• RPV Applications in the U.S. Navy

      Friichtenicht, R. D.; Naval Air System Command Headquarters (International Foundation for Telemetering, 1975-10)
      The continuing evolution to smaller, more reliable electronics packages has had a tremendous impact throughout industry and the world. One application that has just recently started receiving wide spread attention is Remotely Piloted vehicles (RPVS). The smaller computers, electro-optical devices, infra-red systems, etc. have brought the RPV out of its "model airplane" stage and into the military arena. RPVs offer some distinct advantages over manned aircraft, which places them in a very competitive position for accomplishment of selected missions. Cost savings promise to be significant and their comparatively small size make them attractive for operation from small naval ships. However, the Navy faces some unique problems that must be addressed before RPVs are an integral part of the Naval Forces. The most immediate and overriding problem is recovery. Not only is the recovery platform very small, but ship's movement through all three axis further complicates the problem. This paper discusses some of the possible naval applications of RPVs, and outlines the Navy's program for solving the recovery problem.
    • A 200 Megabit Per Second Data Handling/Data Link Simulator

      Goodwin, John E.; Martin Marietta Aerospace (International Foundation for Telemetering, 1975-10)
      A multimegabit serial data channel, or slower parallel channels may be needed to monitor multiple input data (including video) from sources such as Earth Resources Experiments, Communication Satellites, and surveillance systems. It is desirable to operate space equipment at low power, which is contrary to the use of fast circuits. Low powered circuits are compatible with the speeds of parallel systems, but multiple channel RF systems are usually costly in both size and weight. A parallel series compromise appears to minimize these problems. A laboratory breadboard of a parallel-series data handling simulator consisting of a data acquisition unit (DAU), a 200 Mb/s serial data link (SDL), and a data recovery unit (DRU) was built and tested to operate satisfactorily up to 230 Mb/s in a typical noisy environment.
    • Command and Data System for an Undersea Dredge

      Linders, Thomas E.; Lockheed Missiles & Space Co. (International Foundation for Telemetering, 1975-10)
      By the use of commercial equipment whose original purpose was to provide alarm monitoring (fire and burglar) over telephone lines, a command and data system was constructed to control an undersea dredge. The system was designed around the Larse Corporation Data Communicators (trademark), and only a PAM multiplexer and a digital demultiplexer were added to make the system perform. The system requirements were analyzed, and only after the candidate design was agreed upon were the ideas put to paper. The system was designed in modules, with the various components grouped according to their function, to simplify interconnecting and test/checkout. The system has performed well, no component failures have occurred to date, and all data and command functions have worked as expected.
    • Detection and Discrimination of X-Ray Radiation Sources

      Beresin, V. I.; Koslov, V. D.; Moskalenko, E. I.; Mishenkova, T. S.; Novikov, Yu. V.; Sviridenko, V. A.; Sannikov, V. G.; Institute for Space Research (International Foundation for Telemetering, 1975-10)
      While studying radiation sources in X-ray range by devices, carried to the near-Earth orbit, there appeares some problems, called by the necessity of uninterrupted scanning of the sky sphere and high speed of canals' test, which leads, consequently, to a considerable volume of data. Side by side with strong sources of radiation one shows great interest to the weak ones which may turn out to be unknown to the science stars. On detecting the source, it is necessary to get a number of parameters, characterizing its structure. Devices of the space station "Saljut 4", carried an enormous deposit into the study of sources in X-ray range. The analyses of results shows, that beside useful signal from X-ray telescopes, a considerable number of superfluous references enters the radioline. Highly effective algorythm of detection and discrimination of useful signals, allowing to raise the informational capability of radioline is represented in the work. Superfluous references, which are stipulated by a galactic background are excluded from the whole data stream. The use of this kind of algorythm allows to discriminate more legible the sources of radiation in on-board and on-Earth use. The effectiveness of this algorythm is shown in adaptation of experimental data, got from X-ray telescopes of the space station "Saljut-4".
    • L-Band Maritime Experiments

