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Search Publications by: Archita Hati (Fed)

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Displaying 1 - 25 of 90

Ultra-Low Phase Noise Frequency Division with Array of Direct Digital Synthesizers

December 25, 2023
Author(s)
Marco Pomponio, Archita Hati, Craig Nelson
In this article, we present a four-channel direct digital synthesis (DDS) design that operates with a common clock ranging from 500 MHz to 24 GHz and generates output frequencies up to 1.75 GHz. A key feature of this board is its custom field-programmable

30 GHz regenerative frequency divide-by-3

August 15, 2022
Author(s)
Archita Hati, Marco Pomponio, Connor Humiston, John Lettang, Craig Nelson
We report the performance of a 30 GHz to 10 GHz regenerative frequency divider. The proposed divider design incorporates the conventional Miller regenerative frequency divider (divide-by-2) with an additional regenerative path. We achieve output referred

10 GHz Generation with Ultra-Low Phase Noise via the Transfer Oscillator Technique

February 8, 2022
Author(s)
Nicholas Nardelli, Tara Fortier, Marco Pomponio, Esther Baumann, Craig Nelson, Thomas Schibli, Archita Hati
We generate 10 GHz microwave signals using the transfer oscillator technique, which employs digital and RF analog techniques to coherently remove the additive noise from an optical frequency comb. This method permits transfer of the frequency stability and

FPGA-based Low-Latency Digital Servo for Optical Physics Experiments

October 22, 2020
Author(s)
Marco Pomponio, Archita Hati, Craig Nelson
We propose a general-purpose dual-channel field-programmable gate array (FPGA) based digital servo with a minimum latency around 200 ns. This servo implements a proportional, dual- integration and derivative (PIID) controller along with internal numerical

Field Compressed Sensing

January 17, 2020
Author(s)
Anthony B. Kos, Fabio C. Da Silva, Jason B. Coder, Craig W. Nelson, Grace E. Antonucci, Archita Hati
Imaging solutions based on wave scattering seek real-time performance, high dynamic range, and spatial accuracy at scales spanning from nanometers to thousands of kilometers. Compressed sensing algorithms use sparsity to reduce sample size during image

Multipath Mitigation from FM-AM Correlation

October 3, 2019
Author(s)
Archita Hati, Craig W. Nelson
Multipath is one of the limiting factors for an accurate outdoor and indoor localization. We proposed an approach that uses a multipath mitigation derived from the undesired frequency-to- amplitude conversion of a frequency modulated (FM) signal

W -Band Vibrometer for Noncontact Thermoacoustic Imaging

June 20, 2019
Author(s)
Archita Hati, Craig Nelson
Noncontact thermoacoustic imaging (TAI) has several desirable characteristics for applications such as explosive detection in high-water-content media. In this letter, we report a detection technique using millimeter-wave interferometry based on sensitive

W-band Vibrometer for Non-contact Thermoacoustic Imaging

June 20, 2019
Author(s)
Archita Hati, Craig W. Nelson
Non-contact thermoacoustic imaging (TAI) has several desirable characteristics for applications such as explosive detection in high-water content media. In this paper, we report a detection technique using mm-wave interferometry based on sensitive phase

Effect of Local Oscillator Performance on UWB Based Indoor Localization System

May 21, 2018
Author(s)
Archita Hati, Fabio C. Da Silva, Vladislav P. Gerginov, Craig W. Nelson
We discuss the performance of a commercial Ultra-wideband (UWB) ranging technique for indoor localization. We study the influence of local oscillator's phase noise and its frequency drifts due to temperature variations on the range estimation and ranging

Optically referenced broadband electronic synthesizer with 15 digits of resolution

September 5, 2016
Author(s)
Franklyn J. Quinlan, Tara M. Fortier, A. Rolland, Frederick N. Baynes, A. J. Metcalf, Archita Hati, Andrew D. Ludlow, Nathan M. Hinkley, M. Shimizu, Joe Campbell, Scott A. Diddams
Increasing demands in the high tech industry for higher data rates and better synchronization necessitates the development of new wideband and tunable sources with improved noise performance over traditional synthesis based quartz oscillators. Precision

Measurement of AM-to-PM Conversion in a Quartz-MEMS Resonator

May 9, 2016
Author(s)
Craig W. Nelson, Archita Hati, David A. Howe
This work investigates the new aspects of the non-linear response in a quartz-MEMS resonator at 635 MHz. We characterize its major cause of AM-to-PM conversion as a function of power and drive frequency; this is important in developing noise compensation

Power Splitter Thermal Noise Correlations in Cross-spectrum Noise Measurements

May 9, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We discuss collapse of the cross-spectrum phase noise measurement of thermally-limited oscillator due to anti-correlated thermal noise of the Wilkinson power splitter. We also examine effect of thermal noise of various resistive power splitters on such

Practical Evaluation of a 50 km Fiber Link Utilizing a Commercial Modem

May 9, 2016
Author(s)
Corey A. Barnes, Archita Hati, Craig W. Nelson, David A. Howe
We evaluate the stability of two-way time and frequency transfer over a 50 km fiber optic link established using a commercially available fiber optic modem. For this evaluation we report the residual phase noise, total Allan deviation, total time deviation

Cross-spectral Collapse from Anti-correlated Thermal Noise in Power Splitters

April 4, 2016
Author(s)
Craig Nelson, Archita Hati, David A. Howe
We discuss the cross-spectral collapse due to anti-correlated thermal noise that originates from the common-mode power divider (splitter) in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its

Oscillator PM-noise reduction from correlated AM-noise

March 11, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We demonstrate a novel technique for reducing the phase modulation (PM) noise of an oscillator in steady state as well as under vibration. It utilizes correlation between PM noise and amplitude modulation (AM) noise that can originate from the oscillator's

Cross-spectrum Measurement of Thermal-noise Limited Oscillators

March 1, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
Cross-spectrum analysis is a commonly-used technique for the detection of phase and amplitude noise of a signal in the presence of interfering noise. It extracts the desired correlated noise from two time series which also contain uncorrelated interfering

Optical-to-RF Frequency Synthesis: Application Priorities for Ultra-low Phase Noise

October 18, 2015
Author(s)
David A. Howe, Archita Hati, Craig W. Nelson, Lora L. Nugent-Glandorf
We describe operational challenges and progress of optical frequency-comb dividers (OFDs) that synthesize RF signals from the optical domain. Our priorities include: (1) ultra-low phase-noise, (2) continuous operation, and (3) broadly low Allan deviation.

PM Noise Measurement at W-Band

December 12, 2014
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We present improved performance for a 92 - 96 GHz cross-spectrum phase modulated (PM) noise measurement system previously reported. The system is principally designed to measure amplifiers in pulsed mode with a duty cycle of 10% to 100% (CW) at a given

A 40 GHz Air-Dielectric Cavity Oscillator with Low Phase Modulation

September 1, 2014
Author(s)
Archita Hati, Craig W. Nelson, Billy F. Riddle, David A. Howe
We describe the design of a low-phase modulated (PM) noise, 40 GHz oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator to improve the PM noise of a commercial 10 GHz dielectric resonator oscillator (DRO)

Reducing oscillator PM noise from AM-PM noise correlaiton

August 14, 2014
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We present a new scheme for improving the phase modulated (PM) noise of an oscillator from correlation between amplitude modulated (AM) and PM noise. Experimental results of this correlation effect are presented. An improvement of almost 10 dB in the PM