• GREATER THAN 3 MHZ MULTICHANNEL A/D CONVERSION ON A SINGLE VME BOARD

      JARYNOWSKI, ROBERT J.; New Mexico State University (International Foundation for Telemetering, 1991-11)
      A VME computer can be used to provide the basis for a telemetry data processing station. Using “off-the-shelf cards” the designer is able to build up a front end that meet several of the data processing requirements. The ease in interfacing to the VME bus also provides a convenient platform for the development of highly specialized interfaces requiring programmable control. The results are a low-cost highperformance system that is easily expandable as needs and/or technology grow. Based on this strategy, the Physical Science Laboratory (PSL) at New Mexico State University developed a multichannel high-speed analog-to-digital converter (ADC) assembly on a single VME board. The design approach used at PSL to develop the VME-based ADC is discussed in an effort to describe both developments in analog-to-digital conversion integrated circuits and the use of a VME CPU to control them for data processing purposes.
    • THE BRIDGE FUNCTION TELEMETRY SYSTEM

      Qishan, Zhang; BEIJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS (International Foundation for Telemetering, 1991-11)
      Based on the theory of orthogonality, two orthogonal multiplex systems called frequency division multiplexing(FDM) and time division multiplexing(TDM) have long been developed. Therefore, many people tend to think that these two systems represent the ONLY two multiplexing methods that satisfy the orthogonal condition. However, after years of research, we've discovered a new kind of orthogonal functions called Bridge functions. The Bridge functions have the every promise of being the basis for constructing an entirely new kind of telemetry system, which has been named as sequency division multiplexing(SDM). Since the Bridge functions are the mathematical basis of the new telemetry system, we will give a summary of the Bridge functions at first. We have successfully constructed an experimental prototype called BAM-FM system in our laboratory. The main ideas, block diagram, operational principles, and technical problems are discussed in this paper. All our work has proved that SDM has not only research interests, but also practical value.
    • COMMON AIRBORNE INSTRUMENTATION SYSTEM (CAIS)

      Faulstich, Raymond J.; Naval Air Test Center (International Foundation for Telemetering, 1991-11)
      In March, 1991 the Naval Air Test Center awarded a design, development and limited production contract to SCI Technology, Inc. for a Department of Defense (DoD) Common Airborne Instrumentation System (CAIS). This system is being developed to meet the flight test needs of the Air Force, Army and Navy into the 21 century. st The CAIS will be a time-division multiplexed data acquisition system comprised of a standard modular complement of hardware and software. These systems will be used on both existing and future aircraft. CAIS will not be airframe or weapon system dependent nor will its use be restricted to any Test and Evaluation activity. This paper describes the CAIS system as specified and proposed for implementation.
    • MODERNIZING THE REMOTE TRACKING STATION

      Blanchard, W. N. (International Foundation for Telemetering, 1991-11)
      Since the inception of the Air Force Satellite Control Network (AFSCN) in the late 1950s, capabilities of the network’s Remote Tracking Stations (RTSs) were evolutionarily developed to meet satellite Tracking, Telemetry, and Commanding (TT&C) needs. The result, although fully satisfactory operationally, was an RTS network requiring manpowerintensive mission support. Additionally, reconfiguration of an RTS between satellite contacts consumed far more time than was operationally desirable as demands for RTS contact support continued to grow. To improve network responsiveness and cost effectiveness, the Air Force undertook, in the mid-1980s, a major “block upgrade” under the Automated Remote Tracking Station (ARTS) Program. This paper traces historical RTS capabilities, identifies emerging mid1980s RTS support requirements, and defines the operational and financial advantages accruing to the Air Force through ARTS implementation to meet those requirements. Possible future upgrades to further enhance AFSCN TT&C mission capability are also briefly discussed.
    • FREQUENCY DOMAIN EFFECTS OF LOW RESOLUTION DIGITIZATION

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1991-11)
      There is a requirement to digitize certain wide-band analog signals in telemetry applications. Typically, an analog-to-digital converter (ADC) with eight or more bits of resolution is used. The resulting signal requires a much larger transmission bandwidth than the original analog signal. The frequency domain information is of primary interest for many applications. In these cases, there are several methods for minimizing the transmitted bandwidth. One method is to perform fast fourier transforms (FFTs) on the signals and only transmit information about the largest signals. The disadvantages of this approach include: relatively long time delay before transmission, resolution bandwidth fixed when FFT performed (unless phase information is also transmitted), and extra complexity in the telemeter. This paper will discuss some effects of minimizing the transmitted bandwidth by quantizing to a small number of bits. The performance will also be compared with analog frequency modulation (FM). Measured performance will be presented for four different input signals and one-, three-, and eight-bit quantization. These signals are amplitude modulation, angle modulation, sum of sine waves, and frequency sweep. The test setup is shown in figure 1. The analyses presented in this paper were performed using either fast fourier transforms (FFTs) or a Kay DSP Sonagraph. The FFT length was 1024 points and a Hann (cosine) window was used. The analysis hardware used for these tests has an analog input, therefore, all digitized signals were converted to analog signals before analysis. The signals were low pass filtered before analysis to minimize aliasing in the analysis and display process.
    • IMPLEMENTATION OF A VLSI LEVEL ZERO PROCESSING SYSTEM UTILIZING THE FUNCTIONAL COMPONENT APPROACH

