Now showing items 1-20 of 47

    • A New Concept in Low Flutter High Environmental Recorders

      Hadady, R. E.; Bentley, R.; Kinelogic Corporation (International Foundation for Telemetering, 1967-10)
      To improve the performance of tape recorders operating under severe vibration, acceleration, and shock environments, two new flutter reduction design concepts have been developed: 1. Capstan servoing during the recording process to servo out flutter before it is recorded. 2. A new reel drive system in which the reels are coupled together to minimize tape tension variations and eliminate the possibility of throwing a tape loop. Test data on a prototype spaceborne recorder has proven the validity of the concept. The prototype has shown a capability to reduce flutter by factors ranging from 3 to 10 over conventional high-environrnent recorders. Typical flutter performance figures on the prototype (which accommodates 600 feet of 0.25" wide tape and operates at 30 ips) are: 0.36% p/p to 5000 Hz - on the bench 1.8% p/p to 5000 Hz - under environment (20 g rms random vibration) Time displacement errors (TDE) are ± 3 microseconds - on the bench ± 6 microseconds - under environment (20 g rms random vibration)
    • Delta-T Curves for Measuring Magnetic Tape Link Jitter

      Sos, J. Y.; Poland, W. B., Jr.; Cole, J. M.; Weiss, G.; Goddard Space Flight Center; U. S. Army, Electronics Command; Laboratory for Electronics Research, New York University (International Foundation for Telemetering, 1967-10)
      Magnetic instrumentation tape recording links are usually required to be substantially transparent data channels. One of the most important deviations from this requirement, both in FM and direct recording modes, occurs in the area of time delay error. A method for measuring the root-mean-square time delay error (Δ) between points on a record vs their separation in playback time (T) has been described in the literature (Refs. 1 and 2), but the implications and interpretation of this technique have not been fully developed. This paper derives the theoretical relationships between the Δ-T curve and the autocorrelation function of a pure sine wave recorded on the tape, and uses this correspondence to establish a connection between jitter spectra and Δ-T curves. A simple instrument for measuring these curves with high accuracy is described, and results of measurements made on a number of intermediate-band tape units in use at the Goddard Space Flight Center are presented. These measurements show that a low-mass tape unit may be superior to high mass units by more than an order of magnitude. The utility of the Δ-T measurement technique is discussed on the basis of its direct relationship to PCM and coherent recording applications, and its value as a standard means for evaluating time delay error in magnetic tape links is described. It is also shown that the technique can be used to determine FM modulation index.
    • Adaptive PCM Pattern Synchronization

      Van de Houten, R. S.; Dynatronics, Inc. (International Foundation for Telemetering, 1967-10)
      The trend toward more automated PCM decommutation systems demands less operator intervention in their operation. A weak link in this progression has been in the implementation of group synchronizer strategy. A new synchronizer has been developed based on the optimum properties of sequential probability ratio testing which requires only one program based on required worst case decision error probabilities and which is independent of the PCM format being synchronized. A mathematical model is formulated which accurately describes the operating characteristics of this technique. These operating characteristics are then compared to conventional synchronizer characteristics which demonstrate the superiority of this approach. The decision process described inherently adapts to signal conditions by making decisions faster and with less chance of error as bit error rate decreases. Only the Check Mode is discussed, but the same techniques apply to the Lock Mode.
    • Possibilities of PCM-Encoding

      Hommel, Harr. R.; Liebelt, H.; Triendl, E.; Deutsche Versuchsanstalt fuer Luft- und Raumfahrt e.V. (International Foundation for Telemetering, 1967-10)
      This paper concerns with the various possibilities to encode space-signals for PCM-telemetry. It first reviews the logic design schemes to count binary events, to read out counted numbers, to compress data by floating point representation, and to convert analog signals with large dynamic ranges to binary numbers. Then, sane technical solutions, which are under development by DVL in cooperation with German industry, are described as examples. For these, heavy use of integrated circuits, monolythics, and hybrids was made.
    • A High Speed 10 Bit D/A Integrated Circuit

