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Azimuth correlation simulates large antenna aperature. It uses charge-coupled-device (CCD) technology to simplify complex, digital, signal-improvement process. In aircraft or spacecraft, correlator processes images onboard and in real time to simplify transmission to ground stations.
The network is designed for two-way communications with unmanned spacecraft traveling approximately 16,000 km (10,000 miles) from earth to the farthest planets and to the edge of our solar system. The objectives, functions, and organization of the Deep Space Network are summarized. Deep space station, ground communication, and network operations control capabilities are described.
NATO-3C, the third in a series of NATO defense-related communication satellites, is scheduled to be launched on a delta vehicle from the Eastern Test Range no earlier than November 15, 1978. NATO-3A and -3B were successfully launched by Delta vehicles in April 1976 and January 1977, respectively. The NATO-3C spacecraft will be capable of transmitting voice, data, facsimile, and telex messages among military ground stations. The launch vehicle for the NATO-3C mission will be the Delta 2914 configuration. The launch vehicle is to place the spacecraft in a synchronous transfer orbit. The spacecraft Apogee Kick motor is to be fired at fifth transfer orbit apogee to circularize its orbit at geosynchronous altitude of 35,900 km(22,260 miles) above the equator over the Atlantic Ocean somewhere between 45 and 50 degrees W longitude.
Data were collected by primarily twelve ground stations positioned throughout the eastern shore - tidewater area of Virginia and North Carolina. From an analysis of the ozone and wind data, certain trends were found such as the existence of a bias in ozone concentrations between stations and a linear correlation between average ozone concentration and latitude. In addition, higher ozone levels were found with surface winds from certain preferred directions at the various sites. The results, however, do not substantiate ozone or ozone precursor transport.
The author has identified the following significant results. Approximately 400 miles of low altitude scanner data of good quality was acquired over the Powder River Basin between 13-16 Oct. 1978. Radiometric and meteorological data from three ground stations were also acquired in support of low altitude U.S.G.S. overflights.
The objectives, functions, and organization of the Deep Space Network are summarized; deep space station, ground communication, and network operations control capabilities are described.
The objectives, functions, and organization of the Deep Space Network are summarized. Deep space station, ground communication, and network operations control capabilities are described.
The interfaces between the Ku-band system and the TDRSS, between the S-band system and the TDRSS, GSTDN and SGLS networks, and between the S-band payload communication equipment and the other Orbiter avionic equipment were investigated. The principal activities reported are: (1) performance analysis of the payload narrowband bent-pipe through the Ku-band communication system; (2) performance evaluation of the TDRSS user constraints placed on the S-band and Ku-band communication systems; (3) assessment of the shuttle-unique S-band TDRSS ground station false lock susceptibility; (4) development of procedure to make S-band antenna measurements during orbital flight; (5) development of procedure to make RFI measurements during orbital flight to assess the performance degradation to the TDRSS S-band communication link; and (6) analysis of the payload interface integration problem areas.
Data obtained from the backscattering ultraviolet instrument on Nimbus 4 are compared with standardized observations such as ground based Dobson and M83 measurements. Results of the comparison are discussed and their impact on planning for a satellite ozone monitoring program is assessed. It is suggested that the satellite data be used as a transfer standard whereby, if a discrepancy in an individual ground station is detected, that station instrument would be noted for recalibration.
It is shown that pseudo-range measurements to four GPS satellites based on correlation of the pseudo random code transmissions from the satellites can be used to determine the relative position of ground stations which are separated by several hundred kilometers to a precision at the centimeter level. Carrier signal measurements during the course of passage of satellites over a pair of stations also yield centimeter precision in the relative position, but oscillator instabilities limit the accuracy. The accuracy of solutions based on either type of data is limited by unmodeled tropospheric refraction effects which would reach 5 centimeters at low elevation angles for widely separated stations.
The pulse-height analyzer basically resembles a time-sharing multiplexing data-acquisition system which acquires analog data (from energetic particle spectrometers) and converts them into digital code. The PHA simultaneously acquires pulse-height information from the analog signals of the four input channels and sequentially multiplexes the digitized data to a microprocessor. The PHA together with the microprocessor form an on-board real-time data-manipulation system. The system processes data obtained during the rocket flight and reduces the amount of data to be sent back to the ground station. Consequently the data-reduction process for the rocket experiments is speeded up. By using a time-sharing technique, the throughput rate of the microprocessor is increased. Moreover, data from several particle spectrometers are manipulated to share one information channel; consequently, the TM capacity is increased.
The objectives, functions, and organization of the Deep Space Network are summarized; deep space station, ground communication, and network operations control capabilities are described.
The objectives, and organization of the Deep Space Network are summarized. Deep space station, ground communication, and network operations control capabilities are described.
Certain elements of solar power satellite design and system engineering studies are reviewed analyzing solar power satellites as a potential baseload electric power source. The complete system concept concept includes not only the satellites and their ground stations, but also the space transportation for delivery of the satellites, piece by piece, into space, and the factories for their construction in space. Issues related to carrying the solar power satellite concept from the present design study phase through implementation of actual hardware are considered. The first issue category is environmental aspects of the SPS systems. The second category of issues is the technology risks associated with achieving the necessary component and subsystem performances. The third category includes the engineering issues associated with carrying out such a large scale project. The fourth issue category is financial: the funding required to bring such a project into being and the costs of the satellites and resulting cost of the power produced as compared to potential alternative energy sources.
An experimental microwave multilateration system has been developed by NASA to provide highly accurate position and velocity measurements during the approach and landing phase of VTOL aircraft. The system uses an angle modulated ranging signal to provide both range and range rate measurements between an aircraft transponder and multiple ground stations. Range and range rate measurements are converted to coordinate measurements, and the coordinate information is transmitted via an integral data link to the aircraft. This paper describes the development of the multilateration system and the associated digital signal processing techniques. Advantages and disadvantages of several processing techniques are discussed. The operation and accuracy of the system as determined from both analytical studies and flight experiments will be described.
The basic features of the NASA remote sensing program are briefly outlined. Consideration is given to physical data acquisition and preprocessing, archiving for bulk retrieval, availability of Landsat data, and the role of foreign ground stations.
The paper describes Spacelab Mission Development Test III (SMD III) whose principal scientific objective was to demonstrate the feasibility of conducting biological research in the Life Sciences Spacelab. The test also provided an opportunity to try out several items of Common Operational Research Equipment (CORE) hardware being developed for operational use in Shuttle/Spacelab, such as rodent and primate handling, transportation units, and a 'zero-g' surgical bench. Operational concepts planned for Spacelab were subjected to evaluation, including animal handling procedures, animal logistics, crew selection and training, and a 'remote' ground station concept. It is noted that all the objectives originally proposed for SMD III were accomplished
The University of Michigan minipod, which is released from a balloon and floats down on a parachute, is designed for stratospheric testing. The present paper briefly describes the evolution of antenna designs for the minipod 1.5 GHz transceiver, which communicates with and relays information to an aircraft and ground station. The following stages are noted: ordinary monopole, crossed dipole, capacitative antenna, fat monopole, the addition of parasitic elements, and a thinner monopole with taper.