• PERFORMANCE OPTIMIZATION OF PCM/SCO TELEMETRY SYSTEMS

      Jeske, Harold O.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      These hybrid TM system design procedures indicate how PCM channel performance comparable with that obtainable from an optimally designed PCM/FM transmission system may be obtained even though numerous subcarrier channels are included in the system. Optimal design goals are those that permit satisfactory telemetry system operation with a minimum of transmitted power. By careful control of the transmitter modulation levels and the use of predetection filtering during playback, a lowering of the PCM channel’s threshold, equivalent to at least quadrupling the transmitter power over conventional practices, is obtained. This report briefly discusses the design objectives of FM/FM and PCM/FM systems followed by a more detailed discussion of hybrid systems using FM subcarriers above the PCM signal on the baseband. A simplified, but comprehensive, discussion of FM sidebands is presented in the appendices to aid in understanding the limits and restrictions in this hybrid TM system design procedure.
    • PHASE AND FREQUENCY TRACKING CONSIDERATIONS FOR HETERODYNE OPTICAL COMMUNICATIONS

      Kaufmann, John E.; Massachusetts Institute of Technology (International Foundation for Telemetering, 1982-09)
      In heterodyne optical communications, phase or frequency tracking is generally needed to avoid performance degradation when signaling in the presence of laser frequency jitter and Doppler shifts. This paper examines a phase-lock loop approach for BPSK and two forms of frequency tracking for MFSK. Using a statistical model for laser frequency instability, the performance of these schemes is calculated by a linear analysis of the tracking loop in the small-error regime.
    • PLANETARY SOIL WATER ANALYZER (PSWA) PROTOTYPE

      Cashin, William F.; Anderson, Duwayne M.; Ball Aerospace Systems Division; State University of New York (International Foundation for Telemetering, 1982-09)
      A microprocessor-based differential scanning calorimeter is being designed for eventual use in planetary soil water analysis. The uniqueness of this effort is in the use of the microprocessor as an integral section of the system control loops, instead of as merely an auxilary processor of output data. The use of differential scanning calorimetry is advantageous in determining water content of soil samples. The basic idea is to use two matched ovens, one with a soil sample included. The average temperature of the ovens is forced to track a desired programmed temperature (normally a slow ramp) with one control loop, while a second control loop forces the oven temperatures to be equal, even during a transition. The power necessary to keep the temperatures equal is monitored, containing information as to the transition energy, and thus the water content at programmed water transition temperatures. This approach uses the microprocessor to close both of the loops, taking oven sensor temperatures as an input, and providing power duty cycles as outputs. In actuality, two microprocessors are used - a slave to accumulate and process sensor information, and a master to generate the loop control, output data control, and temperature program control. The PSWA performance is compared to a state-of-the-art commercial instrument using analog loop control. The major advantage of the microprocessor loop control utilized in the PSWA is the capability of remote operation, including remote alignment and adjustment. Further advantages include accommodation of oven changes with software reprogramming, a flexible single oven capability, correction for system nonlinearities using software, and auto gain and auto zero control for the sensor circuitry. The analog loop control approach has somewhat better sensitivity, resolution, and noise performance. The current phase of the development of the PSWA is a feasibility study and circuit design, performed for the Planetary Geology Program Office, NASA Headquarters. The next developmental phases would include breadboarding, software design, testing, and evaluation. In conclusion, this instrument is a significant advance in the state-of-the-art for automatic water measurements, and will be of great value in further planetary exploration.
    • POLARIZATION DIVERSITY CAPABILITY THROUGH SAMPLING AT THE RF LEVEL

      Endler, Harvey; Turner, William; Electra Magnetic Processes, Inc. (International Foundation for Telemetering, 1982-09)
      Novel RF circuitry for selecting the stronger of two telemetry signals (RHCP or LHCP) is presented. Polarization diversity capability with uninterrupted data flow can be achieved without using two expensive single channel data receivers and a diversity combiner. In certain dedicated systems only a single AM/FM receiver is required. This paper describes the RF signal processing and logic circuitry of a developed system and describes how it is applied in a lightweight polarization diversity single channel monopulse tracking system.
    • POWER COMBINING AND SIGNAL ROUTING IN THE GALAXY TT&C EARTH STATION

      KNOX, K. D.; MALLETTE, L. A.; HUGHES AIRCRAFT COMPANY (International Foundation for Telemetering, 1982-09)
      This paper describes the signal routing and power combining function of the C-band uplink frequency signals in the Galaxy TT&C earth station.
    • POWER EFFICIENT OPTICAL COMMUNICATIONS FOR SPACE APPLICATIONS

