scheme based on three-point differentiation, offering better noise suppression than traditional methods in CMB polarization measurements.

Findings

Significant noise suppression improvements with the new scheme

Enhanced noise floor observed in real detector tests

Effective removal of narrow-band noise

Abstract

We propose an innovative demodulation scheme for coherent detectors used in cosmic microwave background polarization experiments. Removal of non-white noise, e.g., narrow-band noise, in detectors is one of the key requirements for the experiments. A combination of modulation and demodulation is used to extract polarization signals as well as to suppress such noise. Traditional demodulation, which is based on the two- point numerical differentiation, works as a first-order high pass filter for the noise. The proposed demodulation is based on the three-point numerical differentiation. It works as a second-order high pass filter. By using a real detector, we confirmed significant improvements of suppression power for the narrow-band noise. We also found improvement of the noise floor.