Berdugo, Albert; Pesciotta, Eric; Teletronics Technology Corporation (International Foundation for Telemetering, 2007-10)
      Modern aircraft now employ widely accepted and standardized technology commonly found in COTS applications. One such technology, Fibre Channel, has been deployed to transport both low and high-speed measurement data. Data as varied as “command and control”, “Radar Sensors” and “video” are being transmitted over fibre channel on many aircrafts. Some of these applications require data monitoring in listening mode only where transmission from the instrumentation equipment is not allowed or possible. As a result, standard off the shelf Fibre Channel devices cannot be used, and a development of a general purpose Fibre Channel monitor/ analyzer device and product is required. This paper discusses the concept, merits, and implementation of fibre channel bus monitoring in modern data acquisition systems. Techniques for tapping into an optical fibre channel network, as well as, a recording format for IRIG106 Chapter 10 are included. An overview of fibre channel topologies and protocols is also provided.
    • The Sum-Rate Capacity of a Cognitive Multiple Access Sensor Network

      Panagos, Adam; Kosbar, Kurt; Dynetic, Inc.; University of Missouri (International Foundation for Telemetering, 2007-10)
      This paper investigates the sum-rate capacity of a cognitive multiple access (MAC) sensor network. The multiple access network consists of K sensors communicating to a common base station. Outside of the network exists another user of the radio spectrum. Each sensor of the MAC network is aware (i.e. cognitive) of this user, denoted the primary user, and transmits in a manner to avoid any interference to this user. No interference transmission is achieved using the dirty-paper coding technique. The sum-rate capacity is the theoretical maximum of the sum of the simultaneously achievable rates of each sensor within the network. Using a recently derived iterative algorithm, we quantify the sum-rate capacity of this network and investigate its behavior as a function of the number of sensors, cognitive signal-to-noise ratio (CSNR) and primary SNR (PSNR) in a Rayleigh fading environment. We also derive bounds and scaling results for the ergodic sum-rate capacity.
    • Iterative Decoding and Sparse Channel Estimation for an Underwater Acoustic Telemetry Modem

      Iltis, Ronald A.; University of California (International Foundation for Telemetering, 2007-10)
      An acoustic modem employing direct-sequence spread-spectrum (DSSS) signaling is considered with LDPC coding. The underwater acoustic channel is tracked using a Kalman filter which requires accurate data decisions. To improve KF performance and reduce the overall error rate, joint iterative LDPC decoding and channel estimation is proposed based on a factor graph and sum-product algorithm approximation. In this scheme, the decoder posterior log likelihood ratios (LLRs) provide data decisions for the KF. Decoder extrinsic LLRs are similarly incorporated into the detector LLRs to yield improved priors for decoding. Error rate simulations of the overall modem are provided for a shallow-water channel model with Ricean/Rayleigh fading.

      Perrins, Erik; Damodaran, Kanagaraj; University of Kansas (International Foundation for Telemetering, 2007-10)
      We propose serially concatenated convolutional codes with continuous phase modulation for aeronautical telemetry. Such a concatenated code has an outer encoder whose code words are permuted by an interleaver, and a modulation, which is viewed as a code and takes the interleaved words as its input and produces the modulated signal. Since bandwidth expansion is a concern when coding is introduced, we focus on high rate punctured codes of rates 2/3 through 9/10. These are obtained by puncturing the basic rate 1/2 convolutional codes with maximal free distance. At the receiver end we use a reduced complexity iterative decoding algorithm which is essentially a soft input soft output decoding algorithm. These simple highly powerful concatenated codes produce high coding gains with minimum bandwidth expansion.

      Gilorma, Mike; Apogee Labs, Inc. (International Foundation for Telemetering, 2007-10)
      Asynchronous JavaScript and XML (AJAX) has improved web applications in a way that has enhanced performance and made the user experience more like that of a desktop application. As the performance of PCs increases and broadband Internet access is more prevalent, switching between web pages is less painful than ever. One of the biggest advantages of AJAX is the ability for a web application to update only a small piece of data without refreshing the whole page. AJAX also allows for piecewise validation of user entry as opposed to the standard form entry with which we have become so accustomed. This paper describes how AJAX enabled applications are different from classic web applications and shows the advantages and disadvantages from both client and server sides of an AJAX enabled application. AJAX is not a new technology, but rather a new approach to web applications that uses standards already in place for XHTML, CSS, DOM, XML, and JavaScript. It is this new approach that eliminates the full page refresh that was so commonplace and now gives web applications the ability to look and feel more like desktop applications.
    • SIMPLIFIED 2-state Detectors for SOQPSK-TG and SOQPSK-MIL