      Lesh, James R.; Supervisor, Communications Concepts Research Jet Propulsion Laboratory (International Foundation for Telemetering, 1982-09)
      Optical communications technology promises substantial size, weight and power consumption savings for space to space high data rate communications over presently used microwave technology. These benefits are further increased by making the most efficient use of the available optical signal energy. This presentation will describe the progress to date on a project to design, build and demonstrate in the laboratory an optical communication system capable of conveying 2.5 bits of information per effective received photon. Such high power efficiencies will reduce the need for photon collection at the receiver and will greatly reduce the requirements for optical pointing accuracy, both at the transmitter as well as the receiver. A longer range program to demonstrate even higher photon efficiencies will also be described.
    • PRESAMPLING FILTERING, SAMPLING AND QUANTIZATION EFFECTS ON THE DIGITAL MATCHED FILTER PERFORMANCE

      Chang, Horen; Stanford Telecommunications, Inc. (International Foundation for Telemetering, 1982-09)
      Due to the increased capability and reduced cost of digital devices, there has recently been a growing trend to digitize the matched-filtering data detector in the receiver. Comparing with an idealized integrate-and-dump analog matched filter, the digital matched filter (DMF) requires more Eb /No in order to achieve the same bit error rate performance because of the presampling filtering, sampling, and quantization effects. This paper analyzes the performance degradation resulting, separately and jointly, from these three effects. Quantitative results are provided for commonly chosen sets of design parameters. For a given performance degradation budget and complexity limitation, these results could be applied to choose the optimum DMF design parameters including the presampling filter bandwidth, the sampling rate, the number of quantization bits, and the spacing between adjacent quantization levels.
    • PROCESSOR TECHNOLOGY OFFERS UNREALIZED FLEXIBILITY IN TOMORROW’S TELEMETRY GROUND STATIONS

      THOM, GARY A.; AYDIN MONITOR SYSTEMS (International Foundation for Telemetering, 1982-09)
      Today’s state of the art in semiconductor technology coupled with innovative computer architecture techniques can provide tomorrow’s telemetry industry with advanced ground station capabilities. Computer systems have traditionally been used to process all of the telemetry data. As data transmission speeds increase, the computer system can no longer handle real time processing so preprocessors are being used to handle the additional computational requirements. An alternative approach is to embed special purpose processors into applicable elements of the front-end equipment. These processors can be optimized for the function they are to perform, which prevents under utilization of processing power and enhances the flexibility and performance of the front-end element. These special purpose processors take up little real estate when implemented with todays LSI and VLSI semiconductors. The modules which are ideally suited for this type of technology are serial data correlators, decommutators, real time data correction, engineering units conversion, quick look display, data simulation and many special application modules. These processing elements provide the building blocks for a very powerful, cost effective family of modular telemetry and communications products for the 80’s and beyond.
    • PROGRAMMABLE TELEMETRY TEST SYSTEM

      GUADIANA, JUAN M.; NAVAL SHIP WEAPON SYSTEMS ENGINEERING STATION (International Foundation for Telemetering, 1982-09)
      The U.S. Navy has traditionally operated several missile ranges around the world. However, as the exercises it conducts require greater areas and improved security, it has taken the more ambitious exercises to open ocean, away from ranges. Portable shipboard Telemetry Receiving Systems are designed based on similar methods to those used by range system designers. However, the portable field station must be very small (less then 600 lbs) and system designers are hard pressed to include sophisticated hardware to offset the lower performance of light weight front ends. After the design stage, it is always found that no further weight or volume may be allocated to test equipment. The result has been to practice exercising the live round (missile) for the purpose of testing the ground station. This Test System was designed to meet a need for a portable system to test shipboard telemetry systems used for evaluating performance of missile systems in the surface missile fleet. The technical information presented describes the capabilities of a small test system that is programmable to accurately simulate any missile in the current Navy inventory. It provides test and calibration signals so that telemetry system status may be verified, giving the field operator unprecedented confidence in the station’s condition. The Programmable RT Test System is a product of Navy’s Engineering Initiative Program which supports limited engineering efforts designed to enhance service to the fleet.
    • PULSE CODE MODULATION TELEMETRY

