Wurth, Timothy J.; Rodzinak, Jason; NuWaves Engineering (International Foundation for Telemetering, 2007-10)
      Meeting the filtering requirements for telemetry transmitters and receivers can be challenging. Telemetry systems use filters to eliminate unwanted spurious or mixing products. The use of tunable microwave filters for both L and S Band can improve filter selectivity and provide low insertion losses in the filter passband. Along with meeting specifications, these microwave filters with the ability to tune an octave, reduce size and cost by the reduction of multiple, fixed-frequency filters. As size, weight and power are often a concern with aeronautical telemetry systems, this paper will demonstrate that microstrip tunable filters can be small in size and use minimal power. Telemetry transmitters are subject to difficult spurious emission and interference specifications and require selective filters to eliminate spurious signals before the final amplification. Telemetry receivers on the other hand are subject to intense Image and Local Oscillator (LO) rejection requirements and demand low insertion loss for front-end filtering. Low insertion loss filtering before the Low Noise Amplifier (LNA) circuit limits degradation to the system noise figure (NF). By using different filter topologies and state-of-the-art, high-Q varactor diodes, tunable microwave filters can be optimized for two different functions. The two functions emphasize either low insertion loss or selectivity. An important design consideration with tunable filters, when compared to typical fixed frequency filters, is the degraded intermodulation performance. This is largely due to the non-linear behavior of the varactor diodes. This paper describes the benefits and limitations of microwave tunable filter architectures suitable for both aeronautical telemetry transmitters and telemetry receivers. Information on the computer modeling of varactor diodes will be covered as a critical part of the design. Potential design considerations for microwave tunable filters will also be covered. Through the use of simulation software and filter prototypes, this paper presents dramatically improved filter performance applicable to telemetry transmitters and receivers.

      L3 Communications – Telemetry East; Cridland, Doug; Dehmelt, Chris (International Foundation for Telemetering, 2007-10)
      While any vehicle that is typically part of a flight test campaign is heavily instrumented to validate its performance, long term vehicle health monitoring is performed by a significantly reduced number of sensors due to a number of issues including cost, weight and maintainability. The development and deployment of smart sensor buses has reached a time in which they can be integrated into a larger data acquisition system environment. The benefits of these types of buses include a significant reduction in the amount of wiring and overall system complexity by placing the appropriate signal conditioners close to their respective sensors and providing data back over a common bus, that also provides a single power source. The use of a smart-sensor data collection bus, such as IntelliBus™1 or IEEE-1451, along with the continued miniaturization of signal conditioning devices, leads to the interesting possibility of permanently embedding data collection capabilities within a vehicle after the initial flight test effort has completed, providing long-term health-monitoring and diagnostic functionality that is not available today. This paper will discuss the system considerations and the benefits of a smart sensor based system and how pieces can be transitioned from flight qualification to long-term vehicle health monitoring in production vehicles.

      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.

      Katulka, G.; Hall, R.; Peregino, P.; Muller, P.; Hundley, N.; McGee, R.; Army Research Laboratory; Dynamic Sciences Inc.; Data Matrix Solutions (International Foundation for Telemetering, 2007-10)
      The Defense Advanced Research Projects Agency (DARPA) and the US Army are engaged in a high-risk/high-payoff project for the development of precision-guided 60mm mortars for the benefit of the optically designated attack munition (ODAM). This paper describes the antenna design and performance characteristics required for a telemetry-based onboard diagnostic system. Efforts executed at the U.S. Army Research Laboratory, Aberdeen Proving Ground, MD met our primary objective to demonstrate rapid response low-cost capability for body-mounted antennas compatible with commercially-available telemetry products. This presentation reviews the theoretical design and antenna radiation pattern characteristics, tuning process, and returned in-flight signal strength along the trajectory. Experimental results compared favorably with theoretical link analyses. Lessons learned, ongoing applications, and future improvements are also presented.

