• Analysis and Test Results of a Hybrid PCM/FM-subcarrier Baseband Multiplex on an FM Carrier

      Nichols, M. H.; The Aerospace Corporation (International Foundation for Telemetering, 1974-10)
      Engineering formulae have been developed for estimating the performance of a telemetry system utilizing an NRZ PCM multiplex plus an FM/FM multiplex frequency modulating a carrier. These formulae have been checked against a laboratory simulation and the agreement is within 1 dB for the PCM and 1.8 dB for the FM/FM. About 1 dB of the 1.8 dB is tentatively accounted for on the basis of lack of symmetry of the carrier predetection (IF) filter used.
    • SAMTEC Integrated Telemetry System Analysis

      Kern, L.; Smith, B.; Miller, M.; Straehley, T.; Vandenberg Air Force Base; Logicon, Inc. (International Foundation for Telemetering, 1974-10)
      The goals of TCAS were to recommend a Telemetry Integrated Processing System (TIPS) that will improve SAMTEC mission support, increase flexibility and modularity of the system, and provide a system that is more easily operated by the range operations personnel with an associated reduction in overall operating cost. SAMTEC has completed the conceptual phase of the classical system life cycle. The validation phase is now well underway and the development phase is expected to start early in the calendar year 1975. The Integrated Telemetry System was derived utilizing the fundamentals of good engineering practices, common sense, and very extensive analysis. The resultant system should satisfy the goals of improved support, flexibility and modularity, and should provide at least a 20 to 40 percent reduction in the current telemetry processing expenditures.
    • Capacity of Noncoherent MFSK Channels

      Bar-David,I.; Butman, S. A.; Klass, M. J.; Levitt, B. K.; Lyon, R. F.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1974-10)
      This article computes the capacity of a noncoherent multifrequency-shift-keying channel as a function of the number of orthogonal signals, M, and the predetection signal-to-noise ratio, ST/N₀, for three basic receiver types; these are hard decision, unquantized (optimum), and quantized (soft decision). Computational cutoff rates for sequential decoding are also computed.
    • Evolution of the Douglas Flight-Test Data System

      Crowley, L. D.; Douglas Aircraft Company (International Foundation for Telemetering, 1974-10)
      The process of developing new techniques and systems for the purpose of flight-test data acquisition, communication, and processing is, in fact, an evolutionary one. It is filled with potential mutations formed when an orderly or direct path is not taken in any of supporting disciplines or when the capabilities of one link greatly exceed those of another. The rigid design philosophy that made the Douglas system so successful in support of numerous test programs has had both a negative and positive effect of limiting, or at least slowing, the future growth in flexibility. Upgrading the system with new hardware and software must be accomplished in a manner that does not degrade the existing performance and throughput capabilities while making room for the new species to evolve. Problems have been minimized by placing the development of the acquisition and processing systems under common management and, in turn, having this group accountable to the project users of the system. Constant feedback between system developers and users has ensured a degree of adaptability to the hostile environment of test program costs and schedules.
    • 117.6 Kilobit Telemetry from Mercury-A Major Deep Space Telecommunication Advance

      Clarke, Victor C.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      For nearly eight hours on March 29, 1974, Mariner 10 transmitted imaging telemetry in real time at 117.6 Kbps from Mercury. During this time, 562 very high quality frames were received, even though the bit error rate was only about 1 in 40. The transmission of 117.6 Kbps from Mercury is a magnificent telecommunications achievement, which permitted an order of magnitude increase in imaging science data return. The Mariner 10 imaging scientists' requirements, simply stated, were to obtain maximum area coverage at highest spatial resolution. More precisely, they desired photomosaics which were equivalent to the best earth-based pictures on the Moon, i.e., about 1 km resolution. The purpose of this paper is principally to relate the methods by which these "desirements" were translated into measurable telecommunication system requirements and some of the attendant tradeoffs. Additionally, same of the steps taken to achieve their goal are recited.
    • Simulation of PCM Data Utilizing a General Purpose Computer

