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NASA NTRS2003

Relating Downlink Data Products to Uplink Commands

An improved data-labeling system provides for automatic association of data products of an exploratory robot (downlink information) with previously transmitted commands (uplink information) that caused the robot to gather the data. Such association is essential to correct and timely analysis of the data products -- including, for example, association of the data with the correct targets. The system was developed for use on Mars Rover missions during the next few years. The system could also be adapted to terrestrial exploratory telerobots for which delays between commands and data returns are long enough to give rise to questions as to which commands resulted in which data returns. The main advantage of this system over prior data-labeling systems is that given a downlink data product, the uplink command and sequence hierarchy that produced it are automatically provided, and given an uplink sequence and command, the downlink data products that it produced are automatically provided.

Backes, Paul↗

NASA NTRS2013

Uplink Summary Generator (ULSGEN) Version 1.0

The Uplink Summary Generator (ULSGEN) provides a convenient means of gathering together a set of uplink related files, parsing and analyzing these files, and producing a summary of their contents, which may then be electronically signed by one or more reviewers to verify the commands. Spacecraft operations personnel view this summary as a final sanity check before actual radiation of the uplink data.

Wang, Yeou-Fang↗

NASA NTRS2011

Uplink Array Technology Development

Objective: Develop and demonstrate Uplink Array CALIBRATION and BLIND TRACKING TECHNOLOGIES at X-band, under realistic operational conditions relevant to future DSN uplink arrays

planetary radar↗

NASA NTRS2012

CASSIUS: The Cassini Uplink Scheduler

The Cassini Uplink Scheduler (CASSIUS) is cross-platform software used to generate a radiation sequence plan for commands being sent to the Cassini spacecraft. Because signals must travel through varying amounts of Earth's atmosphere, several different modes of constant telemetry rates have been devised. These modes guarantee that the spacecraft and the Deep Space Network agree with respect to the data transmission rate. However, the memory readout of a command will be lost if it occurs on a telemetry mode boundary. Given a list of spacecraft message files as well as the available telemetry modes, CASSIUS can find an uplink sequence that ensures safe transmission of each file. In addition, it can predict when the two on-board solid state recorders will swap. CASSIUS prevents data corruption by making sure that commands are not planned for memory readout during telemetry rate changes or a solid state recorder swap.

Cassini mission↗

NASA NTRS2011

Power Spectrum of Uplink Array Signals with Random Phase and Delay Errors

Link Array signals emanating from different antennas must be compensated for Doppler and delay in order to achieve the N(sup 2) array gain predicted by theory. However compensation is never perfect, leaving residual errors that cause losses in array gain and degradation in signal quality. Here we develop a mathematical model for Uplink Array signals in the presence of phase and delay errors, similar to well-known multipath analyses but with features unique to this problem. The resulting losses and distortions are described, and the power spectral density of the array signal derived first conditioned on a given error vector, then averaged over distributions deemed suitable for Uplink Array applications. The impact of phase and delay errors on array gain and signal distortion are addressed, and the maximum data throughput is quantified in terms of the assumed error statistics.

uplinks arrays↗

NASA NTRS2003

Deep Space C3: high power uplinks

The uplink transmitters of the Deep Space Network (DSN) perform three support functions in support of space missions: navigation, command, uplink, and emergency recovery.

vacuum↗

NASA NTRS1976

Signal design study for shuttle/TDRSS Ku-band uplink

The adequacy of the signal design approach chosen for the TDRSS/orbiter uplink was evaluated. Critical functions and/or components associated with the baseline design were identified, and design alternatives were developed for those areas considered high risk. A detailed set of RF and signal processing performance specifications for the orbiter hardware associated with the TDRSS/orbiter Ku band uplink was analyzed. Performances of a detailed design of the PN despreader, the PSK carrier synchronization loop, and the symbol synchronizer are identified. The performance of the downlink signal by means of computer simulation to obtain a realistic determination of bit error rate degradations was studied. The three channel PM downlink signal was detailed by means of analysis and computer simulation.

