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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

A capacitive accelerometer suitable for telemetry

The design and development of a miniature 0.635 cm (0.25 in.) diameter capacitive accelerometer for use in free flight wind tunnel telemetry are presented. Instruments with full scale ranges from + or - 1 to + or - 200 g were constructed, calibrated, and used in several wind tunnel telemetry projects. Flat, high frequency response from 0 to 1000 Hz or more was obtained by employing the inherent damping and stiffness in the air film surrounding the diaphragm-type spring that supports the inertial mass of the accelerometer. Design features to achieve minimum off-axis sensitivity and temperature stability are discussed, and the design requirements for use of the transducer with telemetry systems are derived. A transducer capacitance change of 0.16 pF full scale gave excellent resolution and provided a frequency deviation of 0.75 MHz for a 100 MHz FM oscillator. Although the present design of the capacitive accelerometer was optimized by using units of 0.635 cm diameter, construction of experimental accelerometers as small as 0.36 cm (0.14 in.) diameter has demonstrated the feasibility of further miniaturization.

Coon, G. W.↗
NASA NTRS1973

A new approach to telemetry data processing

An approach for a preprocessing system for telemetry data processing was developed. The philosophy of the approach is the development of a preprocessing system to interface with the main processor and relieve it of the burden of stripping information from a telemetry data stream. To accomplish this task, a telemetry preprocessing language was developed. Also, a hardware device for implementing the operation of this language was designed using a cellular logic module concept. In the development of the hardware device and the cellular logic module, a distributed form of control was implemented. This is accomplished by a technique of one-to-one intermodule communications and a set of privileged communication operations. By transferring this control state from module to module, the control function is dispersed through the system. A compiler for translating the preprocessing language statements into an operations table for the hardware device was also developed. Finally, to complete the system design and verify it, a simulator for the collular logic module was written using the APL/360 system.

Broglio, C. J.↗
NASA NTRS1973

User microprogrammable processors for high data rate telemetry preprocessing

The use of microprogrammable processors for the preprocessing of high data rate satellite telemetry is investigated. The following topics are discussed along with supporting studies: (1) evaluation of commercial microprogrammable minicomputers for telemetry preprocessing tasks; (2) microinstruction sets for telemetry preprocessing; and (3) the use of multiple minicomputers to achieve high data processing. The simulation of small microprogrammed processors is discussed along with examples of microprogrammed processors.

Pugsley, J. H.↗
NASA NTRS1974

Study of the redundancy of telemetry information of the Luna-9 and Luna-13 automatic lunar probes

Knowledge of the statistical characteristics of natural telemetry information is important for the development of principles and methods of reduction of redundancy of telemetry messages as well as planning of on-board information compression devices. An evaluation was made to determine these characteristics for the telemetry information of the Luna-9 and Luna-13 automatic lunar probe, to allow estimation of the redundancy of the information. Histograms as well as numerical characteristics were used.

Kantor, A. V.↗
NASA NTRS1976

Viking X-band telemetry experiment

In order to uncover operational and design problems in the use of X-band by the 1977 Mariner Jupiter-Saturn mission and future spacecraft using the Deep Space Network, the Viking X-band telemetry experiment was conducted. The experiment was conducted during the months of December 1975 and January 1976. During each of the five successful passes, a periodic sequence (in lieu of ranging) was transmitted to the spacecraft and returned by the spacecraft transponder on both S- and X-bands. These telemetry-like signals were received, demodulated, and detected. From a variety of measurements at the station, four independent measurements were made of the received signal-to-noise ratio (SNR). These four SNRs were later compared with each other and the predicted SNR. The principal result of the experiment is that X-band telemetry works as expected. That is, the measured SNRs were consistent relative to each other and to the predicted values within the accuracy of the experiment.

Weber, W. J., III↗
NASA NTRS1975

The SAS-3 programmable telemetry system

Basic concept, system design and operation principles of the telemetry system developed for the Small Astronomy Satellite-3 (SAS-3) are analyzed. The concept of programmable format selected for the SAS-3 represents an optical combination of the fixed format system of SAS-1 and SAS-2, and the adaptive format concept. The programmable telemetry system permits a very wide range of changes in the data sampling order by a ground control station, depending on the experimental requirements, so that the maximal amount of useful data can be returned from orbit. The programmable system also allows the data format to differ from one spacecraft to another without changing hardware. Attention is given to the command requirements and redundancy of the SAS-3 telemetry system.