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1982-09)
      This paper discusses the performance of pulse code modulation/frequency modulation (PCM/FM), pulse code modulation/phase modulation (PCM/PM) and phase shift keying (PSK) in the “real-world” of range telemetry. The topics addressed include: 1. Radio frequency (RF) spectra 2. Bit error rate (BER) versus pre-detection signal-to-noise ratio (SNR) 3. Peak carrier deviation 4. Premodulation and receiver predetection filtering 5. PCM codes 6. Magnetic recording The purpose of this paper is to provide the reader with information needed to choose the best modulation method, PCM code, premodulation filter bandwidth and type, receiver settings, and recording method for a particular application.
    • RADSCAN A NOVEL CONICALLY SCANNING TRACKING FEED

      Sullivan, Arthur; Electro Magnetic Processes, Inc. (International Foundation for Telemetering, 1982-09)
      This paper presents a description of RADSCAN, a novel conically scanning tracking feed which has only one moving part and utilizes a solid state optical commutator for reference. The feed operates continuously from 1435 to 2400 MHz thereby covering all the existing telemetry bonds in addition to the proposed new bond from 2300 to 2400 MHz. The performance of RADSCAN is compared to that obtainable with the single-channel monopulse technique.
    • RANGE STANDARDS PANEL DISCUSSION

      Ashley, Carl G.; Pacific Missile Test Center (International Foundation for Telemetering, 1982-09)
      The Telemetry Group (TG) of the Range Commanders Council is the primary means of exchanging telemetry technical and operational information and coordinating and standardizing systems, techniques, methods, and procedures. The TG is concerned with such telemetry gathering instrumentation as airborne sensing devices and modulation and multiplexing equipment. In addition, the group monitors developments in telemetry processing and storage systems and special display devices. The group is also responsible for writing and updating the Telemetry Standards Document and a series of five volumes on Text Methods for Telemetry Systems and Subsystems.
    • REAL-TIME DATA DISPLAY FOR AFTI/F-16 FLIGHT TESTING

      Harney, Paul F.; NASA Ames Research Center (International Foundation for Telemetering, 1982-09)
      The overall objective of the advanced fighter technology integration/F-16 (AFTI/F-16) advanced development program is to demonstrate, separately and in combination, advanced fighter technologies to improve air-to-air and air-to-surface weapon delivery and survivability. Real-time monitoring of aircraft operation during flight testing is necessary not only for safety considerations but also for rapid preliminary evaluation of flight test results. The complexity of the AFTI/F-16 aircraft requires an extensive capability to accomplish real-time data goals; this paper describes that capability and the resultant product.
    • RECOVERY OF PCM TELEMETRY DATA IN THE PRESENCE OF INTERFERENCE SIGNALS

      Hahn, Jacob C.; Rockwell International M/S DA-37 (International Foundation for Telemetering, 1982-09)
      PCM data is recorded on magnetic tape on-board the Space Shuttle during flight. After the vehicle has landed these tapes are played back into a laboratory tape recorder and copies or dubs are made. PCM data from the vehicle is also recorded during manufacture and preflight testing and dubs of these tapes are made. Signals from other electronic equipment at the recording site can be picked up and mixed with the PCM data. This can cause dropouts (loss of data) during playback. The low frequencies are easily removed by filtering but higher frequencies that lie in the same range as the data cannot be removed by filtering. Methods for dealing with this problem have been worked out with some success. The work has just started. Some of the results are described here.
    • A REVIEW OF THIRTY YEAR’S DEVELOPMENTS AND RESEARCHES ON UNCODED QPPM SYSTEMS

      Chang, Jiang; Yingcai, Chen; Beijing Research Institute of Telemetry; Engineering Chinese Academy of Space Technology (International Foundation for Telemetering, 1982-09)
      In recent years the researches and applications of QPPM systems in telemetry have drawn much attention, but there are still some problems to be clearified and solved. In this paper we reviewed the classical literatures on un-coded QPPM systems which were published in the past thirty years. After analysing the conclusions and related derivation presented in these publications, we got: 1) M.J.F, Golay and JRA Jacobs stated that the QPPM’s efficiency ß may indefinetely approach Shannon theoretical limit with as small error probability as desired as soon as one can appropriately choose the parameters of the system. In our opinion, this conclusion cannot hold true. In fact, the efficiency curve ß = F(α) of QPPM is only similar in form to the Shannon theoretical limit and there is still a large difference. 2) In past 30 years Golay and the others analysed merely the relation between the word error probability PWE and the efficiency ß , They didn’t study the relation between the bit error probability PBE and ß . Some authors regarded QPPM’s PWE as being equal to other digital system’s PBE, and concluded that QPPM is better than the other systems. We consider that this is not appropriate. 3) In order to remedy the untouched problem, we derived the relation PBE =F(α) of QPPM system. As it is seen from these relation curves that the required α of QPPM is 4.CdB~4.4dB more than the ß of coherent detection PSK system when PBE=10^-4 and α varries from 2 to 100. (ie. the efficiency of QPPM is worse than PSK.)
    • S-BAND ACQUISITION AND TRACKING SYSTEM (SATS), WSMR SYSTEM FOR SPACE SHUTTLE ACQUISITION