Source record↗

NASA NTRS1982

Potential reduction of DSN uplink energy cost

DSN Earth stations typically transmit more power than that required to meet minimum specifications for uplink performance. Energy and cost savings that could result from matching the uplink power to the amount required for specified performance are studied. The Galileo mission was selected as a case study. Although substantial reduction in transmitted energy is possible, potential savings in source energy (oil or electricity) savings are much less. This is because of the rising inefficiency in power conversion and radio frequency power generation that accompanies reduced power output.

Dolinsky, S.↗

NASA NTRS1984

X-band Uplink Technology Demonstration at DSS-13

The status of the X-band uplink development program is examined from a systems' viewpoint. The hardware, designed and built under the program, is now in place at DSS-13. System stability testing is underway. An X-band receive capability is being implemented on both the Galileo and the Venus Radar Mapper spacecraft. Experiments are planned to demonstrate the capabilities of the X-band uplink system and to permit performance of the gravitational wave experiment on the Galileo orbiter and obtain a more detailed gravity map of Venus.

Meeker, J. G.↗

NASA NTRS1985

Spacecraft commanding for unmanned planetary missions - The uplink process

A general description of the command generation process for unmanned planetary missions is presented. Emphasis is given to those mission characteristics which significantly affect the cost of the uplink process including: the level of mission activity; mission strategies; permissible risk; and spacecraft design. Pertinent examples of the command generation procedures used in the Voyager, Mariner, and Viking programs are given in order to illustrate the different stages of the uplink process.

Linick, T. D.↗

NASA NTRS1989

Automating the uplink process for planetary missions

The dual challenges of increased capability along with lower costs are addressed with regard to flight operations. A program has been formulated to take advantage of advances in software and hardware in order to design, and prototype where indicated, a set of tools which can be applied to the building of a more productive uplink process for NASA missions that are envisaged for the the next decade. Techniques such as object-oriented programming, expert systems, natural-language parsing, interactive graphics, and parallel processing are employed in the quest for increased productivity. The paper is organized hierarchically with the level of 'goal', 'objectives' and 'tasks'. A brief review of the uplink process is included.

Mclaughlin, William I.↗

NASA NTRS1996

Preliminary analysis of fluctuations in the received uplink-beacon-power data obtained from the GOLD experiments

Uplink data from recent free-space optical communication experiments carried out between the Table Mountain Facility and the Japanese Engineering Test Satellite are used to study fluctuations caused by beam propagation through the atmosphere. The influence of atmospheric scintillation, beam wander and jitter, and multiple uplink beams on the statistics of power received by the satellite is analyzed and compared to experimental data. Preliminary analysis indicates the received signal obeys an approximate lognormal distribution, as predicted by the weak-turbulence model, but further characterization of other sources of fluctuations is necessary for accurate link predictions.

M. Jeganathan↗

NASA NTRS1996

Preliminary Analysis of Fluctuations in the Received Uplink-Beacon-Power Data Obtained From the GOLD Experiments

Jeganathan, M.↗

NASA NTRS2002

Automated testing of the Deep Space Network's Uplink Subsystem

This paper describes some of the lessons we learned in implementing two different Tcl-basedtest frameworks used to automate testing of the Deep Space Network's new Uplink Subsystem, and discusses the advantages and disadvantages of each. The first framework was external to the Uplink Subsystem's software and provided complete control of the environment; the second was integrated with the software and provided less control, but motivated more and better testing. Some implementation details of the second frameworkare discussed as well.