      Lee, Jeffrey C.; Steppler, Missy; L-3 Communications (International Foundation for Telemetering, 2007-10)
      Modern telemetry systems using state of the art field programmable gate arrays (FPGAs) and signal processing components require lower voltage supplies to support various CMOS core geometries while still needing multiple higher voltage rails to support legacy interfaces. Addressing these power supply requirements efficiently requires switching power supply topologies that if left unchecked can generate high input surge currents and high levels of detrimental noise for both the sensitive analog signal processing circuitry and the power supply input source. This paper focuses on the design considerations and tradeoffs associated with implementing an efficient telemetry encoder power supply while mitigating the resulting noise effects typically associated with switching power supplies. This noise can negatively affect the power supply input source and the linear signal processing circuitry within the telemetry encoder.

      Moore, Michael S.; Grim, Evan T.; Kamat, Ganesh U.; Moodie, Myron L.; Southwest Research Institute (International Foundation for Telemetering, 2007-10)
      Network-based instrumentation systems are rapidly replacing traditional fixed serial interconnected instrumentation in both commercial and military flight test environments. Modern network-based flight test systems are composed of large numbers of devices including high-speed network switches, data acquisition devices, recorders, telemetry interfaces, and wireless network transceivers, all of which must be managed in a coordinated fashion. Management of the network system includes configuring, controlling, and monitoring the health and status of the various devices. Configuration by hand is not a realistic option, so algorithms for automatic management must be implemented to make these systems economical and practical. This paper describes the issues that must be addressed for managing network-based flight test systems and describes a network management approach that was developed and employed to manage a large-scale network-based flight test system.

      Brown, T. Gordon; Bukowski, Ed; Ilg, Mark; Brandon, Fred; U.S. Army Research Laboratory; Dynamic Science. Inc (International Foundation for Telemetering, 2007-10)
      In pursuit to understanding the flight behavior and characterizing the stability of a flarestabilized projectile, an experiment was conducted to assess the robustness of an inertial sensor suite the size of a dime (17.5mm) by integrating to a telemetry system for recording. The system had to survive launch acceleration exceeding 25,000G’s. This is the beginning of an effort to reduce the size of telemetry systems and diagnostic devices for use in medium caliber munitions and smaller. A description of the telemetry system and subsystem will be presented along with the results.

      Malatesta, William; Fink, Clay; Naval Air Systems Command; Johns Hopkins University (International Foundation for Telemetering, 2007-10)
      CTEIP has launched the integrated Network Enhanced Telemetry (iNET) project to foster advances in networking and telemetry technology to meet emerging needs of major test programs. In the past these programs have been constrained by vendor proprietary equipment configuration utilities that force a significant learning curve on the part of instrumentation personnel to understand hardware idiosyncrasies and require significant human interaction and manipulation of data to be exchanged between different components of the end-to-end test system. This paper describes an ongoing effort to develop a measurement-centric data model of airborne data acquisition systems. The motivation for developing such a model is to facilitate hardware and software interoperability and to alleviate the need for vendor-specific knowledge on the part of the instrumentation engineer. This goal is driven by requirements derived from scenarios collected by the iNET program. This approach also holds the promise of decreased human interaction with and manipulation of data to be exchanged between system components.

      Adamski, Greg; L-3 Communications (International Foundation for Telemetering, 2007-10)
      Telemetry missions spanning multiple years of tests often require access to archived configuration data for replay and analysis purposes. The needs for versioning vary from simple file-naming conventions to advanced global database versioning based on the scale and complexity of the mission. This paper focuses on a flexible approach to allow access to current and past versions of multiple test article configurations. Specifically, this paper discusses the characteristics of a versioning system for user-friendly and feature-rich solutions. It analyzes the tradeoffs of various versioning options to meet the needs of a given mission and provides a simple framework for users to identify their versioning requirements and implementation.