      Shi, Jianfei; Horner, Ward P.; Grebowsky, Gerald J.; Chesney, James R.; RMS Technologies, Inc.; Data Systems Technology Division, Code 520 (International Foundation for Telemetering, 1991-11)
      A high rate Level Zero Processing system is currently being prototyped at NASA/Goddard Space Flight Center (GSFC). Based on state-of-the-art VLSI technology and the functional component approach, the new system promises capabilities of handling multiple Virtual Channels and Applications with a combined data rate of up to 20 Megabits per second (Mbps) at low cost.
    • ADVANCED ORBITING SYSTEMS FRONT END

      Hand, Sarah; Kram, Howard; Speciale, Nicholas; NASA/Goddard Space Flight Center (International Foundation for Telemetering, 1991-11)
      NASA’s Space Station and Earth Observing System (EOS) will be utilizing the Customer Data Operations Systems (CDOS) for data acquisition, capture, and production processing. The Advanced Orbiting Systems (AOS) Front End System being designed at NASA’s Goddard Space Flight Center (GSFC) is a prototype front end system which is designed to demonstrate the core front end functions required in the CDOS system in a realistic data processing environment. The overall goal is to provide a low cost environment for evaluating and verifying AOS and CDOS requirements before the actual operational systems are built. Additionally, the prototype will provide a data transport mechanism to move data to prototype production data systems and to other processing facilities via the new NASCOM II system. This paper describes the overall architecture of the AOS Front End (AFE) system, its core processing functions and performance requirements, and the possible implementation architectures and solutions being developed to handle key required AOS services
    • A DIGITAL DEVICE FOR FAST ACQUISITION OF PSEUDO-RANDOM CODE

      Gu, X.M.; Wang, J.P.; Yuan, S.J.; Li, W.S.; Zhang, Y.J. (International Foundation for Telemetering, 1991-11)
      A digital device for rapid acquisition of the initial phase of PN code has been implemented. The principles and results of the experiment are introduced in this paper. The m PN code is modulated on IF with BPSK type. The cycle of PN code P=255 chips. The rate of PN code R=5.1 × 10 chips /s. The IF is not acquired. The shift in Doppler 6 frequency f is within l-4KHz. In these conditions, the phase of PN code can be acquired d within 3 ms and the error of sychronization is less than 0.5 chip.
    • A SIMPLE DECOMMUTATION SCHEME FOR THE TELEMETRY TEST STATION

      Martin, Kamalini; Vanitha, M.; Manjunath, P.C. (International Foundation for Telemetering, 1991-11)
      The Telemetry Test Station has been developed at the Digital Systems Division, ISRO Satellite Centre, to test the housekeeping telemetry packages which will be flown onboard satellites. The heart of the test procedure is the decommutation, display and processing of the telemetry output format. The decommutation has been achieved by designing a simple plug in card to an IBM PC/XT compatible computer and writing the related assembly language software. The card and the software have been extensively tested and found to work satisfactorily upto 60 Kbps PCM data rate. To make the hardware and software flexible and truly general purpose, the acquisition should be independent of the modes of operation and data formats. All the parameters which define acquisition display and processing are therefore programmable and can be changed at any time. The parameters which influence acquisition are bit rate, word rate, frame rate, length of word, length of frame and frame synchronous code. The bit rate is transparent, i.e., need not be set by the user. The word length is assumed to be 8 bits or multiples of 8 bits. The other parameters are programmable at any time during the test session. Similarly, the parameters which affect display are the display rate, and positioning of the format including highlighting, alarm signals, related information etc. This gives a user the facility to tailor the display to his liking. The storage is also flexible and independent of display. All these modes are in real time and have therefore been coded in assembly. It has been found that a large part of the software is needed for user interface alone and user requirement is far more changeable than expected. The software is therefore designed for change. The problems and solutions in achieving these features are discussed in this paper.
    • A PRECISION TRANSPORTABLE TRACKING TELEMETRY SYSTEM

