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Amy Lowitz

Publications and source records attributed to Amy Lowitz.

3 recordsLinked to original sources

A Direct Calibration Algorithm for ADC Interleaving

We introduce a novel direct calibration algorithm to address phase delay, gain, and offset mismatches in Analog-to-Digital Converter (ADC) time interleaving systems. These mismatches, common in high-speed data acquisition, degrade system performance and signal integrity, particularly in applications such as radio astronomy and very long baseline interferometry (VLBI). Our proposed algorithm uses a sinusoidal reference signal and Fourier analysis to isolate and correct each type of mismatch, providing a computationally efficient solution. Extensive numerical simulations validate the algorithm's effectiveness and demonstrate its ability to significantly enhance signal reconstruction accuracy compared to existing methods. This work provides a robust and scalable solution for maintaining signal fidelity in interleaved ADC systems and has broad applications in fields that require high-speed data acquisition.

astro-ph.IM

QUBIC: Exploring the primordial Universe with the Q\&U Bolometric Interferometer

In this paper we describe QUBIC, an experiment that will observe the polarized microwave sky with a novel approach, which combines the sensitivity of state-of-the art bolometric detectors with the systematic effects control typical of interferometers. QUBIC unique features are the so-called "self-calibration", a technique that allows us to clean the measured data from instrumental effects, and its spectral imaging power, i.e. the ability to separate the signal in various sub-bands within each frequency band. QUBIC will observe the sky in two main frequency bands: 150 GHz and 220 GHz. A technological demonstrator is currently under testing and will be deployed in Argentina during 2019, while the final instrument is expected to be installed during 2020.

astro-ph.IM

Optical Characterization of the SPT-3G Focal Plane

The third-generation South Pole Telescope camera is designed to measure the cosmic microwave background across three frequency bands (95, 150 and 220 GHz) with ~16,000 transition-edge sensor (TES) bolometers. Each multichroic pixel on a detector wafer has a broadband sinuous antenna that couples power to six TESs, one for each of the three observing bands and both polarization directions, via lumped element filters. Ten detector wafers populate the focal plane, which is coupled to the sky via a large-aperture optical system. Here we present the frequency band characterization with Fourier transform spectroscopy, measurements of optical time constants, beam properties, and optical and polarization efficiencies of the focal plane. The detectors have frequency bands consistent with our simulations, and have high average optical efficiency which is 86%, 77% and 66% for the 95, 150 and 220 GHz detectors. The time constants of the detectors are mostly between 0.5 ms and 5 ms. The beam is round with the correct size, and the polarization efficiency is more than 90% for most of the bolometers

astro-ph.IM