Radar antenna system for acquisition and tracking Patent
Interferometric tuning acquisition and tracking radar antenna system
Broderick, R. F.↗
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Dynamic vibration absorber Patent
Tuned damped vibration absorber for mass vibrating in more than one degree of freedom for use with wind tunnel models
Igoe, W. B.↗
Phase modulator Patent
Phase modulator with tuned variable length electrical lines including coupling and varactor diode circuits
Brown, K. H.↗
Methods of measurement for semiconductor materials, process control, and devices
Tuning and photovoltaic methods and identification of test conditions for measurement of semiconductor materials, process control, and devices
Bullis, W. M.↗
Observation of intense superradiant emission in the high-gain infrared transitions of HF and DF molecules
Intense superradiant emission in HF and DF molecules high gain IR transitions, examining spectral distributions with pneumatically tuned Fabry-Perot interferometer
Goldhar, J.↗
Visible CW parametric oscillator using barium sodium niobate
Visible thermal tuning CW parametric oscillator using barium sodium niobate as nonlinear material
Laurence, C.↗
A voltage-tunable three-terminal Gunn device
Newly developed Gunn oscillator is three-terminal device which consists of piece of gallium arsenide with source, drain, and gate contacts. Voltage tunable three-terminal device does not require bulky resonant cavity and allows oscillation frequency to be rapidly tuned with simple circuitry.
Schwartz, R. J.↗
Mechanically and thermally stable maser cavity resonator
New type cavity resonator is designed for hydrogen maser. Resonator consists of three pieces of glass-ceramic material having extremely low thermal coefficient of expansion and provides very stable mechanical tuning.
Vessot, R. F. C.↗
Wagging tail vibration absorber
A 750-foot cantilever length of extendible-tape boom (very low stiffness) was considered as the main system to be damped. A number of tail lengths were tried from 20 feet to 80 feet after which 40 feet was investigated further as a desirable compromise between performance and practical lengths. A 40-foot damping tail produced a damping effect on the main boom for the first mode equivalent in decay rate to 3.1 percent of critical damping. In this case the spring-hinge and tail were tuned to the main boom first mode frequency and the hinge damping was set at 30 percent of critical based on the tail properties. With this same setting, damping of the second mode was .4 percent and the third mode .1 percent.
Barclay, R. G.↗
Inertial navigation system using three TDF gyroscopic sensors not jointly mounted on a stable platform
An inertial navigation system is described and analyzed based on two two-degree-of-freedom Schuler-gyropendulums and one two-degree-of-freedom azimuth gyro. The three sensors, each base motion isolated about its two input axes, are mounted on a common base, strapped down to the vehicle. The up and down pointing spin vectors of the two properly tuned gyropendulums track the vertical and indicate physically their velocity with respect to inertial space. The spin vector of the azimuth gyro is pointing northerly parallel to the earth axis. The system can be made self-aligning on a stationary base. If external measurements for the north direction and the vertical are available, initial disturbance torques can be measured and easily biased out. The error analysis shows that the system is practicable with today's technology.
Stieler, B.↗
Research investigation directed toward extending the useful range of the electromagnetic spectrum
The lifetimes and fine structure of He(-) were studied using time-of-flight techniques and quenching by a static axial magnetic field. Using level-crossing spectroscopy the hyperfine constants A and B and the lifetime of the 3 2P3/2 state of Li-7 were measured. Polarization of the Ru 7S level was created as a first step in determining the hyperfine structure of the alkali excited S state. The parametric interaction between light and microwaves in optically pumped Rb-87 vapor were investigated. Measurements and analyses of transitions in formaldehyde and its isotopic species and in the lowest two excited vibrational states of H2CO were also made, as well as of transitions in furan, pyrrole, formic acid, and cyanoacetylene. The Hanle effect was studied in the NO molecule, and RF oscillators were developed with flat, wideband output to observe excited state hyperfine transitions at zero field. Data was generated on the time-dependent behavior of photon echoes in ruby. Stimulated Raman scattering was studied in atomic Tl vapor. A Q switched, temperature-tuned ruby laser was developed which operates between 6934 and 6938 A. The frequency shift due to resonant interaction between identical radiating atoms was calculated.
