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NASA NTRS1992

The ITU as a means of facilitating international collaboration on space radiocommunication systems

The role of the International Telecommunication Union (ITU) in the international collaboration in the field of space radio communications is reviewed. The history of the ITU, its structure and activities, and the functions of the permanent organs of the ITU are briefly discussed. Attention is then given to new space service applications for communications around 400 MHz, space services near 2 GHz, new space service applications above 20 GHz, and links for future planetary missions. The discussion also covers deep space allocations near 32/34 GHz, space VLBI applications, new earth exploration satellite service applications, and future work.

Kimball, H.↗

NASA NTRS1993

Dynamic Termination On Radiating Coaxial Cable

Radiation pattern dithered to reduce adverse effect of nulls. In improved system for radio communication between base station and portable units within building, tunnel, ship, or other large structure, radiating or "leaky" coaxial cable serves as base-station antenna, and radiation pattern of cable dithered by dithering impedance of termination at end of cable remote from base station.

Lombardi, Robert↗

NASA NTRS1993

The Telecommunications and Data Acquisition Report

Posner, E. C.↗

NASA NTRS1991

Hazard assessment and cockpit presentation issues for microburst alerting systems

Issues pertaining to the development of an alerting system for microbursts in the terminal area are studied. A methodology for evaluating microburst hazard criteria is developed on the basis of batch aircraft flight simulations. A preliminary evaluation of a selected set of hazard criteria is performed. The results indicate that the total headwind change along the aircraft flight path ('total divergence') does not correlate well with the approach degradation caused by microbursts. A preliminary piloted simulator study on cockpit presentation of wind shear alerts in verbal, alphanumeric, and graphical formats is performed. Graphical alerts were found to produce better decision-making and lower crew workload, and to be greatly preferred by pilots. Alphanumeric alerts were not well liked and exhibited no advantages over standard verbal radio communications.

Wanke, Craig↗

NASA NTRS1994

Computer-Aided Remote Driving

System for remote control of robotic land vehicle requires only small radio-communication bandwidth. Twin video cameras on vehicle create stereoscopic images. Operator views cross-polarized images on two cathode-ray tubes through correspondingly polarized spectacles. By use of cursor on frozen image, remote operator designates path. Vehicle proceeds to follow path, by use of limited degree of autonomous control to cope with unexpected conditions. System concept, called "computer-aided remote driving" (CARD), potentially useful in exploration of other planets, military surveillance, firefighting, and clean-up of hazardous materials.

Wilcox, Brian H.↗

NASA NTRS1994

Approximating Effect Of Spherical Radiation Pattern

Time-division multiple-access TDMA multichannels radio communication system implements scheme of temporal and spatial multiplexing of signals to approximate effect of spherical antenna radiation pattern. Signal to be transmitted sped up by factor of n and transmitted in n replicas via n antennas. During reception, incoming signal processed by use of maximum-signal-selection or diversity-reception demodulated-signal-combining technique.

Sickles, Louis, II↗

NASA NTRS1994

Frequency-Shift Hearing Aid

Proposed hearing aid maps spectrum of speech into band of lower frequencies at which ear remains sensitive. By redirecting normal speech frequencies into frequency band from 100 to 1,500 Hz, hearing aid allows people to understand normal conversation, including telephone calls. Principle operation of hearing aid adapted to other uses such as, clearing up noisy telephone or radio communication. In addition, loud-speakers more easily understood in presence of high background noise.

Weinstein, Leonard M.↗

NASA NTRS1991

The Telecommunications and Data Acquisition Report

This quarterly publication provides archival reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA). In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN). Also included is standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. In the search for extraterrestrial intelligence (SETI), 'The TDA Progress Report' reports on implementation and operations for searching the microwave spectrum. In solar system radar, it reports on the uses of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets. In radio astronomy, the areas of support include spectroscopy, very long baseline interferometry, and astrometry.

Posner, Edward C.↗

NASA NTRS1994

The Telecommunications and Data Acquisition Report

Reports on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA) are provided. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other agencies through NASA.

Yuen, Joseph H.↗

NASA NTRS1994

The Telecommunications and Data Acquisition Report

This quarterly publication provides archival reports on developments in programs in space communications, radio navigation, radio science, and ground-based radio and radar astronomy. It reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standardization activities at the Jet Propulsion Laboratory for space data and information systems.

Yuen, Joseph H.↗

NASA NTRS1995

STS-67 Post Flight Presentation

This video is the post-flight presentation by the astronauts of the STS-67 Space Shuttle Mission. The astronauts were: Steve Oswald (Mission Commander), Bill Gregory (Shuttle Pilot), John Grunsfeld (Mission Specialist), Sam Durrance (Payload Specialist), Ron Parise (Payload Specialist), and Tammy Jernigan (Payload Commander). Footage includes: pre-launch suitup and launch (liftoff), the deployment of the telescope package payload (Hopkins UV telescope, Wisconsin UV polarimeter, and Astrostar Tracker) for their astronomical observations of different stellar objects, inside Shuttle shots of data collection stations, protein crystal growth experiments, medical BSO of head and eye functions in microgravity environment, storm activity over the United States and other Earth observation shots, Mid-deck Act Control Experiments, school-Shuttle direct radio communication, and descent and landing footage. This launch was a night launch and the flight was a 17 day flight (extended two days from original flight plan).

