• IF DBPSK Modems Design for Command Link and Telemetry Systems

      Hsu, Cherng-Shung; Liang, Junn-Kuen; Lu, Fu-Chao; Chung Shan Institute of Science and Technology (International Foundation for Telemetering, 1986-10)
      In this paper, the 70 MHz IF differential binary phase shift keying (DBPSK) modem is designed and implemented. At the transmitter, the data are first differentially encoded, and then sent to the binary phase modulator, which is followed by a delicatedly designed band pass filter to suppress the undesired sideband spectrum. At the receiver, the DBPSK signal is coherently demodulated by a Costas loop which is carefully analyzed and designed in this paper. In order to maintain the overall loop gain within a desired range for keeping a better loop performance, an IF preconditioning AGC (Automatic Gain Control) circuit is added in the demodulator to keep the IF amplifier output level almost constant even at low signal to noise ratio. In order to improve the false lock due to the data sideband, especially for low rate modems, and to enhance acquisition, a modified Costas loop and an automatic sweep search acquisition circuit are included in the demodulator. Besides the carrier recovery, the bit rate clock must be recovered from the received DBPSK signal. Instead of serial processing, i.e., clock recovery comes after carrier recovery, a parallel processing of the received DBPSK signal is employed, i.e., clock recovery is parallel to carrier recovery. In other words, the carrier and clock recovery circuits independently process the same received DBPSK signal at the same time. The advantages obtained from the parallel processing are faster overall system acquisition and reduction of information loss. The recovered clock is derived from a bandlimited DBPSK signal by an envelope detector followed by a phase-locked loop (PLL). The key features of this suboptimum clock recovery circuits are simplicity and low cost for practical hardware implementation. An example for modem design will be given and the modem will be implemented and then tested. Parameters selection and hardware implementation of important building blocks in the modem circuit are all given careful consideration. Furthermore, the block of the IF AGC, modified Costas loop scheme and sweep search circuits will also be described with emphasis on their key functions. Finally, the bit error rate performance of the experimently implemented modem will be tested and presented.

      Eccles, Lee H.; Muckerheide, John J.; Boeing Commercial Airplane Company (International Foundation for Telemetering, 1986-10)
      The Experimental Flight Test organization of the Boeing Commercial Airplane Company has an onboard data reduction system known as the Airborne Data Analysis/Monitor System or ADAMS. ADAMS has evolved over the last 11 years from a system built around a single minicomputer to a system using two minicomputers to a distributed processing system based on microprocessors. The system is built around two buses. One bus is used for passing setup and control information between elements of the system. This is burst type data. The second bus is used for passing periodic data between the units. This data originates in the sensors installed by Flight Test or in the Black Boxes on the airplane. These buses interconnect a number of different processors. The Application Processor is the primary data analysis processor in the system. It runs the application programs and drives the display devices. A number of Application Processors may be installed. The File Processor handles the mass storage devices and such common peripheral devices as the printer. The Acquisition Interface Assembly is the entry point for data into ADAMS. It accepts serial PCM data from either the data acquisition system or the tape recorder. This data is then concatenated, converted to engineering units, and passed to the rest of the system for further processing and display. Over 70 programs have been written to support activities on the airplane. Programs exist to aid the instrumentation engineer in preparing the system for flight and to minimize the amount of paper which must be dealt with. Additional programs are used by the analysis engineer to evaluate the aircraft performance in real time. These programs cover the tests from takeoff through cruise testing and aircraft maneuvers to landing. They are used to analyze everything from brake performance to fuel consumption. Using these programs has reduced the amount of data reduction done on the ground and in many cases eliminated it completely.

      Ricci, Fred J.; RAMCOR, Inc. (International Foundation for Telemetering, 1986-10)
      With the advent of higher and higher data rates and signal processing requirements for onboard satellite processing, the need for a faster computational capability has grown well beyond the capabilities of existing space-qualified computers. This has become a major technical issue in the design of next-generation satellite systems for commercial and military use. As a matter of fact, it is becoming a major issue in the Strategic Defense Initiative (SDI), the development of the MILSTAR Satellite System, and in future infrared (IR) and radar satellites/platforms. Future platforms will require larger onboard processing systems than are currently in use in order to satisfy their data processing and commandand-control communications requirements. The platforms of tomorrow will be very sophisticated and therefore expensive. For such systems to have acceptable life-cycle costs, they must be produced from highly reliable hardware that will operate in space for system design lifetimes of up to 10 years. This paper will summarize the processing needs of onboard systems and present a specific example of the design of a VLSI/VHSIC processor for an onboard satellite controller in an airborne platform.
    • International Telemetering Conference Proceedings, Volume 22 (1986)