      Perrins, Erik; Kumaraswamy, Balachandra; University of Kansas (International Foundation for Telemetering, 2007-10)
      We study simple trellis-based detectors for SOQPSK that have a minimal level of complexity. In particular, we show that the state complexity can be cut in half relative to previous approaches—from 4 states down to 2—with asymptotically optimum performance. We give two possible means of achieving this: the pulse amplitude modulation (PAM) technique and the pulse truncation (PT) technique; both of these techniques make use of recent advances in SOQPSK technology based on a continuous phase modulation (CPM) interpretation of SOQPSK. The proposed simplifications are significant since trellis-based SOQPSK detectors are 1–2 dB superior to widely-deployed symbol-by-symbol detectors. These performance gains come at the expense of complexity, and the proposed 2-state detectors minimize this expense. Thus, these simple detection schemes are applicable in settings where high-performance and low complexity are needed to meet restrictions on power consumption and cost.

      Pellarin, Steve; Musteric, Steven; Teletronics Technology Corporation; Eglin Air Force Base (International Foundation for Telemetering, 2007-10)
      Adding an instrumentation / telemetry system to a test article has historically required an intrusive installation. Power, wiring, and available space typically present significant challenges. There has been a long-standing need in the test and training community for a non-intrusive, flexible and modular instrumentation and telemetry system that can be installed on an aircraft or other test article without the need for permanent modifications. In addition, as available space in aircraft weapon bays, small weapons, and unmanned vehicles becomes a premium, the miniaturization of remote sensors and telemetry units becomes critical. This paper describes the current status of the Advanced Subminiature Telemetry System (ASMT) Initial Test Capability Project. It discusses the challenges that have been overcome in developing a wireless sensor network system for use in an airborne test environment. These include wireless sensor packaging design, selection of operating frequencies, COTS wireless devices, batteries, system synchronization and data bandwidth calculations. The paper will also document the progress to date including preliminary test results.

      Shaw, Christopher; Rice, Michael; Brigham Young University (International Foundation for Telemetering, 2007-10)
      This paper considers the use of Amplitude-Phase Shift Keying (APSK) for a telemetry system. Variable rate turbo codes are used to improve the power efficiency of 16- and 32-APSK. We discuss compensation techniques for power amplifier nonlinearities. Simulation results show the improved spectral efficiency of this modulation scheme over those currently defined in telemetry standards.

      Formeister, Richard; Teletronics Technology Corporation (International Foundation for Telemetering, 2007-10)
      Multipath propagation continues to be the dominant channel impairment in many aeronautical mobile telemetry (AMT) applications. Avoidance and diversity techniques continue to be the only practical means to combat this problem. In 2004 limited results from the development of a new post-detection, no-hit diversity selector were reported. Late breaking results from flight test were reported orally. A review of the methodology, flight test results and conclusions are presented in this paper. Also presented is an update describing enhancements of the implementation which emphasize operational flexibility as well as support for alternate demodulator products.

      Roach, John; Teletronics Technology Corporation (International Foundation for Telemetering, 2007-10)
      The development of network-based data acquisition systems has resulted in a new architecture for supporting flight instrumentation that has the potential to revolutionize the way we test our aircraft. Unlike conventional flight test instrumentation, networks provide for a two-way communication path between all elements of the system, utilize packetized data, support communication protocols, have dynamic quality of service levels, can be subject to loss of data, utilize asynchronous transmission behavior and provide an even higher level of time synchronization. Different flight test architectures can be realized which combine each of the previous attributes in different ways; finding the best architecture for a set of given applications while minimizing cost and complexity is a very difficult problem. For the last 3 years, the Network Products Division at Teletronics has been involved in the design and evaluation of aircraft instrumentation networks for both customers and the iNET program. This paper describes the result of these efforts by discussing the high-level design of a modular architecture for an aircraft instrumentation network.

