DeVries, James M.; Pacific Missile Test Center (International Foundation for Telemetering, 1983-10)
      The microstrip antenna has recently gained popularity because it offers the advantage of flush mounting, small size, and low cost when fabricated by etched circuit techniques. In an effort to further reduce the aperture requirements, two circular microstrip antennas were placed one on the other and fed independently. Utilization of the field null at the center of the circular disk antenna allows independent excitation. In this configuration, two different frequencies can be transmitted simultaneously while sharing the same physical aperture. Polarization of the antennas is linear with well behaved radiation patterns exhibiting gains of 6 dBi. Moderate power levels can be accommodated by selection of suitable substrates and control of dielectric thickness. As a result of the reduced size, the antenna can now be placed in areas otherwise thought impractical. Placement in front of certain antennas or retrodirective reflectors has a very minor effect on their performance.

      Petit, Richard D.; Kode Inc., a Subsidiary of Odetics Inc. (International Foundation for Telemetering, 1983-10)
      The need for margin analysis in high density digital data storage systems is established. A review of margin analysis techniques is presented. This review includes a discussion of time interval analysis and a series of instruments which have evolved as a means of performing this analysis. Emphasis is given to a high resolution (1 nanosecond) statistically oriented embodiment of such an instrument.

      Kudrna, Ken; Ball Aerospace Systems Division (International Foundation for Telemetering, 1983-10)
      An Electronic Switching Spherical Array (ESSA) Antenna has been developed for low obiting spacecraft requiring medium gain (+13 dBic) transmit and receive relay capability through the Tracking and Data Relay Satellite Systems (TDRSS). This 145 radiating element antenna is steered with a microprocessor controller by selecting arrays of 12 elements at a time. Approximately 1800 beams can be selected for near hemispherical coverage. The primary method for evaluating this antenna is a composite Radiation Distribution Plot (RDP).

      von der Embse, U. A.; Hughes Aircraft Co. (International Foundation for Telemetering, 1983-10)
      The probe-to-orbiter data link for the Jovian mission uses a Manchester encoded BPSK waveform which is demodulated by the Galileo probe relay receiver. Signal acquisition and tracking consists of a sequential probability ratio signal search, frequency acquisition with a least-squares estimator, wide-band phase lock acquisition, and a self-regulating mode control. A discrete Fourier transform serves as the basic mechanism to generate the algorithms that provide this orderly transition to phase tracking. Acquisition and tracking is addressed in this paper with emphasis on key algorithms, rationale, and theorectical/ measured performance.

      Tsang, Chit-Sang; Lindsey, W. C.; LinCom Corporation; University of Southern California (International Foundation for Telemetering, 1983-10)
      Bit synchronization in the presence of asymmetric channel noise has not appeared in the open literature. It is the purpose of this paper to study the performance of a popular digital clock synchronizer, the Digital Data Transition Tracking Loop (DTTL), in the presence of asymmetric noise. A comparison of the DTTL and Cross Spectrum Synchronization Loop (CSSL) is also provided for special parameter values of greatest interest. Numerical results are presented for design of bit synchronizer in this environment.

      Udalov, Sergei; Axiomatix (International Foundation for Telemetering, 1983-10)
      This paper describes a digital real-time implementation of a Hilbert transformer for the generation of single-sideband signals (SSB’s). Design criteria for the transformer are presented and the experimental results are discussed for a typical voice-band channel having a nominal bandwidth of 300 to 3500 Hz. Techniques for generating two independent sidebands (ISB’s) on a single carrier are also described.