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NASA NTRS1995

Digital Baseband Architecture For Transponder

Proposed advanced transponder for long-distance radio communication system with turnaround ranging contains carrier-signal-tracking loop including baseband digital "front end." For reduced cost, transponder includes analog intermediate-frequency (IF) section and analog automatic gain control (AGC) loop at first of two IF mixers. However, second IF mixer redesigned to ease digitization of baseband functions. To conserve power and provide for simpler and smaller transponder hardware, baseband digital signal-processing circuits designed to implement undersampling scheme. Furthermore, sampling scheme and sampling frequency chosen so redesign involves minimum modification of command-detector unit (CDU).

Nguyen, Tien M.↗

NASA NTRS1995

The Telecommunications and Data Acquisition Report

This quarterly publiction provides archival reports on developments in programs managed by JPL Telecommunications and Mission Operations Directorate (TMOD), which now includes the former communications and Data Acquisition (TDA) Office. In space communications, radio navigation, radio science, and ground-based radio and radar astronomy, it reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standards activity at JPL for space data and information systems and reimbursable DSN work performed for other space agencies through NASA. The Orbital Debris Radar Program, funded by the Office of Space Systems Development, makes use of the planetary radar capability when the antennas are configured at science instruments making direct observations of planets, their satellites, and asteroids of our solar system.

Yuen, Joseph H.↗

NASA NTRS1996

Spectrum-Sharing Scheme For Two BPSK Systems

Scheme proposed to enable two binary-phase-shift-keyed (BPSK) radio-communication systems to operate simultaneously in same frequency band. Estimate of interference spectrum generated in one of interference cancelers and subtracted from total spectrum of received signal + noise to obtain interference-free spectrum.

Gutierrez-Luaces, Benito O.↗

NASA NTRS1996

Development of the command data system and ground software for the SEDSAT-1 microsatellite

SEDSAT-1 is designed to be a low cost scientific satellite which is to be used to perform a minimum of five tasks which include: (1) the acquisition of a number of important parameters associated with the tethering processes from the payloads perspective (such as accelerations incurred and imaging data of the tether during deployment), (2) to act as a remote sensing platform for making measurements of the Earth's Atmosphere (allowing research to be performed in such areas as vertical lightning observation, visible light spectrography, and cloud cover studies, (3) to act as a general purpose amateur radio communication satellite relaying information back to earth, (4) to demonstrate the feasibility of the deployment in low earth orbit of advanced technology such as the Gallium Arsenide Solar Cells, Nickel Metal Hydride batteries, and multi-chip module technology and, (5) to support student's active participation in applying the disciplines of engineering and science to space-based hardware platforms. The project includes the Three-axis Accelerometer System, TAS, Experiment which is designed to report the accelerations that the satellite undergoes during the tethering operations and during the second phase of the mission when the free floating satellite comes in contact with orbit debris. The SEASIS (SEDS Earth, Atmosphere, and Space Imaging System) is another SEDSAT experiment designed to provide images of the tether during its deployment and the earth during the second phase of the mission. To control these experiments and virtually all other satellite operations the Command Data System, CDS is employed. This system utilizes a moderate complexity micro-controller controlled by tasks operating under a real-time operating system to dynamically monitor and control the satellite. The scope of this researchers efforts has been in the general area of coordinating and assisting the student researchers with the development of the CDS and ground station interfaces. This included the low level CDS hardware design and the formulization of a general software plan and schedule for both the CDS and ground station portions of the project.

Wells, B. Earl↗

NASA NTRS1961

Project Echo: System Calculations

The primary experimental objective of Project Echo was the transmission of radio communications between points on the earth by reflection from the balloon satellite. This paper describes system calculations made in preparation for the experiment and their adaptation to the problem of interpreting the results. The calculations include path loss computations, expected audio signal-to-noise ratios, and received signal strength based on orbital parameters.

Ruthroff, Clyde L.↗

NASA NTRS1961

Project Echo: FM Demodulators with Negative Feedback

The primary experimental objective of Project Echo was the transmission of radio communications between points on the earth by reflection from the balloon satellite. Owing to the large path losses from transmitter to receiver via the satellite, a wide-band frequency modulation technique was used in which bandwidth was traded for signal-to-noise ratio. This paper describes the FM receiving demodulators employed. Negative feedback applied to the local oscillator reduces the FM modulation index in the receiver IF amplifiers, resulting in threshold performance superior to that of conventional FM receivers.

Ruthroff, Clyde L.↗

NASA NTRS1998

STS-88 Endeavour: TCDT-Press Q & A at KSCNF Auditorium

Live footage of the (Terminal Countdown Demonstration Test) TCDT shows the crew of STS-88, Commander Robert D. Cabana, Pilot Frederick W. Sturckow, and Mission Specialists Nancy J. Curry, Jerry L. Ross, James H. Newman, and Sergei K. Krikalev, participating in a press conference. The moderator Bruce Buckingham is seen introducing Bob Cabana, who then introduces the rest of the crewmembers. Cabana explains the mission and addresses the flight day activities. He includes the building of the Node 1 station element to the Functional Energy Block (FGB) which will already be in orbit, and two space-walks to connect power and data transmission cables. The crewmembers took turn answering questions from both the audience and via radio communication with the Johnson Space Center.

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