      Shultenburg, K. G.; Ehrsam, E. E.; Control Data Corporation; Vandenberg Air Force Base (International Foundation for Telemetering, 1974-10)
      Due to the increased complexity and capabilities of modern missile telemetry systems, it has become increasingly difficult to provide an effective yet flexible simulation capability for the verification and validation of PCM decommutation systems. Control Data Corporation, under contract with the Space and Missile Test Center (SAMTEC) at Vandenberg Air Force Base, California, recently completed the development of a powerful and flexible simulation system utilizing a CDC 3300 computer. This Telemetry Decom Validation System (TDVS) now allows personnel to develop a simulated PCM data stream using a telemetry-oriented compiler to generate telemetry instructions. The compiled program can then be executed in a microprogrammable processor which generates the defined PCM stream through the interpretation of the specially designed instruction set output by the compiler. Data can be simulated at rates up to 2 megabits using any of the seven IRIG code conventions or Miller Code.
    • Deep Space Telecommunications-Pioneer Mission to Jupiter

      Heist, E. K.; TRW Inc. (International Foundation for Telemetering, 1974-10)
      The Telecommunication subsystem for the Pioneer 10 and 11 spacecraft is described in terms of the exacting design requirements which have been met and the operational performance which has been achieved. Those features which are unique or novel and which contribute substantially to our knowledge of advanced techniques for future interplanetary missions, are emphasized. The discussion includes earth-pointing of the spacecraft high gain antenna by an on-board conical scan system, tracking, telemetry, and command functions at multi-million kilometer distances complicated by round trip communication delays of 90 minutes, and the versatility of special data formats which cater to certain instrument high rate sampling requirements during selected phases of the mission. With the successful flyby of the planet Jupiter by Pioneer 10 in December 1973, the technology and experience for much more ambitious, challenging, and complex missions to the outer planets has been demonstrated.
    • Rendezvous Radar for Space Shuttle Orbiter Vehicle

      McQuillan, W. F.; Bologna, A. W.; Calabrese, D. M.; Rockwell International Corporation (International Foundation for Telemetering, 1974-10)
      To successfully complete many of the Space Shuttle Program proposed missions involving Orbiter rendezvous with orbiting satellites, some method of detecting and tracking remote targets is desirable. Several studies to establish the requirements for a rendezvous radar system indicated the feasibility of the concept. Extensive application of state of the art components is possible, and system parameters can be determined in a general sense to avoid impacting Orbiter development. Considerations of size and weight are necessary to the choice of any system, as well as the operational capabilities of the candidate. Two radar systems appeared to meet the requirements: a microwave radar and a laser radar. Although the laser radar was highly competitive, difficulty was encountered in assessing the operational risk of such a system. The microwave radar was therefore selected as the rendezvous sensor most suitable for Space Shuttle Program use.
    • Space Shuttle Antenna Subsystem Design

      Ellis, H.; Cubley, H. D.; Symonds, Richard J.; Rockwell International; NASA/Lyndon B. Johnson Space Center (International Foundation for Telemetering, 1974-10)
      The unique nature of the Shuttle orbiter is that all of its systems must meet the design requirements of a spacecraft as well as the basic aircraft requirements for atmospheric flight. The Shuttle antenna system design, therefore, faces many unique problems. Some of the most significant of these problems include the interface with the Shuttle thermal protection system, the wide range of thermal extremes and rates to be encountered, the long life requirement, and the need for lightning protection. In addition, the radiation coverage requirements of some of the Orbiter antennas are complicated by the multiple requirement for operation during launch, from earth orbit to both ground station and relay satellites, and to the landing area during atmospheric flight. The unique engineering problems that result from these requirements will be described along with techniques that are planned for their solution.
    • The Data Handling System of the Helios Probes

      Pabst, Dietrich; Digital Space Applications (International Foundation for Telemetering, 1974-10)
      The Helios probes A and B will have a maximum distance of 2AU from Earth. The typical requirements which are applicable to all deep space missions, especially decreasing link capacity, need a flexible data handling system. Taking the Helios probe as an example, it will be shown how the specific problems of data handling in deep space probes were solved from the technical standpoint. The system processes 4 selectable scientific formats at 8 to 4096 bit/sec with 320 subcommutated housekeeping channels, also to be transmitted in a separate engineering format. Simultaneously, a special format is stored cyclically with up to 16kbit in a 0.5Mbit memory, which can also be used for the storage of all the other data in an automatic sequence mode. Telemetry data are convolutional coded. Due to its flexibility and its multiplicity, the data handling system is a useful instrument for deep space missions.
    • A Markov Model for NASA's Ground Communications Facility

