• PHASE AND FREQUENCY TRACKING CONSIDERATIONS FOR HETERODYNE OPTICAL COMMUNICATIONS

      Kaufmann, John E.; Massachusetts Institute of Technology (International Foundation for Telemetering, 1982-09)
      In heterodyne optical communications, phase or frequency tracking is generally needed to avoid performance degradation when signaling in the presence of laser frequency jitter and Doppler shifts. This paper examines a phase-lock loop approach for BPSK and two forms of frequency tracking for MFSK. Using a statistical model for laser frequency instability, the performance of these schemes is calculated by a linear analysis of the tracking loop in the small-error regime.
    • MULTIPLEXING HIGH SPEED PCM DATA WITH PREPROCESSORS

      Willis, James; New Mexico State University (International Foundation for Telemetering, 1982-09)
      This paper deals with the use of preprocessors to reduce loading on real-time computers. The problem of multiplexing large amounts of data, exceeding the processing capabilities of most large-scale, real-time computers is discussed in detail. Implementation of hardware solutions to multiple Pulse Code Modulation (PCM) link multiplexing is dealt with. Use of firmware algorithms to reduce preprocessor front-end loading, as well as through-put reduction is discussed. The paper covers the different techniques used to take advantage of modern firmware preprocessor/multiplexers to select data for real-time computer processing.
    • THE EFFECT OF PREMODULATION FILTERS ON BIT ERROR RATE PERFORMANCE

      Bobrek, Pavlo; Sangamo Weston, Schlumberger (International Foundation for Telemetering, 1982-09)
      This paper examines the effect of different types of premodulation filters on the time waveshapes of PCM signals. Using a simplified model of this effect, an expression for the Probability of Error in the presence of Gausian Noise is derived and compared for systems with and without premodulation filtering. A simple single bit decision feedback detector is designed and an evaluation made of its usefulness in improving bit error rate performance using different filters in the presence of different amounts of noise.
    • AUTOMATIC ADDRESSING OF TELEMETRY CHANNELS

      Lucero, L. A.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      To simplify telemetry software development, a design that elminates the use of software instructions to address telemetry channels is being implemented in our telemetry systems. By using the DMA function of the RCA 1802 microprocessor, once initialized, addressing of telemetry channels is automatic, requiring no software. In this report, the automatic addressing scheme is compared with an earlier technique that uses software to address telemetry channels. In comparison, the automatic addressing scheme effectively increases the software capability of the microprocessor, simplifies telemetry dataset encoding, eases data set changes, and may decrease the electronic hardware count. The software addressing technique uses at least three instructions to address each channel. The automatic addressing technique requires no software instructions. Instead, addressing is performed using a direct memory access cycle stealing technique. Application of an early version of this addressing scheme opened up the capability to execute 400 more microprocessor instructions than could be executed using the software addressing scheme. The present version of the automatic addressing scheme uses a section of PROM reserved for telemetry channel addresses. Encoding for a dataset is accomplished by programming the PROM with channel addresses in the order they are to be monitored. Software for one of our telemetry units was written using the software addressing scheme, then rewritten using the automatic addressing scheme. While 1000 bytes of memory were required by the software addressing scheme, the automatic addressing scheme required only 396 bytes. A number of prototypes using AATC have been built and tested in a telemetry lab unit. All have worked successfully.
    • TELEMETRY RECORDING AND REDUCTION EQUIPMENT FOR SHIPBOARD SUPPORT OF MISSILE EXERCISES

      Daniel, Jack T.; Jones, Gary P.; E-Systems Inc., ECI Division (International Foundation for Telemetering, 1982-09)
      Evolving growth in Navy ship-to-air missile design has resulted in a need for larger quantities of telemetry information with increasing emphasis on digital telemetry. This has inherently led to the requirement for telemetry processing equipment that is adaptable to these changing missile telemetry data formats. The design for the Telemetry Recording and Reduction Equipment (TRRE), that incorporates today’s technology into a compact, realtime analysis tool for shipboard use, is presented in this paper. The TRRE was designed to process both the Pulse Amplitude Modulation (PAM) telemetry data formats of existing missile designs and the Pulse Code Modulation (PCM) data formats of evolving missile designs. The TRRE design minimizes the required operator interace through preprogrammed telemeter formats and programmable decommutation tables. A microprocessor is utilized in the design to program the decommutation hardware configuration.
    • PLANETARY SOIL WATER ANALYZER (PSWA) PROTOTYPE

