A study of true product modulators, phase 3 Final report
Field effect transistor modulator suitable for ground based telemetry applications
Summers, W. M.↗
SEARCH · Engineering Papers
Results for “Phase modulation”
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.
Acquisition time for sideband modulated phase lock loops.
In this paper a definition for acquisition of a sideband modulated carrier is proposed for the phase lock loop, and the acquisition differential equation solved for a region of the modulation parameter space to determine the expected value of acquisition time. Principally the case of modulation by a single unmodulated subcarrier is considered. The numerical analysis is made for the noiseless case.
Gilbert, A. L.↗
Multiple-Symbol Noncoherent Decoding of Uncoded and Convolutionally Codes Continous Phase Modulation
Recently, a method for combined noncoherent detection and decoding of trellis-codes (noncoherent coded modulation) has been proposed, which can practically approach the performance of coherent detection.
multiple-symbol continous phase modulation coding ↗
Phase modulation for reduced vibration sensitivity in laser-cooled clocks in space
Explore the source record for details and available documents.
frequency standards atomic clocks phase modulation↗
Neural Networks For Demodulation Of Phase-Modulated Signals
Hopfield neural networks proposed for demodulating quadrature phase-shift-keyed (QPSK) signals carrying digital information. Networks solve nonlinear integral equations prior demodulation circuits cannot solve. Consists of set of N operational amplifiers connected in parallel, with weighted feedback from output terminal of each amplifier to input terminals of other amplifiers. Used to solve signal processing problems. Implemented as analog very-large-scale integrated circuit that achieves rapid convergence. Alternatively, implemented as digital simulation of such circuit. Also used to improve phase estimation performance over that of phase-locked loop.
Altes, Richard A.↗
Analysis of crew performance in the Apollo command module, phase I. Volume II - Appendix
Analysis of crew performance in Apollo command module
ASTRONAUT PERFORMANCE↗
Multidimensional Trellis Coded Phase Modulation Using a Multilevel Concatenation Approach: Code Design - Part 1
The first part of this paper presents a simple and systematic technique for constructing multidimensional M-ary phase shift keying (MMK) trellis coded modulation (TCM) codes. The construction is based on a multilevel concatenation approach in which binary convolutional codes with good free branch distances are used as the outer codes and block MPSK modulation codes are used as the inner codes (or the signal spaces). Conditions on phase invariance of these codes are derived and a multistage decoding scheme for these codes is proposed. The proposed technique can be used to construct good codes for both the additive white Gaussian noise (AWGN) and fading channels as is shown in the second part of this paper.
Rajpal, Sandeep↗
Effects and correction of magneto-optic spatial light modulator phase errors in an optical correlator
The optical phase errors introduced into an optical correlator by the input and filter plane magnetooptic spatial light modulators have been studied. The magnitude of these phase errors is measured and characterized, their effects on the correlation results are evaluated, and a means of correction by a design modification of the binary phase-only optical-filter function is presented. The efficacy of the phase-correction technique is quantified and is found to restore the correlation characteristics to those obtained in the absence of errors, to a high degree. The phase errors of other correlator system elements are also discussed and treated in a similar fashion.
Downie, John D.↗
Development of a self contained heat rejection module, phase 2 and 3
This is the final report for Phases II and III of the Development of a Self Contained Heat Rejection Module Program conducted under NASA contract NAS9-14408. The objective of this program was to perform detail design and construct a prototype test article Self Contained Heat Rejection Module (SHRM). Also to install this test article in the NASA/JSC Space Environment Simulation Laboratory Chamber A and conduct thermal vacuum demonstration and performance testing. The end product of this contract was the prototype hardware, the test article and the test results.
M L Fleming↗
Hubble Space Telescope spectra of the phase-modulated wind in the SMC O+WR binary R31
We present HST/GHRS profiles of C IV 1500 A at conjunction phases 0.21, 0.26, and 0.72 of the 6.5 day O6+WN3 binary R31 in the SMC. We also use IUE archival data covering other orbital phases, There are strong changes in the line profile, depending on the line of view through an ionization bubble near the WR star. We fit a model for the stellar wind and discuss the unique probe of mass loss found in this system. We also discuss the strong interstellar components of the line arising in the Galactic foreground and in the SMC.
Hutchings, J. B.↗
Opto-Electronic Oscillator Using Suppressed Phase Modulation
A proposed opto-electronic oscillator (OEO) would generate a microwave signal having degrees of frequency stability and spectral purity greater than those achieved in prior OEOs. The design of this system provides for reduction of noise levels (including the level of phase noise in the final output microwave signal) to below some of the fundamental limits of the prior OEOs while retaining the advantages of photonic generation of microwaves.
Dick, G. John↗
Study of self-focusing and self-phase-modulation in the picosecond-time regime.
Study of the propagation of a single picosecond pulse of a mode-locked Nd-glass laser in CS2 nitrobenzene and toluene by observations of the birefringence and spectral changes in self-focused laser light. Multiple second-harmonic probing beams are used for birefringence measurements in a single IR pulse in various portions of the active cell. The orientational Kerr effect is found to be the prime factor of induced birefringence in nitrobenzene and toluene. The results for CS2 are also consistent with this mechanism and show that the duration of an IR pulse in the focal volume is less than that of the incident pulse. The properties of beams which are focused within the cell by an external lens are also investigated.
Reintjes, J.↗
Wideband phase modulator works directly on carrier
Multiplier-induced problems related to undesirable effects of the varactor multiplier on the modulation spectrum are eliminated in a modulator circuit which operates directly at the desired output frequency. The principles of operation of the new circuit are discussed and attention is given to requirements for high-Q components and the possibility of linear frequency deviation.
Rippy, R. R.↗
Measurement of klystron phase modulation due to ac-powered filaments
A technique for determining the intermodulation components in the RF spectrum of the S-band radar transmitter generated by having the klystron filaments heated by 400-Hz ac power is described. When the klystron is being operated with 400-Hz (ac) on the filament, the IPM is buried in the 400-Hz equipment interference noise. The modulation sidebands were separated and identified and found to be-67 db below the main carrier. This is well below the transmitter specifications, and operating the filaments on ac would not degrade the spectrum to where it would be detrimental to the radiated RF.
Finnegan, E. J.↗