• STANDARD INTEROPERABLE DATALINK SYSTEM, ENGINEERING DEVELOPMENT MODEL

      Cirineo, Tony; Troublefield, Bob; NAWCWPNS (International Foundation for Telemetering, 1995-11)
      This paper describes an Engineering Development Model (EDM) for the Standard Interoperable Datalink System (SIDS). This EDM represents an attempt to design and build a programmable system that can be used to test and evaluate various aspects of a modern digital datalink. First, an investigation was started of commercial wireless components and standards that could be used to construct the SIDS datalink. This investigation lead to the construction of an engineering developmental model. This model presently consists of wire wrap and prototype circuits that implement many aspects of a modern digital datalink.
    • REVIEW OF BANDWIDTH EFFICIENT MODULATION SCHEMES

      Osborne, William P.; Ara, Sharmin; New Mexico State University (International Foundation for Telemetering, 1995-11)
      The national telemetry ranges are being pushed to provide higher data rate telemetry services by users with increasingly complex test procedure for increasingly complex weapon systems. At the same time they are having trouble obtaining more spectrum in which to provide these higher rates because of the demand for spectrum in SHF range from various mobile/cellular Personal Communications Services (PCS) as well as congress’s desire to auction spectrum and to transfer as much spectrum as possible to commercial uses. In light of these pressures the industry is in need of a modulation standard that will out perform the existing PCM/FM standard. The motivation for the present review and analysis of the performance of various coded/uncoded modulation schemes arises from this issue. Comparison of the performance of these schemes will be utilized in the following work to find a suitable solution to the existing problem.
    • DSP BASED SIGNAL PROCESSING UNIT FOR REAL TIME PROCESSING OF VIBRATION AND ACOUSTIC SIGNALS OF SATELLITE LAUNCH VEHICLES

      T.N., Santhosh Kumar; A.K., Abdul Samad; K.M., Sarojini; Indian Space Research Organisation (International Foundation for Telemetering, 1995-11)
      Measurement of vibration and acoustic signals at various locations in the launch vehicle is important to establish the vibration and acoustic environment encountered by the launch vehicle during flight. The vibration and acoustic signals are wideband and require very large telemetry bandwidth if directly transmitted to ground. The DSP based Signal Processing Unit is designed to measure and analyse acoustic and vibration signals onboard the launch vehicle and transmit the computed spectrum to ground through centralised baseband telemetry system. The analysis techniques employed are power spectral density (PSD) computations using Fast Fourier Transform (FFT) and 1/3rd octave analysis using digital Infinite Impulse Response (IIR) filters. The programmability of all analysis parameters is achieved using EEPROM. This paper discusses the details of measurement and analysis techniques, design philosophy, tools used and implementation schemes. The paper also presents the performance results of flight models.
    • REMOTE OPERATION OF THE YSCAT SCATTEROMETER

      Reed, Ryan; Long, David G.; Arnold, David V. (International Foundation for Telemetering, 1995-11)
      A scatterometer is a radar system designed to make precise measurements of the magnitude of the radar echo scattered from surface. If the measurement is made over the ocean's surface, the surface wind speed and direction can be inferred. In order to better understand the relationship between the radar return and the ocean winds we have developed a unique ultra-wide band research scatterometer known as Yscat. The Yscat radar system is computer controlled, with a separate computer collecting environmental data. During a typical deployment, such as a recently completed 7 month deployment on Lake Ontario, the radar system is required to operate unmanned for weeks at a time, collecting data at a rate of up to 2 GB per week. Controlling such a complex system, and handling such large amounts of data presents a challenging remote operation problem. We used a novel combination of personal computers, telephone controlled switches, modems, and off the shelf software packages to enable us to perform daily monitoring, trouble shooting, and data transfer via a simple telephone connection. Data was stored on 4 mm DAT tapes for weekly pickup by a technician. This paper describes the Yscat system and our approach to control, monitoring, and data storage. While our approach is relatively "low tech", it has been very cost effective. This type of approach may be of interest to other designers of unique instrumentation at remote sites.
    • PERFORMANCE OF PCM/FM DURING FREQUENCY SELECTIVE FADING