      Rosen, Charles; Microcom Corporation (International Foundation for Telemetering, 1983-10)
      The paper is an extension of two previous works published in the ITC 1974 and 1976 proceedings by the same author. It is the intent of this publication to summarize the two previous papers; to include corrections; to expand the explanations; and to add new material. This information has been accumulated from many system designs based on the described procedures. It deals with a variety of transmission systems and combinations of multiplexing schemes. A number of tables and constants are provided as standards to be used in telemetry system design thereby reducing calculating time. System engineers are given a basic step by step procedure and format for the design of any type of transmissions system. Also a computer program is now available to automatically calculate all of the parameters necessary for the system design. The last presentation of the system design procedure dealt with the information accumulated over several years, and established the parameters from which the design equations for PCM and PAM were updated. Since that time a concentrated effort was initiated to verify the correct bandwidth equation which would be optimum for FM/FM Multi-tone Systems. Again cognizant scientists and engineers were contacted and interviewed. From past history and successes, it was well known that the bandwidth equation known as “Carson’s Rule” provided an adequate bandwidth to guarantee the system accuracies. However, it was also known that systems were in use, operating with smaller bandwidth than specified by Carson’s Rule, and also providing acceptable data accuracies. From the best information available, these systems were designed empirically with painstaking testing effort to insure their accuracy. The investigation lead to another bandwidth equation which appears to be the correct approach for providing the optimum bandwidth for Multi-Tone Systems. There is no doubt that this is not the first application of this bandwidth equation, but this author could not find any documented information as to its use or validity when applied to multi-tone systems. This presentation has designated the new bandwidth equation as the “Multi-Tone Bandwith Equation” or “M/T Bc”. The actual equation and its verification are provided later in this presentation. A second corrective update was made in the design of the PAM/FM/FM Channel where the subcarrier design equations are established based on the same parameters as PCM. Since PCM and PAM are both pulse modulation, their design theories are similar for a subcarrier channel. In the final PAM/FM/FM analysis, a lower frequency SCO will be used as compared to that which was previously specified. Again, the validity and verification of this update in the procedure is described later. Finally, a third and significant addition to this presentation has been provided by Mr. Matthew Egler, of Microcom Corporation, who has written four (4) computer programs based on this procedure. Not only does this program provide the system design effort, but also provides a program for the mixing networks required for systems with PCM or PAM baseband, modulation together with a higher frequency SCO Multiplex system on the same baseband PCM/PAM/FM + FM/FM. Without this network, the baseband pulse adulation is rendered useless when coupled with an SCO Multiplex system. A third program available on the same floppy disc, is the computation of the SCO Voltages and mixer amplifier gain necessary for modulating a transmitter with a specified modulation sensitivity in accordance with the channel deviations as computed by the System Design program. The final program is the margin calculation based on the equations and procedure specified in Attachment E of this presentation. Hopefully this presentation will represent the final procedures and equations. However, if any new information is accumulated based on analysis, experimentation, or field use, which has an impact on the result of this paper, a further update will be submitted to keep the methods described herein current and state-of-the-art. It is the author’s contention that the capability to accurate system design lies in the use of the noise equations, and the procedures developed around those equations.

      Schoeck, Kenneth O.; Kobylecky, George M.; Western Space and Missile Center; Federal Electric Corporation (International Foundation for Telemetering, 1983-10)
      Since development of the initial system in 1980, the Western Space and Missile Center (WSMC) has been refining computerized test techniques for instrumentation magnetic tape recorder/reproducers. These tests include standard IRIG tests such as flutter, time base error (TBE), interchannel time displacement error (ITDE), harmonic distortion, frequency response and signal-to-noise ratio (SNR), as well as slot noise, crosstalk and intermodulation distortion (IMD). The test philosophy is to duplicate results that can be obtained manually, but at the same time greatly reduce test time and operator intervention. Such parameters as data sampling periods and number of samples have been refined to obtain maximum correlation and minimum test times. Also, a complete set of self-check and troubleshooting programs have been developed.

      Blais, Richard A.; NASA (International Foundation for Telemetering, 1983-10)
      In 1979, NASA was faced with the problem of providing a ground facility magnetic tape recorder to store and retrieve serial Pulse Code Modulation (PCM) bit streams of up to 50 megabits per second (MBPS) which originated within Spacelab and its experiments. These recorders were required at the Kennedy Space Center (KSC), Johnson Space Center (JSC), and the Goddard Space Flight Center (GSFC). The Spacelab requirements presented a wide variety of problems which no existing “offthe- shelf” recorder could accommodate at the time. As a consequence, an extensive and complex performance specification was developed. This specification necessitated many advances in the “state-of-the-art” in the field of High Density Digital Recorders. The 9000 SL High Density Digital Recorders designed and fabricated by Thorn-EMI Technology, Inc., under contract to NASA, have successfully met or exceeded all of the Spacelab requirements as identified in the performance specification. These recorders demonstrate the latest in high density digital recording technology. This technology includes the capability of recording 50 MBPS of data with a bit error rate of better than 1 bit in 108, completely automatic bit synchronization, auto selection of the optimum replay equalization, and a data coding scheme giving up to 50% greater data packing density than traditional codes.

