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John Mower

Research Scientist/Engineer - Senior

Email

mowerj@apl.washington.edu

Phone

206-616-4787

Education

B.S. Electrical Engineering, University of Washington, 2010

M.S. Electrical Engineering, University of Washington, 2012

Publications

2000-present and while at APL-UW

Pulse compression for an X-band marine wave-sensing radar

Mower, J.M., G. Farquharson, B. Frazer, and J.G. Kusters, "Pulse compression for an X-band marine wave-sensing radar," Proc., MTS/IEEE OCEANS, 27-31 October 2019, Seattle, WA, doi:10.23919/OCEANS40490.2019.8962784 (IEEE, 2020).

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20 Jan 2020

As part of the Office of Naval Research's Environmental and Ship-Motion Forecasting project, we have developed a four-antenna vertically-polarized coherent X-band radar to measure the orbital Doppler velocities of the sea-surface. This Advanced Wave-Sensing Radar (AWSR) initially used a gated CW pulse to radiate the scatterers using a traveling-wave tube amplifier (TWT) in full-saturation. To improve the performance of the system under low wind conditions, we implemented a pulse compression scheme to increase the average transmitted power. In this application, the range-sidelobes associated with compressed waveforms was required to be less than 40dB. Nonlinear FM chirp were considered but these waveforms require larger time-bandwidth products than the near-range requirements of the wave-sensing application would allow. A weighted linear FM chirp was chosen but linearization of the pulsed TWT is required. In this paper we will demonstrate the AWSR pulse-compression scheme detailing the waveform generation, real-time IF correlation and averaging, and digital predistortion.

Phase calibration of an along-track interferometric FMCW SAR

Deng, H., G. Farquharson, J. Sahr, Y. Goncharenko, and J. Mower, "Phase calibration of an along-track interferometric FMCW SAR," IEEE Trans. Geosci. Remote Sens., 56, 4876-4886, doi:10.1109/TGRS.2018.2841837, 2018.

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1 Aug 2018

We introduce a phase calibration scheme for an interferometric frequency-modulated continuous-wave (FMCW) synthetic aperture radar (SAR) to correct range-dependent phase errors in FMCW SAR interferograms. We demonstrate that the receiver filters operating on the FMCW beat frequency signal account for most of the phase mismatch between the different receiver channels. The scheme presented estimates the phase error in each channel. We present results of the scheme for three estimation approaches (curve fitting, joint least squares, and maximum likelihood) for two different phase models. The results are quantified by computing the reduction in spectral energy associated with the phase mismatch. We find that phase error can be reduced by 14 dB using the approach.

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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