Engineering topics

Zemba, Michael J.

Publications and source records attributed to Zemba, Michael J..

14 records

NASA NTRS2019

Comparison of Integrated Digital Radiometer with Concurrent Water Vapor Radiometer using the Alphasat Receivers in Milan, Italy

In June 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) jointly deployed a pair of coherent 20 GHz and 40 GHz beacon receivers to the POLIMI campus in Milan, Italy to characterize the atmospheric channel at Ka- and Q-band within the framework of the Alphasat experiment. The Milan receivers observe the continuous-wave beacons broadcast over Europe by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and, in September 2017, both channels were upgraded to incorporate a novel digital radiometer (DR) measurement which NASA has recently employed in other propagation measurement campaigns. In November 2016, a co-located water vapor radiometer (WVR) was also installed at POLIMI, and the concurrent data from both the WVR and DR thusly enables validation of this new DR technique against the established WVR. Herein, we preliminarily investigate the calibration of the DR measurements using the WVR data and also assess a calibration method that may be implemented where WVR data is not readily available.

Zemba, Michael J.↗

NASA NTRS2018

Two Years of Atmospheric Measurements in Edinburgh, Scotland

Since March of 2016, NASA Glenn Research Center (GRC) and Heriot Watt University (HWU) have jointly operated an atmospheric propagation terminal to measure and characterize propagation phenomena near 40 GHz at the HWU campus in Edinburgh, Scotland within the framework of the Alphasat experiment. The system was also recently upgraded in June 2018 to take simultaneous measurements near 20 GHz. The Q-band system utilizes a novel design which combines a beacon receiver and digital radiometer into the same RF front-end and observes the 39.402 GHz beacon of the European Space Agency's Alphasat Aldo Paraboni TDP#5 experiment. Atmospheric measurements can thusly be assessed to characterize link performance. The objective in orchestrating these types of measurements is to improve statistical understanding of the atmosphere at these frequencies of interest, as well as to contribute to the development and improvement of International Telecommunications Union (ITU) models for prediction of communications systems performance within the Q-band. Herein, we provide an overview of the system design, as well as an analysis of the first two years of data collected in Edinburgh, including attenuation, fade duration, and fade slope.

Zemba, Michael J.↗

NASA NTRS2018

Three Years of Atmospheric Characterization at Ka/Q-band with the NASA/POLIMI Alphasat Receiver in Milan, Italy

Since June of 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have jointly conducted a propagation campaign within the framework of the Alphasat propagation experiment through a propagation terminal at the POLIMI campus in Milan, Italy. The terminal utilizes the 20 GHz and 40 GHz beacons broadcast by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and consists of dual coherent Ka- and Q-band beacon receivers. These provide a direct measurement of the signal attenuation and scintillation and are complemented by concurrent weather instrumentation that provides measurements of the atmospheric conditions at the receiver. The primary goal of these measurements is to improve model predictions of communication system performance at 40 GHz. Over three years of concurrent measurements have now been collected from the terminal, and herein we present a statistical analysis of the results thus far, as well as a summary of recent hardware upgrades to the receivers that were made in September 2017.

Radio Transmission↗

NASA NTRS2017

Design of a Combined Beacon Receiver and Digital Radiometer for 40 GHz Propagation Measurements at the Madrid Deep Space Communications Complex

NASA Glenn Research Center (GRC) and the Jet Propulsion Laboratory (JPL) have jointly developed an atmospheric propagation terminal to measure and characterize propagation phenomena at 40 GHz at the Madrid Deep Space Communications Complex (MDSCC) in Robledo de Chavela, Spain. The hybrid Q-band system combines a 40 GHz beacon receiver and digital radiometer into the same RF front-end and observes the 39.402 GHz beacon of the European Space Agencys Alphasat Aldo Paraboni TDP5 experiment. The goals of these measurements are to assist MDSCC mission operations as well as to contribute to the development and improvement of International Telecommunications Union (ITU) models for prediction of communications systems performance within the Q-band. Herein, we provide an overview of the system design, characterization, and plan of operations to commence at the MDSCC beginning in March 2017.

