Relay system operations
In-orbit operational aspects of Relay I satellite and requirements for satellite command and for real time telemetry data reduction
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In-orbit operational aspects of Relay I satellite and requirements for satellite command and for real time telemetry data reduction
The routine on-orbit calibration of the Hubble Space Telescope (HST) rate gyro assemblies (RGA's) has depended on several related algorithms for drift rate bias calibration. The gyros have exhibited time-varying biases, which must be regularly corrected to maintain pointing stability. Currently, gyro drift parameters are uplinked to the spacecraft every 1-2 days for low rate mode and every 7 days for high rate mode. In order to minimize the impact of frequent calibrations on the HST science schedule, we have refined the gyro calibration algorithms and data collection schemes to reduce the amounts of telemetry data and processing time required for accurate bias calibration. We present a review of the evolution of the gyro calibration algorithms, with particular attention to what we have called the long-baseline bias (LBBIAS) technique, and describe the relative success of these methods in maintaining spacecraft stability.
Acoustic measurements were made with the Moog SureFly vehicle in hover and for the vehicle performing a combined takeoff and landing maneuver. The objectives of the effort were to identify the far field, obtain data to construct a noise hemisphere for prediction tool validation, and to obtain out-and back data for use in perceived noise studies. Vehicle telemetry data and future plans for the acoustic analysis were presented.
Dual detection system for processing AIMP satellite pulse frequency modulated telemetry data
Ground data handling equipment characteristics for PCM telemetry link utilizing convolutional coding
When telemetry data is transmitted through a communication link, some degradation in telemetry performance occurs as a result of the imperfect frequency response of the channel. The term telemetry degradation as used here is the increase in received signal power required to offset this filtering. The usual approach to assessing this degradation is to assume that it is equal to the signal power loss in the filtering, which is easily calculated. However, this approach neglects the effects of the nonlinear phase response of the filter, the effect of any reduction of the receiving system noise due to the filter, and intersymbol interference. Here, an exact calculation of the telemetry degradation, which includes all of the above effects, is compared with the signal power loss calculation for RF filtering of NRZ data on a carrier. The signal power loss calculation is found to be a reasonable approximation when the filter follows the point at which the receiving system noise is introduced, especially if the signal power loss is less than 0.5 dB. The signal power loss approximation is less valid when the receiving system noise is not filtered.
Synchronous data processing equipment used at source of remote site telemetry data compressor, stressing system design techniques
Data reduction facility for rapid analysis of space flight telemetry data
Measurements and analyses of resources within permanently shadowed craters and along steep embankments on extraterrestrial surfaces pose extreme challenges since astronauts and rovers cannot access them. However, these areas offer the potential for the greatest scientific returns. Researchers at the NASA Langley Research Center (LaRC) invented a deployable wireless micro-spectrometer that can access those challenging areas and deliver telemetry data to a receiver safely outside those extreme environments. The micro-spectrometers are designed for deployment by an astronaut, a rover, or a lander flying overhead. This device can also be installed on rover tires, under the astronaut’s shoes, or on a cane stick. The bullet-like, expendable micro-spectrometer can penetrate into soil to spectrally identify the components of soil, such as water, He-3, or other minerals. The signals from the soil assay data are transmitted to a mother station through a telemetry system. This LaRC developed micro-spectrometer bullet consists of micro-spectrometer optics with an all-imbedded, burst-mode, light-emitting-diode ultraviolet (LED UV) light source, a super-capacitor with control electronics, and telemetry electronics. Prototypes have been fabricated to demonstrate a spectral assay of soil components. Further maturation of this technology would be necessary for demonstrations on the Moon.
Real-time ground processing of space mission telemetry data from orbiting telescopes
Research being undertaken to develop expert systems for reducing telemetry data from spacecraft is described. The use of the Hubble Space Telescope Electrical Power System as a testbed is examined. The Nickel Cadmium Battery Expert System is briefly addressed, and the I-DARE (Intelligent Data Reduction) prototype system is discussed.
An overview is presented of the Solar-A telemetry data files which are to be created and the format and organization which the files are to use. The organization chosen is to be efficient in space, to facilitate access to the data, and to allow the data to be transportable to different machines. An observing log file is to be created automatically, using the reformatted data files as the input. It will be possible to perform searches with the observing log to list cases where instruments are in certain modes and/or seeing certain signal levels. A user will be able to search the observing log and obtain a list of all cases where a given set of conditions are satisfied. An event log will be created listing the times when the instrument or spacecraft modes change.
Calibrated signal-strength data obtained at 10 sites in the Rockies and NASA telemetry data regarding the signal levels in the ATS 6 spacecraft are presented along with methodology to use the data to compute the carrier-to-noise rations and signal-to-noise rations at each of the calibrated sites. The data and methodology are also used to estimate the median values of these quantities for sites in the Rockies, Alaska, and Appalachia. Results are discussed.
Auxiliary data processor does computations related to synchronization of frames of telemetry data, relieving main processor of task. Called frame-synchronization-assisting module (FSAM), sorts through large amounts of data to determine whether valid and how configured. Module connected to main processor of computer through direct-memory-access (interface) module. Examines data in computer memory to find frame-synchronizing codes.
SondeHub aggregates radiosonde telemetry data uploaded from community-run radiosonde receiver stations. This radiosonde telemetry dataset is open-source, available to anyone through Amazon S3. There are also other public radiosonde datasets such as National Centers for Environmental Information (NCEI)’s Integrated Global Radiosonde Archive (IGRA). While there are many similarities between the two datasets, there are many differences as well due to the nature of the two datasets: one is community-run, while the other is managed by a government agency. This report presents the result of analyzing and comparing the two datasets.
The Station Data Acquisition and Control System (STADAC), a multicomputer data handling and control system, is expected to be installed in six network stations, the first station to be established at Goddard Space Flight Center. Network control data, in the form of schedules and acquisition pointing data, flow from the Network Control Center to the stations, while station status data flow in the other direction. The system will format spacecraft telemetry data for real-time transmission of control and status data to the project operations control centers and for transmission of experiment data to the data processing facilities. The system will also schedule station equipment resources, perform prepass tests to assure data quality, and automatically set up selected station equipment.
The Apollo management of data for postflight engineering evaluation is described. The sources of Apollo telemetry data, the control of data processing by a single data team, the data techniques used to assist in evaluation of the large quantity of data, and the operation of the data team before the mission and during the evaluation phase are described. The techniques used to ensure the output of valid data and to determine areas in which data were of questionable quality are also included.
A multitasking, data acquisition system was written to simultaneously collect meteorological radar and telemetry data from two sources. This system is based on the personal computer architecture. Data is collected via two asynchronous serial ports and is deposited to disk. The system is written in both the C programming language and assembler. It consists of three parts: a multitasking kernel for data collection, a shell with pull down windows as user interface, and a graphics processor for editing data and creating coded messages. An explanation of both system principles and program structure is presented.