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The testing of a new design high power S-band diplexer is reported. The megawatt Cassegrain diplexer (MCD) is to be used for DSN operations. The tests described were performed at 100 kW at the Venus Deep Space Station (DSS 13) transmitter test area. At 100 kW or less no degradation of receive performance was detected.
The relativity experiment on Helios (Experiment 11) uses S-band and Doppler data, and spacecraft-solar-orbital data to measure the effects of general relativity in the solar system and the quadrupole moment in the solar gravitational field. Specifically, Experiment 11 is converned with measuring the following effects: (1) relativistic orbital corrections described by two parameters of the space-time metric which are both equal to unity in Einstein's theory; (2) orbital perturbations caused by a finite quadrupole moment of an oblate sun, described by zonal harmonics in the solar gravitational field.
The end-to-end spin tests conducted on the Synchronous Meteorological Satellite are described in detail. It is noted that the objective of these tests was to demonstrate that the satellite performed its intended functions under spinning conditions and that all satellite functions were tested except for solar-panel illumination, pyrotechnic-device operation, VISSR infrared operation, and auxiliary propulsion-system operation. Tests discussed include antenna pointing, S-band and UHF equivalent isotropic radiated power, output-power ripple, bit error rate, synchronous electromagnetic interference, earth width measurement, and satellite magnetic-field measurement. The purpose, technique, salient results, and problems of each test are outlined.
An overview is given of the HET experiment on ATS-6. The paper is divided into nine parts, including a technical overview, a preliminary evaluation of the HET demonstration, a review of operations at the Denver uplink terminal, a discussion of remote ground terminals, a review of C-band comprehensive terminals and of S-band comprehensive terminals, and parts devoted to general network operations, technical management and effectiveness of the network, and the site equipment operator.
The paper describes the utilization of ATS-6 to relay tracking and telemetry data from Geos-5 and then from Nimbus-6. The experiment configuration consists of a ground station which receives data from ATS-6 through C-band links; ATS-6, in turn, transmits command data and receives telemetry data from the low-orbit satellites through S-band links. The ground and satellite equipment are described along with results of ground tests.
The all-weather ice information system described uses the X-band side-looking airborne radar to determine the aerial distribution, location, and type of ice cover in the Great Lakes and an airborne S-band short-pulse radar to determine the ice thickness. Results from the 1974-1975 winter season demonstrated the ability of the system to provide all-weather ice information to shippers at the required time.
The S-193 Skylab radar altimeter was operated in a round-the-world pass on Jan. 31, 1974. The main purpose of this experiment was to test and 'measure' the variation of the sea surface topography using the Goddard Space Flight Center (GSFC) geoid model as a reference. This model is based upon 430,000 satellite and 25,000 ground gravity observations. Variations of the sea surface on the order of -40 to +60 m were observed along this pass. The 'computed' and 'measured' sea surfaces have an rms agreement on the order of 7 m. This is quite satisfactory, considering that this was the first time the sea surface has been observed directly over a distance of nearly 35,000 km and compared to a computed model. The Skylab orbit for this global pass was computed using the Goddard Earth Model (GEM 6) and S-band radar tracking data, resulting in an orbital height uncertainty of better than 5 m over one orbital period.
Results are reported for simultaneous observations of the growth and decay of the clear-air convective mixing layer near a coastline, which were made with an FM-CW radar, a high-power narrow-beam S-band radar, and an acoustic echo sounder. The main purpose of this study was to determine the relationship between the rise rate of the convective depth and the lapse rate of temperature, particularly in the morning hours. The results indicate that the three remote sensors can provide excellent mutually supporting data on the convective depth. It is found that this depth is well behaved during the day and that its rise rate varies roughly linearly with the inverse square root of the temperature lapse rate during the morning. The data suggest that some models concerning the rise rate require modification, since these models imply that the surface heat flux would have to be unreasonably large to produce the observed relationship.
The TDRSS and tracking services define the telecommunication performance of the TDRSS between the RF interface with user spacecraft and the data interface with NASCOM at the ground terminal. Attention is given to system constraints, forward link services, multiple-access signal design parameters, S-band single access signal design parameters, multiple-access return link services, and single-access return link services.
