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John Mower Research Scientist/Engineer - Senior 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
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Publications |
2000-present and while at APL-UW |
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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
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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. |
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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
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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. |
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Calibration of a miniaturized FMCW ATI-SAR for normalized radar cross section measurement Farquharson, G., S. Aslebagh, and J. Mower, "Calibration of a miniaturized FMCW ATI-SAR for normalized radar cross section measurement," In Proc., IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 26-31 July, Milan, Italy, doi:10.1109/IGARSS.2015.7326008 (IEEE, 2015). |
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12 Nov 2015
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A radiometric calibration scheme that exploits time-domain backprojection is evaluated using a squinted frequency-modulated continuous wave radar and corner reflectors. We find that the calibration scheme compensates for most of the variation in image intensity due to changes in aircraft attitude, and that for good signal to clutter ratios, the return from the corner reflectors varies by for most cases by around 1 dB, although a 3 dB difference was observed in one case. |
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