      Rudin, M. B.; O'Day, R. L.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      A new high speed 10 Bit D/A integrated circuit is described as well as the basis for its design. Principal applications are given, notably a successive approximation A/D employing the circuit as its feedback D/A.
    • An Integrated 16-Channel Differential Analog Multiplexer

      Rudin, M. B.; Botchek, C. M.; Rotunda, R. F.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      The salient characteristics of a multi-channel differential MOS analog multiplexer are presented and compared with the requirements of time division telemetry systems discussed in the paper, "A Family of Linear Integrated Circuits for Telemetry," by M. B. Rudin and R. L. O'Day. Particular emphasis is given to the more important terminal parameters -- channel R(on) variation, switching speed, channel leakage and crosstalk, protection against spurious signals, and power supply requirements. It is shown that this type of design is acceptable for both high and low level signals. The MOS supply levels are special, and some speculation is presented on how future designs could use supplies more compatible with bipolar needs.
    • A Low Noise Low Drift Monolithic Integrated Operational Amplifier

      Fullagar, D. J.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      An operational amplifier is described which has been designed specifically for applications where low noise and low drift are of primary importance. The factors affecting noise and drift are discussed, and the methods used to minimize these outlined. For low level signal amplification purposes the performance is shown to be superior to currently available designs.
    • A Micropower Low Noise Integrated Operational Amplifier

      Pilling, D. J.; Wilson, G. H.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      This paper describes a new integrated operational amplifier designed specifically for low standby power consumption. This amplifier is intended for use in portable instrument and telemetry equipment where low battery power drain is an important consideration. This high gain, low power, low noise operational amplifier is fabricated on a single silicon chip. Recent development of a low noise transistor process and a compatible high value resistor process led to its development. The highlights of its performance specifications are its high input impedance, low offset, low noise, and, for the first time in a commercially available operational amplifier, quiescent power consumption in the microwatt range. The circuit has excellent common mode and power supply rejection which, coupled with the high voltage process, insure operation over a supply voltage range of ±2.7 v to ±18 v. The amplifier, as shown in Figure 1, has a differential input and a single ended output. The general parameters of this amplifier are shown in Table 1.
    • A Family of Linear Integrated Circuits for Telemetry

      Rudin, M. B.; O'Day, R. L.; Fairchild Semiconductor (International Foundation for Telemetering, 1967-10)
      Advances in monolithic circuit and process techniques are making available a steadily increasing number of linear integrated circuits especially applicable to telemetry systems. This paper reviews the principal types of telemetry systems--PCM, PAM, PDM, and FM/FM. It demonstrates that a compatible family of monolithic IC's in various stages of development at Fairchild can perform most of the circuit functions required by these systems--namely: (1) signal conditioning amplifiers, (2) multiplexer, (3) sample and hold, (4) unity gain A/D buffer amplifier, (5) A/D and PDM comparator, (6) D/A reference and switches, (7) D/A summing amplifier. In addition, future integration of functions not performed by the above circuits is discussed.
    • A Pulse-Code-Modulation (PCM) Telemetry System Utilizing Multiple Integrated Circuit Technologies

      Fox, D. C.; Autonetics (International Foundation for Telemetering, 1967-10)
      This paper describes a Pulse-Code-Modulation (PCM) Telemetry System contained on a module that is unique in several ways: 1. Uses all Integrated Circuits (Ics). 2. Integrates many IC types and technologies for superior system physical, environmental, and performance characteristics. 3. Multiplexer section: a. Uses one type of IC (MCIS multifunction IC) b. Is bipolar (both positive and negative voltages can be multiplexed) c. Accepts low- or high-voltage inputs (±51.1 mv to ±5.11 v) d. Is extremely small and compact (5 ICs total, provides 48-channel multiplexing) e. Accepts both differential and single ended channels f. Is controlled by random or sequential addressing modes 4. Amplifier section: a. Has high input impedance (100 meg ohms) b. Has high common mode rejection (to 120 db) c. Has gain (1 or 100) d. Has sample and hold capability 5. Analog-to-Digital Converter (ADC) section: a. Is bipolar (both positive and negative voltages can be converted) b. Has high accuracy (10 bits) c. Uses current summation with successive approximation d. Has high speed (up to 1 MHz)
    • Ruggedized Quartz Oscillator Crystals for Gun-Launched Vehicles

