• International Telemetering Conference Proceedings, Volume 17 (1981)

      International Foundation for Telemetering, 1981-10
    • AN INSIDE VIEW OF PSEUDORANGE AND DELTA PSEUDORANGE MEASUREMENTS IN A DIGITAL NAVSTAR GPS RECEIVER

      Ward, Phil; Texas Instruments Incorporated (International Foundation for Telemetering, 1981-10)
      The goal of this paper is to develop insight into the real-time nature of GPS observables measured by a digital receiver. The concept of how independent pseudorange and deltapseudorange measurements are captured as a by-product of the code and carrier tracking loops of a digital NAVSTAR GPS receiver is explained. The classical equations defining true range and delta range are derived in terms of pseudorange and delta pseudorange. The actual GPS receiver measurements are then related to these equations. The difference between GPS measurement resolution and precision is treated and the sources of the GPS receiver contribution to the total GPS error are identified. The total GPS error, in terms of user equivalent range error (UERE) and user equivalent delta range error (UEDRE), is characterized. However, an unaided GPS navigation process can filter out only the unbiased random error in the observables, not the total UERE and UEDRE content. Also, the random error in GPS observables is not stationary. Hence, the random error in UERE and UEDRE is identified and characterized.
    • Telemetering Standards Coordination Commitee

      McAnally. Claude W. (International Foundation for Telemetering, 1981-10)
    • WORD ERROR PERFORMANCE OF VITERBI AND TAILBITING DECODERS

      King, M. A.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
    • VARIABLE DATA BIT RATES WITH A FIXED HOP RATE NONCOHERENT FH/MFSK SYSTEM

      Omura, Jim K.; School of Engineering and Applied Science Los Angeles (International Foundation for Telemetering, 1981-10)
    • THEORETICAL AND PRACTICAL ASPECTS OF OPTIMIZATION IN FINITE WORD-LENGTH DIGITAL SIGNAL PROCESSING

      Pollara-Bozzola, F.; Yao, K.; Univ. of California (International Foundation for Telemetering, 1981-10)
      We consider a general class of digital signal processing problems in which some sytem parameters restricted to some finite set of values are selected based on the minimum meansquare error criterion. This class of problems are relevant in the design of modern communication, radar, and antenna array systems under finite word-length con-constraints. Linear problems allowing infinite precision values are given by the classical Wiener solutions. However, under the finite word-length constraints, optimum solutions can be obtained in principle by using techniques from integer quadratic programming problems. Practical solutions obtained in this manner, such as from the branch-and-bound algorithm, usually use a large amount of active computer memory space and thus are not applicable to real-time on-board processing situations. In this paper, we shall consider various theoretical and practical aspects of exhaustive search algorithms over shrinking sequences of constrained regions known to contain the desired optimum solution. Properties and bounds on the number of points to be searched as well as specific system problems shall be presented.
    • SIGNALING PERFORMANCE OVER A PIECE-WISE LINEARLIMITED CHANNEL IN THE PRESENCE OF INTERFERENCE AND GAUSSIAN NOISE

      HUANG, T. C. (International Foundation for Telemetering, 1981-10)
      Presented here is a model and analysis for evaluating bit error probability of a BPSK signal transmitted through a piece-wise linear (PWL) limited channel subject to a CW interference as well as additive Gaussian noise. The CW interference is assumed to have a random phase Θj over (0, 2π) and a fixed frequency fj which may be either inband or outof- band of the signal channel band. The analysis is carried out in two steps: First an explicit expression for the desired signal, CW tone and their harmonics conditioned on the uplink channel noise if obtained at the output of a PWL limiter. Each of these CW tones and harmonics is modeled into two components--one sinusoid with a mean power and coherently related to Θj and an equivalent Gaussian noise, independent of each other. This equivalent Gaussian noise is also independent of the noise component associated with the desired signal. The interference model is reasonable provided that the frequency fj is not close to the carrier frequency of the signal. Based on the interference model, a conditional error probability expression, whose statistics are constructed through known moment techniques, is formed and averaged over the appropriate random variables. Numerical results for interference model and error rate curves will be compared with those of hardlimited channels in order to illustrate the effect of a PWL limiter.
    • INFORMATION RATES IN FIBEROPTIC LINKS WITH MULTI-LEVEL PULSE INTENSITY ENCODING (MPIM)