      Brandel, D. L.; Kaminsky, Y.; NASA GSFC; MITRE Corp (International Foundation for Telemetering, 1975-10)
      The authors have directed the technical portion of the MARAD maritime communications experiments using the NASA ATS-6 satellite. The MARAD experiments were conducted with satellite terminals placed on two commercial ships for evaluation of the communication service similar to that which will be available with the maritime commercial satellite system. These experiments also evaluated the benefits to fleet management through utilization of the communications services. Furthermore, evaluation of position determination using satellites was also made. These experiments were conducted from the MARAD earth station located at Kings Point, N. Y., and the NASA earth station at Rosman, N. C. Three modems having voice and digital data and a stabilized shipboard L-band antenna system were evaluated. Present results indicate that future commercial communications satellite systems will provide the expected high-quality service, particularly when attention is given to improving the reliability of components, such as the vertical reference system used by the shipboard antenna. The results of the experiments conducted indicate that the ship antenna demonstrated successful tracking of the satellites for test period intervals of 4 to 6 hours without the need for operator adjustment. The ship position determination tests show good measurement repeatability, but with significant bias errors which may result from satellite ephemeris. Finally, the data analyzed demonstrated the ability of future commercial satellite systems to achieve a probability of bit error of better than 10-5. Further data analysis is needed to completely confirm these digital data results.
    • Performance of Coded MFSK in a Rician Fading Channel

      Modestino, J. W.; Mui, S. Y.; R.P.I. (International Foundation for Telemetering, 1975-10)
      The performance of convolutional codes in conjunction with noncoherent multiple frequency shift-keyed (MFSK) modulation and Viterbi maximum likelihood decoding on a Rician fading channel is examined in detail. While the primary motivation underlying this work has been concerned with system performance on the planetary entry channel, it is expected that the results are of considerably wider interest. Particular attention is given to modeling the channel in terms of a few meaningful parameters which can be correlated closely with the results of theoretical propagation studies. Fairly general upper bounds on bit error probability performance in the presence of fading are derived and compared with simulation results using both unquantized and quantized receiver outputs. The effects of receiver quantization and channel memory are investigated and it is concluded that the coded noncoherent MFSK system offers an attractive alternative to coherent BPSK in providing reliable low data rate communications in fading channels typical of planetary entry missions.
    • A Decision Directed Detector for the Phase Incoherent Gaussian Channel

      Kazakos, D.; NASA Johnson Space Center (International Foundation for Telemetering, 1975-10)
      A general vector digital signalling scheme for data communication through an additive Gaussian channel is made adaptive for the purpose of simultaneous communication of information and phase estimation. The phase estimate is shown to converge to the true value, therefore the adaptive nature of the detector effectively achieves phase acquisition and improvement in performance. Qualitative comparison to other phase acquisition techniques is made. The basic virtues of the proposed method are that no separate synchronization interval is required, and phase fluctuations can be tracked simultaneously with the transmission of information.
    • Terrestrial TT&C Data Processing for the COMSTAR and MARISAT Systems

      Cooperman, R. S.; Parker, H. L.; Wallace, R. W.; COMSAT Labs (International Foundation for Telemetering, 1975-10)
      Terrestrial TT&C data processing for the COMSTAR and MARISAT commercial communications satellites is provided by two earth stations operating in conjunction with a system control center (SCC). The system is configured to operate in a highly centralized manner, with the SCC monitoring and exercising direct control over the synchronous operational satellites. The design approach has consisted of developing a reliable, efficient, and cost-effective system with minimum operational manpower requirements. The system has been designed to be capable of continuous collection and monitoring of data from several satellites, collection and processing of range/track data for orbital determination, and exercising remote control over the earth station configuration from the SCC. Each earth station is linked to the SCC by a single dedicated telephone channel for full simultaneous duplex voice, TTY, and PCM data traffic.
    • Image Detection in Signal Dependent Noise

      Cunningham, D. R.; Laramore, R. D.; Barrett, E.; University of Missouri-Rolla; Missouri Engineering; ESL, Inc. (International Foundation for Telemetering, 1975-10)
      The detection of two dimensional optical signals which have been corrupted by noise is considered. Discussion is limited to the detection of a known object in a known location. The problem is approached from the classical statistical technique of hypothesis testing. Initially the solution is formulated in very general terms. The decision rule is derived for a signal distorted by noise of an unspecified type which may include signal dependent noise. Once the decision rule is obtained, the probabilities of false alarm and detection are evaluated from a priori knowledge of the noise and imaging system. The general results are applied to Poisson noise and signal dependent Gaussian noise.
    • Detectors Based on Conditional Tests

      Kassam, Saleem A; Thomas, John B.; Princeton University (International Foundation for Telemetering, 1975-10)
      The detection of a known signal in additive noise is an important function in many receivers. Nonparametric detectors, such as the sign detector, will result in systems with a constant false alarm rate, but usually suffer from a lower power compared to optimum parametric detectors. In this paper a conditional statistical test is used to obtain nonparametric detectors more powerful but still almost as simple to implement as the sign detector. The technique of conditional testing is therefore useful in obtaining improved detectors for practical use.
    • Concentration of Binary FM Spectra