      Cashin, William F.; Anderson, Duwayne M.; Ball Aerospace Systems Division; State University of New York (International Foundation for Telemetering, 1982-09)
      A microprocessor-based differential scanning calorimeter is being designed for eventual use in planetary soil water analysis. The uniqueness of this effort is in the use of the microprocessor as an integral section of the system control loops, instead of as merely an auxilary processor of output data. The use of differential scanning calorimetry is advantageous in determining water content of soil samples. The basic idea is to use two matched ovens, one with a soil sample included. The average temperature of the ovens is forced to track a desired programmed temperature (normally a slow ramp) with one control loop, while a second control loop forces the oven temperatures to be equal, even during a transition. The power necessary to keep the temperatures equal is monitored, containing information as to the transition energy, and thus the water content at programmed water transition temperatures. This approach uses the microprocessor to close both of the loops, taking oven sensor temperatures as an input, and providing power duty cycles as outputs. In actuality, two microprocessors are used - a slave to accumulate and process sensor information, and a master to generate the loop control, output data control, and temperature program control. The PSWA performance is compared to a state-of-the-art commercial instrument using analog loop control. The major advantage of the microprocessor loop control utilized in the PSWA is the capability of remote operation, including remote alignment and adjustment. Further advantages include accommodation of oven changes with software reprogramming, a flexible single oven capability, correction for system nonlinearities using software, and auto gain and auto zero control for the sensor circuitry. The analog loop control approach has somewhat better sensitivity, resolution, and noise performance. The current phase of the development of the PSWA is a feasibility study and circuit design, performed for the Planetary Geology Program Office, NASA Headquarters. The next developmental phases would include breadboarding, software design, testing, and evaluation. In conclusion, this instrument is a significant advance in the state-of-the-art for automatic water measurements, and will be of great value in further planetary exploration.
    • A COMMUNICATION SYSTEM ARCHITECTURE FOR INTEROPERABLE SYSTEMS

      LaVean, Gilbert E.; Sonderegger, Ronald E.; Defense Communications Agency (International Foundation for Telemetering, 1982-09)
      This paper describes a Worldwide Digital System Architecture that was developed in response to tasking from the Office of the Secretary of Defense to the Defense Communications Agency (DCA). This tasking directed DCA to develop a Worldwide Digital System Architecture in coordination with the Military Departments, the TRI-TAC office, and other interested agencies and commands. The main purpose for developing this architecture is to take a first step toward assuring that the many command and control communications and information processing systems are sufficiently interoperable in order to achieve needed survivability and endurability.
    • Telemetering Standards Coordination Commitee

      Jennings, Vernon A. (International Foundation for Telemetering, 1982-09)
    • A STATISTICAL MODEL OF THE PHOTOMULTIPLIER GAIN PROCESS WITH APPLICATIONS TO OPTICAL PULSE DETECTION

      Tan, Harry H.; University of California (International Foundation for Telemetering, 1982-09)
      The complete statistical behavior of the random gain of a photomultiplier tube (PMT) has not previously yielded to exact analysis. In this paper a Markov diffusion model is used to determine an approximate probability density for the random gain. This approximate density preserves the correct second order statistics and appears to be in reasonably good agreement with previously reported experimental data. The error performance of a simple binary direct detection optical communication system is analyzed using this density.
    • TELEMETRY SYSTEMS AND MEASUREMENT TECHNIQUES ASSOCIATED WITH ARTILLERY PROJECTILES

      Radomsky, Israel; Hochman, D.; Israel Military Industries (International Foundation for Telemetering, 1982-09)
      The Israel Military Industries (IMI), Systems Division, has had requirements for telemetry systems and measurements techniques to obtain data regarding projectiles performance in-flight and in-bore. This paper presents a brief description of a new programmble PCM telemetry system which employs several novel techniques like flexible multiplexing, programmable signal conditioner on a channel per channel basis for multiple gains and offsets), and a miniature size due to thick film hybrid construction and all thses along with very high shock survivability and long term reliability. This paper also presents a description of a very low cost telemetry package for measuring the in-flight spin rate using a specially designed transmitting antenna, a telemetry package for measuring event type phenomena and analog data (acceleration, pressure, strains, etc.) while the projectile is traveling in-bore. Examples of data obtained during actual firings are presented and discussed.
    • POWER EFFICIENT OPTICAL COMMUNICATIONS FOR SPACE APPLICATIONS

      Lesh, James R.; Supervisor, Communications Concepts Research Jet Propulsion Laboratory (International Foundation for Telemetering, 1982-09)
      Optical communications technology promises substantial size, weight and power consumption savings for space to space high data rate communications over presently used microwave technology. These benefits are further increased by making the most efficient use of the available optical signal energy. This presentation will describe the progress to date on a project to design, build and demonstrate in the laboratory an optical communication system capable of conveying 2.5 bits of information per effective received photon. Such high power efficiencies will reduce the need for photon collection at the receiver and will greatly reduce the requirements for optical pointing accuracy, both at the transmitter as well as the receiver. A longer range program to demonstrate even higher photon efficiencies will also be described.
    • PULSE CODE MODULATION TELEMETRY

