Engineering topics

Morse, Jacquelynne R.

Publications and source records attributed to Morse, Jacquelynne R..

8 records

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

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

This paper describes the design and performance of a coherent KQ-band (2040 GHz) 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 (TDP5) beacon experiment. The goal of this experiment is to characterize rain fade attenuation at 40 GHz 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 58 dB at 1 Hz and better than 48 dB at 10 Hz rates.

beacon receiver↗

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

Design of a K/Q-Band Beacon Receiver for the Alphasat Technology Demonstration Payload (TDP) #5 Experiment

rain fade↗

NASA NTRS2010

Path Length Fluctuations Derived from Site Testing Interferometer Data

To evaluate possible sites for NASA's proposed Ka-band antenna array, the NASA Glenn Research Center has constructed atmospheric phase monitors (APM) which directly measure the tropospheric phase stability. These instruments observe an unmodulated 20.2 GHz beacon signal broadcast from a geostationary satellite (Anik F2) and measure the phase difference between the signals received by the two antennas. Two APM's have been deployed, one at the NASA Deep Space Network (DSN) Tracking Complex in Goldstone, California, and the other at the NASA White Sands Complex, in Las Cruces, New Mexico. Two station-years of atmospheric phase fluctuation data have been collected at Goldstone since operations commenced in May 2007 and 0.5 station-years of data have been collected at White Sands since operations began February 2009. With identical instruments operating simultaneously, we can directly compare the phase stability at the two sites. Phase stability is analyzed statistically in terms of the root-mean-square (rms) of the tropospheric path length fluctuations over 10 min blocks. Correlation between surface wind speed and relative humidity with interferometer phase are discussed. For 2 years, the path length fluctuations at the DSN site in Goldstone, California, have been better than 757 micrometer (with reference to a 300 m baseline and to Zenith) for 90 percent of the time. For the 6 months of data collected at White Sands, New Mexico, the path length fluctuations have been better than 830 micrometers (with reference to a 300 m baseline and to Zenith) for 90 percent of the time. This type of data analysis, as well as many other site quality characteristics (e.g., rain attenuation, infrastructure, etc.), will be used to determine the suitability of both sites for NASA s future communication services at Ka-band using an array of antennas.

Acosta, Roberto J.↗