      Adeyemi, Oduoye (International Foundation for Telemetering, 1974-10)
      For those burst noise channels that can be mode l led by finite state Markov chains (FSMC) this paper presents a 'natural' way of constructing such models and in particular gives a five-state Markov chain as a model of errors occurring on the NASA's Ground Communications Facility (GCF). A Maximum Likelihood procedure applicable to any FSMC is developed for estimating all the model parameters starting from the data of error runs. Then we give a few of the statistics important for estimating the performance of error control strategies on the channel.
    • A Transponder for Deep Space Probes-Design and Performance Characteristics

      Go, G. Bie; AEG-Telefunken (International Foundation for Telemetering, 1974-10)
      Deep space probes necessitate the use of coherent ranging transponders. The requirements for this class of transponder can be divided into telemetry, command and ranging requirements. Usually the telemetry requirements are rather straightforward and concern more with hardware design aspects. On the other hand, command requirements generally requires iterative computations to achieve an optimum system design. Ranging requirements are based either on a simple turn-around ranging channel, or on the complex regenerative channel. The design of this transponder is based on the former type of ranging channel. This paper shows the system design for such a transponder and a comparison with measured performance characteristics. Additionally, spurious signal analysis for the ranging operation is dealt with briefly.
    • The Antenna System of the Helios Solar Probe

      Horwath, L.; Liesekötter, B.; Tymann, G.; Messerschmitt-Boelkow-Blohm GmbH. (International Foundation for Telemetering, 1974-10)
      For the Helios solar probe a complete antenna system was developed and manufactured which is suitable for the various mission requirements, as near earth phase varying aspect angles, close sun flyby and maximum distance of 3,0. 10⁸ km with spin axis orientation perpendicular to the ecliptic. The near earth phase requirements were covered by a low gain antenna system with an isotropic radiation pattern. After the rough orientation of the spin axis a medium gain antenna with an omnidirectional radiation pattern will be used. After final orientation of the spin axis perpendicular to the ecliptic plane a high gain antenna with a despun wire grid reflector will be used for the telemetry link. By switching devices and/or hardwire connections the antenna systems are partly redundant in order to get the required high reliability. The maximum operating temperature range of the antenna system is + 200° to - 200°C.
    • A Flexible Preprocessor for ERTS MSS Data

      Waltz, Edward L.; Bendix Aerospace Systems Division (International Foundation for Telemetering, 1974-10)
      The requirements to preprocess Earth Resources Technology Satellite (ERTS) multispectral scanner (MSS) data from its 24 channel tape format at real time rates can be met most efficiently by a parallel processor with a flexible interface for compatibility with a wide range of digital computers. The ability of the preprocessor and tape unit to playback data at programmable rates (real-time and half and quarter real-time) provides the additional ability to adjust preprocessing rate to optimize system throughput for several image processing computer system configurations, and processing modes. The MSS Data Interface described in this paper has been developed to meet these requirements for ERTS processing facilities of those nations which record ERTS data in the NASA-compatible format on 28 channel tape units. The first MDI which has been delivered to the Brazilian government is compatible with the Digital Equipment Corporation PDP-11 computer and can be operated in either a single or dual processor system configuration.
    • Carrier Tracking, Bit Synchronization, and Coding for S-Band Communications Links

