Author ORCID Identifier

https://orcid.org/0000-0002-9218-1624

Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Lane Department of Computer Science and Electrical Engineering

Committee Chair

Kevin Bandura

Committee Member

Matthew Valenti

Committee Member

Natalia Schmid

Committee Member

David Graham

Committee Member

Maura McLaughlin

Abstract

Precise calibration of radio telescope beams and gains is a central requirement for 21 cm intensity mapping experiments, which aim to measure large scale cosmological structure through the redshifted emission line of neutral hydrogen. Bright astrophysical foregrounds dominate the sky at these frequencies, and separating them from the cosmological signal demands precise control over instrumental systematics, particularly the telescope beam and its frequency-dependent response. Existing aerial calibration sources are incoherent broadband emitters, detectable only as total power. They provide no direct phase information and suffer from poor sensitivity in low signal-to-noise regimes.

We present the Precision Emitter for 21cm Array Coherent Calibration (PEACC), digitally synthesized wideband calibration source designed to address these limitations. The system generates 1.2 GHz-wide Gaussian noise, time-synchronized to a 1 pulse-per-second output from a GPS-disciplined oscillator, and is optimized for deployment on an aerial platform such as a drone. A dual-source architecture is employed: one unit is carried on the aerial platform while a second reference unit is connected directly to the radio data acquisition system. By correlating the received aerial signal against this local reference, the system enables simultaneous measurement of both amplitude and phase for each baseline of the interferometric array. This approach improves sensitivity in the low signal-to-noise regime and provides an independent cross-check of telescope-pair visibility phases. The system supports configurable band selection, allowing adaptation to a range of 21 cm intensity mapping telescopes.

We validated PEACC through anechoic chamber measurements and by integrating the source on a drone flown over a local radio dish testbed. In both settings, the correlated channel substantially outperformed the auto-correlation channel across all signal-to-noise regimes of interest, confirming the key advantage of the dual-source architecture. To our knowledge, this is the first published demonstration of a free-space coherent calibration signal synchronized only by clocks, the first deployment of such a source on a drone, and the first published beam measurements made with such a source. Given the growing interest in drone-based calibration for 21 cm arrays, this work establishes the feasibility of high-fidelity digital calibration for next-generation 21 cm instruments, and provides a practical path towards improved foreground control and beam calibration in future arrays.

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