      Hayes, Bob; L-3 Communications Cincinnati Electronics (International Foundation for Telemetering, 2007-10)
      Next generation satellite communication systems require efficient coding schemes that enable high data rates, require low overhead, and have excellent bit error rate performance. A newly rediscovered class of block codes called Low Density Parity Check (LDPC) codes has the potential to revolutionize forward error correction (FEC) because of the very high coding rates. This paper presents a brief overview of LDPC coding and decoding. An LDPC algorithm developed by Goddard Space Flight Center is discussed, and an overview of an accompanying VHDL development by L-3 Communications Cincinnati Electronics is presented.

      Wegener, John A.; Zettwoch, Robert N.; Roche, Michael C.; The Boeing Company (International Foundation for Telemetering, 2007-10)
      This paper describes the integration activities associated with the instrumentation and telemetry system developed for an F/A-18 Hornet Flight Test program, including bench integration, avionics integration, and aircraft ground and flight checkout. The system is controlled by a Boeing Integrated Defense System (IDS) Flight Test Instrumentation designed Instrumentation Control Unit (ICU), which interfaces to an avionics pilot display and Ground Support Unit (GSU) to set up the instrumentation during preflight and control the instrumentation during flight. The system takes in MIL-STD-1553, analog parameters, Ethernet, Fibre Channel, and video, and records these with onboard recorders. Selected subsets of this data may be routed to the telemetry system, which features two RF streams, each of which contains up to four PCM streams combined into a composite by a data combiner. The RF streams are transmitted by multi-mode digital transmitters capable of PCM-FM or Shaped Offset Quadrature Phase Shift Keying (SOQPSK), with selectable Turbo-Product Code (TPC) Forward Error Correction (FEC). This paper describes integration of the system with the IDS Flight Test Integration Test Bench (ITB), production avionics integration facilities, and final aircraft ground checkout and initial flight tests. It describes results of integration activities and bench evaluation of the telemetry system.

      Torgerson, Leigh; Hutcherson, Joseph; McKelvey, James; California Institute of Technology (International Foundation for Telemetering, 2007-10)
      In support of iNET maturation, NASA-JPL has collaborated with NASA-Dryden to develop, test and demonstrate an over-the-horizon vehicle-to-ground networking capability, using Iridium as the vehicle-to-ground communications link for relaying critical vehicle telemetry. To ensure reliability concerns are met, the Space Communications Protocol Standards (SCPS) transport protocol was investigated for its performance characteristics in this environment. In particular, the SCPS-TP software performance was compared to that of the standard Transmission Control Protocol (TCP) over the Internet Protocol (IP). This paper will report on the results of this work.

      Vu, Doug; Berdugo, Albert; Lockheed Martin Aeronautics Co.; Teletronics Technology Corporation (International Foundation for Telemetering, 2007-10)
      The Joint Strike Fighter program is the largest DOD contract ever awarded. There are three F-35 Lightning II variations, each intended to meet the specific needs of the Air Force, Navy, Marine Corps, and U.S. Allies. The Data System required for this flight test program challenged the conventional ways used in instrumenting test aircraft. Typical data systems available today don’t provide the level of hardware and software integration required for today’s complex applications. For example, cockpit control panels, recording systems, TM transmitters, data acquisition systems and avionic bus interface units are all independent systems. Additionally, avionic bus catalogs, ground-based systems, and flight setup software have historically been independent components. This paper will describe the hardware and software components used by the F-35 flight test program to provide an integrated system. A special emphasis will be given to the methods used to accommodate rapid changes to the IEEE-1394B avionic bus catalog including the acquisition of that data, and the use of an IRIG-106 Chapter 10 distributed multiplexer / recorder system, which is being used simultaneously as a data acquisition system.

      Lee, Jeffrey C.; L-3 Communications – Telemetry-West (International Foundation for Telemetering, 2007-10)
      Modern telemetry systems require flexible bit rate telemetry encoders in order to optimize mission formats for varying data rate requirements and/or signal to noise conditions given a fixed transmitter power. Implementing a variable bit rate telemetry encoder requires consideration of several possible architectural topologies that place different system requirements on data acquisition modules within the encoder in order to maintain adequate signal fidelity of sensor information. This paper focuses on the requirements, design considerations and tradeoffs associated with differing architectural topologies for implementing a variable bit rate encoder and the resulting implications on the encoder systems data acquisition units.
    • Modeling Channel Estimation Error in Continuously Varying MIMO Channels

      Kosbar, Kurt; Potter, Chris; University of Missouri (International Foundation for Telemetering, 2007-10)
      The accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings.