Radio Attenuation↗

NASA NTRS2016

Design of a Ka-band Propagation Terminal for Atmospheric Measurements in Polar Regions

This paper describes the design and performance of a Ka-Band beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed alongside an existing Ka-Band Radiometer located at the east end of the Svalbard Near Earth Network (NEN) complex. The goal of this experiment is to characterize rain fade attenuation to improve the performance of existing statistical rain attenuation models. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation by directly measuring the propagated signal from the satellite Thor 7.

propagation↗

NASA NTRS2016

Design of a Ka-Band Propagation Terminal for Atmospheric Measurements in Polar Regions

This paper describes the design and performance of a Ka-Band beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed alongside an existing Ka-Band Radiometer [2] located at the east end of the Svalbard Near Earth Network (NEN) complex. The goal of this experiment is to characterize rain fade attenuation to improve the performance of existing statistical rain attenuation models. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation [3] receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation by directly measuring the propagated signal from the satellite Thor 7.

propagation↗

NASA NTRS2015

Long-Term Trends in Space-Ground Atmospheric Propagation Measurements

Propagation measurement campaigns are critical to characterizing the atmospheric behavior of a location and efficiently designing space-ground links. However, as global climate change affects weather patterns, the long-term trends of propagation data may be impacted over periods of decades or longer. Particularly, at high microwave frequencies (10 GHz and above), rain plays a dominant role in the attenuation statistics, and it has been observed that rain events over the past 50 years have trended toward increased frequency, intensity, and rain height. In the interest of quantifying the impact of these phenomena on long-term trends in propagation data, this paper compares two 20 GHz measurement campaigns both conducted at NASAs White Sands facility in New Mexico. The first is from the Advanced Communications Technology Satellite (ACTS) propagation campaign from 1994 to 1998, while the second is amplitude data recorded during a site test interferometer (STI) phase characterization campaign from 2009 to 2014.

attenuation↗

NASA NTRS2015

Long-Term Trends in Space-Ground Atmospheric Propagation Measurements

Propagation measurement campaigns are critical to characterizing the atmospheric behavior of a location and efficiently designing space-ground links. However, as global climate change affects weather patterns, the long-term trends of propagation data may be impacted over periods of decades or longer. Particularly, at high microwave frequencies (10 GHz and above), rain plays a dominant role in the attenuation statistics, and it has been observed that rain events over the past 50 years have trended toward increased frequency, intensity, and rain height. In the interest of quantifying the impact of these phenomena on long-term trends in propagation data, this paper compares two 20 GHz measurement campaigns both conducted at NASA's White Sands facility in New Mexico. The first is from the Advanced Communication Technology Satellite (ACTS) propagation campaign from 1994 - 1998, while the second is amplitude data recorded during a site test interferometer (STI) phase characterization campaign from 2009 - 2014.

Radio Attenuation↗

NASA NTRS2015

Preliminary Statistics from the NASA Alphasat Beacon Receiver in Milan, Italy

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 GHz band. NASA GRC has developed and installed a KQ-band (20-40 GHz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20-40 GHz signals broadcast from the Alphasat Aldo Paraboni TDP5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we provide an overview of the design and data calibration procedure, and present 6 months of preliminary statistics of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The Q-band receiver has demonstrated a dynamic range of 40 dB at an 8-Hz sampling rate. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models

Radio Transmission↗

NASA NTRS2014

Frequency Estimator Performance for a Software-Based Beacon Receiver

As propagation terminals have evolved, their design has trended more toward a software-based approach that facilitates convenient adjustment and customization of the receiver algorithms. One potential improvement is the implementation of a frequency estimation algorithm, through which the primary frequency component of the received signal can be estimated with a much greater resolution than with a simple peak search of the FFT spectrum. To select an estimator for usage in a QV-band beacon receiver, analysis of six frequency estimators was conducted to characterize their effectiveness as they relate to beacon receiver design.