      Unknown author (International Foundation for Telemetering, 1986-10)

      Sullivan, Arthur; Electro Magnetic Processes, Inc. (International Foundation for Telemetering, 1986-10)
      Currently, the majority of telemetry tracking systems in use throughout the world operate in the S-Band frequency range. While this frequency band serves as an adequate vehicle for most applications, some require an additional higher frequency for high bit-rate data. This requirement necessitates use of a dual frequency antenna and, more often than not, suffering an attendant performance compromise at both frequencies which is typically realized in such a device. One agency had such a requirement but was unwilling to accept the usual compromise in the S-band and X-band down-links used in aircraft testing. The design implemented by EMP Inc. satisfied the S-band requirements with the reputable, EMP developed, RADSCAN conical scan feed positioned at the focal plane of an eight foot paraboloidal reflector. The RADSCAN feed radome was redesigned, shaping the frontal surface to form a hyperboloidal dichroic subreflector for the X-band Cassegrain antenna. The subreflector was transparent to S-band while presenting a highly reflective surface to X-band energy. The hyperboloid was fed by a profiled corrugated horn mounted at the vertex of the paraboloidal reflector. The X-band Cassegrainian system produced optimum performance with no degradation whatsoever from the S-band Newtonian antenna. The degradation of the S-band system was less than 0.15 dB. The system provided simultaneous reception of both bands with collimated beams. The S-band system also included a side lobe comparison antenna which precludes acquisition of a target vehicle on a side lobe.

      Hansen, R. C.; Pacific Missile Test Center (International Foundation for Telemetering, 1986-10)
      Telemetry instrumentation antennas often require several beams to allow simultaneous tracking of several targets. These multiple beams can be provided several ways, including multiple beam antennas and phased arrays. A brief review of the tradeoffs involved in implementing multiple beams with phased arrays is given. Planar arrays, which may be combined to provide wide angular coverage, include a corporate feed giving multiple independent beams, a distributed configuration with independent beams, the Butler beamformer, and the Gent-Rotman beamformer. Conformal implementations include cylindrical and conical arrays, and the spherical dome lens.

      Sulecki, Joan M.; Lerner, Theodore; LTV Aerospace & Defense Co. (International Foundation for Telemetering, 1986-10)
      A major factor in the performance of a Telemetry System over the sea is the effect of multipath. The reflected signal from the surface of the sea may, in general, add to or subtract from the direct signal, and may therefore lead to severe fading and possible loss of useful signal. The multipath is a function of the sea state and the polarization of the signal. In order to reduce the effect of multipath on performance, a dual polarization diversity system is being built for the Airborne Telemetry Relay System for the Gulf Range. An analysis of the performance of the dual polarization diversity system in the presence of multipath for different sea states, different reflection angles, and different initial polarization angles is presented. For comparison, a similar analysis is presented for a circular polarization receiving antenna system.

      Richards, William F.; University of Houston, University Park (International Foundation for Telemetering, 1986-10)
      A study has been undertaken to determine the feasability of dynamically controlling the input impedance of a microstrip antenna element by changing its reactive loading. The major applications of such an element would be for use in a scanned phased array. By changing the loading of individual elements appropriately, one could alter the active array impedance of the elements to compensate to some degree for the onset of scan blindness. While the ultimate feasability of such applications cannot yet be firmly established, a single element can be controlled using PIN diodes to effectively alter its input impedance. The generalized theory of loaded microstrip antennas has been used to predict the impedance of a variety of microstrip, antenna configurations with multiple loads. This work has shown the possibilities of changing the input impedance of the radiator over a wide range of values without affecting its resonant frequency or radiation pattern by moving a set of short-circuited loads from one position to another. Actual printed-circuit antennas were fabricated based on this design and good correlation was found between theory and experiment.

      Dalloul, Nizar M.; Baghdady, Elie J.; Boston University, College of Engineering Boston (International Foundation for Telemetering, 1986-10)
      This paper addresses the problem of analog multiplication for analog VLSI implementation, with particular emphasis on multiplication accuracy (low intrinsic noise) and speed. High-speed low noise analog multiplication for analog VLSI has very important implications in analog signal processing, signal generation, signal detection and ultra precise frequency and phase control. The various candidate multiplier mechanisms and circuits proposed todate are surveyed and a comprehensive comparison of them developed, leading to the conclusion that the Steerable Localized Injection Multiplier (SLIM) holds the greatest promise for low noise and high speed analog VLSI multiplication.

