Advanced study of video signal processing in low signal to noise environments Semiannual progress report, 1967 - 1968
Parameter space calculation for phase lock loop operation in low signal to noise environment
Carden, F. F.↗
SEARCH · Engineering Papers
Results for “phase locked loops”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Coding and synchronization - The signal design problem.
Synchronization in coded communication systems, considering phase lock loop and square wave correlation function
Stiffler, J. J.↗
Wide-range tracking oscillator generates phase and frequency coherent output
Tracking oscillator consists of modified phase-lock loop which controls voltage-controlled oscillator capable of automatic lock-on and track of periodic input waveform over frequency ratio 500-1. It is used in telemetry and communications systems where large signal fluctuations are encountered.
Howard, J. R.↗
Study of applications of retrodirective and self-adaptive electromagnetic wave phase controls to a Mars probe, part 2 Final report, 26 Jan. - 31 Dec. 1967
Phase-locked loop operation in multipath environment and multipath effect on detection for Mars probe
Bershad, N. J.↗
Optimal space communications techniques Status report, 16 Dec. 1969 - 15 Mar. 1970
All digital phase locked loop FM demodulator, and optimum adaptive delta modulator designed for improving space communication
Schilling, D. L.↗
Performance improvement analysis for the Apollo unified S-band system Semiannual progress report
Performance improvement analysis for Apollo unified S band system, including computerized simulation techniques and phase lock loop studies
Shelton, R. D.↗
Threshold extension techniques using impulse noise elimination
Threshold extension techniques using impulse noise detection and elimination implemented at phase lock loop demodulator output
Loch, F. J.↗
Wide-band high-resolution determination of absolute frequency
Absolute frequency wideband high resolution determination, using frequency synthesizer as phase locked loop local oscillator
Farthing, W. H.↗
A delta modulation threshold extension technique for frequency modulation systems
Delta modulation threshold extension technique for phase lock loop FM demodulator
Arndt, G. D.↗
New filter technique improves home television reception
Program studies and designs combline filters and analyzes their effectiveness in improving TV quality. Signal tracking methods are improved. Combline phase-lock loop provides significant sensitivity improvement above and below threshold.
Develet, J. A., Jr.↗
Linear modulator test procedure and report
Linear modulator, demodulator, and phase locked loops breadboard test procedures and results
Source record↗
Linear modulator Final report
Design, operation, and alignment of single channel breadboard modulator, demodulator, and phase locked loops for double sideband signals
Source record↗
Advanced study of video signal processing in low signal to noise environments Semiannual progress report, Jun. - Nov. 1970
Video signal processing in low signal to noise environments - bandpass filter in multi-filter phase lock loop
Bowden, R.↗
Digital command system second-order subcarrier tracking performance
Equations to determine tracking performance for second order, phase locked loop used for subcarrier synchronization on digital command system
Holmes, J. K.↗
Design and performance evaluation of a wideband FM spread-spectrum multiple-access system
The system described performs the tracking and communications functions of a tracking and data relay satellite system (TDRS). The spread-spectrum signal format is achieved through wide deviation FM by a sinusoidal subcarrier unique to each multiple-access user. A compound phase-locked loop tracks carrier and subcarrier and demodulates data and ranging signals. Design parameters of user and ground terminals for TDRS are given. Acquisition procedures are described. Performance analyses are presented including the effects of noise, RFI, multipath and other users.
Wachsman, R. H.↗
Investigation of techniques for improving Saturn 5 RF tracking and ranging systems
Results of theoretical analyses of 12 problems are presented and comparisons of theoretical and experimental results are given. The investigations covered were: (1) techniques for improving the Saturn radar altimeter, (2) performance of the phase lock loop of the offset Doppler transponder, (3) signal processing equipment design for an orbital altitude radar return experiment, (4) spectral studies of signals present in the command and communication system (CCS) up-link transmitter, (5) intermodulation in the CCS down-link data demodulators, (6) error rate performance of the CCS transponder command demodulator, (7) flame attenuation effects on telemetry transmissions during Saturn launches, (8) design of a digital television system which converts a standard monochrome picture to a slow-scan picture, (9) methods of obtaining an additional CCS 72-kilobit/sec telemetry channel, (10) computation of the CCS S-band down-link spectra, (11) modeling of portions of the communications systems, and (12) modeling of a telemetry transmitter.
Walsh, J. R., Jr.↗
A very high frequency radio interferometer for investigating ionospheric disturbances using geostationary satellites. Determination of changes in exospheric electron content by a comparison of group delay and Faraday rotation
The theory and development of a VHF correlation radio interferometer for investigating ionospheric disturbances are discussed. The system was developed to receive signals from the geostationary Applications Technology Satellites. Amplitude and phase variations of the signal passing through the ionosphere can be detected by this instrument. The system consists of two superheterodyne receivers separated by a distance known as the baseline of the system. Since the system is a phase sensitive instrument, the local oscillators of the two receivers must be phase coherent. This is accomplished by using phase-locked loops for generating the local oscillators. The two signals from the separate receivers are cross-correlated by multiplying the two signals together and then time averaging the result. The sensitivity of the instrument is increased by off-setting one of the local oscillators by a small amount.
Terry, R.↗
Multipath error in range rate measurement by PLL-transponder/GRARR/TDRS
Range rate errors due to specular and diffuse multipath are calculated for a tracking and data relay satellite (TDRS) using an S band Goddard range and range rate (GRARR) system modified with a phase-locked loop transponder. Carrier signal processing in the coherent turn-around transponder and the GRARR reciever is taken into account. The root-mean-square (rms) range rate error was computed for the GRARR Doppler extractor and N-cycle count range rate measurement. Curves of worst-case range rate error are presented as a function of grazing angle at the reflection point. At very low grazing angles specular scattering predominates over diffuse scattering as expected, whereas for grazing angles greater than approximately 15 deg, the diffuse multipath predominates. The range rate errors at different low orbit altutudes peaked between 5 and 10 deg grazing angles.
Sohn, S. J.↗