      Lux, Jessica; Downing, Bob; Sheldon, Jack; NASA Dryden Flight Research Center; Arcata Associates, Inc. (International Foundation for Telemetering, 2007-10)
      The Western Aeronautical Test Range (WATR) at the NASA Dryden Flight Research Center (DFRC) employs the WATR Integrated Next Generation System (WINGS) for the processing and display of aeronautical flight data. This report discusses the post-mission segment of the WINGS architecture. A team designed and implemented a system for the near- and long-term storage and distribution of mission data for flight projects at DFRC, providing the user with intelligent access to data. Discussed are the legacy system, an industry survey, system operational concept, high-level system features, and initial design efforts.

      Grossman, Hy; Teletronics Technology Corporation (International Foundation for Telemetering, 2007-10)
      Historically, aircraft power monitoring has required the use of multiple signal conditioning functions to measure various parameters including voltage, current, frequency and phase. This information was then post processed to determine the characteristics of the 3-phase power quality on the aircraft. Recent developments in embedded DSP processors within signalconditioning systems provide the instrumentation engineer with expanded capabilities for realtime on-board power quality monitoring. Advantages include reduced space and bandwidth requirements and minimal wiring intrusion. For each phase, output data may include peak positive and negative voltages and currents, peak-to-peak, average and RMS voltages and currents, phase power (real and apparent), phase power factor, phase period (frequency), phase shift measurement from phase 1 (the reference phase) to phase 2, and from phase 1 to phase 3. In addition, a Fast Fourier Transform (FFT) is performed on each phase voltage to provide Total Harmonic Distortion measurements. This paper describes the methods employed in the implementation of these functions on a single signal-conditioning card in order to provide detailed information about the power quality of a three-phase aircraft power source.

      Rice, Michael; Palmer, Joseph; Brigham Young University (International Foundation for Telemetering, 2007-10)
      A single-tone frequency estimator for a non-uniformly sampled sinusoid is proposed. A nonuniformly sampled sinusoid may be generated from the received training sequences of a telemetry link. The frequency of the sinusoid matches the carrier-frequency-offset (CFO) of the received signal, and estimation of this quantity allows a receiver to compensate for the CFO. The performance bounds of this type of estimator have been investigated in the literature, though little work has been published on practical algorithms. The estimator proposed in this paper is a generalization of phase-increment estimators previously described in the literature. It exhibits a low computational complexity yet converges to theoretical bounds at high SNR. The paper argues that a periodic training sequence structure, combined with the new estimator, allows for a high-accuracy and lowcomplexity CFO compensator.
    • An Optimum Detector for Space-Time Trellis Coded Differential MSK

      Rice, Michael; Dang, Xiaoyu; Brigham Young University (International Foundation for Telemetering, 2007-10)
      The accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings. Space-time (ST) coding using Continuous Phase Modulation (CPM) has spectral advantages relative to linear modulations. In spite of the spectral benefits, Space-Time Trellis Codes (STTC) using the CPM implementation of Minimum Shift Keying (MSK) scheme has inherent inphase and quadrature interference, when the received complex baseband signal is the input into the matchfilter to remove the shaped sinusoid pulses. In this paper a novel optimum transmitting and detecting structure for STTC-MSK is proposed. Treating the Alamouti scheme as an outer code, each STTC MSK waveform frame is immediately followed by the orthogonal conjugate waveform frame at the transmit side. At the receiver first orthogonal wave forming is applied, then a new time-variant yet simple trellis structure of the STTC-MSK signals is developed. This STTC-MSK detector is absolutely guaranteed to be I/Q interference-free and still keeps a smaller computation load compared with STTC-QPSK. Simulations are made over quasi-static AWGN fading channel. It is shown that our detector for ST-MSK has solved the I/Q interference problem and has around 2.8 dB gain compared with the Alamouti Scheme and 3.8 dB gain for bit error rate at 5 X 10^(-3) in a 2 by 1 Multiple Input Single Output system.