      Papantoni-Kazakos, P.; Rice University (International Foundation for Telemetering, 1975-10)
      The spectrum of a digital FM signal can be considered as an indicator of the resistance of the signal to distortions caused by band-limitation. The study in this paper is oriented toward the design of signaling pulses that will achieve an FM signal spectrum concentrated about the carrier frequency. Convenient spectrum expressions and general guarantees of optimality are found for binary FSK signals.
    • Telecommunications, Health and Education

      Christenson, Ralph P.; Mountain States Health Corp. (International Foundation for Telemetering, 1975-10)
      Prior to 1971 there were many experiments conducted in order to demonstrate or test the feasibility, acceptance and effectiveness of communications technology applied to health care and education systems. Within the past year two groups of experiments were completed. One, utilizing terrestrial broad band systems, included seven separate applications. The other, which utilized the National Aeronautics and Space Administration's Applications Technology Satellite Six (ATS-6), had five experiments in health care and education. Each of these experiments is briefly described. Further experimentation is needed with special emphasis being given to the impact of technology on human systems. There is growing acceptance of the fact that demonstrations of feasibility are no longer needed. This particular session is concerned with "Telemetry for the Benefit of Mankind." I will assume that telecommunications is not excluded and that I can spend my time in describing some of the applications of communications technology to health care delivery and health education. I will not attempt to include all applications but will limit my attention to those that seem most timely and effective. Since all applications that will be mentioned were experimental in nature, concerned largely with feasibility and effectiveness, cost-benefits were incidental considerations.
    • The Influence of an Ambient Magnetic Field on Magnetic Tape Recorders

      Jorgensen, Finn; TRW Systems (International Foundation for Telemetering, 1975-10)
      Magnetic recorders are susceptible to external magnetic fields and hence prone to data degradation. This is primarily observed in instrumentation (space and ground) and computer recorders, where little or no shielding of the heads is provided. The magnetic core material in the heads attracts flux lines and will with certain orientations concentrate these in the record, play back or erase gaps. During recordings a foreign field may therefore be superimposed on the intended recording field and may cause errors in the form of phase shift and dc offset; these affects are agravated when AC bias is used in the recording process. If an external field is present during playback only, partial or complete erasure may take place. One external field is always present: The earth s magnetic field which has a magnitude of roughly one Gauss (or Oersted). The writer is not aware of any errors per se caused by this field, but it has numerous times caused difficulties in achieving a perfect demagnetization of heads (An oscillating and simultaneously decreasing field from a degausser does then in essence record a permanent magnetization into the heads, which in turn will result in noisy and distorted recordings). Other fields are man made, such as originating from heavy currents in cable harnesses. The analysis presented in this paper was undertaken to establish susceptibility limits for a field generated by a magnetic attitude control system for spacecrafts. This is illustrated in Figure 1, where three orthogonal electromagnets on board a spacecraft generate a magnetic moment (M), variable in magnitude and orientation. The attitude correcting torque (T) on the spacecraft is expressed as the cross product between this moment and the earth's field. Recording equipment may be located within a few feet of the center of the attitude control field, which must be limited in magnitude or the recorder shielded to avoid data errors and/or erasure.
    • On The Concatenation of Self-Orthogonal Codes

      Wu, W. W.; COMSAT Labs (International Foundation for Telemetering, 1975-10)
      The concatenation of convolutional self-orthogonal codes with threshold decoding is suggested on the basis of extensive error run length statistical observations at the outputs of the decoders. Simulation results are reported and some discussion is provided.
    • Prospect for International Standardization

      Henriques, Vico E. (International Foundation for Telemetering, 1975-10)
      The prospects for international standardization depend largely on activities of a number of official and semi-official international programs for standards. Many of the national standards developed by the technologically advanced countries are proposed for international standardization and the process of compromise and modification is necessary to make specific standards acceptable on a broad basis. A second area of dialogue is necessary for education so that the parties to a standardization effort are capable of talking at the same level of technological detail. And, thirdly, the specific types of standards that are needed fall into areas which range from easily quantifiable to agreements on communication and national standardization are on a continuum which ranges from technical refinement to preliminary discussion and candidate standard identification.
    • A Telemetry Link for an Earth Penetrator