      Law, Eugene L.; NAWCWPNS (International Foundation for Telemetering, 1995-11)
      This paper will discuss the performance of pulse code modulation (PCM)/frequency modulation (FM) during frequency selective fading. Frequency selective fading occurs when the attenuation in part of the frequency band of interest is much greater than in the rest of the band of interest. The frequency selective fading model used in this paper assumes that two paths with different delays exist between the transmitter and receiver (multipath). The two-path model was simulated in the laboratory and the effects of frequency selective fading on the radio frequency (RF) spectrum and on the waveforms at the output of the FM demodulator were measured. A mathematical model was also used to predict the effects of frequency selective fading. The predicted waveshapes are compared with the laboratory data. A simple demodulator which alleviates the effects of frequency selective fading on PCM/FM at moderate signal-to-noise ratios (SNRs) will be described. This demodulator is created by detuning the telemetry receiver by a frequency equal to approximately one-half of the intermediate frequency (IF) bandwidth and using the receiver’s amplitude modulation (AM) detector output rather than the FM detector output. The performance of this offset AM demodulator will be compared with the performance of an FM demodulator. Frequency selective fades measured in real-world environments will be also presented.
    • INCREASING DATA DENSITY ON 1/2 INCH CASSETTE TAPE

      Buschbach, Charles W.; Metrum (International Foundation for Telemetering, 1995-11)
      Half inch Super VHS (S-VHS) tape is an exceptional media for recording telemetry instrumentation data. Due to high volume mass production for the commercial and industrial video markets, high quality S-VHS media is available at a low cost. Advances in head technology as well as data path electronics contribute to increased data densities recorded on this media. Present system capabilities of 50,000 bits per inch will soon be replaced with newer technology systems that will record at linear densities up to 100,000 bits per inch.
    • A NEW GENERATION OF DATA RECORDERS FOR REMOTE SENSING GROUND STATIONS

      Kayes, Edwin (International Foundation for Telemetering, 1995-11)
      Magnetic tape is the primary medium used to capture and store unprocessed data from remote sensing satellites. Recent advances in digital cassette recording technology have resulted in the introduction of a range of data recorders which are equally at home working alongside conventional recorders or as part of more advanced data capture strategies. This paper shows how users are taking advantage of the convenience, economy and efficiency of this new generation of cassette-based equipment in a range of practical applications.
    • A 400 Mbps High Density Digital Recording System

      Kibalo, Tom; Miles, Ben; Alliant Techsystems Inc. (International Foundation for Telemetering, 1995-11)
      A highly versatile 400 Mbps High Density Digital Recording System for telemetry and GPS downlink acquisition at Vandenberg AFB, California is discussed. The system supports 24 channels of data acquisition, is realized using entirely COTS components, and achieves full IRIG compatibility without any compromise in the desired system performance and operation.
    • RE-ENGINEERING UEVE TELEMETRY MONITORING OPERATIONS: A MANAGEMENT PERSPECTIVE AND LESSONS LEARNED FROM A SUCCESSFUL REAL-WORLD IMPLEMENTATION

      Biroscak, D.; Losik, L.; Malina, R. F. (International Foundation for Telemetering, 1995-11)
      The Extreme Ultraviolet Explorer (EUVE) Science Operations Center at UC Berkeley was recently successful in implementing an automated monitoring system that allowed reduced operations staffing from 24 hours per day to 9 hours per day. The payload safety is monitored exclusively by artificial intelligence (AI) telemetry-processing systems for 16 hours per day. At launch, the EUVE Science Operations Center was staffed and operated as a typical satellite control center, receiving real-time and tape recorder data 24 hours per day. From September 1993 through February 1995, EUVE science operations were redesigned in a phased, low-cost approach. A key factor in the implementation was to utilize existing personnel in new roles through additional training and reorganization. Through- out this period, EUVE guest observers and science data collection were unaffected by the transition in science operations. This paper describes the original and actual implementation plan, staffing phases, and cost savings for this project. We present the lessons learned in the successful transition from three-shift to one-shift operations.
    • AFFORDABLE GROUND STATION EQUIPMENT FOR COMMERCIAL AND SCIENTIFIC REMOTE SENSING APPLICATIONS

