5,861 research outputs found
Digitally synthesized phased antenna for multibeam global positioning
In a system according to the proposed technique (see figure), the signal received by each element of the array antenna would be subjected to downconversion, and spread-spectrum demodulation and correlation as necessary; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. For the GPS implementation, following downconversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudo random-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be a relatively inexpensive and flexible means for exploiting the inherent multiple-peak/multiple-null aiming capability of a phased-array antenna. In the original intended GPS application, the peaks and nulls could be directed independently for each GPS signal being tracked by the GPS receiver. This will improve the SNR simultaneously for each GPS signal being tracked while steering multiple nulls toward sources of interference. The technique could also be applied to other code-division multiple-access communication systems
Receiver Would Control Phasing of a Phased-Array Antenna
In a proposed digital signal-processing technique, a radio receiver would control the phasing of a phased-array antenna to aim the peaks of the antenna radiation pattern toward desired signal sources while aiming the nulls of the pattern toward interfering signal sources. The technique was conceived for use in a Global Positioning System (GPS) receiver, for which the desired signal sources would be GPS satellites and typical interference sources would be terrestrial objects that cause multipath propagation. The technique could also be used to optimize reception in spread-spectrum cellular-telephone and military communication systems. During reception of radio signals in a conventional phased-array antenna system, received signals at their original carrier frequencies are phase-shifted, then combined by analog circuitry. The combination signal is then subjected to down-conversion and demodulation. In a system according to the proposed technique (see figure), the signal received by each antenna would be subjected to down-conversion, spread-spectrum demodulation, and correlation; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. Following analog down-conversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudorandum-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be a relatively inexpensive and flexible means for exploiting the inherent multiple-peak/multiple-null aiming capability of a phased-array antenna. In the original intended GPS application, the peaks and nulls could be directed independently for each GPS signal being tracked by the GPS receiver. The technique could also be applied to other code-division multiple-access communication systems
A review of New World Asiracinae (Hemiptera: Auchenorrhyncha: Delphacidae) with five new taxa
Die Gattungen der Asiracinae der Neuen Welt werden im Kontext mit neu entdeckten Taxa aus Ecuador diskutiert und revidiert. Twölf nominelle Gattungen, davon drei Ugyopinae und neun Asiracinae (eine neu) werden aus der Neuen Welt gemeldet. Die tatsächliche Gattungszugehörigkeit der einer bislang zur Gattung Asiraca gestellten Art konnte nicht geklärt werden. Schlüssel zu den Asiracinae der Neuen Welt (ohne Asiraca) und zur Gattung Tetrasteira werden präsentiert. Neu beschrieben werden Pentasteira gen. nov. (Asiracinae: Platysystatini) mit P. albifrons n. sp., sowie drei Arten der Gattung Tetrasteira (Asiracinae: Tetrasteirini): T. vulgaris, n. sp., T. trimaculata n. sp., and T. solata n. sp. Große Mengen von Tetrasteira vulgaris n. sp. wurden im Amazonasbecken von Ecuador in Regenwäldern außerhalb von Überflutungsgebieten durch „canopy fogging“ gesammelt.The genera of New World asiracine planthoppers are reviewed and discussed in the context of new taxa discovered in canopy fogging samples from Ecuador. Twelve nomative genera, including 3 Ugyopinae and 9 Asiracinae (1 new) are reported from the New World, although the generic identity of the single Asiraca species could not be verified. A key to New World asiracinae genera, excluding Asiraca, is provided. The new taxa include Pentasteira gen. nov. (Asiracinae: Platysystatini) with 1 species (P. albifrons n. sp.) and a new Tetrasteira (Asiracinae: Tetrasteirini), prompting a generic revision with three new described species (T. vulgaris, n. sp., T. trimaculata n. sp., and T. solata n. sp.). A key to the species of Tetrasteira is provided. Tetrasteira vulgaris n. sp. has been taken in large numbers in canopy fogging samples from terre firme forest in the Amazon basin in Ecuador
Heifer Spay
Spaying heifers dates back to the 1850\u27s when it was used to prolong the productivity of milking cows. These cows were spayed at 30 to 40 days after calving or before they came into estrus. This would prolong the milking period of these older cows for two to three years. The cows would also fatten faster on high energy feed for slaughter
Assessing the Knowledge Level of Social Service Professionals on Post-Traumatic Stress Disorder (PTSD): Creating Training Guides
Objective: Creating training guides for social service workers to deliver more effective services for veterans with post-traumatic stress syndrome. Background: Effective service delivery for veterans with post-traumatic stress syndrome is often hampered by a lack of knowledge about how to identify the signs and symptoms of post-traumatic stress disorder (PTSD). Appropriate training guides can provide integral benefits including: improved situational awareness, more accurate data gathered in the intake process, a reduction in veteran homelessness and prevention of chronic homelessness. Method: A pre-and post-test design was used to determine levels of knowledge guided by Bloom’s Taxonomy (1956). The study focused on 11 respondents who were social workers in various roles including case managers to determine their aptitude in identifying the signs of post-traumatic stress disorder. All data was reviewed and hand-coded for analysis. Results: On the basis of the analysis, the post-test indicated that after training using a guide developed by Dr. Charles Lawrence, a veteran services counselor, key findings revealed an increase in knowledge of social workers in identifying the signs and symptoms of PTSD. Conclusion: The results of the research supported the literature on how or why training is important for personnel who assist veterans. Application: Increased knowledge is critical in helping social workers develop an individualized service plan for veterans that are based on accurate psycho-social attributes and thus are more effective
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