      Kupferschmidt, Benjamin; Pesciotta, Eric; Teletronics Technology Corporation (International Foundation for Telemetering, 2007-10)
      Many engineers express frustration with the multitude of vendor specific tools required to describe measurements and configure data acquisition systems. In general, tools are incompatible between vendors, forcing the engineer to enter the same or similar data multiple times. With the emergence of XML technologies, user centric data modeling for the flight test community is now possible. With this new class of technology, a vendor neutral, standard language to define measurements and configure systems may finally be realized. However, the allure of such a universal language can easily become too abstract, making it untenable for hardware configuration and resulting in a low vendor adoption rate. Conversely, a language that caters too much to vendor specific configuration will defeat its purpose. Achieving this careful balance is not trivial, but is possible. Doing so will produce a useful standard without putting it out of the reach of equipment vendors. This paper discusses the concept, merits, and possible solutions for a standard measurement metadata model. Practical solutions using XML and related technologies are discussed.

      Juneau, Jill; NASA/Columbia Scientific Balloon Facility (International Foundation for Telemetering, 2007-10)

      Altan, Hal; Honeywell International (International Foundation for Telemetering, 2007-10)
      As the frequency spectrum becomes more crowded each day, preparation for placement of tracking ground station in tracking environment gains more importance. Existence of high power weather ground radars, airport approach equipment, and various other RF sources in the environment necessitates the test teams to be more cautious. This paper discusses, implemented design changes to an S-band antenna system to reduce the in-band interfering power, calculation of the effects from nearby interferers, analysis of the environment during placement of the mobile ground system by Honeywell telemetry teams.
    • 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.

      Rajendran, Saravanakanthan; Keidar, Michael; Boyd, Iain D.; Jones, Charles H.; Mork, Brian; University of Michigan; Edwards Air Force Base (International Foundation for Telemetering, 2007-10)
      Real-time transmission of airborne images to a ground station is highly desirable in many telemetering applications. Such transmission is often through an error prone, time varying wireless channel, possibly under jamming conditions. Hence, a fast, efficient, scalable, and error resilient image compression scheme is vital to realize the full potential of airborne reconnaisance. JPEG2000, the current international standard for image compression, offers most of these features. However, the computational complexity of JPEG2000 limits its use in some applications. Thus, we present a scalable low complexity coder (SLCC) that possesses many desirable features of JPEG2000, yet having high throughput. Continuous radio-wave telemetry is required during planned tests of directed-energy weapons systems in order to characterize in situ the effects of laser irradiation on different target materials. Unfortunately, the incident radiation can cause disruption of the radio signal during the directed-energy testing. Several phenomena associated with directed-energy impact can lead to communication path losses, such as ablation, charged particle emission, charring, and chemical changes in the target materials. Directed-energy impact on the target material leads to target heating and consequent ablation. In this paper, a numerical model has been developed to describe the laser induced ablation of metal surfaces. The model describes the absorption of the laser energy by the metal and the resulting temperature rise in the surface. This temperature rise then induces ablation of the target material. Results for an aluminum target irradiated with a KrF laser were obtained. Temperature profiles in the target material and surface temperature changes are presented along with the ablation rate as a function of time as the aluminum target is irradiated. This report presents results for cases when laser energy absorption by the plasma plume created above the surface is not significant.

      Ramírez, Eduardo Díaz; Universidad de Chile (International Foundation for Telemetering, 2007-10)
      A digital antenna control system has been designed and installed on a pedestal that was formerly used to drive a VHF array and that has now been replaced with an 11 meter S-Band parabolic reflector. In this Paper, the former analog tracking system will be described, showing all the drawbacks that made it unusable for S-Band. Subsequently, the development and implementation of the digital S-Band tracking system, using Labview, C++ & digital control theory will be discussed. Finally, there will be a comparison between the digital and analog system, too.
    • Multiple Bit Differential Detection of SOQPSK with Diversity Reception

      Perrins, Erik; Ramakrishnan, Madhusudhan; University of Kansas (International Foundation for Telemetering, 2007-10)
      In this paper, we consider multiple bit differential detection (MBDD) of differentially encoded shapedoffset quadrature phase-shift keying (SOQPSK) over slow fading channels, especially Rayleigh fading channels. SOQPSK is a highly bandwidth efficient and popular form of constant envelope continuous phase modulation (CPM). We present two versions of the MBDD algorithm: the full-size version (FMBDD) which uses a detection window that spans the entire N-bit observation window, and an improved version (I-MBDD) which maintains the original N-bit observation window but detects only N − 2 bits within the window. The complexity of both algorithms is shown to increase linearly with the order of diversity reception, L, and exponentially with the size of the observation window, N; the I-MBDD achieves the best performance for given values of L and N. As expected, the performance in the case of diversity reception shows a marked improvement over the single channel case.