      Chesney, James R.; Bakos, Roger; TSI TelSys, Inc. (International Foundation for Telemetering, 1995-11)
      The remote sensing industry is experiencing an unprecedented rush of activity to deploy commercial and scientific satellites. NASA and its international partners are leading the scientific charge with The Earth Observation System (EOS) and the International Space Station Alpha (ISSA). Additionally, there are at least ten countries promoting scientific/commercial remote sensing satellite programs. Within the United States, commercial initiatives are being under taken by a number of companies including Computer Technology Associates, Inc., EarthWatch, Inc., Space Imaging, Inc., Orbital Imaging Corporation and TRW, Inc. This activity is due to factors including: technological advances which have lead to significant reductions in the costs to build and deploy satellites; an awareness of the importance of understanding human impact on the ecosystem; and a desire to collect and sell data some believe will be worth $1.5 billion (USD) per year within five years. The success and usefulness of these initiatives, both scientific and commercial, depends largely on the ease and cost of providing remotely sensed data to value added resellers and end-users. A number of these spacecraft will provide an interface directly to users. To provide these data to the largest possible user base, ground station equipment must be affordable and the data must be distributed in a timely manner (meaning seconds or minutes, not days) over commercial network and communications equipment. TSI TelSys, Inc. is developing ground station equipment that will perform both traditional telemetry processing and the bridging and routing functions required to seamlessly interface commercial local- and wide-area networks and satellite communication networks. These products are based on Very Large Scale Integration (VLSI) components and pipelined, multi-processing architectures. This paper describes TelSys’ product family and its envisioned use within a ground station.
    • RADAR BACKSCATTER MEASUREMENT ACCURACY FOR SPACEBORNE SCANNING PENCIL-BEAM SCATTEROMETERS

      Long, David G. (International Foundation for Telemetering, 1995-11)
      A radar scatterometer transmits a series of RF pulses and measures the total-power (energy) of the backscattered signal. Measurements of the backscattered energy from the ocean's surface can be used to infer the near-surface wind vector [7]. Accurate backscatter energy measurements are required to insure accurate wind estimates. Unfortunately, the signal measurement is noisy so a separate measurement of the noise-only total-power is subtracted from the signal measurement to estimate the echo signal energy. A common metric for evaluating the accuracy of the scatterometer energy measurement is the normalized signal variance, termed K(p). In designing a scatterometer tradeoffs in design parameters are made to minimize K(p). Spaceborne scatterometers have traditionally been based on fan-beam antennas and CW modulation for which expressions for K(p) exist. Advanced pencil-beam scatterometers, such as SeaWinds currently being developed by NASA use modulated Signals so that new K(p) expressions are required. This paper outlines the derivation of the generalized K(p) expression. While very complicated in its exact form, with a simplified geometry the K(p) expression can be related to the radar ambiguity function. The resulting analysis yields insights into the tradeoffs inherent in a scatterometer design and permits analytic tradeoffs in system performance.
    • A Low-Cost, Autonomous, Ground Station Operations Concept and Network Design for EUVE and Other Earth-Orbiting Satellites

      Abedini, A.; Moriarta, J.; Biroscak, D.; Losik, L.; Malina, R. F. (International Foundation for Telemetering, 1995-11)
      The Extreme Ultraviolet Explorer (EUVE) satellite was designed to operate with the Tracking and Data Relay Satellite System (TDRSS) and Deep Space Network (DSN). NASA, the Jet Propulsion Laboratory and the Center for EUV Astrophysics have been evaluating a commercially available ground station already used for NASA's Low Earth Orbit (LEO) weather satellites. This ground station will be used in a network of unattended, autonomous ground stations for telemetry reception, processing, and routing of data over a commercial, secure data line. Plans call for EUVE to be the initial network user. This network will be designed to support many TDRSS/DSN compatible missions. It will open an era of commercial, low-cost, autonomous ground station networks. The network will be capable of supporting current and future NASA scientific missions, and NASA's LEO and geostationary weather satellites. Additionally, it could support future, commercial communication satellites in low, and possibly medium, Earth orbit. The combination of an autonomous ground station and an autonomous telemetry monitoring system will allow reduction in personnel. The EUVE Science Operations Center has already reduced console work from three shifts to one by use of autonomous telemetry monitoring software.
    • GLOBAL EXPLORATION OF TITAN’S CLIMATE: OFF THE SHELF TECHNOLOGY AND METHODS AS AN ENABLER