Peterson, M. R.↗
NASA NTRS1977

Radio-frequency interference effects of continuous sinewave signals on telemetry data

Continuous sinewave interference effects on telemetry data obtained at the Goldstone Deep Space Station (DSS 11) were analyzed. The continuous sinewave interference is treated as an extraneous noise. Empirical telemetry data degradation and drop-lock models were then developed based on test data and certain physical characteristics of the telemetry data processing system. These models will be used as a portion of the radio frequency interference detection tools in the first version of the Deep Space Interference Prediction software.

Low, P. W.↗
NASA NTRS1976

Telemetry packetization for improved mission operations

The requirements for mission-operations data management will accelerate sharply when the Space Transportation System (i.e., Space Shuttle) becomes the primary vehicle for research from space. These demands can be satisfied most effectively by providing a higher-level source encoding function within the spaceborne vehicle. An Instrument Telemetry Packet (ITP) concept is described which represents an alternative to the conventional multiplexed telemetry frame approach for acquiring spaceborne instrument data. By providing excellent data-integrity protection at the source and a variable instrument bandwidth capability, this ITP concept represents a significant improvement over present data acquisition procedures. Realignments in the ground telemetry processing functions are described which are intended to take advantage of the ITP concept and to make the data management system more responsive to the scientific investigators.

Greene, E. P.↗
NASA NTRS1978

A packet telemetry system employing ARQ error control

A proposed packet telemetry system employing automatic retransmission request (ARQ) mode of error control is characterized. Limitations of the present multiplexing/demultiplexing approach are considered, and the use of the proposed system in near-earth satellites in the 1980s is suggested. Onboard processing and an adaptive multiplexing technique are described, as is an elastic buffer, required because the instantaneous data rate will be different from the telemetry transmission rate. The telemetry packets would be encoded into a powerful error-detection block code. A mechanism involving temporary buffering in a long shift register will permit retransmission request from the ground station for packets received in error. The ARQ mode of operation should ensure essentially error-free transmission at lower signal-to-noise ratios and at considerably higher transmission rates than are usually used.

Greene, E. P.↗
NASA NTRS1977

In-vivo bone strain telemetry in monkeys /M. nemestrina/

A new method for collecting in-vivo bone strain data in monkeys has been developed and tested. The method includes a system which consists of a new design of implantable strain transducer and its companion telemetry package. The transducer fits into a hole drilled in a monkey tibia and is threaded for subsequent bone ingrowth. The transducers and telemetry package are biocompatible for over 503 days. The telemetry package uses Pulse Interval Ratio Modulation (PIRM) to transmit strain information to receiving equipment located outside the animal housing cage.

Young, D. R.↗
NASA NTRS1979

Single frequency RF powered ECG telemetry system

It has been demonstrated that a radio frequency magnetic field can be used to power implanted electronic circuitry for short range telemetry to replace batteries. A substantial reduction in implanted volume can be achieved by using only one RF tank circuit for receiving the RF power and transmitting the telemetered information. A single channel telemetry system of this type, using time sharing techniques, was developed and employed to transmit the ECG signal from Rhesus monkeys in primate chairs. The signal from the implant is received during the period when the RF powering radiation is interrupted. The ECG signal is carried by 20-microsec pulse position modulated pulses, referred to the trailing edge of the RF powering pulse. Satisfactory results have been obtained with this single frequency system. The concept and the design presented may be useful for short-range long-term implant telemetry systems.

Ko, W. H.↗
NASA NTRS1981

Mark 4-A DSCC telemetry system description

This system is designed as a replacement for the Mark III. Two major changes in the DSCC portion of the DSN Telemetry System are discussed: the addition of two 34 meter antennas to each DSCC; and the configuration of the telemetry system. The telemetry system is configured to support either two deep space missions and one highly elliptical orbit, or two highly elliptical orbits and one deep space mission.

Burt, R.↗
NASA NTRS1981

The effect of noisy carrier reference on telemetry with baseband arraying

Imperfect carrier reference causes a degradation in detection performance in coherent communication systems. A measure of this degradation is the radio loss, which is the amount of increase in data signal to noise ratio (SNR) per bit required to achieve the same bit error rate when carrier reference is perfect. Performance analysis and numerical results are obtained for the Voyager high rate telemetry link with maximum likelihood convolutional decoding. The arraying of antennas provides not only improved performance due to an increase in effective antenna aperture, but also a decrease in radio loss with respect to a single antenna. This telemetry link performance improvement is a function of the carrier loop SNR and data bit error rate. When the carrier loop SNR's are low, it provides a significant improvement in the telemetry link performance since the decrease in radio loss with respect to a single station is substantial.