      Leite, Nelson Paiva Oliveira; Walter, Fernando; CTA - Grupo Especial de Ensaios em Vôo; ITA - Divisão de Eletrônica (International Foundation for Telemetering, 2007-10)
      For the final evaluation of a GPS attitude determination algorithm, it was determined its true performance in terms of its accuracy, reliability and dynamic response. To accomplish that, a flight test campaign was carried out to validate the attitude determination algorithm. In this phase, the measured aircraft attitude was compared to a reference attitude, to allow the determination of the errors. The system was built using non-dedicated THALES Z-FX airborne GPS receivers and a complete Flight Tests Instrumentation (FTI) System. Each GPS receiver operates synchronized with its internal time base. The FTI measurements are synchronized to an IRIG-B time base. All time bases have their own random walk characteristic. To avoid C/A code ambiguity, when its internal time base approaches ±1ms error from the GPS time, its clock is then corrected causing time and phase observables discontinuities. A multiple time base synchronization process was developed to correlate GPS and FTI data. The results are presented and the residual errors were considered acceptable. These data allowed the determination of the performance and accuracy of the GPS attitude determination algorithm. The tests profiles are fully compliant with the Federal Aviation Administration (FAA) Advisory Circular (AC) 25-7A.

      Guadiana, Juan; Benitez, Jesus; Tiqui, Dwight; White Sands Missile Range (International Foundation for Telemetering, 2007-10)
      Migrating analog architectures and equipments to network architectures is underway all across the globe. There is no doubt, a modern instrument must fit the network environment or simply will not be procured. Yet, funding constraints temper wholesale changes to net-centric technologies. The last analog stronghold in our data center is the oscillograph. Over 50 Gould TA 6000 Oscillographs reside at White Sands Missile Range. These are digital implementations of analog recorders, hence require analog signaling. Digital telemetry data (most common format) must be converted to analog to drive an oscillograph that converts analog back to digital to plot the data. The oscillograph’s interface board may be “hacked” by removing the Analog to Digital Converter (ADC) gaining direct access to the digital signal path. This idea was worth attempting as the prospect of replacing that many recorders with the newer network driven oscillographs is costly hence remote. This paper’s topic is the conversion of the hardware and a discussion on software issues. Though not pretty, it does preserve the large recorder investment for the time being. Issues with analog signaling, such as noise, drift and ground loops are gone. A commercial ethernet to digital adapter drives the new digital interface and transforms the recorder into an net-centric instrument.

      Price, Jeremy C.; Moore, Michael S.; Southwest Research Institute (International Foundation for Telemetering, 2007-10)
      When network-centric flight test system components are developed concurrently, it is necessary to produce relevant simulated network traffic for exercising the network devices and other processing subsystems prior to system integration. Having an accurate and repeatable pattern of simulated network traffic is extremely important for debugging and subsystem integration. The simulated network traffic must be both representative of the real system and repeatable to aid test efforts. Our solution to this problem was to develop a model-driven network traffic generator – NETGEN. Using NETGEN to resolve errors, stress test, and verify requirements, we have achieved otherwise unattainable correctness, reliability, and success in our systems.
    • Network Design Considerations in Telemetry Systems

      Grebe, Andy; Klein, Wayne; Apogee Labs, Inc. (International Foundation for Telemetering, 2007-10)
      In today’s world, computer networking has become common place both in industry as well as home, however all networks are not the same! The Telemetry world, like with many industries, has critical design considerations that need to be evaluated when you begin a new system or just adding on to a current infrastructure. This paper is intended to outline needed considerations when planning or implementing a network design in Telemetry Systems. These applications can range from sensor data transport through High Definition/High Speed Video applications.