Hartmann, S. R.↗
A 10, 6-micrometer laser receiver RF subsystem
A simplified laser receiver carrier tracking loop is described. The laser carrier is optically mixed with a locally generated 10.6 micrometer signal, thereby translating the received signal to an IF signal that varies between dc and GHz. This signal is fed to a second order carrier tracking loop that contains a transistor LC oscillator tuned by a varactor over a 1 GHz range; transistor shunt capacitance increases the upper frequency bound of the oscillator in a high Doppler environment.
Santarpia, D. E.↗
Computer-aided CO2 laser cavity-length selection for reduced line competition
The advantages of carbon dioxide lasers for space communications systems are considered. An attempt was made to predict the signature of CO2 lasers. It was found that this requires accurate data on the laser wavelengths (accuracy on the order of 10 MHz). The results of absolute frequency measurements of CO2 lines were utilized, and a list of accurate frequencies was calculated. A computer program was written for the signature prediction. A second program was written which searches through large ranges of cavity length and prints lists of regions where a particular line is well separated from adjacent lines in the signature. Lasers designed according to this list will have an undisturbed tuning profile for one or more lines.
Schiffner, G.↗
Research in nonlinear optics
A theoretical investigation revealed that a steady state mode-locked solution appropriate to ultrashort pulses is induced by Kerr liquids. An experimental investigation using a Q-switched ruby laser passively mode-locked by the insertion of a Kerr liquid verified the theory. Pulses of about 10 to the -11th power sec were generated when the relaxation time of the liquid was temperature tuned to approximately 10 to the -11th power sec.
Yariv, A.↗
Remote double resonance coupling of radar energy to ionospheric irregularities
Experimental results indicate that low frequency modulation of a high power radar beam, tuned to one of the critical frequencies of the ionosphere, may produce field-aligned density irregularities when the modulation frequency matches an ionospheric eigenfrequency. By choosing the radar carrier frequency and polarization, a number of interaction layers were selected. The variety of possible excitations shows that the double resonance technique may be adaptable to a number of different objectives.
Kennel, C. F.↗
Dynamic testing of a single-degree-of-freedom strapdown gyroscope
Test methods and results are presented for the equivalent average input rate of a single-degree-of-freedom gyroscope operated both open loop and with a ternary-logic pulse-torque-to-balance loop during multiaxis angular oscillation. For the open-loop tests, good agreement was obtained with theoretical results. Two-axis testing was performed for oscillations about the Input-Output axes, the Input-Spin axes, and the Spin-Output axes. These tests run in the torque-to-balance mode revealed significant departures from open-loop results in the induced drift rate. An analysis is developed explaining much of the closed-loop data presented. Test data for the gryoscope in a ternary torque-to-balance loop with constant input rates is presented. The tests demonstrate that the instrument rate linearity does not change with interrogation frequency from 3,600 to 14,400 Hz if the torque coil is tuned to offer a resistive load to the current switch. Analysis cited shows that gyroscope lag compensation eliminates multiple pulsing and other equivalent forms of degraded resolution in a wide variety of quantizing loops. This result is test verified for the ternary delta-modulator loop.
Lory, C. B.↗
Rubidium-87 gas cell studies, phase 1
The construction of a quartz bulb-quartz cavity type rubidium maser is described, and the results obtained with two of these masers are presented. The tuning characteristics, medium term stability, and short term stability are reported. It is concluded that the stability of the masers in the short term region is superior to any of the oscillators presently existing. On this basis it is believed that future development of the masers to reduce their size and improve their medium term stability is well justified.
Vanier, J.↗
Measurement of total electron content with a geostationary satellite during the solar eclipse of March 7, 1970.
This note deals with the measurement of the total electron content of the ionosphere at the Goddard Space Flight Center, looking towards the geostationary satellite ATS 3 during the solar eclipse of Mar. 7, 1970. Obscuration at this site was nearly total. Faraday rotation was measured with a stationary circularly polarized antenna and a dual-channel phase-lock receiver tuned to 137.350 MHz. By comparing the electrical phase of the two opposite circularly polarized components, a continuous chart recording was made of Faraday rotation vs local time. A depletion of about 25% in electron content was observed from first contact to the time of minimum electron content. The time variations of the electron content during the eclipse are briefly examined in the light of current theories of ionospheric processes.
Rangaswamy, S.↗