      Blazosky, David M.; Kroeger, O. Paul; US Army White Sands Missile Range (International Foundation for Telemetering, 1982-09)
      The requirement for WSMR to independently acquire and track the NASA Space Shuttle presented WSMR with one of the basic problems associated with missile and air defense systems - acquiring and maintaining a precision track of an incoming target. The popular solution is to use two radars--a broad beam for acquisition and a narrow beam for precision track. The WSMR solution is the S-Band Acquisition and Tracking System (SATS) which uses two existing passive telemetry trackers (J-10 and J-67) in conjunction with WSMR precision track radars. The existence of an S-Band transmitter in the Shuttle made the use of the Telemetry trackers possible.
    • SATELLITE DATA LINK STANDARDS*

      Lt. Gibson, Col. R.H.; Maj. Sutton, R.V.; Rodriguez, T.M.; Tamura, Y.; Air Force Systems Command; The Aerospace Corporation (International Foundation for Telemetering, 1982-09)
      Flexibility and survivability of Space Communications dictate the interoperability of communication links between as many satellites as feasible. Interoperability increases survivability by providing alternate paths. Interoperability also improves total system reliability and cost effectiveness, and it permits a flexible, distributed communications architecture to evolve. To implement this approach, functional satellite data link standards are needed to pull together mission data relay, communications, and tracking, telemetry and command (TT&C) requirements so that they can be satisfied by a common link design. The basic requirement which unifies these diverse users is their need for uplink jamming protection and scintillation resistance (in a perturbed atmosphere) at low (75 bps to 19.2Kbps) data rates. While the downlink and crosslink requirements are more diverse, they do not constitute major drivers of the standard. This paper describes Space Division’s standardization effort, the links to be standardized, the parameters that must be defined and an evolutionary implementation approach. The first satellite-ground links to be standardized will use 44/20 GHz with wideband spreading for jam resistance, while the crosslinks will use 60 GHz to avoid terrestrial jamming. Key issues are discussed, such as the conflicting requirements between TT&C and communications and the tradeoffs between minimum designs and flexibility.
    • SEMICONDUCTOR OPTOELECTRONIC DEVICES FOR FREE SPACE OPTICAL COMMUNICATIONS

      Katz, Joseph; Jet Propulsion Laboratory (International Foundation for Telemetering, 1982-09)
      Light emitting devices based on AlGaAs lasers are very useful radiation sources in free space optical communications systems. After a brief review of the properties of individual injection lasers, more complex devices are described. These include, or are relevant to, monolithic integration configurations of the lasers with their electronic driving circuitry, power combining methods of semiconductor lasers, and electronic methods of steering the radiation patterns of semiconductor lasers and laser arrays. Fabrication of such devices is one of the major prerequisites for realizing the full potential advantages of free space optical communications.
    • SHOCK-HARDENED, HIGH FREQUENCY, PCM SYSTEM WITH MEMORY FOR EARTH PENETRATOR STUDY APPLICATIONS

      Barnes, David E.; Sandia National Laboratories (International Foundation for Telemetering, 1982-09)
      Increasing data requirements for earth penetrating vehicles have necessitated the design of a new digital telemetry system with greater signal frequency response, higher resolution, and more memory capacity than used previously. The new system encodes data into 8 bit digital words at a rate of 3.2 megabits per second and stores the data into a 640 Kbit CMOS memory for readout after the recovery of the penetrating vehicle. This paper describes the penetrator program and the new telemetry system developed for it.
    • SINGLE CHANNEL PROTOCOL FOR TELEMETRY SETUP AND CONTROL

      Hahn, Karl; Sangamo Weston, Schlumberger (International Foundation for Telemetering, 1982-09)
      In any telemetry data system whose functions are distributed over a number of physical units, it is desirable, if not necessary that these units be woven into a unified control network. It is this control network that makes a telemetry system out of the separate units. It turns out that this problem can be solved inexpensively, allowing new telemetry units to be easily added to the system, and without impacting the data flow between units. This paper describes one such solution, and details its flexibility and power. Some topics covered are central control, device independence, and relationships between user stations and physical units.