      Kono, Michael E.; Brininstool, Michael R.; Naval Ocean Systems Center (International Foundation for Telemetering, 1983-10)
      A brief description is presented on a current application of fiber optic technology to Remotely Operated Vehicle (ROV) design. Significant advantage is realized in terms of weight and space, EMI immunity, high bandwidth, and long length transmission capability. Current design practice utilized a standard graded index 50/125 micron telecommunications fiber “ruggedized” with a composite armor. On-going development seeks to make this cable element small and expendable while preserving the high bandwidth and low loss nature of the fiber. To free the system designer from mechanical considerations, the cable is pre-spooled and carried and deployed by the vehicle. Three dedicated communications channels are proposed on the single fiber by utilizing optical wavelength multiplexing.
    • An Effective Simple Error Correction Scheme

      Riner, John; DATA SYSTEMS DIVISION AMPEX Corp. (International Foundation for Telemetering, 1983-10)
      A simple yet effective error correction scheme for high bit rate digital recording (HBR) using an IRIG tape format is presented. The system is independent of input data rate and requires no analog dropout detection. Typically, 3 orders of magnitude of correction are achieved. The error correction system requires no adjustments. Theoretical results are presented along with emperical data.
    • A Programmable Real-Time Data Processor

      Dianhua, Gao; Gensheng, Wu; Chengdu Institute of Radio Engineering (International Foundation for Telemetering, 1983-10)
      A new type of programmable data processor for a telemetry system is described, in which the functional tables constructed by EPROM’s was employed for fast conversion of the measured binary code to easily understood data results by people, and a printer/plotter made in our country was used as Recordin device. Synchronization problems between the printer/plotter turning in high speed and the telemetry system have been solved fairly good. The data processing speed is 13200 characters per second. All of the circuit elements were mounted on a printed circuit board and we enclosed it in the case of the printer/plotter. The processor is directly linked to the synchnizer of telemetry system and the timer, and can process all the data obtainned from certain telemetry system in real-time.

      Grebe, David; AYDIN MONITOR Systems (International Foundation for Telemetering, 1983-10)
      Generalized use of ECL in telemetry systems requires the reduction of transmission line theory, power distribution, topology considerations, and device characteristics to an implementation that is reproducible, permits rapid changes, and is cost effective. Bringing high data rates (up to 150 Mb/s) to everyday status was one goal in the development of a LANDSAT-D format synchronizer. The unit had to perform preamble and minor frame synchronization followed by decoding, decommutation, and formatting at the Thermatic Mapper real-time rate of 85 Mb/s. To additionally handle MSS and standard telemetry, as well as stream simulation and bit error rate measurements, a generalized solution was required. This is in opposition to a specially designed unit to fulfill only LANDSAT mission requirements. To produce the unit best suited to telemetry disciplines where formats change rapidly, the unit was implemented using wire wrapped modules with the stated goals realized.

      Willis, Jim; Stabilized High Altitude Research Platform Physical Science Laboratory New Mexico State University Las Cruces (International Foundation for Telemetering, 1983-10)
      The Physical Science Laboratory (PSL) is developing a balloon-launched platform that will support a wide range of high-altitude projects. The Stabilized High Altitude Research Platform (SHARP) will house several on-board microprocessor-based subsystems to provide telemetry, command, and navigation data. Support for a wide variety of scientific experiments requires versatile electronic subsystems aboard the platform. Using the STD bus as a building block component, the Laboratory has designed and fabricated such subsystems. The STD bus, a standard interface throughout the computer industry, was chosen for the design because of its availability, ruggedness, versatility, and wide selection of compatible, off-the-shelf components.

      LaPrade, J. Nicholas; RCA Astro-Electronics (International Foundation for Telemetering, 1983-10)
      A solid-state power amplifier now routinely replaces the traveling-wave tube amplifier in C-band communications satellites. The immediate benefit of superior performance is realized by increased transponder capacity. Long-term benefits of higher reliability and reduced production costs are also projected. This paper describes salient features of the first solid-state power amplifier to fully replace the traveling-wave tube amplifier in spaceborne transponders. The 8.5-watt, 60-dB gain amplifier employs a chain of gallium-arsenide field-effect transistors to provide a 160-MHz usable bandwidth within the 3.7- to 4.2-GHz downlink band. Data typical for this amplifier are presented. The key parameters of efficiency, intermodulation distortion, and phase effects are described in detail. The amplifier is being manufactured for numerous communications satellite programs. Aspects of reproducibility and automated testing at the various stages of amplifier production are addressed. Forty-eight amplifiers are now operational at geosynchronous altitude with several times that number scheduled for launch within the next few years.

