Search NASA⌕ Search

Engineering topics

B Nold

Publications and source records attributed to B Nold.

Initial Results of Wyatt EIRP- The Ground Based Power and Ambiguity Function Monitor for P-Band Signals of Opportunity Sources

The Wideband Year-round AmbuguiTy-function Track-ing Effective Isotropic Radiated Power (WYATT EIRP)instrument is designed to support P-Band based Sig-nals of Opportunity (SoOp) remote sensing instrument.SoOp utilizes pre-existing non-cooperative microwavetransmitters as sources of illumination. This remotesensing method requires knowledge of the signals EIRP,position and ambugituty function’s shape.WYATT EIRP is designed to periodically generateEIRP measurements, ambuguity functions and transmit-ter elevation. It uses an array of RHCP and LHCPantennas, mounted on a rotating antenna pedestal togenerate EIRP measurements. A secondary observationantenna is placed to allow time difference of arrival mea-surements for transmitter elevation estimates. Both thepedestal and reference antenana are used to generateamituigyt fionctions. The pedestal will also be used tovalidate existing P-Band background noise temperaturesky maps. WYATT EIRP will be commissioned in thefirst quarter of 2024 and will be used to provide calibra-tion data to the upcoming spaceborne SigNals Of Op-portunity: P-Band Investigation (SNOOPI) instrument.

Remote Sensing↗

Development of Spaceborne SoOp Reflectometry Model for Complex Terrains

Following the launch of multiple global navigation satel-lite system (GNSS) reflectometry (GNSS-R) missions, theSignals of Opportunity (SoOp) method has proven to be apowerful tool for geophysical parameter retrieval for land ap-plications such as soil moisture. Having demonstrated thefeasibility of the SoOp techniques at P- and S-band, the devel-opment of SoOp measurements beyond the GNSS frequencyregime is highly anticipated. The SoOp Coherent Bistatic(SCoBi) model and simulator, developed in 2017 and open-sourced in 2018, has been made available to provide multi-frequency, fully polarimetric SoOp simulations for ground-based applications through the joint use of analytical wavetheory and distorted Borne approximation to evaluate landcontributions from multilayer dielectric profiles composed ofsoil moisture, vegetation, and surface roughness effects. Thispaper describes the advancement of SCoBi from a ground-and airborne-based model to a spaceborne model. This ex-tension allows for fully polarimetric, complex delay-Dopplermap (DDM) simulations through evaluation of the coherentsuperposition of electric fields emerging from a grid of ori-ented facets. The model generates a grid of facets by de-termining the geometry of contributing elements from digitalelevation models, with each element providing its contribu-tion under a flat-earth assumption. This module will enablethe analysis of fully polarimetric scattering from frequenciesavailable across the ultra-high frequency (UHF) regime.

D R Boyd↗