      Sorensen, A. N.; Gagliardi, R. M.; The Aerospace Corporation; University of Southern California (International Foundation for Telemetering, 1981-10)
    • APPLICATION OF ERROR-CORRECTING CODES IN DATA TRANSMISSION SYSTEMS WITH BIPHASE MODULATION

      Gao, Jiapens; Chengdu Institute of Radio Engineering (International Foundation for Telemetering, 1981-10)
      The polarity uncertainty in coherent demodulation of biphase signal raises a new question to the application of error-correcting codes. In this paper the real capability of errorcorrecting codes used with differential biphase modulation is analysed and, with the special cases of cyclic Hamming codes and two BCH codes, the degree of performance deterioration is estimated. Three methods for solving polarity inversion with preserving the error-correcting capability at the cost of one information bit lost are proposed. Practical implementation of these methods is briefly discussed.
    • ANTIJAM PERFORMANCE OF CODED FH/MFSK

      Huth, Gaylord K.; Tokunow, Lawrence S. (International Foundation for Telemetering, 1981-10)
      Frequency hopping (FH) is a powerful antijam spread spectrum modulation when combined with multiple-frequency-shift-keying (MFSK) and error correction coding. This paper determines the antijam message error rate performance of various formats of FH/MFSK with convolutional error correction coding techniques. The worst case jammer is determined for each signalling format and coding technique and the antijam performance for all configurations are compared.
    • VIDEO BASED INSTRUMENTATION SYSTEMS AND TECHNIQUES FOR MERGING DATA INTO VIDEO

      Keller, P.; Naval Weapon Center (International Foundation for Telemetering, 1981-10)
      A need is shown for the development of standardization in data into video encoders and decoders for instrumentation systems. Features such a standardized system should have are listed and discussed based on the authors experience with video instrumentation systems at the Naval Weapons Center and as a consultant.
    • EXPLOITING TELEMETRY DATA IN THE VERTICAL BLANKING INTERVAL

      Ryan, Thomas J.; Bechtel National, Inc. (International Foundation for Telemetering, 1981-10)
      This paper describes how ongoing developments in digital and video technology have been merged to exploit the telemetry data inserted into the vertical blanking interval of the composite-video signal. The insertion of 96 bits of digital data into two lines of the vertical blanking interval is reviewed. The automatic retrieval and reformatting of the digital data for use by a Main-Frame Computer is explored. A unique video editing and data merging facility coupled to the computer is described. To emphasize the versatility of this systems approach, specific industrial applications will be outlined. Finally, future considerations and applications involving control systems will be discussed.
    • DIGITAL DATA IN VIDEO PROCESSING SYSTEMS

      Morse, Bob A.; BELL TECHNICIAL OPERATIONS (International Foundation for Telemetering, 1981-10)
      Digital information in video systems is an expanding field. The use of digital video equipment is continuously being examined and updated at USAYPG. There are fully operational systems currently being used by BELL TECH. OPS at the proving ground. I shall cover some of the uses and capability of the systems as well as the individual pieces of equipment in the systems
    • DIDON: DIGITAL DATA IN VIDEO

      BERNHEIM, J.-P.; Communications Enaineer (International Foundation for Telemetering, 1981-10)
    • APPLICATION OF REGRESSION ANALYSIS TO VIDEO DIGITAL DATA FOR DETERMINING PROJECTILE IMPACT LOCATIONS

      Robertson, Greta; Hughes Helicopters, Inc. (International Foundation for Telemetering, 1981-10)
      The correlation of two grid systems can be estimated by application of regression analysis to data whose relationship is assumed to be explained by linear transformation model. The two grid systems are a surveyed target range and real-time video of the range during testing of 30mm chain gun/2. 75"FFAR conducted for research and development of the YAH-64 Advanced Attack Helicopter (AAH) target acquisition and weapons system. The regression model and computational method are discussed; analysis of the impact location determination errors, operator error and errors due to skewness, introduced by camera position and orientation, are presented.
    • THROUGHPUT DELAY FOR MIXED-LENGTH, MIXED-PERIOD PACKETS WITH BUSY-SENSE MULTIPLE-ACCESS PROTOCOL