      Liss, F. T.; Richardson, J. F.; Harry Diamond Laboratories (International Foundation for Telemetering, 1967-10)
      This paper describes a small hermetically sealed quartz oscillator crystal assembly capable of withstanding gun-launch accelerations of 30,000 g and some larger experimental units that have survived accelerations up to 70,000 g.
    • Single Side Band Translation Techniques for FM Data Acquisition Systems

      Roth, Allen R.; Lear Siegler, Inc. (International Foundation for Telemetering, 1967-10)
      A Single Side Band Data Translator has been developed and used successfully with any combination of reference and data frequencies from 100 Hz to 10 MHz. This translator, consisting of a computer calculated 90° phase difference network and field effect transistor multiplier circuits yielded undesired sideband signals which were at least 50 db below the desired sideband level over an input frequency range of ten to one. The translator was used to implement a system which recorded 75 time-correlated broadband data channels on a single track of a 5 MHz rotating head tape recorder. After de-translation, a signal to noise ratio of 60 db was measured with the recorder by-passed and a signal to noise ratio of 40 db was measured with all channels recorded. This paper presents the results of research carried out under Contract No. N123(60530)51701A sponsored by U. S. Navy.
    • Optimum Telemetry for a Meteorological Platform

      O'Bryant, Richard; Hoover, Wayne M.; Sharpe, John H.; Texas Instruments Incorporated (International Foundation for Telemetering, 1967-10)
      In order to predict the large-scale elements of the atmospheric circulation, measurements must be made on a global scale. One such method of measurement involves the telemetry of meteorological data from balloons floating at a constant level over the earth. The balloons are interrogated and their data relayed through a synchronous satellite to a central ground station. A study, funded by the Environmental Science Services Administration, has been made to determine the optimum electronics, in the sense of low cost, for the interrogation and telemetry systems within the constraints of minimum weight and power. This paper presents the problems of such a system, the approaches to the selection of an optimum system, the system selected, and a discussion of the implementation of the electronics of the selected system.
    • Data Collection Station for Automobile Safety Testing

      Goes, Ing F.; Hill, John J.; Volkswagen Works; Defense Electronics, Inc. (International Foundation for Telemetering, 1967-10)
      Increased emphasis on the incorporation of additional safety features in automobile designs has accelerated the adaptation of aerospace telemetry and datahandling techniques to the field of automotive performance testing. Described is a multiple link FM/FM telemetry ground station as used for acquisition of data from an automotive test track. System inputs adhere to aerospace telemetry standards, the output being a computer-compatible digital tape. Detailed attention is given to the high-speed sampling, data conversion, and digital tape formatting subsystem.
    • Telemetry of Piston Parameters at Elevated Temperatures

      Slaffer, M.; Admiralty Engineering Laboratory (International Foundation for Telemetering, 1967-10)
      A system is described whereby piston information is continuously monitored using frequency modulation of carriers in the band 2 to 10 mc/s. The basic design of a miniaturised one channel transmit-ter for temperature measurement has been completed and practical details are given in the text. A thermistor was used as sensor. Trials with two operating channels have been carried out on a Lister engine over periods exceeding five hours without component replacement. The choice of high frequency band vras influenced by the desire to avoid the use of an iron cored sensor when the measurement of displacement was to be considered.
    • Multichannel, Free-Flight Base Pressure Telemetry in Wind Tunnels