      Morris, R.A.; Powell, W.R.; Bundick, S.N.; Scientific-Atlanta, Inc.; NASA/Goddard Space Flight Center (International Foundation for Telemetering, 1991-11)
      Changing mission requirements have forced NASA to procure a new generation of tracking telemetry system with performance and features greatly exceeding existing system capabilities in many areas. These requirements and the system that was designed to meet them are discussed. Initial results of system testing are presented.
    • IMAGE DATA COMPRESSION (USING DPCM)

      Karki, Maya; Shivashankar, H.N.; Rajangam, R.K.; Dept. of Electrical Engg., U.V.C.E., Bangalore; DSD-ISRO, Bangalore (International Foundation for Telemetering, 1991-11)
      Advances in computer technology and mass storage have paved the way for implementing advanced data compression techniques to improve the efficiency of transmission and storage of images. The present paper deals on the development of a data compression algorithm suitable for images received from satellites. The compression ratio of 1.91:1 is achieved with the proposed technique. The technique used is 1-D DPCM Coding. Hardware-relevant to coder has also been proposed.
    • THE USE OF DIVERSITY TECHNIQUES TO IMPROVE TRACKING & RECEPTION OF TELEMETRY FROM INSTRUMENTED AIRBORNE VEHICLES

      SULLIVAN, ARTHUR; ARTHUR SULLIVAN & ASSOCIATES (International Foundation for Telemetering, 1991-11)
      Tracking performance and data reception can be considerably improved by the use of one or more types of diversity in the receiving system. Various schemes of optimizing signal strength and quality are currently in use. These include polarization, frequency, space, and time diversity. The question of why, when and what kind of system to be used baffles many of us who are required to make mission-dependent decisions. This paper discusses the nature and magnitude of improvement for the various types of diversity. It also discusses which systems should be used for various mission requirements. Methods of combining the diverse signals are adequately discussed in the referenced literature.
    • DESIGN PARAMETERS FOR A FM/FM SYSTEM

      Carden, Frank; New Mexico State University (International Foundation for Telemetering, 1991-11)
      Design parameters for a FM/FM telemetry system are determined in terms of the IRIG specifications for proportional bandwidth channels. Three mathematical models used by designers of the above processes are extended and compared. That is, FM multitone models are used to establish the relationship between frequency deviations, modulation indices, signal-to-noise and IF bandwidth for the IRIG channels. Since spectral efficiency and signal quality are of major importance, a goal of the design is to have a minimum IF bandwidth, while fixing as large as possible the values of the modulation indices for the subcarriers modulating the carrier in order to achieve as large as needed output signal-to-noise ratio.
    • ON IMPLEMENTATION OF REMOTELY OPERATED UNMANNED TELEMETRY TRACKING SYSTEMS WITH FIBER OPTIC CABLE

      TURNER, WILLIAM C.; ELECTRO-MAGNETIC PROCESSES, INC. (International Foundation for Telemetering, 1991-11)
      The high cost of real estate in countries with expanding populations, coupled with the long range capability of modern weapon systems has resulted in the need to expand test ranges to remote desert areas or areas over sea water. In order to preclude the cost of duplicating existing test centers, and the high cost of manually operating ground tracking stations, the requirement for unmanned remotely controlled telemetry tracking systems has emerged. Until recently, implementation of such systems has been trivial because the microwave link had sufficient bandwidth. However, with the advent of multi-TM bands, encrypted T.V. video and dual-polarization diversity requirements, implementation of unmanned remote stations has become cumbersome, expensive and less reliable. For instance, a pair of dedicated computers are now required to remotely control as many as eight receivers and four diversity combiners. This paper analyzes the advantages, limitations and feasibility of remotely controlling a wide-band antenna/pedestal with the restriction that all frequency downconverters, receivers, and combiners be located at the test center where they can be manually controlled and monitored, and more readily maintained. A comparison is made between the use of coaxial cable and fiber-optic cable as short-haul (0.25 to 25 kilometers) RF transmission media.
    • GULF RANGE DRONE CONTROL UPGRADE SYSTEM MOBILE CONTROL SYSTEM

      Wagner, Steven M.; Goodson, John H.; General Electric Government Services, Inc.; Eglin Air Force Base, Florida (International Foundation for Telemetering, 1991-11)
      The Gulf Range Drone Control Upgrade System (GRDCUS) Mobile Control System (GMCS) is an integral part of the test ranges located on the Gulf of Mexico. This paper begins with a brief overview of the current Gulf Range systems. These systems consist of five major components: ground stations, ground computer systems, data link/transponders, consoles, and software. The GMCS van contains many of these components to provide a stand-alone range capability for remote operations. This paper describes the development and assembly of the GMCS van and focuses on the on-board computer systems, consoles, and data link technology. An overall system engineering approach was used during GMCS development and is highlighted through the use of rapid prototyping. This methodology and the lessons learned are presented in the paper. Suggestions for future applications are considered.
    • HIGH RATE DIGITAL CASSETTE RECORDERS