Divsalar, D.↗
NASA NTRS1980

Telemetry Computer System at Wallops Flight Center

This paper describes the Telemetry Computer System in operation at NASA's Wallops Flight Center for real-time or off-line processing, storage, and display of telemetry data from rockets and aircraft. The system accepts one or two PCM data streams and one FM multiplex, converting each type of data into computer format and merging time-of-day information. A data compressor merges the active streams, and removes redundant data if desired. Dual minicomputers process data for display, while storing information on computer tape for further processing. Real-time displays are located at the station, at the rocket launch control center, and in the aircraft control tower. The system is set up and run by standard telemetry software under control of engineers and technicians. Expansion capability is built into the system to take care of possible future requirements.

Bell, H.↗
NASA NTRS1982

The performance of VLA as a telemetry receiver for Voyager planetary encounters

The Very Large Array (VLA) was proposed for use as a supplement to the Deep Space Network (DSN) for telemetry reception at Voyager 2 Uranus and Neptune encounters. The main problem with the use of VLA for telemetry is that it is not capable of producing a continuous stream of data. Gaps of one millisecond follow every 51 milliseconds of data. The effect of these millisecond gaps on coded telemetry is investigated. An upgapped system of the same aperture as the VLA would be capable of handling data rates of 38.4 kbps at Uranus encounter and 19.2 kbps at Neptune encounter. It is shown that VLA with (7, 1/2) convolutional coding (the baseline coding scheme for Voyager) will support a data rate of 10.8 kbps but not 19.2 kbps at both Uranus and Neptune. It is also shown that by implementing Voyager's concatenated Reed-Solomon/convolutional coding capability, data rates of 38.4 kbps and 19.2 kbps would be achievable at Uranus and Neptune respectively. Concatenation also offers a factor of 2 improvement in overall throughput.

Deutsch, L. J.↗
NASA NTRS1984

Availability of the DSN Telemetry Data System and Its Major Elements, Including the TWM Assemblies

The DSN discrepancy report system which records all outages of DSN data systems that occur during mission support operations is described. The recorded outages of the telemetry data system for 1981 through 1983 were tabulated and availability characteristics of the telemetry data system and several of its major elements, including the traveling wave maser (TWM) Assemblies were developed. Availability characteristics of the TWM assemblies are compared with those of other DSN subsystems and assemblies. It is found that for a three year period, the availability of the telemetry data system is 99.0%, and its mean time to restore service is 0.9 hours; the availability of the TWM assemblies is 99.83%, and their mean time to restore service is 2.5 hours.

Stevens, R.↗
NASA NTRS1985

Miniature infrared data acquisition and telemetry system

The Miniature Infrared Data Acquisition and Telemetry (MIRDAT) Phase 1 study was performed to determine the technical and commercial feasibility of producing a miniaturized electro-optical telemetry system. This system acquires and transmits experimental data from aircraft scale models for realtime monitoring in wind tunnels. During the Phase 1 study, miniature prototype MIRDAT telemetry devices were constructed, successfully tested in the laboratory and delivered to the user for wind tunnel testing. A search was conducted for commercially available components and advanced hybrid techniques to further miniaturize the system during Phase 2 development. A design specification was generated from laboratory testing, user requirements and discussions with component manufacturers. Finally, a preliminary design of the proposed MIRDAT system was documented for Phase 2 development.

Stokes, J. H.↗
NASA NTRS1986

ICE telemetry performance

Acquiring telemetry data from the International Cometary Explorer (ICE) at its encounter with the comet Giacobini-Zinner on September 11, 1985 proved to be among the more difficult challenges the DSN has met in recent years. The ICE spacecraft began its life as an Earth orbiting monitor of the Solar Wind. At the comet, ICE was nearly 50 times as distant as in its initial role, with its signal strength diminished nearly 2500 times. Collecting enough of that weak signal to provide meaningful scientific data about the comet required unique new telemetry capabilities and special handling by the DSN. This article describes the development and validation of the DSN telemetry capability for ICE from its early planning stages through the successful comet encounter.

Layland, J. W.↗