23,789 research outputs found
Pre-emphasis determination for an S-band constant bandwidth FM/FM station
Telemetry bands are being reassigned to UHF at 1500 and 2200 MHz. Conversion primarily requires changes in equipment used in RF link, while many of same subcarrier oscillators, mixer amplifiers, and frequency discriminators can be used
Possible application of remote-sensing techniques and satellite communications for earthquake studies
Passive and active remote sensing techniques used with satellite communication for earthquake studie
Differences in Dolphin Mortality Rates in Night and Day Sets for the U.S. Eastern Tropical Pacific Tuna Purse Seine Fishery
Because dolphins sometimes travel with yellowfin tuna, Thunnus albacares, in the eastern tropical Pacific (ETP), purse seiners use the dolphins to locate and capture tuna schools. During the process of setting the purse seine nets, dolphins often become entangled and drown before they can be released. Data for the U.S. purse seine fleet in the ETP during 1979-88 show that dolphin mortality rates in sets made during the night are higher than mortality rates in sets made during the day. Even with efforts to reduce nightset mortality rates through the use of high intensity floodlights, night set mortality rates remain higher. The data are also used to simulate a regulation on the fishery aimed at eliminating night sets and show that dolphin mortality rates would decrease
and Perelomov number coherent states: algebraic approach for general systems
We study some properties of the Perelomov number coherent states.
The Schr\"odinger's uncertainty relationship is evaluated for a position and
momentum-like operators (constructed from the Lie algebra generators) in these
number coherent states. It is shown that this relationship is minimized for the
standard coherent states. We obtain the time evolution of the number coherent
states by supposing that the Hamiltonian is proportional to the third generator
of the Lie algebra. Analogous results for the Perelomov
number coherent states are found. As examples, we compute the Perelomov
coherent states for the pseudoharmonic oscillator and the two-dimensional
isotropic harmonic oscillator
Pseudo-noise test set for communication system evaluation
A test set for communications systems is described which includes a pseudo noise sequence generator providing a test signal that is fed to a pair of signal channels. The first channel includes a spectrum shaping filter and a conditioning amplifier. The second channel includes a variable delay circuit, a spectrum shaping filter matched to the first filter, and an amplifier. The output of the first channel was applied to the system under test. The output of the system and the output of the second channel are compared to determine the degree of distortion suffered by the test signal due to the communications system
Method of and means for testing a tape record/playback system
A tape record/playback system was tested by first deriving an analog test signal and a band-limited digital reference signal from a pseudo-noise sequence generator driven by a clock signal. It recorded the signals on respective tracks of the system during operation in a record mode. During the playback mode of operation of the system, a delayed analog reference signal without time base variations was reconstructed from the played back reference signal. It was compared with the played back test signal in order to obtain an error signal that was a measure of the performance of the system
Pump linewidth requirement for optical parametric oscillators
Pumping laser bandwidth requirement for optical parametric oscillator
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