Frequency Domain Analysis↗

NASA NTRS2014

Design of a K/Q-band Beacon Receiver for the Alphasat TDP#5 Experiment

This paper describes the design and performance of a coherent K/Q-band (20/40GHz) beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed at the Politecnico di Milano (POLIMI) for use in the Alphasat Technology Demonstration Payload #5 (TDP#5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40GHz to improve the performance of existing statistical rain attenuation models in the Q-band. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation. The receiver system has been characterized in the lab and demonstrates a system dynamic range performance of better than 58dB at 1Hz and better than 48dB at 10Hz rates.

beacon receiver↗

NASA NTRS2014

Frequency Estimator Performance for a Software-Based Beacon Receiver

As propagation terminals have evolved, their design has trended more toward a software-based approach that facilitates convenient adjustment and customization of the receiver algorithms. One potential improvement is the implementation of a frequency estimation algorithm, through which the primary frequency component of the received signal can be estimated with a much greater resolution than with a simple peak search of the FFT spectrum. To select an estimator for usage in a Q/V-band beacon receiver, analysis of six frequency estimators was conducted to characterize their effectiveness as they relate to beacon receiver design.

Radio Transmission↗

NASA NTRS2014

Ka-Band Atmospheric Phase Stability Measurements in Goldstone, CA; White Sands, NM; and Guam

As spacecraft communication links are driven to higher frequencies (e.g. Ka-band) both by spectrum congestion and the appeal of higher data rates, the propagation phenomena at these frequencies must be well characterized for effective system design. In particular, the phase stability of a site at a given frequency will govern whether or not the site is a practical location for an antenna array, particularly if uplink capabilities are desired. Propagation studies to characterize such phenomena must be done on a site-by-site basis due to the wide variety of climates and weather conditions at each ground terminal. Accordingly, in order to statistically characterize the atmospheric effects on Ka-Band links, site test interferometers (STIs) have been deployed at three of NASA's operational sites to directly measure each site's tropospheric phase stability. Using three years of results from these experiments, this paper will statistically characterize the simultaneous atmospheric phase noise measurements recorded by the STIs deployed at the following ground station sites: the Goldstone Deep Space Communications Complex near Barstow, CA; the White Sands Ground Terminal near Las Cruces, NM; and the Guam Remote Ground Terminal on the island of Guam.

Interferometry↗

NASA NTRS2012

W/V-Band RF Propagation Experiment Design

The utilization of frequency spectrum for space-to-ground communications applications has generally progressed from the lowest available bands capable of supporting transmission through the atmosphere to the higher bands, which have required research and technological advancement to implement. As communications needs increase and the available spectrum in the microwave frequency bands (3 30 GHz) becomes congested globally, future systems will move into the millimeter wave (mm-wave) range (30 300 GHz). While current systems are operating in the Ka-band (20 30 GHz), systems planned for the coming decades will initiate operations in the Q-Band (33 50 GHz), V-Band (50 75 GHz) and W Band (75 110 GHz) of the spectrum. These bands offer extremely broadband capabilities (contiguous allocations of 500 MHz to 1GHz or more) and an uncluttered spectrum for a wide range of applications. NASA, DoD and commercial missions that can benefit from moving into the mm-wave bands include data relay and near-Earth data communications, unmanned aircraft communications, NASA science missions, and commercial broadcast/internet services, all able to be implemented via very small terminals. NASA Glenn Research Center has a long history of performing the inherently governmental function of opening new frequency spectrum by characterizing atmospheric effects on electromagnetic propagation and collaborating with the satellite communication industry to develop specific communications technologies for use by NASA and the nation. Along these lines, there are critical issues related to W/V-band propagation that need to be thoroughly understood before design of any operational system can commence. These issues arise primarily due to the limitations imposed on W/V-band signal propagation by the Earth s atmosphere, and to the fundamental lack of understanding of these effects with regards to proper system design and fade mitigation. In this paper, The GRC RF propagation team recommends measurements that are required to assure that the risk associated with the use of mm-wave is minimized. We develop first order beacon and transponder system payload requirements and beacon terminal requirements. We will suggest and discuss a possible hardware implementation for the space segment, as well for the ground segment. A discussion on a propagation measurement campaign for taking relevant statistical data is also included.

Acosta, Roberto J.↗