      Odenwalder, J. P.; LINKBIT Corporation (International Foundation for Telemetering, 1974-10)
      This paper presents the results of a study of the performance of Viterbi-decoded convolutional codes in the presence of nonideal carrier tracking and bit synchronization. A constraint length 7, rate 1/3 convolutional code and parameters suitable for the Space Shuttle coded communications links are used. Mathematical models are developed and theoretical and simulation results are obtained to determine the tracking and acquisition performance of the system. It is shown that the combined E(b)/N(o) degradation due to nonideal carrier tracking and bit synchronization over that required for the ideal tracking case can be held to less than 1.5 dB and that combined carrier tracking and bit timing can be acquired in only a few seconds for the parameters and operating ranges of the Space Shuttle coded communications links.
    • The Impact of Robots on Planetary Mission Operations

      Hooke, A. A.; Larman, B. T.; Whitney, W. M.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      For reasons of efficiency and safety, unmanned roving vehicles sent to explore remote planetary surfaces must carry out some of their tasks without step-by-step human control. To realize the benefits that such semiautonomous machines can provide will require some changes in how planetary missions axe presently planned and conducted. Specifically, mission profiles will have to be based on tasks or functions rather than sequences of timed events, scientists will have to be more directly involved in the control of their instruments, and present ideas concerning spacecraft safety, testing and simulation of vehicle performance, telemetry design, and ground-system implementation must be reexamined.
    • 117.6-Kilobit Telemetry from Mercury In-Flight System Analysis

      Evanchuk, V. L.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      This paper discusses very specifically the mode of the Mariner Venus/ Mercury 1973 (MVM'73) telecommunications system in the interplexed dual channel 117.6 kilobits per second (kbps) and 2.45 kbps telemetry. This mode, originally designed for only Venus encounter, was also used at Mercury despite significantly less performance margin. Detailed analysis and careful measurement of system performance before and during flight operations allowed critical operational decisions, which made maximum use of the system capabilities.
    • Experientially Guided Robots

      Merriam, E. William; Becker, Joseph D.; Bolt Beranek and Newman Inc. (International Foundation for Telemetering, 1974-10)
      This paper argues that an experientially guided robot Is necessary to successfully explore far-away planets. Such a robot is characterized as having sense organs which receive sensory information from its environment and motor systems which allow it to interact with that environment. The sensori-motor information which it receives is organized into an experiential knowledge structure and this knowledge in turn is used to guide the robot's future actions. A summary is presented of a problem solving system which is being used as a test bed for developing such a robot. The robot currently engages in the behaviors of visual tracking, focusing down, and looking around in a simulated Martian landscape. Finally, some unsolved problems are outlined whose solutions are necessary before an experientially guided robot can be produced. These problems center around organizing the motivational and memory structure of the robot and understanding its high-level control mechanisms. This paper discusses a project which is attempting to develop the "mind" of' a robot which will be capable of experiencing its environment, storing sensori-motor information, and then using its accumulated knowledge to guide its future actions. In Section I, we describe the sort of behavior that an experientially guided robot might exhibit, and we give some reasons why we might want such a thing. Then, in Section II, we discuss the current state of our project, and in Section III we indicate some important issues that are as yet unresolved.
    • Adaptive Bit Synchronizer

      Halpern, Peter H. (International Foundation for Telemetering, 1974-10)
      The motivation for adapting loop bandwidth is reviewed. The ideal loopwidth is shown to be a monotonic function of the ratio of two statistical measurements, namely the input SNR and the present uncertainty of proper phase. This is seen from a relatively simple viewpoint of how to combine independent measurements of the same quantity. Means for measuring the statistical quantities are described. Simple means for varying loop widths are described. Experimental results of the adaptive bit synchronizer are compared with a classical bit synchronizer.
    • An S-Band Telemetry Receiver System for Deep Space Applications

      Lampert, E.; Siemens AG (International Foundation for Telemetering, 1974-10)
      To receive the transmitted signals from the HELIOS space probe a S-band telemetry receiver system was built. Of this system the S-band telemetry receivers and the subcarrier demodulators are described. Measured values are presented. The S-band receiver includes a digitally implemented phase-locked-loop. Polarization tracking is possible in a two channel mode as well as in a single channel mode. In the subcarrier demodulator the subcarrier is demodulated before demodulating the RF-carrier. Good noise thresholds and low degradation is reached because remodulation is used in the subcarrier loop. The equipment works in a fully computer controlled station, this includes all aquisition procedures.