      Caffey, Thurlow W. H.; Sandia Laboratories (International Foundation for Telemetering, 1975-10)
      The design and field-testing of a telemetry link to send signals to the surface of the earth from an earth penetrator are described. The link uses a PCM/FM format at a frequency of 10.5 kHz, dissipates 8 watts, and fits within a cylinder with an inside diameter of 100 mm. A bit error rate of less than 10⁻⁵ was achieved from a depth of 52 meters at a bit rate of 10³ bits per second.
    • Use of Sonobuoys in Ocean Earthquake Studies

      Reichle, Michael; Bradner, Hugh; University of California (International Foundation for Telemetering, 1975-10)
      U.S. Navy anti-submarine-warfare telemetering sonobuoys have recently become an important tool in the study of earthquakes at sea. Earthquake ground motion converts to sub-audio compressional waves in the water and is detected by the sonabuoy hydrophones. The frequency-modulated sonobuoy signals are monitored with commercial VHF receivers on shipboard, aircraft or land, and are recorded on f.m. magnetic tape or strip chart. Subsequent analysis of the seismic signals gives information on location and depth of the earthquake as well as direction of fault motion, stress release and other characteristics of the event. The accuracy of epicenter location is usually limited by the precision of ship navigation but may also be limited by uncertainties in sonobuoy position measured from the ship. Events large enough to be detected on land have been located with better accuracy by sonobuoys than by the land arrays. This paper describes the techniques of using sonobuoys for earthquake research, and gives results of observations of microearthquake swarms in the Gulf of California along the extension of the San Andreas Fault.
    • Atmospheric Propagation Effects on a Laser Ship Mast Detector

      Curtis, Harold O. (International Foundation for Telemetering, 1975-10)
      The performance of a laser gate ship mast detector is evaluated. The laser gate consists of transmitting optics and laser on one side of a shipping channel and receiving optics and detector on the other side of the channel. Expressions relating the probability of detection and the false alarm rate to laser power, noise, visibility or atmospheric attenuation of the beam are developed. Finally, at power levels meeting safety standards and for useful probabilities of detection and false alarm rates, the visibilities which limit system performance are determined as a function of laser gate path length. The gate, at visible wave lengths, will function at visibilities only slightly less than the path length. In the next step, the expected performance of the laser gate using a CO₂ laser radiating at 10.6μ in the infrared is analyzed. The extinction coefficient, which is only a fraction of that in the visible case, is estimated for poor visibility conditions (RVR = 1,000 ft.) from a combination of attenuation measurements relating attenuation to total water content and meterological results relating visibility to total water content. Then, for the infrared system, the same arguments as above are invoked and, in this case, it is shown that the infrared system will provide the required performance at much longer path lengths.
    • Advanced Communications Experiments for Spacelab

      Ehrlich, Eugene; NASA Headquarters (International Foundation for Telemetering, 1975-10)
      The joint NASA-ESA Spacelab project offers the space engineer the opportunity to develop and test advanced communications technology in a new environment. The large volume and weight carrying capability of the Spacelab, plus the presence of an astronaut-engineer, means that large-diameter deployable antennas can be developed; multiple antennas operating at differing frequencies can be employed for propagation experiments and the detection of radio frequency noise sources on earth; and comparative, side-by-side telemetry experiments can be performed employing differing modulation techniques. The zero-gravity, high altitude and frequent flights into space make Spacelab a new tool for the communication engineer to employ for telemetry/ communications research.
    • System Alternatives for the Public Service Satellite Consortium

      Janky, James M.; Potter, James G.; Lusignan, Bruce B.; The Federation of Rocky Mountain States, Inc.; Stanford University- (International Foundation for Telemetering, 1975-10)
      The purpose of the Public Service Satellite Consortium is to foster the shared use of satellites as a distribution mechanism for social services in health and education for public and private non-profit users. The utility of a consortium lies in its ability to aggregate a large number of small, diverse users into a market group which can then share the costs for the space segment and take advantage of the economies of scale in procurement of ground equipment. A summary of the technical analysis of the alternatives for both the space and ground segment equipments is presented, along with cost estimates. The recommended configuration consists of 20-watt transponders and on the ground, eight- to fifteen-foot diameter antennas, using parametric amplifiers. The capital cost for the electronics alone for a Community Antenna is under $9,500 in quantities of 1000 units. This low relative cost makes it possible for many new users to benefit from satellite technology.