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Near-real-time validation of ranging system data is currently restricted to multiple range acquisitions during single passes (Pseudo-DRVID). A technique (Differential Range Validation) which utilizes predicted range and doppler pseudo-residuals to validate two-station, contiguous-pass range acquisitions down to the 10-meter level is described.
Access to high-quality, high-resolution, near-real-time precipitation data is essential for hydrological and meteorological research and disaster mitigation. Traditional tools such as rain gauges and radar networks, though effective, have limitations, including sparse coverage in remote areas and high operational costs. Satellite data, with its global coverage and high spatial and temporal resolutions, mitigates limitations in coverage. Satellite precipitation products like Hydro Estimator (HE), Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG), and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) utilize both geosynchronous thermal infrared (IR) and passive microwave (PMW) data in their operation. PMW sensors offer detailed atmospheric profiles but suffer from higher latency, whereas IR sensors provide lower latency but only capture cloud-top information. Despite this constraint, IR data remains attractive for low-latency precipitation estimation. Recent advances in deep learning, particularly convolutional neural networks (CNNs), have further improved satellite precipitation retrievals. This study introduces PERSIANN-Unet (PUnet or PERSIANN V3), a quasi-global algorithm covering 60°N–60°S that combines IR data, monthly climatology, and the UNet architecture to produce half-hourly precipitation estimates at 0.04° resolution. The product is evaluated against HE, IMERG, and PDIR-Now for 2022–2023. Results show that PUnet closely matches its training target, IMERG V07 Final, at the global scale, and performance is further evaluated against Stage IV as a reference over CONUS. Training PUnet on IMERG (2016–2021) leverages a high-quality, integrated PMW IR-gauge precipitation product while developing an IR-based framework not reliant on PMW availability. By operating on a single global image, PUnet avoids tile partitioning and blending steps, reducing edge discontinuities, and produces more spatially consistent precipitation fields across hemispheres.
Doppler noise generated within the tracking system is modeled as a function of the dominant variable-Doppler sample interval. Additionally, the relationship between media noise and Doppler samples interval is empirically determined, and the ratio of media noise for S- and X-band downlinks is solved for. These functional relationships are incorporated into the previous media noise modeling to obtain a comprehensive two-way Doppler noise model.
Procedures used in monitoring, analyzing, and displaying flight and ground flutter test data are presented. These procedures include three digital computer programs developed to process structural response data in near real time. Qualitative and quantitative modal stability data are derived from time history response data resulting from rapid sinusoidal frequency sweep forcing functions, tuned-mode quick stops, and pilot induced control pulses. The techniques have been applied to both fixed and rotary wing aircraft, during flight, whirl tower rotor systems tests, and wind tunnel flutter model tests. An hydraulically driven oscillatory aerodynamic vane excitation system utilized during the flight flutter test programs accomplished during Lockheed L-1011 and S-3A development is described.
Two computer programs are used to forecast foF2 at points around Australia from daily and hourly ionospheric indices. It is found that for forecasts one day ahead, the most accurate results are obtained using the past variations of foF2 at several stations to determine a latitudinal-average daily ionospheric index. Forecasts made with lead times of zero to three hours do not offer significant improvements over those made one day ahead.
An L-band telemetry system designed to provide the capability of near-real-time processing of calibration data is described. The system also provides the capability of performing computerized spacecraft simulations, with the aircraft as a data source, and evaluating the network response. The salient characteristics of a telemetry analysis and simulation program (TASP) are discussed, together with the results of TASP testing. The results of the L-band system testing have successfully demonstrated the capability of near-real-time processing of telemetry test data, the control of the ground-received signal to within + or - 0.5 db, and the computer generation of test signals.
Houston Manned Spacecraft Center display and control system for near-real-time assessment of Project Gemini data
The purpose of this paper is to describe the system for the display, processing, and production of image data products created to support the Mariner 9 Television Experiment. Of necessity, the system was large in order to respond to the needs of a large team of scientists with a broad scope of experimental objectives. The desire to generate processed data products as rapidly as possible to take advantage of adaptive planning during the mission, coupled with the complexities introduced by the nature of the vidicon camera, greatly increased the scale of the ground image processing effort. This paper describes the systems that carried out the processes and delivered the products necessary for real-time and near-real-time analyses. References are made to the computer algorithms used for the different levels of decalibration and analysis.
The purpose of this paper is to describe the system for the display, processing, and production of image-data products created to support the Mariner 9 Television Experiment. Of necessity, the system was large in order to respond to the needs of a large team of scientists with a broad scope of experimental objectives. The desire to generate processed data products as rapidly as possible, coupled with the complexities introduced by the nature of the vidicon camera, greatly increased the scale of the ground-image processing effort. This paper describes the systems that carried out the processes and delivered the products necessary for real-time and near-real-time analyses. References are made to the computer algorithms used for the different levels of decalibration and analysis.
The feasibility of using a combination of spacecraft-based optical data and earth-based Doppler data to perform near-real-time approach navigation was demonstrated by the Mariner Mars 71 Project. The important findings, conclusions, and recommendations are documented. A summary along with publications and papers giving additional details on the objectives of the demonstration are provided. Instrument calibration and performance as well as navigation and science results are reported.
