Bester, Manfred; Stroozas, Brett; Bester Tracking Systems, Inc.; Stroozas Flight Ops (International Foundation for Telemetering, 2007-10)
      In a modern ground control network for space communications, secure peer-to-peer TCP/IP network socket connections are typically used to transfer real-time telemetry and command frames between satellite operations centers and remote ground stations. Reliable and timely reconfiguration of data paths for upcoming pass supports becomes rather complex when many spacecraft and ground stations are involved. This paper describes a routing software application that was developed to facilitate switching of telemetry and command data paths between multiple ground stations and spacecraft command and control systems, and to forward telemetry streams to multiple client applications in parallel. Fully automated configuration and monitoring of the data flows is accomplished via a remote control interface that is tied into a pass scheduling system. The software is part of the SatTrack Suite and currently supports multi-mission flight operations, including those of the recently launched THEMIS constellation mission at Space Sciences Laboratory, University of California at Berkeley.

      Kilpatrick, Stephen; Rasche, Galen; Cunningham, Chris; Moodie, Myron; Abbott, Ben; Southwest Research Institute (International Foundation for Telemetering, 2007-10)
      Ubiquitous internet protocol (IP) hardware has reached performance and capability levels that allow its use in data collection and real-time processing applications. Recent development experience with IP-based airborne data acquisition systems has shown that the open, pre-existing IP tools, standards, and capabilities support this form of distribution and sharing of data quite nicely, especially when combined with IP multicast. Unfortunately, the packet based nature of our approach also posed some problems that required special handling to achieve performance requirements. We have developed methods and algorithms for the filtering, selecting, and retiming problems associated with packet-based systems and present our approach in this paper.
    • International Telemetering Conference Proceedings, Volume 43 (2007)

      International Foundation for Telemetering, 2007-10

      Dean, Richard; Babalola, Olusola; Morgan State University (International Foundation for Telemetering, 2007-10)
      As part of Morgan’s iNET development, the Mixed Cellular and Mobile Ad hoc Network (MCMN) architecture has been 1proposed to provide coverage to over-the horizon test articles. Nodes in MCMN are assigned to one of three possible modes- Ad hoc, Cellular or Gateway. We present architecture for the proposed MCMN and some performance analysis to characterize the network. The problem of organizing nodes in this mixed network with optimal configuration is significant. This configuration gives nodes ability to know the best mode to operate and communicate with other nodes. Node organization is critical to the performance of the mixed network and to improve communication. The configuration of nodes required to optimally organize nodes in MCMN is demonstrated. The problem of evaluating configuration parameters for nodes in a mixed network is a nonlinear and complex one. This is due to the various components like the number of nodes, geographical location, signal strength, mobility, connectivity and others that are involved. Clustering techniques and algorithms have been used in literature to partition networks into clusters to support routing and network management. A clustering technique is employed to dynamically partition the aggregate network into Cluster Cells (CCs). A gateway node is selected for each CC which relays traffic from the cellular to the Ad hoc and vice versa. A trade-off analysis of the cellular boundary is presented using the maximum of the minimum data rate in the network. Numerical analysis and experiments are provided to show that the coverage can be extended to test articles in over-the-horizon region. It is also shown that, when the network is well organized, performance is improved.

      Xuming, Fan; Xiaoxian, Bai; Baoqiang, Zhao; Junmin, Zhang; Chinese Flight Test Establishment (International Foundation for Telemetering, 2007-10)
      An rfNET solution based on IEEE 802.11 wireless network is presented to perform one-way remote transmission of airborne instrumentation data and multi-channel video images in flight test by modifying the wireless network bridge and UDP protocol. Its architecture and structure is introduced briefly and the results of ground transmission test and flight demonstration transmission are provided. It also points out the major problems of this solution for engineering application and their solutions.

      Temple, Kip; Jefferis, Robert; Selbrede, Robert; Edwards Air Force Base (International Foundation for Telemetering, 2007-10)
      This paper baselines the performance of common, single band telemetry blade antennas in two telemetry bands and compares that performance to two very differing multi-band antenna designs. A description of each antenna is presented followed by flight testing results and conclusions. Results are in the form of received signal strength versus geographic location, derived in-flight antenna patterns, link availability, and bit error analysis.
    • A Common Solution to Custom Network Applications

      Yin, Jennifer; Dehmelt, Chris; L-3 Communications – Telemetry East (International Foundation for Telemetering, 2007-10)
      The deployment of networks has become ubiquitous in the avionics world, as they have opened the door to a rich suite of common and open hardware and software tools that provide greater functionality and interoperability. Unfortunately, a number of networked avionic and other related applications can be affected by vendor or application specific proprietary implementations. These “closed” implementations may reduce or eliminate the benefits of a standardized network, requiring the customization of the data acquisition system to allow it to properly operate with the other devices. This paper presents the approach that was recently employed for the development of a network interface module that can be quickly reconfigured to address the changing requirements of network applications, including monitoring of industry standard and proprietary networks, or providing the command and data interface to the data acquisition system itself. This reconfigurability of the module is shown in a review of four different specific applications.
    • 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.

      Kosbar, Kurt; Pratt, Jason; University of Missouri (International Foundation for Telemetering, 2007-10)
      Cognitive radio is a reasonably new branch of research aimed at more fully utilizing the RF spectrum. This is accomplished by allowing wireless communication systems to dynamically choose a frequency band, and a modulation technique, based on the current state of the RF spectrum as perceived by the cognitive radio network. This paper will give a brief introduction of cognitive radio networks, and describe a hardware platform designed at the IFT/UMR Telemetry Learning Center. The test-bed will accommodate future research into cognitive networks, by allowing the user to dynamically change both its carrier frequency and modulation technique through software. A general description of the design of the platform is provided.
    • 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.