      Choate, R. H.; ARO, Inc. (International Foundation for Telemetering, 1967-10)
      Radio telemetry techniques permit the acquisition of aerodynamic data from free-flight models in wind tunnels, a method which ensures that the data are completely free from support interference effects. No serious difficulties were experienced in the development of a telemetry system to record simultaneously four channels of base pressure data from a free-flight model; however, precautions were necessary to prevent interactions between channels and to prevent interference between telemetered and extraneous signals. This telemetry system is based upon small, transistorized, transmitter units, placed aboard the model, which are directly modulated (FM) by capacitance-type pressure transducers. All units are powered from a single battery package. These units, one for each data channel, transmit to antennas located outside the tunnel. All units are interchangeable between models, and have built-in provisions for preselecting full-scale pressure range (0.0005-0.1 psid) to provide optimum data resolution under a variety of test conditions in three different wind tunnels (at nominal Mach numbers of 8, 10, and 20). Oscillograph traces resulting from tests of typical models, both in free flight and on a sting mount, are compared and discussed from an instrumentation point of view. Satisfactory system operation is demonstrated by comparing telemetered base pressure data to data obtained by conventional means during a test of a sting-mounted model.
    • Redundancy Removal Algorithms Applies to Gemini XII Data

      Jory, H. M.; McDonnell Douglas Corporation (International Foundation for Telemetering, 1967-10)
      This report presents the results of a company funded computer study to deter-mine the effectiveness of redundancy removal algorithms as applied to manned spacecraft data. The company familiarity with and access to manned space flight data provided an almost unique opportunity to study this method of data compression using data representative of that which will be required from a Manned Mars Mission. A total of 28,500 seconds of the Gemini XII flight is examined using seven algorithms and three different tolerance bands. Over eleven million samples have been examined using terminology and descriptions consistent with previously published literature to allow direct comparison of actual flight data with previous results using synthetic data. The outputs from the computer presented the following information: A. Compression ratios as a function of technique, channel number and type of data for each of the activity periods. B. Buffer input rates and accumulated queue lengths every 2.4 seconds for the ZFN technique. C. Error distribution, for each of the techniques for six different apertures. The results indicate that the zero order - variable corridor - adjusted preceding sample transmitted (ZVA) technique can provide data compression ratios of 187:1 using a 1.2% tolerance. Nominal buffer sizes of 20K bits are adequate to handle the data activity period involved. The error distribution evaluation indicates that the error distribution is primarily a function of the technique and the aperture.
    • Computer-Controlled Data Compression at 100 KC

      Schoen, Emil; Scientific Data Systems, Inc. (International Foundation for Telemetering, 1967-10)
      This paper describes a real-time computer-controlled telemetry system that can accommodate a 100 kc sample rate. The system's operating structure allows high-speed, asynchronous PCM data to be simultaneously decommutated, compressed, displayed, and merged. Data generated during test firings of the U. S. Navy's Poseidon missile will be reduced and processed by this system. Emphasis of the paper is on a description of the telemetry system's hardware and software.
    • Carrier Synthesis from Perturbed DSB/SC Signals

      Simpson, R. S.; Tranter, W. H.; University of Alabama (International Foundation for Telemetering, 1967-10)
      In suppressed-carrier AM-baseband systems, the process of synthesizing carriers necessary for demodulation usually constitutes a difficult problem, especially when noise or recorder flutter is present. In this paper a particular scheme1, which synthesizes a demodulation carrier directly from a DSB/SC signal, is investigated for the purpose of determining the effect of noise and recorder flutter upon each of the various elements in the carrier synthesis loop. Curves are presented which illustrate the relationship between phase error in the demodulation carrier and various system parameters.
    • Some Analysis of the WSMR Test Results on DSB

      Nichols, M. H.; Duke University; Duke University | White (International Foundation for Telemetering, 1967-10)
      The purpose of this paper is to relate results of ref. (1), the previous experimental paper, Double Sideband Suppressed Carrier System, by F. J. Schmitt, to theory and to the application of DSB/FM to wideband vibration type data. Inasmuch as the notch noise test was one of the basic tools for the laboratory investigation, the notch noise results and the DSB results are compared. Preliminary data on the effects of tape recording, including flutter, are discussed. Comparison of CBW FM/FM and DSB/FM for vibration telemetry is made on the basis of requirements outlined in ref. (2). The experimental data indicate a 13 to 18 db carrier power improvement of DSB/FM over FM/FM. Reasons for this improvement are given.