The sleep monitoring experiment permitted an objective evaluation of sleep characteristics during the first two manned Skylab flights. Hardware located onboard the spacecraft accomplished data acquisition, analysis, and preservation, thereby permitting near-real-time evaluation of sleep during the flights and more detailed postmission analysis. The crewman studied during the 28-Day Mission showed some decrease in total sleep time and an increase in the percentage of Stage 4 sleep, while the subject in the 59-Day Mission exhibited little change in total sleep time and a small decrease in Stage 4 and REM sleep. Some disruption of sleep characteristics was seen in the final days of both missions, and both subjects exhibited decreases in REM-onset latency in the immediate postflight period. The relatively minor changes seen were not of the type nor magnitude which might be expected to be associated with significant degradation of performance capability.
Optical navigation uses spacecraft television pictures of a target body against a known star background in a process which relates the spacecraft trajectory to the target body. This technology was used in the Mariner-Venus-Mercury mission, with the optical data processed in near-real-time, simulating a mission critical environment. Optical data error sources were identified, and a star location error analysis was carried out. Several methods for selecting limb crossing coordinates were used, and a limb smear compensation was introduced. Omission of planetary aberration corrections was the source of large optical residuals.
The state-of-the-art of automatic multispectral scanner data analysis and interpretation is reviewed. Sources of system variability which tend to obscure the spectral characteristics of the classes under consideration are discussed, and examples of the application of spatial and temporal discrimination bases are given. Automatic processing functions, techniques and methods, and equipment are described with particular attention to those that are applicable to large land surveys using satellite data. The development and characteristics of the Multivariate Interactive Digital Analysis System (MIDAS) for processing aircraft or satellite multispectral scanning data are discussed in detail. The MIDAS system combines the parallel digital implementation capabilities of a low-cost processor with a general purpose PDP-11/45 minicomputer to provide near-real-time data processing. The preprocessing functions are user-selectable. The input subsystem accepts data stored on high density digital tape, computer compatible tape, and analog tape.
Advantages in the use of TV on board satellites as the primary data-recording system in a manned space laboratory when certain types of experiments are flown are indicated. Real-time or near-real-time validation, elimination of film weight, improved depth of field and low-light sensitivity, and better adaptability to computer and electronic processing of data are spelled out as advantages of TV over photographic techniques, say, in fluid dynamics experiments, and weightlessness studies.
The principal objective was to determine for each experiment how the operating procedures and modes of equipment onboard shuttle can be managed in real-time or near-real-time to enhance the quality of results. As part of this determination the data and display devices that a man will need for real-time management are defined. The secondary objectives, as listed in the RFQ and technical proposal, were to: (1) determine what quantities are to be measured (2) determine permissible background levels (3) decide in what portions of space measurements are to be made (4) estimate bit rates (5) establish time-lines for operating the experiments on a mission or set of missions and (6) determine the minimum set of hardware needed for real-time display. Experiment descriptions and requirements were written. The requirements of the various experiments are combined and a minimal set of joint requirements are defined.
The Deep Space Network Command System Mark III-78 implementation and functional operation are described. Software upgrade enables expanded storage capacity in the Deep Space Station Command Processor Assembly. Store-and-forward command data handling is operational for Voyager and Helios. Near-real-time command data handling was retained for Viking and Pioneer.
Trends in automation of planetary spacecraft are examined using data from missions as far back as Mariner '67 and up to the highly sophisticated Galileo. Nine design considerations which influence the degree of automation such as protection against catastrophic failures, highly repetitive functions, loss of spacecraft communications, and the need for near-real-time adaptivity are discussed. Rapid growth of automation is shown in terms of on-board hardware by plots of number of processors on board, the average speed of processors, and total core memory. The number of commands transmitted from the ground has grown to 5 million bits in Voyager, so that increases in mission complexity have increased both in spacecraft automation and ground operations. Achieving greater automation by transferring ground operations to the spacecraft with the current means of controlling missions, are considered noting proposed changes. For the future, improved computer technology, more microprocessors and increased core storage will be used, and the number of automated functions and their complexity will grow. It is concluded that using the growing computational capability of spacecraft will achieve more autonomy thus reversing the trend of increased mission complexity and cost.
The Satellite Data Distribution System (SDDS) serves to process satellite-derived ocean observations, generate ocean analysis and forecast products, and distribute the products to a limited set of commercial users. The SDDS functions in series with the U.S. Navy Fleet Numerical Oceanography Center (FNOC) to provide products on a near-real-time basis to commercial marine industries. Conventional meteorological and oceanographic observations provided to FNOC serve as the input set to the numerical analysis and forecast models. Large main-frame computers are used to analyze and forecast products on a routine, operational basis (at 6-hour and 12-hour synoptic times). The products, reformatted to meet commercial users needs, are transferred to a NASA-owned computer for storage and distribution. Access to the information is possible either by a commercial dial-up packet-switching network or by a direct computer-computer connection.