      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.

      Weir, Malcolm; Ampex Data Systems, Inc. (International Foundation for Telemetering, 2007-10)
      This paper discusses how IRIG 106 Chapter 10 recording techniques could be employed in a network-centric environment, while maintaining as many of the strengths of the traditional approach. In the course of that discussion, aspects of the published standard which would have to be disregarded or reinterpreted for a network-centric approach to be adopted are illustrated.

      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.

      Peregino, Philip J., II; Bukowski, Edward F.; U.S. Army Research Laboratory (International Foundation for Telemetering, 2007-10)
      The Endevco model 7270A high-g accelerometer has been used successfully in numerous flight tests at the U.S. Army Research Laboratory. The accelerometer is available in ranges as low as 6,000 g’s up to 200,000 g’s so they can be used in a variety of situations to measure setback, set forward and balloting in artillery rounds, mortars and tank projectiles to name a few. However, one of the disadvantages of the model 7270A is its physical size, in the era of die level and surface mount components, the 7270A is relatively large. The sensing element is packaged inside a metal case with screw holes for mounting to a rigid surface. In addition, there are wires protruding from the case for electrical connections. In the area of munitions, small cavities don’t always afford the room for a large gauge. It was desirable to repackage the die in a smaller container and make it a surface mount component for a printed circuit board. A contract was developed for Endevco to repackage the die and to develop a tri-axial version with the repackaged die. The newly developed accelerometers were tested and evaluated by the U.S. Army Research Laboratory.

      Spjut, Erik; Acon, Chris; George, Nisha; Kimbrell, Scott; Pivonka, Dan; Rowland, Clarence; Schulze, W. Buck; Harvey Mudd College (International Foundation for Telemetering, 2007-10)
      The Edwards Air Force Base Undergraduate Clinic Team at Harvey Mudd College designed, built and tested a laser-based telemetry system for use on test aircraft at the EAFB Flight Test Center. The system was designed to communicate from an aircraft to a stationary, terrestrial receiver at a distance of up to 60 miles while traveling at speeds up to 230 mph. The transmitter system is restricted to the size of a standard 4’ tall 19" wide equipment rack. The transmitter is designed to maintain a constant laser footprint diameter of 100 meters at the receiver and use both coarse acquisition and closed-loop fine tracking systems. The minimum data rate is 10 Mbps. Sub-system testing and integration was not completed. Completed sub-systems included GPS/INS-based tracking (for coarse-tracking), position-sensitive-detector (PSD) optics (a finetracking system component), a transmitter gimbal assembly, software used to integrate and control hardware at the transmitter and receiver, and a complete receiver system. A PSD-based tracking system and an automatic collimation system were designed and constructed, but only partially tested.

      Pho, Tam P.; Wysong, Henry D.; Aerocross Systems, Inc. (International Foundation for Telemetering, 2007-10)
      Aerocross Systems, Inc. is developing a low-cost unmanned airborne telemetry relay system to augment the USAF Air Armament Center’s Eglin Gulf Range instrumentation resources. The system is designed to remotely autotrack and relay S-Band telemetry and VHF/UHF voice communications from test articles beyond the line-of-sight of land-based instrumentation. The system consists of a medium altitude/endurance Unmanned Aerial Vehicle (UAV), a Mission Control Station, and a remotely operated telemetry/voice tracking and relay instrumentation suite. Successfully developed and deployed, the system will contribute to lower range costs while enhancing range instrumentation performance.

      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.

      Perrins, Erik; Chandran, Prashanth; University of Kansas (International Foundation for Telemetering, 2007-10)
      Shaped offset quadrature phase shift keying (SOQPSK) is a highly bandwidth efficient modulation technique used widely in military and aeronautical telemetry standards. It can be classified as a form of continuous phase modulation (CPM), but its major distinction from other CPM schemes is that it has a constrained (correlated) ternary data alphabet. CPM-based detection models for SOQPSK have been developed only recently. One roadblock standing in the way of these detectors being adopted is that existing symbol timing recovery techniques for CPM are not always applicable since the data symbols are correlated. We investigate the performance of one CPM-based timing error detector (TED) that can be used with SOQPSK, and apply it to the versions of SOQPSK used in military (MIL-STD SOQPSK) and telemetry group (SOQPSK-TG) standards. We derive the theoretical performance limits on the accuracy of timing recovery for SOQPSK, as given by the modified Cramer-Rao bound (MCRB), and show that the proposed TED performs close to these bounds in computer simulations and is free of false-lock points. We also show that the proposed scheme outperforms a non-data aided TED that was recently developed for SOQPSK. These results show that the proposed scheme has great promise in a wide range of applications due to its low complexity, strong performance, and lack of false-lock points.

      Gery, Brian; Apogee Labs, Inc. (International Foundation for Telemetering, 2007-10)
      Modern telemetry systems often require signal switching hardware to facilitate signal routing reconfiguration between missions. As these systems have grown more complex with high signal counts and diverse signal types in the same system, the need for flexible switching hardware that can adapt to these changing requirements has emerged. A novel architecture for diverse signal switching hardware is presented that addresses the changing requirements of modern telemetry systems. While conventional commercial switching gear handles each signal type in a separate group, the proposed architecture allows digital and analog signal types to be switched, multiplexed, scaled, and combined (as the signal types allow) all within the same chassis, and between signal types.

      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.