The paper presents results of an onboard EMI survey of an L-band shipboard terminal for operation with two geostationary maritime satellites. Significant EMC results include: (1) antenna noise temperature measurements indicate a maximum of 70 K steady background component at 1.6 GHz at sea for elevation angles of 5 degrees and higher; (2) field intensity measurements from 1-10 GHz show that a L-band terminal can operate simultaneously with onboard S-band and X-band navigation radar; (3) radar transmitter case emissions, below deck, in-band from 1535-1660 MHz, at 1 m distance from the cabinet, are equivalent, or greater than above-deck emissions in the same frequency range; and (4) conducted-emission tests of a ship's power lines to both radars show both narrow band and broad band emissions are 15 dB to 50 dB higher than equivalent U.S. commercial power lines from 150 kHz to 32 MHz.
A microstrip antenna design concept was developed that will provide quasi-omnidirectional radiation pattern characteristics about cylindrical and conical aerospace structures. L-band and S-band antenna arrays were designed, fabricated, and, in some cases, flight tested for rocket, satellite, and aircraft drone applications. Each type of array design is discussed along with a thermal cover design that was required for the sounding rocket applications.
The effects of the use of an X-band carrier frequency on the transmission link margins and on the affected ground station equipment are investigated. The specific effects of the X-band carrier frequency allocation on the link margin are detailed. This includes an examination of a Local User Terminal's (LUT) coverage circle radius requirements, detailed elements of the link calculation, and specific spacecraft and ground configurations that would satisfy the link requirements. The requirements that spacecraft signal acquisition and tracking place on the front-end of the ground station equipment are also examined. The availability of the required ground station equipment and representative costs for these items are included. The costs considered shall be both for procurement of a new ground station (front-end only) and for modification of an existing S-band station to X-band.
The S/X-band experiment on the Mariner Venus/Mercury 1973 spacecraft constituted a unique opportunity to demonstrate the capability of an X-band downlink coherent with the normal S-band downlink. This was both a technological and scientific experiment, and the results indicated that it was successful in both cases. Analysis of the tracking data shows that the new S/X data type was capable of reducing the miss distance at the planet Mercury by 80% (post-processed data). The use of S/X electron content was demonstrated by comparison with Faraday rotation data. An X-band turnaround telemetry experiment showed the feasibility of a planetary X-band link. In the science area, the model atmospheric environment of Venus was refined. The ionosphere of the planet was measured to a higher accuracy than before, and the value of the dual-frequency link for measuring the scale size of turbulence was demonstrated. The estimate of the scale size was increased from 100 m to above 5 km.
During the summer of 1974 and spring of 1975, measurements of attenuation of propagation through rain were made at Wallops Island, VA, using 13 and 18 GHz transmitters operating in the uplink mode toward the ATS-6 satellite. Simultaneously, rain reflectivity levels were measured along the earth-satellite path using a high resolution (0.4 deg beamwidth) S-band radar having a scanning antenna. Four rain-gages and two disdrometers were also located in the vicinity of the transmitters. The radar and disdrometer data were used in a modelling program to predict attenuation levels which were subsequently compared to the directly measured fades over nearly simultaneous time intervals. Predicted attenuation levels were obtained for three drop size distributions. Comparisons between predicted and measured attenuation levels showed the APL dropsize distribution gave the smallest rms difference of 1.3 dB at 13 and 18 GHz although the rms difference corresponding to Marshall-Palmer was close to this value. The good agreement suggests the validity of using radar to model path attenuation to obtain attenuation statistics.
The 26-meter S-X conversion project provides for the conversion of an existing 26-meter S-band subnet to a 34-meter S- and X-band subnet. The subnet chosen for conversion consists of the following stations: DSS 12 near Barstow, DSS 44 in Australia, and DSS 62 in Spain. The main subsystems effected by this project are the antenna mechanical, antenna microwave, and receiver-exciter. In addition to these, there are many project-related electronic equipments that have been added to the existing station equipment. The major subsystems are essentially through the design stage with the antenna mechanical subsystem completed through detail design with procurement in process.
A third-generation S-band radiometer has been calibrated at intervals over 3.5 years. The built-in stabilization concepts have proven to be very effective. In spite of some nonideal conditions (on runway, in wind, and in rain), an rms value of 0.7-K calibration repeatability has been observed with an average temperature deviation (bias error) of 0.03 K.
Parametric amplifier for tracking antenna - Apollo project
Apollo precision frequency source and time standard