      Zhou, R.; Mavretic, A.; Boston University, College of Engineering (International Foundation for Telemetering, 1986-10)
      A general tendency in the digital communication systems is toward multi-level signalling in order to increase the information rate over a fixed bandwidth channel. Multiple valued logic circuits hold the promising potential for this application. including digital modulation, signal power spectrum shaping and coding techniques. Thispaper will present a novel design of quaternary modular adder circuit using multi-semiconductor technology — BI-CMOS process. This circuit demonstrates many advantages in improving noise margin and speed as well as in reducing transistor counts and chip areas. Some comparison with its binary counterpart and SPICE simulation results will also be given. Due to growing interest in multiple-level signalling combining with multiple-valued logic technology in digital communication systems, this paper will also discuss the application of modular adder in correlative coding techniques for spectral shaping. where quaternary modular adder performs efficiently in encoding input signal of non binary form at the transmitting end and in reconstructing the original data input at the receiving end. It also can allieviate the pin and interconnection requirements for equivalent information transfer.

      Richards, William F.; Long, Stuart A.; University of Houston-University Park (International Foundation for Telemetering, 1986-10)
      A dual mode microstrip antenna element has been investigated which has two independently excitable modes resonant at the same frequency. This element has been shown to be capable of producing a broadside maximum, a broadside null, or an end-fire type pattern by suitable choice of its reactive loads and suitable excitation of its degenerate modes. Appropriately located loads can be used to resonate modes normally resonant at quite different frequencies, at a single, common frequency. The results indicate that the nodal lines of the loaded element are accurately predicted by the generalized theory of loaded microstrip antennas, and that two modes can be excited independently of each other by feeding each mode along the nodal line of the other. To verify the theoretical predictions an actual dual mode microstrip element was fabricated and tested. The results of this experiment correlate well with the theoretical model with respect to the overall characteristics of the radiator.

      Munson, Robert E.; Ball Aerospace Systems Division (International Foundation for Telemetering, 1986-10)
      Microstrip antennas are ideal for telemetry applications, especially when a low profile thin conformal antenna is desirable. This paper discusses omni wraparound, directional fixed beam, and conformal electrically scanned microstrip antennas.

      McCulloch, John D.; Federal Electric Corporation (International Foundation for Telemetering, 1986-10)
      The Telemetry Integrated Processing System (TIPS) at the U.S. Air Force Western Space and Missile Center (WSMC), Vandenberg AFB, California, is a large scale, computer based, telemetry decommutation and data processing system. This system is utilized to process telemetry data from numerous missile and aircraft programs supported at the WSMC. In the late 1970’s and early 1980’s, while TIPS was under development, some information on this unique system was presented at the ITC. This paper will present an overview of the operational system as it exists today. Hardware and software components will be discussed. A presentation of the standard, no development cost, features available to Range users will be made. A summary of the current missile/aircraft telemetry systems that must be supported will be included along with some of the special processing developed for these systems. The primary emphasis will be an overview of the system capabilities and the types of telemetry processing encountered in the operational WSMC environment.

      Lingerfelt, C. W.; ITT-Federal Electric Corporation (International Foundation for Telemetering, 1986-10)
      The processing of telemetry data received at the Western Test Range (WTR) requires the use of user supplied measurement attributes information. The telemetry streams currently being presented for support are from technologically advanced test vehicles which often involve complex measurement definition schemes. This document describes some of the current definition schemes and the processing required to obtain and utilize the data. The chaotic state of this environment is in no small part due to the lack of standardization of the measurement definition scheme and its media. The trend has been, and will continue to be, a condition of ever increasing complexity and variety unless some standardization is applied.

      Davis, Edward L.; Grahame, William E.; Loral Instrumentation (International Foundation for Telemetering, 1986-10)
      When flight testing helicopters, it is essential to process and analyze many parameters spontaneously and accurately for instantaneous feedback in order to make spot decisions on the safety and integrity of the aircraft. As various maneuvers stress the airframe or load oscillatory components, the absolute limits as well as interrelated limits including average and cumulative cycle loading must be continuously monitored. This paper presents a complete acquisition and analysis system (LDF/ADS) that contains modularly expandable array processors which provide real time acquisition, processing and analysis of multiple concurrent data streams and parameters. Simple limits checking and engineering units conversions are performed as well as more complex spectrum analyses, correlations and other high level interprocessing interactively with the operator. An example configuration is presented herein which illustrates how the system interacts with the operator during an actual flight test. The processed and derived parameters are discussed and the part they play in decision making is demonstrated. The LDF/ADS system may perform vibration analyses on many structural components during flight. Potential problems may also be isolated and reported during flight. Signatures or frequency domain representations of past problems or failures may be stored in nonvolatile memory and the LDF/ADS system will perform real time convolutions to determine the degrees of correlation of a present problem with all known past problems and reply instantly. This real time fault isolation is an indispensable tool for potential savings in lives and aircraft as well as eliminating unnecessary down time.