      Krause, Lloyd O.; Rockwell International (International Foundation for Telemetering, 1981-10)
      Packet TM of asynchronous multi-instrumented spacecraft requires framing of packets having different lengths and different arrival intervals. A similar situation would occur in a general message networking application with messages of arbitrary length and arrival rate at a network node. Use of a bus-system for packet transfer, or an order wire for message transfer, requires a minimum rate of status inquiry, and of data read rate, to insure stability and non-overloading. Our paper offers a rather general, but compact, throughput delay analysis suited to packet characteristics from uniform to source-dependent period and length. Arrival probability may vary from “soft” or uniform to “hard” arrival induced by slotted delay. The arrival probability is modular in source packet-period. A closed solution form, though expressible, is not tractable, and a recursive solution was used to obtain numerical results. Computed throughput delays for various combinations of identical sources and mixed sources are illustrated. For identical sources, under “hard” periodic arrival probability, channel slotting is desirable to maintain channel capacity. Some comparative results are offered. For mixed sources with source-dependent packet length and rate, slotting may not be feasible or efficient. Only read-rate controls the expected throughput. The analysis and results shown should prove helpful both to further study and present application of packet TM and message networking.
    • A SEQUENCY DIVISION MULTIPLEX SYSTEM

      Qishan, Zhang; Mingrui, Zhang; Yaokun, Liu; Beijing Institute of Aeronautics & Astronautics (International Foundation for Telemetering, 1981-10)
      A sequency division multiplex (SDM) system using Walsh subcarriers was developed for the transmission of telemetry signals at our laboratory The basis of mathematics which can form a telemetry system is orthogonal function. It is the Walsh function that may form a new telemetry system. At the first stage a baseband transmission system has been designed and tested. It shows that the results of experiments are quite good, and the new system works well. At a second stage FM is used as carrier transmission. Now the whole system can work property. A proper choice of the subcarriers minimizes the crosstalk. Principles for the selection of Walsh subcarriers are deduced. It seems that the SDM system has great potentialies.
    • THE INFLUENCE OF ARM FILTER DELAY ON TRACKING PERFORMANCE OF A COSTAS LOOP

      Holmes, Jack K.; Holmes Assoc. Inc. (International Foundation for Telemetering, 1981-10)
      It is demonstrated that the effect of the arm filters with NRZ data in a second-order Costas loop is to introduce delay in the loop which causes the tracking-error jitter to increase. It is shown that the tracking-error jitter becomes unbounded at exactly the same value of delay as the loop becomes unstable. The results are derived for both the one pole passive and the Integrate and Dump arm filter cases. A representative calculation shows that this is normally not a significant problem in properly designed loops.
    • IMAGING TERMINAL GUIDANCE SEEKER

      Mohanty, N. C.; The Aerospace Corporation (International Foundation for Telemetering, 1981-10)
      A certain guidance seeker is designed to aim at the location of the most vulnerable point of a moving target. The seeker extracts an appropriate feature of the target and continuously tracks it using a tracking algorithm. The performance of the tracker was evaluated in terms of probability of acquisition and positional error. The algorithm was verified using a data base obtained from the flight of an A-7E aircraft. The cockpit of the aircraft was continuously identified by a rectangular gate as the seeker’s aimpoint.
    • EXPERIMENTAL COMPARISON OF PCM/FM, PCM/PM and PSK

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1981-10)
      This paper compares the experimental bit error rate (BER) performance of PCM/FM, PCM/PM, and PSK. The data are presented as BERs versus signal-to-noise ratio (SNR) in a bandwidth equal to the bit rate. The effects of premodulation filtering and receiver IF bandwidth are discussed. The necessary RF bandwidths for these modulation methods are also discussed. Two methods of generating PSK signals were used: ±90E linear phase modulation and mulitplication of the RF carrier by ±1 using a double balanced mixer. The first method will be referred to as PCM/PM (±90E) in this paper.