      Banks, Simon; Penny & Giles Data Systems Ltd (International Foundation for Telemetering, 1991-11)
      Recorders conforming to IRIG Standards have served the data recording community well for many years. Initially, most systems were analog in nature, recording data in either direct or FM modes but as the need for digital recording developed, the IRIG recorder was successfully adapted for this purpose by the addition of formatting and coding sub-systems to form the High Density Digital Recorder (HDDR). Today, user requirements for higher speed, higher capacity and more convenient systems have presented equipment designers with new challenges in terms of the correct choice of technology and system architecture. It is not surprising that system designers should turn for inspiration first to the very high speed transverse and helical products which had been developed for the broadcast industry since these technologies possess many of the attributes necessary for a high rate digital data recorder. It is unfortunate that it has now become a truism that the only logical progression from the longitudinal IRIG system is by means of rotary technology. Recent developments in a technology known as micro-track recording now call this assumption into question. Recording systems based on micro-track technology are available and others are in an advanced state of development, and these offer a costeffective, attractive and low risk alternative to rotary systems for both high rate data capture and tape mass storage applications.
    • PCM BIT SYNCHRONIZATION TO AN Eb/No THRESHOLD OF -20 dB

      Schroeder, Gene F. (International Foundation for Telemetering, 1991-11)
      This paper presents an overview of a digital PCM adaptive bit synchronizer capable of bit synchronization down to an Eb/No of -20 dB where Eb/No is the energy contrast ratio. The topics addressed include: 1. Functional block diagrams. 2. Loop bandwidth as a function of synchronization threshold. 3. Accuracy, resolution and stability requirements of the Numerically Controlled Oscillator (NCO) and Loop Filter (LF). 4. Performance data. The purpose of this paper is to highlight the major components of a unit capable of performing this task based on an actual development program.
    • HIGH “G” MICROWAVE TELEMETRY SYSTEM

      KE ZHI, DANG; Xi’an Institute of Electromechanical Information Technology (International Foundation for Telemetering, 1991-11)
      The high “G” microwave telemetry system is a microwavemetre wave compatible telemetry system and a telemetry system of time division-frequency division hybrid. The so-called “hybrid” means by adding a microwave programcontrolled receiving antenna and a microwave frequency converter to the front-end of metre wave telemetry system, the microwave telemetry system shall be made up, by removing the additional front-end microwave head and connecting to metre wave receiving antenna instead, the metre wave telemetry system shall be made up. The so-called high “G” means that the microwave projectile-borne equipment can stand the high acceleration shock overloading and the high-speed rotation of the gunshot. This system is compact in structure, flexible in forming ground equipment and unique in high-strength design for projectile-borne equipment, the system meets the requirements of small-size, all-purpose and economization for range telemetry, therefore it is the necessary equipment for the range.
    • Subcarrier Placement in a PCM-FM-FM/FM Modulation Scheme

      Moser, Juliette Lyn; New Mexico State University (International Foundation for Telemetering, 1991-11)
      In a PCM-FM-FM/FM modulation scheme, one pulse code modulated (PCM) signal is added to a series of FM subcarrier modulated signals, and the sum is modulated on one FM carrier frequency. After the signal is carrier demodulated at the receiver and the signals modulating the subcarriers are individually filtered and demodulated, the information carried by the subcarrier frequencies may be distorted or lost due to interference power of the PCM signal that is passed by the subcarrier signals’ bandpass filters. The effect of the interference power may be reduced when the subcarrier frequencies are chosen to coincide with the zero crossing frequencies of the PCM signal. It will be shown that this choice results in a lower interference power than when the subcarrier frequencies come between the zero crossings. The PCM signal used in this study is of polar nonreturn to zero format.
    • USING DATAFLOW ARCHITECTURE TO SOLVE THE TRANSPORT LAG PROBLEM WHEN INTERFACING WITH AN ENGINEERING MODEL FLIGHT COMPUTER IN A TELEMETRY SIMULATION

      White, Joey; CAE-Link Corporation (International Foundation for Telemetering, 1991-11)
      One of the most challenging technical problems in the development of a spacecraft telemetry simulation is the interface with a flight computer running real-world flight software. The ability of the simulation to satisfy flight software requests for telemetry data, and to load, mode, and control the flight software along with the simulation, can be constrained or degraded using conventional interface solutions. Telemetry dataflow architecture systems can be utilized to solve the interface problems with less constraints. This is an especially attractive solution in a telemetry simulation where the telemetry system can also be used to format and serialize spacecraft telemetry, and receive and preprocess commands. This paper discusses the concepts developed for such a system for a training simulation of the Orbital Maneuvering Vehicle for NASA at Johnson Space Center.