      Rieger, James L.; Naval Weapons Center, China Lake, CA (International Foundation for Telemetering, 1986-10)
      This paper presents an analysis of the proposed increase in satellite power flux density as it would affect present, currently proposed, and possible future telemetry operations at NWC and other ranges and multi-range operations. Also included are proposed methods for mitigation of interference if flux density is raised anyway.

      Jeske, Harold O.; Sandia National Laboratories (International Foundation for Telemetering, 1986-10)
      An increase in the maximum power flux-density (pfd) permitted from satellites in the 2025 to 2300 MHz band is currently under consideration by IRAC. This analysis assumes the worst case conditions for interference to telemetry operations at the missile test ranges as a result of current and proposed satellite pfd levels. Assumptions in the analysis include the maximum permitted power flux-density with uniform energy distribution over the band of interest, polarization compatibility, and alignment of the telemetry station, the missile and the satellite. It was found that the performance of essentially all missile telemetry receiving systems may be appreciably degraded by even the lowest pfd limits currently permitted. For the higher pfd limits under consideration, degradations in the order of 40 dB are to be expected at stations with dish antennas of only five foot diameter. An increase in the size or gain of an antenna will reduce the probability of interference, because of its decreased beamwidth, but will also increase the performance degradation because of the station’s increased figure of merit, G/T. For satisfactory missile telemetry operation under these conditions, the normal missile’s telemetry received signal-to-noise ratio would have to be well over 40 dB to overcome satellite interference. The results of the analysis are actually independent of all receiving station parameters except the station’s figure of merit, G/T. Probability of interference is not addressed because of the variation of conditions and missions of the various test ranges as well as the unknown number of satellites and their characteristics - present and future. If missile and satellite telemetry is to coexist in the 2200 to 2290 MHz band, the implementation of several recommendations is considered necessary. The recommendations are; 1) Satellite pfd levels should remain at the current limits; 2) Coordination between the satellite controllers and the range operations must be established; and 3) Multiple telemetry receiving stations with significantly different aspect angles with respect to the test vehicle during the test should be used.
    • Review of Spectrum Support Information for U.S. Air Force Telemetry Equipment Development and Procurement

      BARNES, LARRY; U. S. Air Force Frequency Management Center (International Foundation for Telemetering, 1986-10)
      This paper presents a review of spectrum support information as it pertains to the development and procurement of U. S. Air Force Telemetry Equipment. Highlights of this review include: Definitions of terms used in this paper that are peculiar to spectrum management; frequency bands encouraged by the U. S. Air Force for Telemetry Equipment Development and Procurement for use in the United States including station, channeling, and bandwidth information; frequency bands discouraged by the U. S. Air Force for Telemetry Equipment Development and Procurement for use in the United States; summary of Telemetry Equipment Electromagnetic Compatibility (EMC) Parameters required when requesting certification of spectrum support in the United States; and finally a summary of telemetry equipment EMC standards associated with the certification of spectrum support in the United States.

      Hales, John C.; Boeing Aerospace Company (International Foundation for Telemetering, 1986-10)
      Standard video cassette recorders (VCR’s) are relatively inexpensive, small, and capable of recording large quantities of data for hours. The problem with using VCR’s to record pulse code modulated (PCM) digital data is that glitches are recorded in the serial data stream coincident with the video sync pulses. This problem can be solved by formating the PCM data stream and synchronizing the video sync pulses to the PCM data.

      Knight, Paul; Pacific Missile Test Center (International Foundation for Telemetering, 1986-10)
      Since the late 1970’s the telemetry processing and display requirements of the Pacific Missile Test Center have been handled by the Telemetry Data Handling System. With the increasing use of embedded computers on test vehicles and the requirements to process and display larger volumes of data at higher data rates, many programs will soon exceed the capabilities of the Telemetry Data Handling System. The Telemetry Processing System is a replacement of the Telemetry Data Handling System that will be brought online in the Pacific Missile Test Center’s Telemetry Data Center in 1990. The Telemetry Processing System is required to meet the processing and display requirements of the Pacific Missile Test Center’s range users for the next decade. A discussion of the functional implementation and performance requirements of Telemetry Processing System is presented.