      Mitchell, B. J.; The Johns Hopkins University (International Foundation for Telemetering, 1995-11)
      Recent narrow band imagery of the surface of Titan reveals a very non-uniform surface. While there are no global oceans of liquid ethane/methane as once conjectured, the imagery does suggest the possibility of seas or lakes of liquid ethane, methane, and other organic materials. If these exist, Titan could be considered a gigantic analog model of the Earth's climate system complete with land masses, moderately thick atmosphere, and large bodies of liquid. By studying the climate of Titan, we could gain further understanding of the processes and mechanisms that shape the Earth's climate. Reuse of existing technology and methods may be a way to speed development and lower costs for the global study of Titan. Surprisingly, one of the key technologies could be a Transit or Global Positioning System (GPS) descendant for use in tracking probes wandering the surface of Titan.
    • A LOW WINDLOAD BROADBAND FLAPS™ ANTENNA FOR TELEMETRY TRACKING SYSTEMS

      Richard, Gaetan C.; Gonzales, Daniel G.; Malibu Research, Inc. (International Foundation for Telemetering, 1995-11)
      The use of low windload FLAPS™ antennas in telemetry tracking systems yields sizable savings in system cost due to the reduced requirements imposed on the pedestal assembly and on the underlying support structure. Traditionally the use of these antennas has been limited to applications in which frequency bandwidths did not exceed 10-13%. This paper describes a variation of the FLAPS™ technology which allows operation over bandwidths in excess of 35% and makes it usable in broadband systems. Two new applications are feasible: one for a ground based telemetry system operating in the 1435-1850 or 1750-2400 MHz band and one for a shipboard satellite communication system operating in the 4000-6000 MHz band.
    • PARAMETER CHARACTERIZATION ON A TELEMETRY CHANNEL INCLUDING THE EFFECTS OF THE SPECULAR RAY

      Dye, Ricky G.; Horne, Lyman D.; Brigham Young University (International Foundation for Telemetering, 1995-11)
      The aeronautical channel model is a good candidate for modeling the effects of multipath interference of telemetry signals on test ranges. The aeronautical fading channel model is parameterized by the signal to noise ratio, the Doppler shift and time delay between the specular and direct components, the specular to direct power ratio, the direct to diffuse power ratio, and the bandwidth of the multipath fading process. Segments of weighting signal data measured during a test at Tyndall AFB provide data which can be used to determine typical values of the above parameters in a variety of telemetering environments. In this paper, the set of parameters which most closely model the actual telemetry channel using the Tyndall data is determined.
    • TELEMETRY AS AUTOMATA

      Jones, Charles H.; Edwards Air Force Base (International Foundation for Telemetering, 1995-11)
      In its simplest form an automaton can be considered a set of inputs, a process, and a set of outputs. Certainly telemetry can be thought of in this way as well. Automata theory is a cross between mathematics and computer science which considers how to precisely define the inputs, the outputs, and the process of translating the one into the other. The input to an automaton can be described using a formal grammar. Two standard bit stream encodings, PCM matrices and MIL-STD-1553, are described using grammars. An example of how a grammar can be used to decode a bit stream is given. Further, ambiguity and complexity of bit stream encodings are discussed in the context of grammars. It is thus illustrated how grammars can be used to cleanly define and decode telemetry bit streams.
    • AN INEXPENSIVE DATA ACQUISITION SYSTEM FOR MEASURING TELEMETRY SIGNALS ON TEST RANGES TO ESTIMATE CHANNEL CHARACTERISTICS

      Horne, Lyman D.; Dye, Ricky G.; Brigham Young University (International Foundation for Telemetering, 1995-11)
      In an effort to determine a more accurate characterization of the multipath fading effects on telemetry signals, the BYU telemetering group is implementing an inexpensive data acquisition system to measure these effects. It is designed to measure important signals in a diversity combining system. The received RF envelope, AGC signal, and the weighting signal for each beam, as well as the IRIG B time stamp will be sampled and stored. This system is based on an 80x86 platform for simplicity, compactness, and ease of use. The design is robust and portable to accommodate measurements in a variety of locations including aircraft, ground, and mobile environments.
    • THE PHILLIPS LABORATORY’S MOBILE GROUND TRACKING STATION (MGTS)