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1982-09)
      This paper discusses the performance of pulse code modulation/frequency modulation (PCM/FM), pulse code modulation/phase modulation (PCM/PM) and phase shift keying (PSK) in the “real-world” of range telemetry. The topics addressed include: 1. Radio frequency (RF) spectra 2. Bit error rate (BER) versus pre-detection signal-to-noise ratio (SNR) 3. Peak carrier deviation 4. Premodulation and receiver predetection filtering 5. PCM codes 6. Magnetic recording The purpose of this paper is to provide the reader with information needed to choose the best modulation method, PCM code, premodulation filter bandwidth and type, receiver settings, and recording method for a particular application.
    • TACTICAL INFORMATION EXCHANGE

      Kroger, Marlin G.; Palos Verdes Estates (International Foundation for Telemetering, 1982-09)
      This paper addresses the development of an architecture or framework to guide the design of future communications links and networks to support tactical military operations. In the next decade military forces are planned to be much more mobile and dispersed than they are today. Improved sensors and information processing capabilities will provide information needed to manage defense actions against numerically superior enemy forces, but the effective use of that information will require greatly improved communications capability. The resultant digital information traffic which consists of bursts of data between and among users and data sources must be accomodated efficiently, something that neither the present circuit-switches nor the current store-and-forward message transmission systems do well. Also, there is a requirement for much more interoperability between the systems of different services and nations. Internetwork routing of data transmissions can provide more robust connectivity via alternate paths, to cope with jamming and physical attacks on specific transmission media or nodes. An approach to data network interconnection structure that has emerged over the past several years is the concept of a hierarchial set of protocol layers, each one building on the one below. In total, they constitute a reference model for “open systems interconnection.” The most common version of such a reference model is the International Organization for Standardization’s reference model of Open Systems Interconnection (ISO OSI) (1). The ISO OSI model has been designed to serve the fixed plant, benign-environment commercial user. DoD has special needs for security, precedence, internetwork data transfer and user mobility that are not yet reflected in the ISO model. Because of these special needs candidate DoD models that are different from the ISO model have been proposed. However, an important consideration in the choice of or development of a DoD standard is that DoD Systems should be able to use commercial equipment and interface with commercial data networks. Also a consideration is that the reference model used for strategic and tactical communications should be a standard throughout DoD, although specific protocols could differ as necessary to support tactical vs. strategic needs. In total, these requirements and considerations constitute a significant design challenge that must be addressed promptly if DoD is to have any influence on the finalization of the ISO OSI model to get it to accomodate DoD requirements as much as possible.
    • RANGE STANDARDS PANEL DISCUSSION

      Ashley, Carl G.; Pacific Missile Test Center (International Foundation for Telemetering, 1982-09)
      The Telemetry Group (TG) of the Range Commanders Council is the primary means of exchanging telemetry technical and operational information and coordinating and standardizing systems, techniques, methods, and procedures. The TG is concerned with such telemetry gathering instrumentation as airborne sensing devices and modulation and multiplexing equipment. In addition, the group monitors developments in telemetry processing and storage systems and special display devices. The group is also responsible for writing and updating the Telemetry Standards Document and a series of five volumes on Text Methods for Telemetry Systems and Subsystems.
    • COMSAT SATELLITE CONTROL NETWORKS

      Johnson, Charles E.; Communications Satellite Corporation Palo Alto (International Foundation for Telemetering, 1982-09)
      The COMSAT family of companies is actively involved in the operation of the Intelsat, COMSAT General, and Satellite Business Systems (SBS) ground networks which currently control twenty-five communications satellites utilizing three control centers and thirteen ground stations with forty-five antennas. Satellites controlled include INTELSAT IV (7), INTELSAT IVA (5), INTELSAT V (4), COMSTAR (4), MARISAT (3), and SBS (2). COMSAT also operates a launch services network consisting of a COMSAT Launch Control Center and Intelsat ground stations, as required, to guide spacecraft to the proper orbit station. Intelsat V flight 4 was launched in March 1982. Two additional Intelsat V’s and one SBS are scheduled for launch this year. The latter will be on the first commercial shuttle mission. The ground control networks contain a commonality traceable to COMSAT’s influence in the design of the satellites and experience in the control of communications satellites dating back to the launch of the Early Bird in 1965. This paper presents an overview of operational and planned networks in which COMSAT plays a significant role.
    • SATELLITE DATA LINK STANDARDS*