DSN automated testing Tcl/Tk↗

NASA NTRS2002

Relating downlink products to uplink commands in Mars Rover operations

We discuss how downlink data products in Mars rover missions need to be associated with their uplink commanded target locations and the uplink commands that produced them.

rover operations data↗

NASA NTRS2008

Mars Reconnaissance Orbiter Uplink Analysis Tool

This software analyzes Mars Reconnaissance Orbiter (MRO) orbital geometry with respect to Mars Exploration Rover (MER) contact windows, and is the first tool of its kind designed specifically to support MRO-MER interface coordination. Prior to this automated tool, this analysis was done manually with Excel and the UNIX command line. In total, the process would take approximately 30 minutes for each analysis. The current automated analysis takes less than 30 seconds. This tool resides on the flight machine and uses a PHP interface that does the entire analysis of the input files and takes into account one-way light time from another input file. Input flies are copied over to the proper directories and are dynamically read into the tool s interface. The user can then choose the corresponding input files based on the time frame desired for analysis. After submission of the Web form, the tool merges the two files into a single, time-ordered listing of events for both spacecraft. The times are converted to the same reference time (Earth Transmit Time) by reading in a light time file and performing the calculations necessary to shift the time formats. The program also has the ability to vary the size of the keep-out window on the main page of the analysis tool by inputting a custom time for padding each MRO event time. The parameters on the form are read in and passed to the second page for analysis. Everything is fully coded in PHP and can be accessed by anyone with access to the machine via Web page. This uplink tool will continue to be used for the duration of the MER mission's needs for X-band uplinks. Future missions also can use the tools to check overflight times as well as potential site observation times. Adaptation of the input files to the proper format, and the window keep-out times, would allow for other analyses. Any operations task that uses the idea of keep-out windows will have a use for this program.

Khanampompan, Teerapat↗

NASA NTRS2010

Atmospheric Compensation for Uplink Arrays via Radiometry

Uplink arrays for communications applications are gaining increased visibility within the NASA and military community due to the enhanced flexibility and reliability they provide. When compared with the conventional large, single aperture antennas currently comprising the Deep Space Network (DSN), for example, smaller aperture antenna arrays have the benefits of providing fault tolerance (reduced single-point failure), reduced maintenance cost, and enhanced capabilities such as electronic beam-steering and multi-beam operation. However, signal combining of antenna array elements spaced many wavelengths apart becomes problematic due to the inherent instability of earth's turbulent atmosphere, particularly at the frequencies of interest to the DSN (i.e., Ka-band). Degradation in the power combining of the individual elements comprising the array arises due to uncorrelated phase errors introduced as the signals propagate through the troposphere. It is well known that the fundamental source of this error is due to the inhomogeneous distribution of water vapor in the atmosphere [1]. Several techniques have been proposed to circumvent this issue, including the use of phase calibration towers and a moon bounce to generate a feedback loop which would provide a means of intermittent calibration of the system phase errors (thermal drifts, atmosphere) [2,3]. However, these techniques require repositioning of the antenna elements to perform this operation which ultimately results in reduced system availability. And, though they are sufficient for compensating for slow varying phase drifts, they are insufficient to compensate for faster varying phase errors, such as those introduced by the atmosphere. In this paper, preliminary radiometry and interferometry measurements collected by the NASA Glenn Research Center are analyzed and indicate that the use of optimized water vapor radiometers as a feedback system in a communications platform could provide the necessary atmospheric compensation technique to enhance the beamforming of uplink arrays.

Nessel, James A.↗

NASA NTRS2015

Wind Information Uplink to Aircraft Performing Interval Management Operations

The accuracy of the wind information used to generate trajectories for aircraft performing Interval Management (IM) operations is critical to the success of an IM operation. There are two main forms of uncertainty in the wind information used by the Flight Deck Interval Management (FIM) equipment. The first is the accuracy of the forecast modeling done by the weather provider. The second is that only a small subset of the forecast data can be uplinked to the aircraft for use by the FIM equipment, resulting in loss of additional information. This study focuses on what subset of forecast data, such as the number and location of the points where the wind is sampled should be made available to uplink to the aircraft.

Ahmad, Nashat↗