      Stone, Christopher E.; Flint, Keith D.; Mathis, Gregory P.; Edwards Air Force Base (International Foundation for Telemetering, 1995-11)
      Phillips Laboratory's Space Experiments Directorate (PL/SX) is operating and upgrading the laboratory's premier transportable satellite tracking station, the Mobile Ground Tracking Station (MGTS) program. MGTS supports orbital, suborbital, and aircraft missions as a range system capable of processing and recording multiple data streams. MGTS receives, processes, displays, and records satellite state-of-health data, infrared images in a variety of wavelengths, video data, and state vector solutions based on IR returns from the Miniature Sensor Technology Integration (MSTI) satellite program. The program has began in 1990 under BMDO sponsorship, with the intent to supplement existing test ranges with more flexibility in range operations. Wyle Laboratories and Systems Engineering and Management Company (SEMCO) provided the technical expertise necessary to create the first MGTS system. Autonomy and off-road capability were critical design factors, since some of the operations envisioned require deployment to remote or hostile field locations. Since inception, MGTS has supported the Lightweight Exo-Atmospheric Projectile (LEAP) sub-orbital missions, the MSTI satellite program, and Air Force wargame demonstrations. In pursuit of these missions, MGTS has deployed to White Sands Missile Range (WSMR), NM; Air Force Flight Test Center (AFFTC), Edwards AFB, CA; Vandenberg AFB, CA; Falcon AFB, CO; and NASA's Wallops Island Flight Facility, VA, to receive critical mission telemetry data conforming to both IRIG and SGLS standards. This paper will describe the evolution of the MGTS program, current hardware configurations and past and future mission scenarios for the MGTS team.
    • A VERY LOW COST 150 MBPS DESKTOP CCSDS GATEWAY

      Davis, Don; Bennett, Toby; Harris, Jonathan; NASA; RMS Technologies (International Foundation for Telemetering, 1995-11)
      The wide use of standard packet telemetry protocols based on the Consultative Committee for Space Data Systems (CCSDS) recommendations in future space science missions has created a large demand for low-cost ground CCSDS processing systems. Some of the National Aeronautics and Space Administration (NASA) missions using CCSDS telemetry include Small Explorer, Earth Observing System (EOS), Space Station, and Advanced Composite Explorer. For each mission, ground telemetry systems are typically used in a variety of applications including spacecraft development facilities, mission control centers, science data processing sites, tracking stations, launch support equipment, and compatibility test systems. The future deployment of EOS spacecraft allowing direct broadcast of data to science users will further increase demand for such systems. For the last ten years, the Data Systems Technology Division (DSTD) at NASA Goddard Space Flight Center (GSFC) has been applying state-of-the-art commercial Very Large Scale Integration (VLSI) Application Specific Integrated Circuit (ASIC) technology to further reduce the cost of ground telemetry data systems. As a continuation of this effort, a new desktop CCSDS processing system is being prototyped that offers up to 150 Mbps performance at a replication cost of less than $20K. This system acts as a gateway that captures and processes CCSDS telemetry streams and delivers them to users over standard commercial network interfaces. This paper describes the development of this prototype system based on the Peripheral Component Interconnect (PCI) bus and 0.6 micron complementary metal oxide semiconductor (CMOS) ASIC technology. The system performs frame synchronization, bit transition density decoding, cyclic redundancy code (CRC) error checking, Reed-Solomon decoding, virtual channel sorting/filtering, packet extraction, and quality annotation and accounting at data rates up to and beyond 150 Mbps.
    • Multi-functions Integration and Intermodulation Interference of TT&C system

      Jiaxing, Liu; The Southwest Insititute of Electronics Technology (International Foundation for Telemetering, 1995-11)
      This paper describes technical problems in system integration, Intermodulatin interference, digitalization, obital accuracy, low-noise design of the new generation TT&C system as well as their solutions.