      Smylie, Robert E.; Stephens, Robert R.; National Aeronautics and Space Administration (International Foundation for Telemetering, 1983-10)
      An unprecedented challenge to NASA’s data systems is presented by the operational Space Transportation System and the attendant planned permanent facilities in space. Large, extremely high data rate experiments are now possible. More importantly, re-visit capabilities permit in-orbit payload change-out, precluding conventional ground testing of the total system. End-to-end data system engineering and flexible architectural design are mandatory if this challenge is to be met economically and effectively. A simple, top-level logical reference model of the end-to-end data system is being developed, which identifies the numerous functions and services which every automated space data system must provide. Each function or service may be mapped into specific physical subsystems, so that interface relationships are evident and “standard” protocols may be identified for development. By virture of this interface standardization, subsystems can be designed not only independently and in parallel, but with confidence that when the subsystems are aggregated the end-to-end system will operate efficiently and at low cost. A second purpose of the model is to identify technical opportunities for interoperability between the space data networks owned by different agencies or countries, thereby promoting cooperative international cross support of space missions. Fully-automated virtual connection between an investigator and a sensor in space is postulated, with the intervening system being fully transparent regardless of the physical configuration or ownership of that system. To date this standardization effort has been principally directed toward a problem unique to space missions, namely the space to ground link. Mature “Guidelines” have been prepared for the formatting and coding of telemetry data, and these guidelines are being coordinated with approximately 12 other countries who have significant space activity. Other developmental Guidelines include telecommand formats and protocols, timetags, radio frequency/modulation techniques, and globally interpretable methods for the exchange of many different types of message data. A formal work-flow has been established whereby these Guidelines progress from concept papers to initial drafts (“White Books”) , then through iterative review cycles where they exist as Drafts (“Red Books”) and finally as completed Guidelines (“Blue Books”). This paper will review the overall program of data system standardization currently underway within NASA.

      Stephenson, Henry B., Jr.; White Sands Missile Range (International Foundation for Telemetering, 1983-10)
      White Sands Missile Range (WSMR) personnel have developed an intelligent, low cost, dual-microprocessor based, Tracking System Interface to be implemented on each telemetry tracking system at WSMR. This interface provides each telemetry tracking system with the capability of acquiring targets based on pointing data from various tracking radars on the Range. The presentation will begin with a historical overview of the WSMR target acquisition system followed by a discussion of the telemetry target acquisition system in particular. The newly developed intelligent interface will be discussed including present attributes. The presentation will conclude with a discussion of future enhancements.
    • Imageless Mixer for Data Translation

      Rieger, James L.; Woodworth, Paul H.; Naval Weapons Center (International Foundation for Telemetering, 1983-10)
      An imageless mixer is described for translation of a wideband data signal to an unoccupied portion of a telemetry link spectrum. The translation produced is identical to translations performed by existing double-sideband systems, but at a saving in hardware and with reduced adjustment. A computer program provided allows evaluation of various phaseshift filters for desired bandwidth and precision.

      Martin, Warren L.; CALIFORNIA INSTITUTE OF TECHNOLOGY JET PROPULSION LABORATORY (International Foundation for Telemetering, 1983-10)
      As space missions have become more expensive, the search for methods to improve efficiency has intensified. One approach offering great potential focuses upon multimission designs in order to avoid early obsolescence. Data handling systems are attractive candidates for the multimission concept because of the high cost of redesign and because the process should be amenable to a high degree of uniformity. By cooperating in the specification of their data systems, NASA and ESA should achieve significant uniformity. Apart from improving the design, this unified approach will facilitate the cross support of one agency’s spacecraft by the other agency’s tracking network. Here, we are concerned with the radio frequency subsystem which links spacecraft instruments with ground-based users. In large measure, the telecommunications system’s characteristics are determined by the ground station’s design. For the concept of cross support to succeed, there must be a substantial similarity between these NASA and ESA designs. Both NASA and ESA have large capital investments in their ground networks. While it might be theoretically satisfying to speak of a single ground system configuration for both agencies, the high cost of the required revisions renders this approach practically unachievable. This paper describes a process for maximizing the commonality of the two agencies’ radio frequency and modulation systems that is consistent with budgetary and scheduling constraints. The two-part program consists of identifying present system similarities and developing a plan for eliminating substantive differences where they are found to exist.

      Connell, Edward B.; Goddard Space Flight Center (International Foundation for Telemetering, 1983-10)
      In an effort to reduce the costs of conducting space missions, the National Aeronautics and Space Administration (NASA) is working to develop data systems standards that are appropriate for application at key interfaces within mission data systems. Use of proper standards can improve multimission support by reducing the need for developing new interfaces and data transforms for each new mission. “Time” is an important parameter for space-acquired measurements because instrument analysis can often be based on a sampled sensor time series and because time provides the most efficient (and often the only possible) linkage between instrument data and externally generated ancillary parameters. Therefore, one of the major aims of the NASA effort has been focused on the development of a standard timecode structure. This paper describes the rationale and form for that structure and provides a proposed definition for an important class of timecodes, the binary unsegmented codes. The structure provides a mechanism for the self-documentation of timecodes, so that any user of the data can interpret time measurements in an unambiguous manner. The binary unsegmented codes are modular and easily machine-readable, and feature expandable resolution and ambiguity periods.