      Lt. Gibson, Col. R.H.; Maj. Sutton, R.V.; Rodriguez, T.M.; Tamura, Y.; Air Force Systems Command; The Aerospace Corporation (International Foundation for Telemetering, 1982-09)
      Flexibility and survivability of Space Communications dictate the interoperability of communication links between as many satellites as feasible. Interoperability increases survivability by providing alternate paths. Interoperability also improves total system reliability and cost effectiveness, and it permits a flexible, distributed communications architecture to evolve. To implement this approach, functional satellite data link standards are needed to pull together mission data relay, communications, and tracking, telemetry and command (TT&C) requirements so that they can be satisfied by a common link design. The basic requirement which unifies these diverse users is their need for uplink jamming protection and scintillation resistance (in a perturbed atmosphere) at low (75 bps to 19.2Kbps) data rates. While the downlink and crosslink requirements are more diverse, they do not constitute major drivers of the standard. This paper describes Space Division’s standardization effort, the links to be standardized, the parameters that must be defined and an evolutionary implementation approach. The first satellite-ground links to be standardized will use 44/20 GHz with wideband spreading for jam resistance, while the crosslinks will use 60 GHz to avoid terrestrial jamming. Key issues are discussed, such as the conflicting requirements between TT&C and communications and the tradeoffs between minimum designs and flexibility.
    • UPLINK COMMAND STRUCTURE WITHIN THE SPACE SHUTTLE ORBITER

      Lasken, Walter W.; Rockwell International (International Foundation for Telemetering, 1982-09)
      This paper presents an overview of the various types of uplink commands available for attached or detached payloads and discusses in detail the manner in which the Space Shuttle orbiter common set and stand-alone computers accept and process these commands. Command and data processing within the orbiter systems during ascent and on-orbit operation are also discussed. The uplink command formats, as they relate to the data processing system, are presented in some detail.
    • SOFTWARE SUPPORT FOR A STORED PROGRAM PCM DECOMMUTATOR

      Peterson, Dwight M.; Fleet Analysis Center (International Foundation for Telemetering, 1982-09)
      Telemetered data generated by missile systems has become increasingly complex with the inclusion of asynchronous data streams, variable word lengths, and discrete encoding. The display of this data for analysis purposes requires sophisticated equipment, usually designed with a programmable architecture. This paper describes software support that was developed for a stored program PCM decommutator. The software includes a cross assembler and supports downline loading of the decommutator from a host computer.
    • DESIGN OF A FOUR-CHANNEL, 50 MBPS, STATISTICAL MULTIPLEXER AND DEMULTIPLEXER

      O’Donnell, John T.; Digital Communications AYDIN MONITOR Systems (International Foundation for Telemetering, 1982-09)
      This paper discusses the design of a 50 Mbps Statistical Multiplexer and Demultiplexer, Model 781, manufactured by AYDIN MONITOR Systems of Fort Washington, PA. Two Model 781s connected through a 50 Mbps communications link constitute a full-duplex, 4-channel data link with a maximum aggregate throughput capability of 48 Mbps.
    • A NONMYSTICAL TREATMENT OF TAPE SPEED COMPENSATION FOR FREQUENCY MODULATED SIGNALS

      Solomon, Otis M., Jr.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      In this paper, the problem of non-constant tape speed is examined for frequency modulated signals. Frequency modulation and demodulation are briefly reviewed. Tape speed variation is modeled as a distortion of the independent variable of a frequency modulated signal. This distortion produces an additive amplitude error in the demodulated message which is comprised of two terms. Both depend on the derivative of time base error, which is the flutter of the analog tape machine. The first term depends on the channel’s center frequency and frequency deviation constant as well as flutter, while the second depends solely on the message and flutter. The relationship between the additive amplitude error and manufacturer’s flutter specification is described. Relative errors and signal-to-noise ratios are discussed for the case of a constant message to gain insight as to when tape speed variation will cause significant errors. An algorithm which theoretically achieves full compensation of tape speed variation is developed. The algorithm is confirmed via spectral computations on laboratory data. Finally, the algorithm is applied to field data. The reference is a temperature signal which is a non-zero constant, and the message is a pressure signal. The spectrum of the uncompensated message is clearly contaminated by the additive amplitude error, whereas the spectrum of the compensated message is not. Incorporation of this algorithm into the data-playback/data-reduction procedures is shown to greatly improve the measurement signal accuracy and quality. The treatment is nonmystical in that all derivations are directly tied to the fundamental equations describing frequency modulation and demodulation.